CN1221687C - Electrolytic phosphating process and composite coating formed on steel surface - Google Patents

Abstract

A phosphating process suitable for electrolytic treatment, which uses a phosphating bath comprising a phosphate ion and phosphoric acid, nitric acid, a metal ion capable of forming a complex with phosphate ion in the phosphating bath and a metal ion having an electric potential at which the metal ion dissolved in the phosphating bath is reduced and deposited as metal of a value same as or higher than that of the anode electrolysis reaction of water, the solvent used in the bath, wherein the bath contains a metal ion other than a component of a coating to be formed in an amount of 0 to 400 ppm and is substantially free of solids affecting a coating film-forming reaction.

Description

Chemical treatment method of electrolytic phosphate and a composite film formed on the surface of steel

technical field

The invention relates to a chemical treatment method of phosphate realized by electrolysis and a composite film formed on the surface of steel.

technical background

Japanese Unexamined Patent Application Publication No. 5-822481 describes an electrolytic treatment using a phosphate chemical treatment solution that is substantially free of deposits and contains phosphate ions, nitrogen-containing oxyacid ions and a thin film constituent metal ions. This treatment solution is characterized in that it does not form deposits at a pH of 2 to 4 and at a treatment temperature of 40°C or lower.

However, the phosphate chemical treatment solution of Japanese Unexamined Patent Application No. 5-822481 uses sodium hydroxide and sodium nitrate to adjust the pH or as an accelerator irrespective of the composition of the film.

Therefore, this method cannot be said to be an electrolytic phosphate chemical treatment method effective in forming a thin film.

So far, in consideration of the above-mentioned problems, the present invention provides a method of phosphate chemical treatment which is effective in forming a thin film and by which a composite thin film can be obtained.

Before explaining the electrolytic phosphate chemical treatment method of the present invention, the difference between "electrolytic treatment" and "non-electrolytic treatment" among surface treatment techniques using an aqueous solution will be explained.

This difference is illustrated by discussing "electroplating", a wet surface preparation technique that is now widely used.

That is, there are two methods of "electrolytic" and "non-electrolytic" plating, and both methods have been put into practical use. However, the mechanism of the treatment fluid is different between these two methods.

More precisely, in the case of "electrolytic plating", the components in the solution do not react. This reaction is an electrochemical reaction using external energy as a reaction energy source. In addition, during the "electrolytic plating" process, no chemical substances (reducing agents) are used for chemically accelerating the electrolytic reaction.

In contrast, in the case of electroless plating, the components in the solution react. And instead of using external energy to provide reaction energy, the electrochemical reaction uses electrochemical energy (energy generated by the potential energy formed by the chemical reaction) by adding a reducing agent in the solution (in the aqueous solution It is formed during the oxidation reaction (anodic reaction) of a chemical species with a small dissociation constant) and the reduction reaction of a metal ion in solution (cathode reaction).

"Electroplating" in the reduction reaction of a metal ion (cation) forms a metal film, while phosphate chemical treatment in the oxidation reaction (dehydrogenation process) of a phosphate ion (anion) forms a phosphate film.

Contents of the invention

The inventor believes that if electrolytic treatment and non-electrolytic treatment are feasible in "electroplating", then in addition to the non-electrolytic phosphate chemical treatment in the prior art, in the phosphate chemical treatment that is the same wet surface treatment as electroplating The practical application of electrolytic treatment may be feasible, leading to the realization of the present invention.

A conceptual explanation of the invention is provided below.

(1) The technical content of the electrolytic phosphate chemical treatment that needs to be reviewed can be determined by comparing the existing wet electrolytic surface treatment technology with the electrolytic phosphate chemical treatment technology based on the existing surface treatment technology.

(2) The optimal treatment conditions can be found by studying the optimal state of the electrolytic phosphate chemical treatment reaction within the research range.

(3) The thin films formed by the proposed electrolytic phosphate chemical treatment method were studied.

[Existing surface treatment technology]

Before explaining the content of the present invention, it is first necessary to understand the relevant surface treatment technology in the prior art. The technology of the electrolytic phosphate chemical treatment method of the present invention is studied by linking the surface treatment technology in the prior art with the electrolytic phosphate chemical treatment technology to be obtained.

Generally, actually established surface treatment techniques, including the technique of the present invention, can be classified according to the methods shown below.

Surface treatment techniques can initially be divided into "dry surface treatment" and "wet surface treatment". This "wet surface treatment" technique can be further divided into "non-electrolytic treatment" and "electrolytic treatment". Typical examples of the surface treatment of "non-electrolytic treatment" herein include "electroless plating" and "non-electrolytic phosphate chemical treatment". In addition, typical examples of "electrolytic treatment" include "electrolytic plating", "anodizing" and "electrodeposition coating", and the "electrolytic phosphate chemical treatment" of the present invention belongs to the classification of "electrolytic plating".

[Wet Surface Treatment (Discussion of Reaction Energy)]

As mentioned above, wet surface treatment is divided into two types, namely "non-electrolytic treatment" and "electrolytic treatment".

The difference between "non-electrolytic treatment" and "electrolytic treatment" lies in the energy that promotes the reaction.

"Non-electrolytic treatment" relies on the chemical energy of chemicals added to the treatment solution, such as reducing agents (electroplating) or oxidizing agents (phosphate chemical treatment). In contrast, "electrolytic processing" relies on externally supplied electrical energy.

Therefore, in the case of "electroplating", the treatment solutions for "electroless plating" and "electrolytic plating" are essentially different, and the treatment solutions for "electroless plating" are not used for electrolytic treatment.

If this idea is applied to the phosphate chemical treatment method, the treatment method between "non-electrolytic plating solution" and "electrolytic plating solution" will have completely different contents.

[Electrolytic treatment in wet surface treatment]

Figure 1 is a schematic diagram of electrolytic treatment. Electrolytic treatment uses an external power source, which consists of three components, which can be roughly divided into the counter electrode, the electrolyte, and the piece to be treated in the electrolytic cell.

Depending on the type of wet electrolytic treatment, the state of these three components in the electrolytic treatment reaction is different. A summary of these different states is shown in Table 1.

Table 1 Classification of wet electrolytic treatment (O: responded X: did not respond) Electrode Electrolyte Workpiece (to be processed) Applied voltage current technology electrolytic plating o x x 10V or higher Anodized (aluminum substance) x o o tens of volts or higher Electrodeposition Coating x o x 100V or higher Electrolytic Phosphate Chemical Treatment o o o 1～50V

The contents of Table 1 will be explained below.

In "electrolytic plating", the coating components that form the anode (counter electrode) (such as the zinc electrode in galvanizing) are dissolved by applying a voltage or current, and the dissolved coating components pass through the electrolyte in a complex state and are deposited on the on the cathode. For this reason, only components on the electrolysis react and dissolve. The object to be treated is the cathode, and the cathode does not undergo a reaction such as dissolution in the electrolytic cell.

In "anodic oxidation", the aluminum substance is dissolved in the treatment solution as an anode, and the solvent (water) and solute ions (anions) decompose as the voltage increases at this time, and the oxygen ions (O ^2- ) Combines with dissolved aluminum resulting in the formation of an aluminum oxide (Al ₂ O ₃ ) film on the surface of the aluminum substance. The substance that does not dissolve (react) in the electrolysis serves as the counter electrode (cathode).

In "electrodeposition coating", a voltage is applied to colloidal organic and inorganic substances dispersed in water, and this colloidal substance is subsequently deposited on the surface of the electrode (work to be treated) by electrophoresis, electrolysis or deposition, etc. and solidified (coating ). That is, "electrodeposition coating" includes the electrolytic reaction of components in the electrolyte, and due to the application of voltage, those substances that react are only solvent water and colloidal substances dispersed in water. The electrodes (to the electrolyzer and the workpiece to be treated) did not dissolve or react in any other way.

In addition, it is very important to keep the electrolyte state within a limited range (interval) in "electrodeposition coating".

If the electrolytic solution cannot maintain its defined state due to changes in the composition of the electrolytic solution due to coagulation or decomposition, etc., it is impossible to form an effective electrodeposited coating film. Therefore, the treatment solution for electrodeposition coating is usually maintained at a specified temperature and subjected to ultrafiltration. Furthermore, the parts to be treated must be washed with pure water before being put into the electrolytic cell to prevent unwanted ions (such as sodium ions) from entering the previous steps.

In comparison, the "electrolytic phosphate chemical treatment" of the present invention is completely different from the above three technologies in that the three components of "counter electrode", "electrolyte" and "object to be treated" all dissolve and react. It is precisely because the prior art did not recognize this difference and could not develop a technology to adjust this change, so the "electrolytic phosphate chemical treatment" in the prior art is difficult to achieve practical application.

[Research project on electrolytic phosphate chemical treatment]

According to researching the various composition changes of existing electrolytic treatment liquid and phosphate chemical treatment liquid, table 2 has listed those items that " electrolytic phosphate chemical treatment " of the present invention will study.

Table 2 Performance comparison of electrolytic treatment solution electrolytic treatment Invention project Reaction of solution components to form a thin film Electrolyte Trends in Treatment Fluids Treatment solution pH control Ions that should not be present The presence of reaction accelerators Inorganic/Organic Difference Existing electrolytic treatment plating No moderate (complexation) No Yes (Na ⁺ ) No Inorganic ion reaction Anodized (aluminum substance) Yes (solvent) Strong (strong electrolyte treatment solution) have No No Inorganic ion reaction Electrodeposition Coating have Weak (no electrolyte treatment solution) have No No organic reaction Phosphate Chemical Treatment Traditional Electrolytic Phosphate Chemical Treatment (Prior Art) have Weak (accelerator added) have Yes (Na ⁺ ) have Inorganic ion reaction Non-electrolytic phosphate chemical treatment (reference) have Weak (weak electrolyte treatment solution) have Yes (Na ⁺ ) have Inorganic ion reaction Electrolytic Phosphate Chemical Treatment (Invention) have moderate (complexation) have No No Inorganic ion reaction

The research projects are the control of the electrolytic treatment reaction where all the existing electrolytic treatment methods "electrolytic plating", "anodization" and "electrodeposition coating" coexist, and the film formation reaction is only on the surface of the electrolytic part in the electrolytic tank carried out, and steps are taken to ensure that reactions do not occur elsewhere in the electrolyzer. That is to say, although it is impossible to completely prevent similar film-forming reactions from taking place in the electrolytic cell except the surface of the part to be electrolyzed, measures are taken to enable the film-forming reaction to occur on the surface of the part to be electrolyzed and to be practically applied .

From this point of view, each study of each electrolytic treatment will be described below.

(1) Although "electrolytic plating" includes the dissolution of the plated metal at the anode and subsequent deposition at the cathode, the accumulation of dissolved metal ions must be prevented. Complexation is used as a method to prevent this aggregation.

The treatment liquid of "electrolytic plating" is a complex liquid of a metal salt. It is precisely because of this that the aggregation and precipitation of metal ions in the electrolyte (the reaction of the solute components in the solution) can be prevented, while the metal to be plated is continuously dissolved from the electrode (anode) and deposited on the cathode. A well known example of complexation is cyano (CN) complexation. Plating treatment solutions are generally not clear and may also contain ions such as sodium ions that are not involved in film formation, and measures must be taken so that complexes in the treatment solution do not decompose. As a result of taking these measures, only metal ions are deposited on the surface of the cathode and form a coating. (Because sodium ions have different deposition potentials from the metal ions to be plated, sodium ions will not deposit on the cathode. This is in line with the principle of electrochemistry.)

(2) "Anodizing" is an electrolytic treatment using an article to be treated as an anode and an insoluble electrode as a cathode. If there are ions not required for the film formation reaction at this time, it will affect the dissolution reaction of the metal (ie, aluminum) and the oxidation reaction (film formation). This is because dissolved aluminum ions are active in the treatment liquid. An anodic oxide film is formed by reacting dissolved aluminum ions with oxygen ions (O ^2- ) decomposed from a solvent in the form of water. Contamination of the treatment solution by impurities must be strictly limited to prevent the dissolved aluminum ions from reacting with other ions.

(3) "Electrodeposition coating" is to form a coating on the surface of an electrode through an electrolytic solution. Only the solvent water and colloidal organic substances dispersed in water react due to the applied voltage. There is no dissolution reaction of the electrodes (to the electrolysis and to the workpiece to be treated).

In the case of electrodeposition coating, it is important to keep the electrolyte in a prescribed state (range) so that a desired coating can be formed. If the state of the solution cannot be controlled due to changes (reactions) due to coagulation and decomposition of the solution components, etc., it is impossible to efficiently form electrodeposited coatings. It is for this reason that the electrodeposition coating treatment solution is always maintained at a constant temperature and subjected to ultrafiltration to prevent the colloidal components dispersed in the treatment solution from coagulating and keep it in a dispersed state.

In addition, the treatment solution of electrodeposition coating should strictly limit the pollution of harmful ions (such as sodium ions) and keep it in a state close to pure water. This is because the presence of harmful ions is not conducive to the deposition reaction on the electrode surface.

The above techniques obtained from prior art electrolytic treatment can be summarized in the manner shown below.

In the case of electrolytic treatment, the components in the solution involved in the formation of the thin film must not be allowed to react other than on the electrode surface (interface), and it was found that the following measures must be taken to accomplish this.

i: Prevent contamination by impurities (anodic oxidation, electrodeposition coating)

ii: Prevent self-coagulation of solution components by continuous filtration, circulation and constant temperature, etc.

(electrodeposition coating)

iii: Using complexation (electroplating)

The method of the present invention can be made practical by referring to the above-mentioned technology and applying it to the "electrolytic phosphate chemical treatment" of the present invention. The above conclusion "in the case of electrolytic treatment, the components in the solution which participate in the formation of the film must not be allowed to react other than on the electrode surface" is a common concept for all forms of electrolytic surface treatment. However, specific measures are required for each treatment.

Why the prior art can't make the effective electrolytic phosphate chemical treatment method reach practical application (the purpose to be realized by the present invention), it is because there is no finding that the components that participate in the formation of the film in the solution are prevented from other reactions except the reaction on the electrode surface specific measures.

[The electrolytic phosphate chemical treatment method of the present invention]

The "electrolytic phosphate chemical treatment method" of the present invention can carry out the electrolysis process without causing the components in the solution that participate in the formation of the film to react at other places besides the reaction on the electrode surface.

In order to achieve this object, the present invention provides a method for forming a thin film containing at least one phosphate and a metal that does not form phosphate on the surface of a conductive object to be treated, by making the object to be treated contact with a phosphate chemical treatment solution containing at least one phosphate ion and phosphoric acid, nitrate ions, metal ions forming complexes in the phosphate chemical treatment solution, and dissolved in Metal ions in the phosphate chemical treatment solution that are reduced and deposited in the form of metals with a potential greater than or equal to the anodic electrolysis reaction potential of the water solvent or greater than or equal to -0.83V (with the standard electrode potential of hydrogen as a reference), The characteristics of the phosphate chemical treatment solution are: the concentration of metal ions other than the metal ions forming the film components is 0-400ppm and does not contain solids that affect the film formation reaction at all; and when used in the phosphate chemical treatment solution The metal substance to be treated is subjected to electrolytic treatment: the metal substance that has formed a complex with the phosphate ion; and the metal ion dissolved in the phosphate chemical treatment solution is reduced and deposited in the form of a metal with a potential greater than or equal to A metal substance whose anodic electrolysis reaction potential of water solvent is greater than or equal to -0.83V (with reference to the standard electrode potential of hydrogen).

Particularly, in the present invention, by making the concentration of other metal ions in the phosphate chemical treatment solution be 0 to 400 ppm except the metal ions forming the film components, and making the phosphate chemical treatment solution completely free from the influence of film formation reaction solid, and no accelerator is added, so that the other reactions except the film forming reaction are reduced as much as possible, so that the film forming reaction can proceed smoothly and effectively on the surface of the workpiece to be treated in the phosphate chemical treatment liquid.

Particularly, in the present invention, since the concentration of other metal ions in the phosphate chemical treatment solution is 0 to 400 ppm except the metal ions forming the film components, and the phosphate chemical treatment solution is completely free of substances that affect the film formation reaction. Solid, film-forming reactions may not be based primarily on the deposition of phosphates from the treatment liquid, thus providing for the first time on the surface of the workpiece to be treated a film containing at least one phosphate and a non-phosphate-forming metal.

In order to efficiently form the thin film, the content of other metal ions in the phosphate chemical treatment solution is preferably 0 to 100 ppm, in addition to the thin film component containing at least phosphate.

In a preferred embodiment, the specific components of the phosphate chemical treatment solution are: the concentration of nitrate ions is 6 to 140 g/l, the concentration of phosphate ions and phosphoric acid is 0.5 to 60 g/l, in the phosphate chemical treatment solution The concentration of metal ions that form complexes with phosphate ions in the medium is 0.5-70 g/l, and the concentration of metal ions that are dissolved in the phosphate chemical treatment solution and are reduced and deposited in the form of metals is 0-40 g/l l.

In phosphate chemical treatment methods, it is preferred not to use acids with a dissociation constant higher than that of the phosphate ion.

Here, an example of an acid having a dissociation constant higher than that of a phosphate ion is nitric acid.

If an acid having a dissociation constant higher than that of phosphate ions is added to the treatment liquid, the film-forming reaction of phosphate on the surface of the object to be treated in the treatment liquid is prevented, thereby preventing the reaction from proceeding effectively.

The metal ion forming a complex with the phosphate ion in the phosphate chemical treatment solution is preferably at least one selected from the group consisting of zinc, iron, manganese and calcium.

Metal ions that are dissolved in the phosphate chemical treatment solution and are reduced and deposited in the form of metals with a potential greater than or equal to the potential of the anodic electrolysis reaction of the water solvent or greater than or equal to -0.83V (with reference to the standard electrode potential of hydrogen) are preferred At least one metal ion selected from the following group: nickel ion and copper ion.

The present invention also provides a method for electrolytic phosphate chemical treatment, which includes contacting the treated piece with the treatment solution, and treating at least phosphate ion and phosphoric acid, nitrate ion and phosphoric acid in the phosphate chemical treatment solution. A method of electrolyzing the phosphate chemical treatment solution of metal ions formed by root ions to form a complex, and forming a film containing at least one phosphate on the surface of the conductive object to be treated, wherein in addition to the metal ions forming the film components The content of other metal ions in the phosphate chemical treatment solution is 0-400ppm, and the phosphate chemical treatment solution does not contain solids that affect the film formation reaction at all, and the phosphate ions in the workpiece to be treated and the phosphate chemical treatment solution The phosphate chemical treatment solution is electrolyzed between the metal species forming the complex.

In the case of using this method, although the obtained film is a chemical film mainly containing phosphate, since the content of other metal ions in the phosphate chemical treatment solution is 0 to 400 ppm except the metal ions forming the film components, In addition, the phosphate chemical treatment liquid does not contain any solids that affect the film formation reaction, so the film formation reaction can be effectively carried out in the phosphate chemical treatment.

In addition to the film component containing at least phosphate, the concentration of other metal ions in the phosphate chemical treatment solution is more preferably 0 to 100 ppm.

In the phosphate chemical treatment solution, the concentration of nitrate ion is preferably 6-140g/l, the concentration of phosphate ion and phosphoric acid is 0.5-60g/l, and the metal that forms a complex with phosphate ion in the phosphate chemical treatment solution The ion concentration is 0.5-70g/l.

In phosphate chemical treatment methods, it is preferred not to use acids with a dissociation constant higher than that of the phosphate ion.

Here, an example of an acid having a dissociation constant higher than that of a phosphate ion is nitric acid.

There is no acid in the phosphate chemical treatment solution having a dissociation constant higher than that of phosphate ions, with the result that film formation can be efficiently performed for the same reason as mentioned above.

Furthermore, the metal ions forming complexes with phosphate ions in the phosphate chemical treatment solution are preferably at least one selected from the following group of metal ions: zinc ions, iron ions, manganese ions and calcium ions.

Electrolysis can be carried out in the phosphate chemical treatment method using the piece to be treated as an anode.

Electrolysis can also be carried out in the phosphate chemical treatment method using the item to be treated as the cathode.

Electrolysis can also preferably be carried out in a phosphate chemical treatment method using the article to be treated as an anode and subsequently using the article to be treated as a cathode.

As a result of this electrolysis, a film-forming reaction can proceed on the surface of the object to be treated after exposing the surface to be fresh by etching the surface of the object to be processed. It is thereby possible to obtain a thin film having improved adhesion to the surface of the object to be treated.

The cathodic electrolytic treatment (wherein the electrolytic treatment uses the article to be treated as a cathode in the phosphate chemical treatment method) is preferably a phosphate chemical treatment in which a metal substance which is dissolved in a phosphate chemical treatment solution is used as an anode And the same metal that becomes metal ion and is reduced and deposited during electrolysis, and/or the conductive substance that is not dissolved in the phosphate chemical treatment solution is used as the anode, and the cathode electrolytic treatment can also be wherein the phosphoric acid Metal substances forming complexes in the salt chemical treatment solution are used for electrolytic treatment of the anode.

As a result of treatment using this method, the compositional ratio of film-forming phosphate and non-phosphate-forming metal can be adjusted, thereby making it possible to form a film with desired properties on the surface of the object to be treated.

The cathodic electrolytic treatment (wherein the electrolytic treatment uses the article to be treated as a cathode in the phosphate chemical treatment method) is preferably a phosphate chemical treatment comprising a cyclic treatment comprising an electrolytic treatment which adopting the same metal substance as the metal ion that is dissolved in said phosphate chemical treatment solution and is reduced and deposited and/or a conductive substance that is not dissolved in said phosphate chemical treatment solution as an anode, Subsequently, another electrolytic treatment is carried out in which a metal forming a complex in said phosphate chemical treatment solution is used as an anode, and this cycle is carried out at least once.

As a result of processing using this method, thick films with the desired properties can be formed, as previously described.

The cathodic electrolytic treatment (wherein the electrolytic treatment uses the article to be treated as a cathode in the phosphate chemical treatment method) is preferably a phosphate chemical treatment method comprising electrolytic treatment by dividing electrolytic cells in which a A metal substance identical to the metal that is dissolved in the phosphate chemical treatment solution to become ions and is reduced and deposited during electrolysis is used as the anode, and/or a conductive substance that is insoluble in the phosphate chemical treatment solution is used as the The anode, and in another electrolytic cell where the electrolytic treatment is performed, a metal substance capable of forming a complex in the phosphate chemical treatment solution is used as the anode.

As a result of processing in this way, the provision of separate electrolytic cells makes it possible to independently control the deposition reactions of the respective components, thereby easily imparting the desired properties to the formed film.

In addition, the same metal substance as the metal which is dissolved in the phosphate chemical treatment liquid to become metal ions and is reduced and deposited at the time of electrolysis is preferably at least one selected from the group consisting of nickel and copper.

The metal species forming complexes in the phosphate chemical treatment solution is preferably at least one selected from the group consisting of zinc, iron, manganese and calcium.

If the article to be treated is not in contact with the phosphate chemical treatment solution, it is preferable to make a metal substance (which serves as the anode in the electrolytic treatment using the article to be treated as the cathode) as the cathode, and a substance insoluble in the phosphate chemical treatment solution as the anode , and apply a voltage of 5V or less between the anode and cathode.

If the article to be treated is not in contact with the phosphate chemical treatment solution, it is preferable that a metal substance (which serves as the anode in the electrolytic treatment using the article to be treated as the cathode) is used as the cathode, and a substance insoluble in the phosphate chemical treatment solution is used as the anode , and apply a voltage between the anode and the cathode so that the cathode is completely insoluble.

In this method, when the workpiece is not in contact with the phosphate chemical treatment solution, dissolution of the metallic substance of the untreated workpiece can be prevented by supplementary measures.

Preferably, a portion of the phosphate chemical treatment solution is removed from the tank containing the phosphate chemical treatment solution to thermodynamically stabilize the energy state of the portion of the phosphate chemical treatment solution and then returned to the treatment solution tank.

Preferably, a portion of the phosphate chemical treatment solution is withdrawn from the tank containing the phosphate chemical treatment solution, and solids precipitated during film formation in the phosphate chemical treatment are removed and then returned to the treatment solution tank.

As a result of the use of this method, for example, in addition to the surface of the part to be treated, reaction products (colloids) and nitrides (NO ₂ ) formed by the reduction of nitrate ions, which are formed by electrolysis Reactions can be removed from the processing fluid. Therefore, unnecessary reactions other than the film forming reaction can be suppressed in the treatment liquid.

When supplementing the composition of the phosphate chemical treatment liquid, it is preferable to remove a part of the phosphate chemical treatment liquid from the tank containing the phosphate chemical treatment liquid, and add a replenishing liquid containing the treatment liquid composition, compared with the removed treatment liquid, the replenishment The concentration of at least one constituent of the phosphate chemical treatment fluid in the fluid is greater than that of the treatment fluid being removed.

According to this method, replenishment of the treatment liquid can be easily performed.

The present invention provides an electrolytic phosphate chemical treatment method, which uses the object to be treated as a cathode, and contains a reaction in which the potential of reduction and deposition in the form of metal is greater than or equal to that of water dissolved in a phosphate chemical treatment solution. The potential of the anodic electrolysis reaction of the solvent, or metal ions greater than or equal to -0.83V (with reference to the standard electrode potential of hydrogen) are reduced from the cationic state by electrolytic treatment and deposited on the surface of the workpiece to be treated; and such a reaction, wherein the The metal ions forming complexes with the phosphate ions in the phosphate chemical treatment solution are deposited as phosphate crystals, and accordingly, the phosphate ions undergo a dehydrogenation reaction.

According to this treatment method, since two different reactions can proceed simultaneously in the treatment liquid, a desired composite film can be formed on the surface of the object to be treated.

In addition, the metal ion forming a complex with the phosphate ion in the phosphate chemical treatment liquid is preferably at least one selected from the group consisting of zinc, iron, manganese, calcium and magnesium.

The metal ions dissolved in the phosphate chemical treatment solution and reduced and deposited as metals are preferably at least one ion selected from the group consisting of nickel ions, copper ions, iron ions and zinc ions.

When electrolytic treatment is performed, it is preferred that the treatment liquid is composed such that the ratio of the concentration (g/l) of metal ions forming complexes with phosphate ions to the concentrations (g/l) of phosphate ions and phosphoric acid is 0.1 or higher.

Phosphoric acid is made by making the ratio of the concentration (g/l) of the metal ion forming a complex with the phosphate ion to the concentration (g/l) of the phosphate ion and phosphoric acid be 0.1 or higher, more preferably 0.25 or higher, to make phosphoric acid (H ₃ PO ₄ ) can exist in the form of phosphate ions (H ₂ PO ₄ ^- ) in the treatment solution, thereby preventing the oxidation reaction of phosphate ions on the surface of the cathode. Again, this also enables the control of phosphoric acid present in the treatment liquid.

In the electrolytic phosphate chemical treatment, in which electrolytic treatment is performed using an object to be treated as a cathode, a varying voltage is preferably applied between metal substances forming the anode and cathode at the start of the electrolytic treatment.

In addition, the variable voltage applied at the start of the electrolytic treatment is preferably a pulsed voltage. As a result of using this method, even at the initial stage of forming a film on the surface of the object to be treated, the film begins to form only at a specific place on the surface of the object to be treated, but under each electrolytic treatment voltage change, the degree of film formation Places are also forcibly changed. Therefore, a uniform thin film can be formed on the surface of the object to be treated.

The present invention provides a composite film comprising a non-phosphate-forming metal and a phosphate compound formed on the surface of steel, wherein the metal and the phosphate compound constituting the film are dispersed throughout the film.

The present invention provides a composite film comprising a non-phosphate-forming metal and a phosphate compound formed on the surface of steel, wherein at least one non-phosphate-forming metal exists on the outermost layer of the film surface.

The present invention provides the formation of a composite film containing a metal that does not form phosphate and a phosphate compound on the surface of steel, wherein the film has no other diffractions except the inevitable phosphate diffraction peak in X-ray diffraction analysis peak.

The present invention provides the formation of a composite film containing a non-phosphate-forming metal and a phosphate compound on the surface of steel, wherein the number of non-phosphate-forming metal atoms is at least the number of phosphorus atoms contained in phosphate crystals 0.25 times.

The non-phosphate-forming metal is preferably at least one selected from the group consisting of Ni, Cu, Fe and Zn.

In addition, the metal forming the composite phosphate is preferably at least one selected from the group consisting of Fe, Zn, Mn, Ca and Mg.

When steel is taken as 100% by weight, steel containing at least 95% by weight of iron (Fe) is preferred.

X-ray diffraction analysis is preferably performed by electron spectroscopic analysis (ESCA) or energy dispersive X-ray diffraction analysis (EDX).

Description of drawings

Figure 1 is a schematic diagram of the entire electrolytic treatment.

Fig. 2 is a schematic diagram of the electrolysis reaction system.

Fig. 3 is a schematic diagram of the composition of electrolytic phosphate chemical treatment equipment.

FIG. 4 is the appearance diagrams of the pieces to be treated in Example 1 and Comparative Example 1, respectively.

FIG. 5 is an EDX analysis curve of the plane portion of the workpiece to be treated in Example 1. FIG.

FIG. 6 is an EDX analysis curve of the cylindrical portion of the workpiece to be treated in Example 1. FIG.

FIG. 7 is an EDX analysis curve of the plane portion of the object to be treated in Comparative Example 1. FIG.

FIG. 8 is an EDX analysis curve of the cylindrical portion of the workpiece to be treated in Comparative Example 1. FIG.

9 is a GDS (glow discharge analysis) analysis curve of the plane portion of the workpiece to be treated in Example 1. FIG.

FIG. 10 is a GDS analysis curve of the cylindrical portion of the workpiece to be treated in Example 1. FIG.

FIG. 11 is a GDS analysis curve of the plane portion of the workpiece to be treated in Comparative Example 1. FIG.

FIG. 12 is a GDS analysis curve of the cylinder portion of the workpiece to be treated in Comparative Example 1. FIG.

FIG. 13 is the appearance diagrams of the pieces to be treated in Example 2 and Comparative Example 2, respectively.

14 is an EDX analysis curve of the plane portion of the workpiece to be treated in Example 2.

FIG. 15 is an EDX analysis curve of the plane portion of the object to be treated in Comparative Example 2. FIG.

FIG. 16 is an EDX analysis curve of the plane portion of the workpiece to be treated in Example 3. FIG.

FIG. 17 is an EDX analysis curve of the cylindrical portion of the workpiece to be treated in Example 3. FIG.

FIG. 18 is an EDX analysis curve of the plane part of the object to be treated in Comparative Example 1. FIG.

FIG. 19 is an EDX analysis curve of the cylinder portion of the workpiece to be treated in Comparative Example 1. FIG.

FIG. 20 is a SEM (scanning electron microscope) micrograph of the plane portion of the object to be processed in Example 3. FIG.

Fig. 21 is an analysis photo of phosphorus in the plane part of the object to be treated in Example 3.

Fig. 22 is an analysis photo of zinc in the plane part of the object to be treated in Example 3.

Fig. 23 is an analysis photo of nickel in the plane part of the workpiece to be treated in Example 3.

Fig. 24 is an analysis photo of iron in the plane part of the object to be treated in Example 3.

FIG. 25 is a SEM (scanning electron microscope) micrograph of the peripheral portion of the workpiece to be processed in Example 3. FIG.

FIG. 26 is a photo of analysis of phosphorus in the peripheral portion of the object to be treated in Example 3. FIG.

FIG. 27 is a photo of analysis of zinc in the peripheral portion of the object to be treated in Example 3. FIG.

FIG. 28 is a photo of analysis of nickel in the peripheral portion of the workpiece to be treated in Example 3. FIG.

FIG. 29 is a photograph of iron analysis in the peripheral portion of the object to be treated in Example 3. FIG.

Detailed ways

A more detailed description of the aforementioned effects and effects will be provided below, along with a comparative study of the prior art.

First, according to the prior art electrolytic phosphate chemical treatment method described in Japanese Unexamined Patent Application No. 5-822481, the composition of the phosphate chemical treatment liquid is the same as that used in the non-electrolytic phosphate chemical treatment.

That is, in the prior art non-electrolytic phosphate chemical treatment, the treatment liquid is extremely active, and the components of the treatment liquid are easily decomposed to form a thin film by the reaction of the components in the treatment liquid. This is because the solutes in the treatment liquid do not react unless the treatment liquid is reactive. In order to activate the treatment liquid, that is, to chemically decompose (oxidize: dehydrogenate) phosphoric acid, a measure to be taken is to add sodium hydroxide or the like to the non-electrolytic phosphate chemical treatment liquid in the prior art to adjust the pH (hydrogen ion concentration) ) to make it within the desired range, or add nitrate ions as an oxidation accelerator to accelerate the reaction. As a result of adding these chemicals, the phosphate chemical treatment liquid contains a large amount of sodium ions, and as a result, the non-electrolytic phosphate chemical treatment liquid contains a large amount of impurities (unwanted substances) that do not form a phosphate film.

The prior art electrolytic phosphate chemical treatment method uses such a phosphate chemical treatment solution containing other components in addition to film components.

Therefore, these components other than the film components prevent the formation of the phosphate chemical treatment film on the surface of the article to be treated, thereby preventing the formation of an effective film on the surface of the treated member.

On the contrary, in the composition of the electrolytic phosphate chemical treatment solution of the present invention, the above-mentioned metal ions that do not participate in the film forming reaction, such as sodium ions, have a concentration of 400 ppm or less in the phosphate chemical treatment solution, and preferably 100 ppm or more Low. As a result, the stability as a solution treatment liquid is greatly improved so that its components cannot form a jelly. Furthermore, it is possible to use a composition in which only the components in the solution are allowed to react on the electrode surface as a result of electrolysis, while during the electrolytic treatment, the treatment solution only reacts on the electrode surface, and at other times and at other places The resulting reaction is completely prevented.

In addition, it is preferable to use the following method to ensure that during the electrolytic treatment, the treatment liquid reacts only on the electrode surface, and reactions occurring at other times and other places are completely prevented.

That is, as an example of such a method, it is preferable to remove a portion of the phosphate chemical treatment solution from the tank containing the phosphate chemical treatment solution so that the energy state of this portion of the phosphate chemical treatment solution is thermodynamically stable, and It is then returned to the treatment tank, and a portion of the phosphate chemical treatment solution is withdrawn from the tank containing the phosphate chemical treatment solution, and the solids that precipitated during film formation in the phosphate chemical treatment are removed, and then removed Return to treatment tank.

In addition, in the case where the article to be treated is not in contact with the phosphate chemical treatment liquid, it is preferable to apply a voltage of 5 V or less between the anode and the cathode, and to use a metal as the cathode The electrolytic treatment process of the cathode is used as the anode), and the substance used as the anode is a substance that is insoluble in the phosphate chemical treatment solution, and if the workpiece to be treated is not in contact with the phosphate chemical treatment solution, preferably between the anode and the cathode A voltage is applied between them so that the cathode is completely insoluble, a metal substance is used as the cathode (the metal substance acts as the anode in the electrolysis process and the object to be treated acts as the cathode), and the substance used as the anode does not dissolve in the phosphate in chemical treatment fluids.

Furthermore, when replenishing the composition of the phosphate chemical treatment liquid, it is preferable to remove a part of the phosphate chemical treatment liquid from the tank containing the phosphate chemical treatment liquid, and add a replenishing liquid containing the treatment liquid components to be mixed with the removed treatment liquid. ratio, at least one of the components that make up the phosphate chemical treatment fluid in the make-up fluid has a higher concentration than that component in the treatment fluid being removed.

In addition, when electrolytic treatment is performed, the composition of the preferred treatment liquid is such that the ratio of the concentration (g/l) of metal ions forming complexes with phosphate ions to the concentrations (g/l) of phosphate ions and phosphoric acid is 0.1 or higher.

As a result of taking the above measures, the phosphate chemical treatment solution does not contain solids that affect the film formation reaction at all, and the reaction only occurs on the electrode surface during the electrolytic treatment, and no reaction occurs at all at other times and other places.

Furthermore, similar to the "electrolytic phosphate chemical treatment method" of the present invention, although "electrodeposition coating" (in which a thin film is formed by the reaction of components in a solution) requires great care to prevent gelatinization and Decomposition, which is due to the fact that the solution is organic, can be regulated by constant filtering and maintaining the treatment solution at the desired temperature to prevent contamination by impurities.

Since the "electrolytic phosphate chemical treatment method" of the present invention includes electrolysis in an inorganic acid solution, it is preferable to make the above-mentioned adjustments in addition to the measures taken for the electrodeposition coating.

Also, since the present invention does not exist other metal ions, such as sodium ions in the prior art, except for metal ions containing film-forming components, a complex is formed with phosphate ions in the phosphate chemical treatment solution Metal ions can exist as complexes in the phosphate chemical treatment solution. Therefore, even if the metal ions are dissolved in the solution, they can exist in the treatment liquid in a stable form, thereby making it possible to prevent the formation of jelly in the treatment liquid and induce the film deposition reaction to occur only on the surface of the object to be treated.

This is equivalent to the cyano complexes often used in electroplating in the prior art, wherein the cyano complexes will not decompose in the solution, but only decompose on the surface of the cathode and exchange charges here intensively and in the form of metal thin films. method of deposition.

Furthermore, such complexation has been used in the past even in prior art non-electrolytic phosphate chemical treatment fluids. That is, metal ions (such as Fe ³⁺ , Zn ²⁺ , or Mn ²⁺ ) deposited on a metal surface as a phosphate compound dissolve in a solution by forming a complex with phosphate ions. However, since the phosphate ion complex used in the non-electrolytic phosphate chemical treatment solution in the prior art contains ions like sodium ions, it is active (unstable) and complexed with the cyano group used for electroplating. The stability of complexation is lower than that of other substances. Thus, the complex dissolves easily and forms films and gels even in the case of non-electrolytic treatment, and this treatment does not use the present invention in any form.

Furthermore, the cyano complex is stable from the viewpoint of the stability of the complex, and in the case of non-electrolytic treatment (electroless plating), this complex does not dissolve (decompose). For this reason, cyano complexes are only used in electroplating.

If the stability of complexation of phosphate ions can be increased, the complexes are not easily decomposed. The stability of the complexation of phosphate ions used in the non-electrolytic phosphate chemical treatment solution in the prior art is low because the pH value of the treatment solution is adjusted (sodium ions, etc. are added thereto for this reason) so that the phosphate ion Very soluble (decomposes by oxidation). In the electrolytic phosphate chemical treatment solution, the pH value of the treatment solution is not adjusted by adding Na ⁺ . It is for this reason that the stability of complexation of phosphate ions can be increased. When the complexation stability of phosphate ions in the treatment liquid is high, it will not be decomposed without electrolysis and a thin film will not be formed. In addition, in the process of electrolysis, since the phosphate ion complex in the solution is not decomposed during electroplating, and the phosphate ion complex is only decomposed on the surface of the cathode where the charge is concentrated and exchanged, the result is the formation of a thin film, basically no glue The formation of the object, and the treatment liquid remains transparent.

If the phosphate ion complex is too stable, it is not suitable for forming thin films by cathodic electrolysis. It is for this reason that the stability of the phosphate ion complex must be kept within an appropriate range.

In order to achieve this purpose in the present invention, when electrolytic treatment is carried out, the composition of preferred treatment solution is the concentration (g/l) of the metal ion that forms complex with phosphate ion and the concentration (g/l) of phosphate ion and phosphoric acid /l) ratio is 0.1 or higher. As a result, the stability of complexation can be guaranteed.

[Characteristics of Electrolytic Phosphate Chemical Treatment]

In addition to methods of purification (such as purification to prevent contamination by impurities) and treatment liquid filtration methods and measures involving complexes, measures must be taken to adapt to the unique characteristics of electrolytic phosphate chemical treatment in order to actually utilize this electrolytic phosphoric acid Salt chemical treatment.

A description of these unique features is provided below.

In the electrolytic phosphate chemical treatment of the present invention, the above-mentioned phosphate chemical treatment method comprising using the above-mentioned article to be treated as an anode for electrolytic treatment and then using the article to be treated as a cathode for electrolytic treatment is preferred.

In this case, it is preferable to use a thin film forming metal such as iron, nickel or zinc as the anode and the object to be treated as the cathode.

Again, in the following two cases, a metallic substance was placed in the electrolytic cell as an anode.

(1) A metal used as an electrode material dissolves and becomes a film-forming component

(2) A metal used as an electrode material does not dissolve or only slightly dissolves

Cathodic electrolytic treatment is performed using the above two electrode materials or only one of them. Their classification is summarized in Table 3.

Table 3 Classification of cathodic electrolytic treatment Type of anode material Cathode electrolysis voltage Description (1) Metal substances that are easily dissolved and deposited and become film components Small Metals that form phosphate compounds Fe, Zn Metal ions dissolved in solution are reduced and deposited as metal elements, easily soluble and depositable metals Cu (2) Substances that are only slightly soluble or insoluble big Substances that have a high dissolution potential and do not form phosphates Ni and other insoluble substances

In the case of (1), in which a metal dissolved and formed into a thin film component is used as an anode, the anode material is electrochemically dissolved by the action of externally supplied energy, and then exists in solution in a dissolved ion state and is deposited (solidified) on A thin film is formed on the cathode.

In the case of (2), in which an insoluble substance which does not dissolve or only slightly dissolves is used as the anode, cations dissolved in solution are deposited on the cathode by the action of an externally supplied energy source. The use of these conditions is determined by the properties of the phosphate chemical film formed.

As stated in Table 3, "metals that form phosphate compounds (such as Fe and Zn)" are relatively easy even under the conditions of the phosphate chemical treatment liquid in the prior art (as described in the non-electrolytic treatment) ( at low voltage) for dissolution and deposition. However, the metals "dissolved in the phosphate chemical treatment solution, and reduced and deposited as metal elements" include those metals that are easily dissolved and deposited under the conditions of the prior art non-electrolytic phosphate chemical treatment solution (such as Cu) , including those metals (such as Ni) that require high voltage and current to dissolve and deposit.

If a metal is a metal such as Ni that requires a large voltage and current to be dissolved and deposited, it is necessary to apply a large voltage and current if it is deposited only by being dissolved from an electrode serving as an anode and supplied to a treatment liquid. This electrolytic treatment results in a relatively high voltage and current being applied across the treatment solution. However, this form of electrolytic treatment (requiring large voltage and current) is not suitable for electrolysis of metals (Fe and Zn) which can form phosphate compounds by applying a relatively low voltage.

The present inventors have realized that there are essentially two "cathode electrolytic treatment" systems that characterize electrolytic phosphate chemical treatment. The present inventors also considered that the two cathodic electrolytic treatment systems should be used appropriately according to the required film properties by recognizing the difference between the two systems. That is, the composition of the treatment liquid and the metal substance used as the anode are determined according to the desired thin film, and the electrolytic treatment (voltage and current) is properly used according to the treatment liquid and the electrode material.

Recognizing the fact that cathodic electrolytic treatment can be essentially divided into two systems, the practical application of electrolytic phosphate chemical treatment must provide for two different systems. That is, in the case of using "a metallic substance that easily dissolves and deposits and forms a thin film component" and "a substance that only slightly dissolves or does not dissolve", different systems need to be provided.

In the case of using "a metal substance that easily dissolves and deposits and forms a thin film component (such as Fe, Zn, or Cu)" of Table 3 as the anode, even when no voltage is applied (even when electrolysis is not performed) , those metals are also readily soluble in phosphate chemical treatment fluids. If this phenomenon (action) is not disturbed, these metal ions are dissolved in the treatment liquid even when the treatment is not performed. As a result, the state of the treatment liquid ends and the treatment cannot be performed. It is therefore necessary to provide a method to prevent its dissolution. This is the first adaptive adjustment to be taken.

The following measures are preferably taken as specific examples of methods for preventing dissolution:

(1) Control the surface area of the metal electrode (anode) during electrolytic treatment,

(2) Controlling the current to the metal electrode (anode) during the electrolytic treatment, and

(3) Perform weak electrolysis (passive electrolysis) so that the metal used as the cathode is insoluble (to the extent that the solution components do not decompose), and at the same time use an insoluble electrode as the anode and an easily soluble metal electrode (Fe, Zn, Cu) as the cathode, when the electrolysis is passivation, this electrolysis is called "passivation electrolysis".

The second adaptation to be taken corresponds to the case of "only slightly soluble or insoluble substances".

For example, although as a required film component, a metal cannot be sufficiently dissolved even when the metal is electrolyzed as an anode to obtain the metal, it is impossible to obtain all the metal ions required for the film component by dissolution from the electrode . In this case, it is preferable to supply the desired metal ions to the treatment liquid by adding dissolved metal ions to the treatment liquid. The goal of cathodic electrolysis is that the electrolytic reactions (reduction and deposition) occur only at the cathode. If this can be done, for example, by electrolytic voltage participation so that Ni that enters the film composition can be reduced, this is consistent with the assumption that film formation occurs by dissolving Ni from the anode. This inventive solution is preferred for practical application of electrolytic phosphate chemical treatment.

[Reactions involved in electrolytic phosphate chemical treatment]

The present invention forms a novel electrochemical phosphate chemical treatment reaction which, as a result, provides an environment for the electrolytic phosphate chemical treatment reaction to take place. This is explained below.

[General Concept of Electrochemical Reaction]

The electrolytic phosphate chemical treatment reaction of the present invention is substantially free of gels.

The electrochemical reaction system includes anodic reaction and cathodic reaction. Anodic reactions are oxidation reactions that occur at the anode. In addition, the cathodic reaction is a reduction reaction that occurs at the cathode. In the electrochemical reaction system, the potential of the electrodes is different, and the potential of the cathode reaction is higher than that of the anode reaction.

Additionally, if the anode undergoes an anodic reaction, then its corresponding solvent and anion are said to undergo a cathodic reaction. If a cation undergoes a cathodic reaction, then its corresponding solvent and anion are said to undergo an anodic reaction.

Figure 2 is a summary of the electrochemical reaction system formed by electrolytic treatment.

As shown in Fig. 2, the electrolysis reaction system is divided into ① "reaction system between electrodes separated in the electrolyte" and ② "reaction system in the electrolyte on the same electrode rather than on the surface of separated electrodes".

The "reaction system between separated electrodes in the electrolyte" of ① forms an anode-cathode reaction system between the separated electrodes. A breakdown of the classification of this reaction system will be given below.

①-1 Electrochemical reaction system involving cations between electrodes (anodic reaction on the anode and cathodic reaction on the cathode)

①-2 Electrochemical reaction system involving anion and solvent between electrodes (cathode reaction on anode and anode reaction on cathode)

The "reaction system in the electrolyte on the same electrode instead of a separate electrode surface" of ② forms an anode-cathode reaction system between cations, anions and solvents on the same electrode surface. A breakdown of the classification of this reaction system will be given below.

②-1 Anodic reaction of cations on the anode surface, and cathodic reactions of anions and solvents

②-2 Cathodic reaction of cations on the cathode surface, and anodic reactions of anions and solvents

Regardless of "non-electrolytic treatment" or "electrolytic treatment", once the electrochemical reaction system is formed, the electrochemical reaction system includes the formation of cathode reaction and anode reaction. However, the electrochemical reaction system of "non-electrolytic treatment" only includes cathodic and anodic reactions on the same surface. In FIG. 2, the reactions are those of ②-1 and ②-2, which include a reaction between a metal (solid) and a solution (liquid).

There is a case where the electrochemical reaction system includes only one pair of cathode and anode reactions, and there is also a case where the electrochemical reaction system includes multiple pairs of cathode and anode reactions. As shown in Figure 2, the electrochemical reaction system of phosphate chemical treatment is a complex system including multiple pairs of cathode and anode reactions. This complexity makes it difficult to control the reaction system.

[Composition of Electrochemical Reaction System in Electrolytic Phosphate Chemical Treatment]

In the case of "cathode electrolytic treatment" of electrolytic phosphate chemical treatment, when Fe, Zn, Ni and Cu were used as the metal electrode (anode) for film formation, the reactions that occurred are shown in Table 4. In addition, in the following examples, iron (steel) was treated with a phosphate chemical treatment solution containing zinc ions, nickel ions, phosphate ions and nitrate ions (phosphate chemical treatment solution).

Table 4 Classification of electrolytic phosphate chemical treatment (cathode treatment) reactions Anode reaction cathodic reaction Anode surface 1. Dissolution (oxidation) reaction of metal electrodes (Fe, Zn, Ni, Cu, etc.) Fe→Fe ²⁺ +2e(-0.44V)(1)Zn→Zn ²⁺ +2e(-0.77V)(2) Ni→Ni ²⁺ +2e(-0.23V)(3)Cu→Cu ⁺ +e(0.52V)(4)Fe ²⁺ →Fe ³⁺ +e(0.77V)(5) 1. Nitrate ion reduction reaction system (NO ₃ ^- →NO ₂ ^- →NO)NO ^3- +3H ⁺ +2e→HNO ₂ +H ₂ O(0.94V)(6)NO ^3- +4H ⁺ +3e→ NO+2H ₂ O(0.96V)(7)NO ^3- +2H ⁺ +2e→NO ₂ ^- +H ₂ O(0.84V)(8) 2. Reduction reaction of water (solvent) O ₂ +4H ⁺⁺ 4e→2H ₂ O(1.23V)(18) Cathode surface (surface to be treated) 1. Phosphate ion oxidation reaction system (H ₃ PO ₄ →H ₂ PO ₄ ^- →PO ₄ ^3- )H ₃ PO ₄ →H ⁺ +H ₂ PO ₄ ^- (9)H ₂ PO ₄ ^- →2H ⁺ + PO ₄ ^3- (10) 2. Crystallization reactions in which the charge of phosphorylation is not changed when metal ions are combined with phosphate ions (Zn, Fe, Mn, Ca ions, etc.) 2PO ₄ ^3- +2Zn ²⁺ +Fe ²⁺ → Zn ₂ Fe(PO ₄ ) ₂ (11)M ^x+ (metal ion)+n(PO ₄ ^3- )→M(PO ₄ )(12) 3. Oxidation reaction of water (solvent) H ₂ +2OH ^- → 2H ₂ O+2e(-0.83V)(19) 1. Reduction reaction of metal ions with charge change (reduction of Ni, Cu, (Fe, Zn) plasma) Ni ²⁺ +2e→ Ni (-0.23V)(13)Cu ⁺ +e→ Cu (0.52V)( 14)Fe ²⁺ +2e→ Fe (-0.44V)(15)Zn ²⁺ +2e→ Zn (-0.77V)(16)Fe ³⁺ +e→Fe ²⁺ (0.77V)(17)Note: The underlined part indicates the film composition

The electrochemical reaction between the electrodes by applying an external energy source as mentioned above basically includes these two reaction systems. The first reaction system between the electrodes is a dissolution reaction involving the formation of a thin film of metal at the anode (cathode reaction) (electrode), and a deposition reaction of dissolved metal ions on the cathode surface (workpiece) (cathode reaction) . Other reaction systems are electrochemical reaction systems that occur on the same electrode surface. This includes the dissolution (oxidation) reaction of the metal at the anode and the reduction of the solution components (nitrate ions and water), and the oxidation of the solution components (phosphate ions and water) and the reduction of the metal ions at the cathode. Furthermore, the oxidation (dehydrogenation) of phosphate ions on the cathode surface is accompanied by metal (such as Zn, Fe or Mn) ions forming complexes with phosphate and depositing on the cathode surface as phosphate.

[Electrochemical Reaction-1 of Phosphate Chemical Treatment Reaction (Non-electrolytic Treatment Reaction)]

The non-electrolytic phosphate chemical treatment reaction is carried out so that the anode and cathode reactions in the above table are carried out on the same surface, and there is no polarization into anode and cathode.

The reason why the non-electrolytic phosphate chemical treatment is mainly focused only on the steel surface is to create such an environment that allows the simultaneous formation of an electrochemical reaction system even without electrolysis between the phosphate chemical treatment solution and the steel.

In addition, chloride ions (Cl ⁻ ) are added when the object to be treated is copper (Cu). In addition, fluoride ions (F ⁻ ) are added in the case where the object to be processed is aluminum (Al). When fluoride ions (F ^- ) are added, Al is easily dissolved (oxidized) and enters the treatment solution (even without electrolysis), and the electrochemical reaction system forms the relevant phosphate chemical treatment. Therefore, the same phosphate chemical film as the steel film is formed by the same method. However, fluoride ions (F ^- ) do not enter the film and are not reduced like nitrate ions (NO ₃ ^- → NO), but are evaporated (gasified) or removed from the solution. Thus, when the concentration of fluoride ions exceeds the desired level, it is necessary to prepare a new treatment solution.

Due to the formation of an electrochemical reaction system on the same surface in the case of a non-electrolytic phosphate chemical treatment reaction, the dissolution of the substance (part to be treated) is limited by film formation. For this reason, the thickness of the film cannot be increased without destroying the film. In order to obtain a thick film, the substance (object to be treated) is dissolved due to excessive continuation of the reaction, and the reaction results in a thick film. This is why the thin film used for lubricating base treatment of cold forging pressure parts formed by non-electrolytic treatment (heat treatment liquid) is thick.

In addition, since the reaction of non-electrolytic phosphate chemical treatment is an electrochemical reaction system that occurs on the same surface without the use of externally provided energy, the reduction and deposition reactions of metal ions accompanied by charge exchange are strictly limited. Therefore, even if Ni ions are contained in the treatment liquid, the reduction and deposition of Ni are very slight. (Ni deposition is possible at the initial stage of film formation only when Fe is dissolved.) The thus formed film mainly contains phosphate. This is the basic situation about the usual non-electrolytic treatment as phosphate chemical treatment.

[Electrochemical reaction of phosphate chemical treatment reaction-2 (anodic electrolytic treatment)]

In electrolytic phosphate chemical treatment, if the film is formed only in anodic treatment, the reaction system is basically the same as in non-electrolytic treatment. The role of anodic treatment is to promote the "dissolution (oxidation) reaction of metal electrodes" in Table 4. "The dissolution (oxidation) reaction of the metal electrode" is firstly the reaction of the initial phosphate chemical treatment (film formation) reaction system. This reaction (dissolution of the article to be treated) is easy to carry out and is also easy to carry out by anodic electrolytic treatment. As a result, a phosphate film is formed on the object (material) to be treated with very good adhesion. However, it is impossible to increase the thickness of the film.

In the case of forming a thin film by performing anodic electrolytic treatment followed by cathodic electrolytic treatment, the role of the anode is limited to the dissolution (oxidation) reaction of the metal electrode and the reduction reaction of water. During the anodic electrolytic treatment, dissolution of the workpiece to be treated is facilitated, and a thin film is formed during the subsequent cathodic electrolytic treatment.

For this reason, in the case of forming a thin film only by anodic electrolytic treatment, the composition of the treatment liquid is different from that in the case of forming a thin film by anodic electrolytic treatment and cathodic electrolytic treatment.

In addition, in the case of only anodic electrolytic treatment, the cathode material selected as its corresponding electrode should not dissolve in the phosphate chemical treatment solution. For this reason, materials that are not soluble in the phosphate chemical treatment solution, such as titanium, will serve as the cathode.

[Electrochemical reaction of phosphate chemical treatment reaction-3 (cathode treatment)]

A method combining anodic and cathodic treatment is used for electrolytic phosphate chemical treatment. In this case, the role of anodizing is to dissolve the surface of the part to be treated and to ensure the adhesion of the film. Cathodic treatment is performed to form a thin film.

In addition, anodizing can be omitted according to special circumstances. Anodic treatment can be omitted in cases where strong adhesion of the film is not required, and in cases where the pH of the electrolytic phosphate chemical treatment solution is lower than that of the usual non-electrolytic treatment solution, the substance tends to For dissolution, even when electrolysis is not performed, the dissolution reaction of the substance can proceed.

In the usual non-electrolytic phosphate chemical treatment, the "dissolution reaction of the article to be treated" and the "reaction related to film formation" take place on the same surface. However, during the cathodic electrolytic treatment of the present invention, as shown in Table 3, the "dissolution reaction of the object to be treated" did not occur on the surface of the object to be treated serving as the cathode. Only "reactions related to film formation" take place on the surface of the object to be treated (cathode).

According to the classification in Figure 2, there are three kinds of electrochemical reaction systems included in the cathodic electrolytic treatment. They are:

i. Oxidation-reduction (dissolution and deposition) reaction system of metal ions between electrodes (anode and cathode) (①-2 and ①-3 in Figure 2)

ii. Oxidation-reduction reaction system of anion and solvent (water) between electrodes (anode and cathode) (②-2 in Figure 2)

iii. The anodic reaction of the anion on the cathode surface and the solvent (water) and the cathodic reaction of the metal ion (②-2 in Figure 2)

Each of these reaction systems will be described below.

i. Oxidation-reduction (dissolution and deposition) of metal ions between electrodes (anode and cathode)

Reaction system (①-1 in Figure 2)

This is a reaction between electrodes formed by a cathodic reaction at the cathode surface (reduction and deposition of metal ions) and an anodic reaction at the anode surface (dissolution of metal). This reaction is an electrolytic reaction using an external power supply. Since the cathode surface is subjected to the large electrochemical energy of the cathodic reaction, the exchange (reduction) deposition reaction with charge can proceed. Cathodic deposition reactions are deposition reactions that are accompanied by charge exchange (reduction) of metal ions such as nickel, copper, iron or zinc, and use an electroplating-like action to attach the metal ions to the base metal. Furthermore, although metals such as iron or zinc used in phosphate do not accompany charge exchange and preferentially deposit films with phosphate, their dissolution and deposition potentials accompanied by charge exchange are higher than or equal to the anodic reaction potential of water ( -0.83V), allowing it to deposit as a metal by charge exchange.

ii. An oxidation-reduction reaction system between electrodes (anode and cathode) and solvent (water) (①-2 and ①-3 in Figure 2)

This reaction between the electrodes consists of an anodic reaction at the cathode surface (dissolution and oxidation of phosphate ions and formation of phosphate and oxidation of solvent (water)) and a cathodic reaction at the anode surface (dissolution and oxidation of nitrate ions). Reduction and solvent (water) reduction) formed. The formation of this electrochemical reaction system makes the phosphate crystals electrochemically connected firmly on the surface of the cathode.

iii. The anodic reaction of anion and solvent (water) and the cathodic reaction of metal ions on the cathode surface (②-2 in Figure 2)

This reaction system is composed of an oxidation reaction of water (anodic reaction of reaction formula (19)) and a cathodic deposition reaction (reaction formula (13), (14), (reaction formula (13), (14), ( 15) and (16)). As a result of the formation of this reaction system, since the potential of the ions (dissolution-deposition equilibrium potential) that is dissolved in the phosphate chemical treatment solution to reduce and deposit the metal is equal to or higher than the anode reaction potential of water -0.83V (with The standard electrode potential of hydrogen is used as a reference), so that it can be deposited directly as a metal. As stated earlier, in an electrochemical reaction system, the potential of the cathodic reaction is defined as being higher than the potential of the anodic reaction. As a result of forming this reaction system like this, the deposition of metal ions that can ensure that the equilibrium potential of dissolution-deposition is higher than or equal to the equilibrium potential of dissolution-deposition of zinc (with the standard electrode potential of hydrogen as a reference, =-0.77V) . That is, the metal deposited at the cathode can be determined.

Metals with low dissolution-deposition equilibrium potentials such as sodium (dissolution-deposition equilibrium potential (referenced to the standard electrode potential of hydrogen) = -2.7V) and potassium (dissolution-deposition equilibrium potential (referenced to the standard electrode potential of hydrogen) )=-2.9V) cannot be deposited by electrolysis and cannot form a thin film either. For this reason, these metal ions are absent in the electrolytic treatment film formation.

In addition, Zn, Fe, etc. can be deposited as metals through their charge exchange. However, Zn, Fe, and the like usually exist in the treatment liquid by forming complexes with phosphate ions. Deposition with phosphate is also more favorable from energy considerations. For this reason, Zn, Fe, etc. are preferentially present as phosphate in the thin film.

In the cathodic electrolytic treatment of the present invention, except the metal ions of the above-mentioned film components, the concentration of all other metal ions is about 0-400ppm, preferably 0-100ppm or lower, because this treatment does not contain any metal ions that affect film formation. Reactive solids and metals that do not form phosphate can enter the film composition, so that the composite film itself has properties close to ordinary "electroplated" films. Therefore, the phosphate chemical film formed can obtain high electrochemical energy, so that it can be firmly attached to the cathode (the object to be treated).

In the present invention, the oxidation-reduction (dissolution-deposition) reaction system of metal ions between the electrodes can be continuously carried out through the connected external power supply. For this reason, ions of Ni and other metals can be reduced and deposited and then distributed throughout the film formation process. In addition, only a specific metal may be contained or a certain metal may not be contained. That is, the cathodic treatment film formation reaction can be controlled.

[Characteristics of Electrolytic Phosphate Chemically Treated Films]

Of particular note in the present invention is that metal deposition with charge exchange can continue throughout the film formation process. This phenomenon is similar to "plating".

That is, the electrolytic phosphate film can be said to be an "electroplated film containing phosphate components". In other words, a thin film can be formed on the outer surface of the phosphate chemical film in which the ratio of the atomic number density is such that the number of atoms of the metal that does not form phosphate (such as Ni) is greater than 1/4 as that of the metal that does not form phosphate. The atomic number of the basic element phosphorus (P). (Refer to Table 10 and the EDX film analysis results of Example 1, and Table 16, the EDX film analysis results of Example 4 and Example 5.) This film was processed in a common non-electrolytic process (wherein the film was obtained by using phosphate Formed by crystallization) is not found in the thin film.

(The atomic number density ratio of Ni/P = 1/4 is consistent with the fact that the ratio in Ni/Zn ₃ (PO ₄ ) ₂ is 1/2.)

In addition, as a result of not performing the cathodic electrolytic treatment of the metal accompanied by the charge change, the deposition of the metal accompanied by the charge change can be completely eliminated in the same manner as in the non-electrolytic treatment. (with reference to the EDX film analysis results of Table 12 and Example 2.)

Furthermore, another feature of the electrolytic phosphate chemically treated film of the present invention is that when the film is analyzed by X-rays, it is found that there is no diffraction peak consistent with phosphate crystals. (See Table 16 Example 3, Figure 16 and Figure 17.) This may also be because deposition of metal (eg Ni) with charge exchange can occur throughout the duration of film formation. That is, this is considered to be a result of deposition of phosphate crystals being subordinate to deposition of metals (such as Ni) accompanied by charge exchange, and phosphate crystals being finely distributed in the metal component. Although the film of Example 3 contained phosphorus (P) and zinc (Zn) and was a phosphate-containing film, phosphate crystals were dispersed in Ni metal. This is shown in photographs taken from EPMA elemental analysis along a cross-section of the film (Table 17, Figures 20-29). This film can be considered as a "composite electroplating film containing phosphate".

As already stated above, in the present invention, an electrolytic phosphate chemical treatment is developed, which is adapted to the general principle of electrochemical reactions.

That is, the present invention can provide a method for phosphate chemical treatment, which can form a phosphate chemical film. Compared with the film in the prior art that mainly contains phosphate crystals, the method of the present invention can form a film containing phosphate and metal. film.

In addition, the composite film obtained by the present invention may contain metal species other than phosphate.

In this way, this novel phosphate chemical treatment can obtain composite thin films, which are suitable for various metal substances, regardless of the type of metal as long as the metal is suitable for electroplating.

[Constitution of Electrolytic Phosphate Chemical Treatment]

Electrolytic phosphate chemical treatment includes: (1) device, (2) composition of treatment solution, (3) electrochemical condition of treatment solution, and (4) electrolysis method.

First, an apparatus used in the electrolytic phosphate chemical treatment method of the present invention will be described with reference to FIG. 3 .

Figure 3 is the setup during cathodic electrolytic treatment.

Here, 1 is the phosphate chemical treatment solution of the present invention, 2 is the workpiece to be treated, 3 and 4 are working electrodes, and the working electrode 3 contains a metal substance that forms a complex with phosphate in the phosphate chemical treatment solution, and the working electrode 4 Contains a metal species that is soluble in a phosphate chemical treatment solution and that has a reduction and deposition potential in metallic form greater than or equal to that of the anodic electrolysis reaction of an aqueous solvent, or greater than or equal to -0.83 V (shown as The standard electrode potential of hydrogen was used as reference).

Furthermore, 5 is an external power supply for applying a voltage between the workpiece 2 and the working electrodes 3 and 4, and 6 is a filter/circulation pump, which is used to remove a part of the phosphate chemical treatment liquid 1 from the treatment liquid tank. Phosphate chemical treatment solution 1, and make the phosphate chemical treatment solution 1 reach a thermodynamically stable energy state, and 7 is a filter for removing solids that have precipitated in the phosphate chemical treatment solution during film formation.

8 is a passivated electrolytic anode that is inert to the phosphate chemical treatment solution, and it is used when the workpiece to be treated does not contact the phosphate chemical treatment solution, and 9 is a chemical replenishment solution having a higher concentration than the phosphate chemical treatment solution 1, And 10 is a chemical replenishment pump for adding chemical replenishment liquid into the treatment liquid.

11 is a control computer, and according to the pH value, ORP value and other parameter information of the treatment liquid measured by the detector 12, it controls the amount of replenishing liquid added, the applied voltage and so on.

The present invention will be explained below with reference to FIG. 3 .

In the present invention, the piece to be treated (piece to be treated) is connected with the cathode by the direct current supplied outside, and contains metal forming a phosphate film or an insoluble conductive substance (called a working electrode) in the treatment solution and Anode connection. In addition, when performing anode electrolysis, the object to be treated is connected to the anode and the conductive substance insoluble in the treatment solution is connected to the cathode.

There is only one working electrode (counter electrode) during anode electrolysis.

Although there is only one working electrode in cathodic electrolytic treatment, various forms of substances can be used as electrodes. Also, it is preferable to install a DC power supply for each working electrode for electrolysis. This is to prevent such a phenomenon that a large amount of current flows through the electrode where the current is easy to pass, and the current does not pass through the place where the current is difficult to pass. This phenomenon is likely to occur when the electrode is connected to a single DC power supply. .

Passivated electrolytic electrodes are installed in the electrolytic cell. Passive electrolysis electrodes (anodes) use a conductive substance that is insoluble in the treatment solution. The role of this electrode is to prevent the dissolution of the working electrode when the object to be treated (the object to be treated) is not being processed (when the electrolysis is stopped). When the electrolysis is stopped, the insoluble conductive substance is used as the anode, and the working electrode as the cathode, and they are connected to an external DC power supply. When it is in operation, only slight electrolysis occurs, but not to such an extent that it dissolves the working electrode. This electrolysis is called passivation electrolysis. As a result of this passivating electrolysis, when electrolytically passivated, decomposition of the treatment solution is prevented by preventing dissolution of the working electrode in the treatment solution.

The circulation pump is used to filter and circulate the treatment liquid. Additionally, filtration removes any sediment that forms. When the electrolytic treatment is completed and the current flow through the article to be treated is stopped, there occurs a phenomenon that electric charges accumulated on the article to be treated are released into the treatment liquid. At this time, a part of the thin film is also dissolved in the treatment solution. Sediments form when this accumulation takes place. If these phenomena are allowed to continue, the jelly will continue to form. Filtration and circulation of the treatment fluid can prevent these phenomena.

Install a pH electrode, ORP electrode, EC (conductive) electrode, temperature measuring electrode, etc. in the electrode chamber of the detector. These electrodes cannot be installed in the treatment tank since the electrolysis current will pass through the treatment tank. They must be installed in isolation.

The make-up chemical liquid tank and the chemical make-up liquid pump are installed to add chemical liquid. It is preferable to keep the part of the added chemical liquid (in the tank) away from the path of filtration and circulation of the treatment liquid in the electrolytic cell. This is because even when the electrolysis stops, there will always be slight hydrolysis in the electrolytic cell, making the electrolytic cell in an electrochemically very active state. If an active chemical substance with a higher concentration than the treatment solution is added to the treatment cell, the chemical The ions of the constituents react to form more sludge before they dissolve in the treatment fluid.

The control computer is installed so that the electrolytic treatment (reaction) can be properly performed.

The dissociation constant of phosphoric acid will be explained below. The electrolytic phosphate chemical treatment solution of the present invention has a pH value of 0.5-5.0. The main factor causing the change in the phosphate chemical treatment liquid is the dissociation of phosphoric acid (H ₃ PO ₄ ), which is one of the components of the treatment liquid (phosphate chemical treatment liquid). That is, the dissolution of phosphoric acid (H ₃ PO ₄ ) and the acid dissociation effect (pKa) of phosphoric acid become larger. The acid dissociation effect (pKa) is the logarithm of the reciprocal value of the ionization constant, and the larger the value, the lower the dissociation constant of the acid. That is, the lower the strength of the acid.

While the dissociation constant of pure phosphoric acid (H ₃ PO ₄ ) is pKa=2.15, the dissociation constant of H ₂ PO ₄ ⁻ after dissociation of H ⁺ ions from H ₃ PO ₄ is pKa=7.2. This means that H ₂ PO ₄ ^- is a weaker acid than H ₃ PO ₄ .

When the treatment solution containing phosphate ions is electrolyzed, the state change of the ions (become a reduced state) is as follows:

And it eventually becomes phosphate (for example as Zn ₂ Fe(PO ₄ ) ₃ ), which is transformed into a thin film.

For this reason, H ₃ PO ₄ is usually dissociated into H ₂ PO ₄ ⁻ in the treatment liquid. This means that the state of phosphoric acid in the treatment liquid mainly exists in the form of H ₃ PO ₄ or mainly in the form of H ₂ PO ₄ ^- , resulting in a significant difference in the acid activity of the treatment liquid.

In the case where phosphoric acid mainly exists in the form of H ₃ PO ₄ , the acid activity of the treatment solution is relatively higher, and it is also stable along the direction of acid (H ⁺ ) consumption in the treatment solution (referring to the dissociation of phosphoric acid). That is, although a solution mainly containing H ₃ PO ₄ consumes acid (H ⁺ ), the target of consumption is to consume acid (H ⁺ ) by dissolving the iron electrode immersed in the treatment liquid. The result of this action is the decomposition of the treatment fluid and the formation of sludge.

There are cases where the treatment liquid mainly containing H ₃ PO ₄ contains a large amount of acid (H ⁺ ), and since it contains a large ratio of acid (H ⁺ ), the ratio of metal ions dissolved in the treatment liquid is correspondingly small . As a result, the ratio of "ions of metal (Zn, Fe, Mn, etc.) constituents which are converted to phosphate and enter the film/(phosphate ions and phosphoric acid)" is correspondingly less.

On the other hand, if the treatment liquid mainly contains H ₂ PO ₄ ⁻ , a large amount of metal ions are substituted for the acid (H ⁺ ), and the ratio of the metal ions dissolved in the treatment liquid is correspondingly greater. As a result, the ratio of "ions of metal (Zn, Fe, Mn, etc.) constituents which are converted to phosphate and enter the film/(phosphate ions and phosphoric acid)" is correspondingly greater.

This means that the dissociation constant of phosphoric acid in the treatment solution can control the ratio of "ions of the metal (Zn, Fe, Mn, etc.) That is, during the electrolysis process, the treatment solution can be stabilized by controlling "the ions of metal (Zn, Fe, Mn, etc.) components are converted into phosphate and enter the film/(phosphate ions and phosphoric acid)". Ions that value _the metal (Zn, Fe, _Mn , ^etc. ) Stabilization of ions (H ₂ PO ₄ ⁻ ). For this reason, even though metal (Ni, Cu, etc.) ions that are phosphates do dissolve, since they cannot form complexes with phosphate ions (H ₂ PO ₄ ^- ), their stabilization of the treatment liquid is None contributed.

Also, the ratio of "the ions of the metal (Zn, Fe, Mn, etc.) component are converted into phosphate and enter the film/(phosphate ion and phosphoric acid)" can be expressed as an ion concentration (g/l) ratio.

In considering the practical application, the stabilization of the treatment fluid is extremely important when considering its process throughput.

The electrolytic phosphate chemical treatment solution contains phosphate ions, nitrate ions, ions of metals (Zn, Fe, Mn, etc.) that are converted into phosphates and enter the film, and metals (Ni, Cu, etc.) ) in the case of ions, "concentration (g/l) of ions of metals (Zn, Fe, Mn, etc.) that are converted into phosphate and enter the film (g/l)/(concentrations of phosphate ions and phosphoric acid (g/l))" The range of the ratio is 1/10 (=0.1) or more, and the preferable range is 1/4 (=0.25)-3.

If the above ratio is 0.1 or lower, the ratio of pure phosphoric acid (H ₃ PO ₄ ) in the treatment liquid increases to result in a decrease in the stability of the treatment liquid. (Although the concentration of Zn ions is 0.4 g/l and the concentration of phosphate ions is 7.6 g/l in Example 1, since the surface area of the Fe electrode is 380 cm ² /electrode and the number of electrolysis is 51A/8 electrodes, compared with other The electrolytic quantity of embodiment is big compared to Fe.Because of this reason, "concentration (g/l)/(phosphate ion and phosphoric acid radical ion) of the ion concentration (Zn, Fe, Mn etc.) that changes into phosphate and enters thin film Concentration (g/l)) "The ratio is recommended to be 1/10 (= 0.1) or higher.)

In addition, the upper limit of the above ratio is determined by "the solubility of metal (Zn, Fe, Mn, etc.) ions converted into phosphate and incorporated into the film in the treatment liquid" and from a practical point of view.

In the present invention, the above-mentioned metal ions converted into phosphate and entering the film are dissolved in the form of nitrate and form a solution (treatment liquid). Zinc nitrate and manganese nitrate have great solubility. By adding about 1 to 10 g/l of phosphate to a zinc nitrate solution or a zinc nitrate+nickel nitrate solution and electrolyzing it. In this case, the main factor that causes the turbidity of the treatment liquid and prevents the formation of the film is the solubility of the solute. In the case of electrolytic phosphate chemical treatment, although Zn, Ni and their solubility are treated in advance, in the case of dissolving zinc nitrate, its zinc concentration can be 100 g/l. Thus, if the solubility is limited, then "concentration (g/l) of ions of metals (Zn, Fe, Mn, etc.) )" The upper limit of the ratio is 10-100.

Another factor in determining the upper limit is "practical perspective". This is based on the fact that the concentration of chemicals is generally required to be low. Judging from this point of view, it is considered that "concentration (g/l) of ions of metals (Zn, Fe, Mn, etc.) It makes sense that the upper limit of the ratio is about 4. (But because Fe ions cannot exist as ferrous ions (Fe ²⁺ ) in the solution but only as ferric ions (Fe ³⁺ ), and iron ions have strong coagulation when they are added to the treatment solution, resulting in deposition formation of substances, so they cannot be used as replenishers.)

[Composition of the treatment liquid]

The electrolytic phosphate chemical treatment solution is basically divided into the following components.

That is, there are anions in the treatment liquid in the form of (1) nitrate ions (oxygen complex acid (oxyacid) ions containing nitrogen, which are not obtained by dissolving nickel nitrate or zinc nitrate, and are not obtained from nitric acid ( HNO ₃ ) and (2) phosphate ions provided in ). In addition, there are cations (1) such as metal ions such as zinc, manganese, calcium, and iron in the treatment solution, which crystallize as phosphate in the film and form complexes with phosphate ions in the phosphate chemical treatment solution and (2) metal ions such as nickel and copper, which are deposited (film-forming) due to charge exchange (reduction) of the metal ions, and whose equilibrium potential as metal deposition is greater than or equal to -0.83V (with a standard electrode of hydrogen potential as a reference), which is the anodic electrolysis potential of water.

This classification of the components of the treatment liquid is characterized in that the components of the treatment liquid are classified into four components according to their role in the film formation reaction. This point of view (knowledge) is not found in usual phosphate chemical treatments.

In addition, in addition to those mentioned above, other ingredients may be added if necessary. Examples of these components include the addition of fluoride ions where the treatment material is aluminum, and the addition of chloride ions where the treatment material is copper.

In the case of non-electrolytic treatment, when steel is treated, the metal ions deposited (film formation) due to the charge exchange (reduction) of metal ions are nickel ions only. Also, since nickel is only deposited at the interface of iron, no nickel is present on the outer surface of the film. This means that the deposition that occurs with the charge exchange of nickel is only related to the solubility of iron. Since there is no dissolution of iron except at the interface of the steel, nickel cannot be deposited elsewhere. This refers to the characteristics of the prior art non-electrolytically treated films. That is, the film obtained by the non-electrolytic treatment mainly contains phosphate.

But in the embodiment of the present invention, metal ions deposited (forming a thin film) due to the charge exchange (reduction) of metal ions like nickel provide an environment in which they can be reduced by using an external power supply, so that the range of the metal ions expand. In principle, metal ions with a dissolution-deposition equilibrium potential (the potential of the cathode deposition reaction) equal to or greater than the potential (-0.83V) of the anodic electrolysis reaction of water on the cathode surface can be deposited during electrolytic treatment. Examples of such metals include copper, nickel, iron, zinc, tin, lead and chromium.

In addition, in many cases, it is desirable that the treatment liquid contains only a small amount (0.1 g/l or less) or does not contain metal ions deposited (film formation) due to charge exchange (reduction) of metal ions. This is due to the fact that these metal ions reduce the adhesion of the film to the material. In films for lubricating treatment of cold forged workpieces of steel, its adhesion to the material is expected to decrease. This is because a high degree of adhesion will lead to deterioration of lubricity. In order to form this type of thin film, the treatment liquid must not contain metal ions deposited by charge exchange (reduction) like nickel.

Furthermore, the composition of the treatment liquid must be such that the content of substances that do not participate in the formation of the film is as small as possible. For this reason, the use of degreasing agents, which contain sodium ions and cause contamination, must be prohibited from the viewpoint of cations (metal ions). Any chemicals containing sodium ions, potassium ions, chloride ions and sulfate ions (SO ₄ ^2- ) cannot be added to the phosphate chemical treatment solution.

It is desirable to keep the amount of sodium ions and other unwanted ions as low as possible. A practical way to accommodate this is to avoid using demineralized water when pre-rinsing. It can be considered as a general rule that it is desirable to have a concentration of sodium ions and other unwanted ions in the treatment liquid of 400 ppm or less, and preferably 100 ppm or less.

Next, each preferred ingredient will be defined below.

The concentration of nitrate ion is preferably 6-140g/l, the concentration of phosphate ion and phosphoric acid is preferably 0.5-60g/l, such as Zn, Mn, Fe or Ca are formed with phosphate ion in phosphate chemical treatment liquid The concentration of at least one metal ion of the complex is preferably 1 to 70 g/l, and such as Ni, Cu, Fe, Zn or Cr are dissolved and reduced in the phosphate chemical treatment solution, and its potential for metal deposition is greater than The concentration of metal ions equal to the potential of the anodic electrolysis reaction of water on the surface of the cathode -0.83 V (referenced to the standard electrode potential of hydrogen) is preferably 0 to 40 g/l.

[Electrochemical conditions of the treatment solution]

Those parameters defined as the electrochemical conditions of the treatment liquid include: pH, ORP (Oxidation-Reduction Potential), EC (Conductivity) and temperature. In the case of non-electrolytic treatment, the energy to promote the electrochemical reaction depends on the chemical energy of the chemical treatment solution. For this reason, it is necessary to precisely define the conditions of the electrochemical reaction, that is, define the state of the electrochemical reaction. But in the case of electrolytic treatment, the energy to promote the electrochemical reaction is dependent on the external power supply. That is, the degree of electrochemical reaction is relatively smaller than that of non-electrolytic treatment. For this reason, it is not necessary to precisely define the electrochemical conditions of the treatment liquid.

This is consistent with the fact that in an actual electrolytic treatment like "electroplating", much management of electrochemical conditions is unnecessary.

A preferred range for each parameter will be indicated below.

First, the preferred range of pH is 0.5-5. The reason for using a wide range of pH values is to accommodate the composition of the treatment fluid. As a general rule, the treatment liquids of embodiments of the present invention are electrolytic treatment liquids that do not contain substances not involved in film formation. For this reason, at pH values of 4 and above, there is no sludge formation in the treatment liquid.

The ORP (Oxidation-Reduction Potential) of the treatment liquid is a reflection of the composition of the treatment liquid. Table 3 gives the reaction equations involved in the electrolytic phosphate chemical treatment. The reaction with the highest reaction potential is the cathodic decomposition reaction of water (1.23V). In addition, the reaction with the lowest reaction potential is also the anodic electrolysis reaction of water (-0.83V). For this reason, the ORP of the treatment liquid of the present invention is preferably between -0.83V and 1.23V in principle. It is more preferably between 0 and 1 V (with reference to the standard electrode potential of hydrogen).

EC (conductivity) is also a reflection of the composition of the treatment liquid. In addition, there is no strict standard for the method of measuring conductivity. The EC determined by a general measurement method is preferably 4 to 60 mS.

When only thin film formation is considered, the temperature of the treatment liquid is preferably 10 to 90°C. This is because since the treatment liquid does not contain ions not involved in film formation, the treatment liquid is stable in view of heating, and the use of an external power source that promotes the reaction can allow energy to be obtained at a low temperature.

The actual temperature varies with the composition of the treatment fluid.

[Electrolysis system (control of cathodic electrolytic phosphate chemical treatment reaction)]

The actual control of cathodic electrolytic phosphate chemical treatment reactions is carried out by combining the following three components: working electrode (anode) material; composition of treatment solution; electrolysis method and conditions according to the properties of the formed film.

Each constituent element will be described below.

The metal substance forming the film is selected as the working electrode (anode) material. Typical examples of such metals include Fe, Zn, Ni and Cu. In addition to these metals, Mn-containing alloys, Ca-containing alloys, and Mg alloys which can form phosphate compounds can also be used. In addition, metal substances such as Sn and Pb which have a standard electrode potential greater than or equal to -0.83V can also be used. These metals can be used alone or in combination as anodes.

The components (anions and cations) of the treatment liquid have been described above. But in the embodiment of the present invention, although the treatment liquid contains no other anions other than nitrate ion and phosphate ion as a general rule, it may contain other ions depending on the type of treatment material. For example, in the case of forming a phosphate chemically treated film on copper, the addition of chloride ions may also be considered. Although during active anodic treatment, chloride ions undergo an underlying anodic reaction with the associated copper.

(20)

Since CuCl is incorporated into the film, chloride ions will not remain in the treatment solution if properly added.

In addition, in the case of thin film treatment of aluminum materials, a small amount of fluoride ions can be added, the purpose of which is to promote the dissolution reaction of aluminum. In this case, although fluoride ions were not transformed into film components, they could effectively promote the dissolution reaction of the aluminum material. For this reason, it is permissible to add a small amount of fluoride ions to the extent that it replenishes the amount lost from the treatment liquid.

The electrolysis method and conditions are related to the voltage and current applied between the selected working electrode (anode) and the workpiece to be treated (cathode). The electrolysis method and conditions vary with the type of working electrode selected and the type of film formed. Two types of working electrodes are commonly used, namely "metals crystallized in the form of phosphates (Zn, Fe, etc.)" and "metals deposited upon reduction of metal ions (Ni, Cu, etc.)".

In order to ensure adhesion to the metal, it is preferable to first use the metal (Ni, Cu, etc.) deposited after metal ion reduction as the working electrode for electrolysis, and then use the "metal crystallized with phosphate (Zn, Fe, etc.)" as the working electrode Either perform electrolysis or use a combination of both types of electrolysis.

In order for the thin film not to adhere to the metal, it is preferable to perform electrolysis using only "a metal crystallized with phosphate (Zn, Fe, etc.)" as a working electrode.

The normal range of the electrolysis voltage is 1-50V, and the electrolysis current is 0.01-10A/dm ² . In addition, there is no particular regulation on the electrolysis time.

Various types of thin films can be formed by adjustment in cathodic electrolytic treatment. For example, a thin film containing a large amount of Zn can be formed by using a treatment liquid containing a large amount of Zn and using a Zn electrode. Such films can be used on the substrate of cold forged workpieces.

In addition, a film containing a large amount of Ni can be formed on the surface of a steel material by using a treatment liquid containing a large amount of Ni ions and first performing electrolysis using a Ni electrode, and then performing electrolysis using a Ni electrode and an Fe electrode, respectively. Films containing a large amount of Ni have good adhesion to iron-based materials (substrates) and are therefore suitable as substrates for electroplating.

[Difference from the electrolytic treatment of the prior art]

The differences of the prior art with respect to the electrolytic phosphate chemical treatment process are shown in Table 5, which further characterizes embodiments of the present invention.

The basic difference is the composition of the treatment liquid. The embodiment of the present invention is that "the treatment liquid does not contain impurities and the electrolytic solution is suitable for reacting the components in solution" In contrast, the electrolytic treatment liquid of the prior art is "the treatment liquid contains Impurities", thus making them very different from this point of view.

Table 5 Differences in electrolytic treatment reaction (between prior art and the present invention) current technology Embodiment of the invention Components of the treatment fluid (1) Phosphate ions, nitrate ions (2) Metal ions that form thin films (3) Cations that do not participate in thin film formation (Na ^+, etc.) (4) Accelerators (nitrate ions, ions with low dissociation constants) (1) Phosphate ion, nitrate ion (2) Metal ion forming a thin film Electrochemical conditions of the treatment solution PH＝2～4ORP＝460～860mV Temperature＝20～40℃ PH＝0.5～5ORP＝200～1000mV Temperature＝10～90℃ Electrolysis conditions Voltage＝0～10V Current＝0.01～4A/dm ² Voltage＝0～50V Current＝0.01～10A/dm ²

[Discussion of Electrolytic Phosphate Chemical Thin Films]

Films obtainable by embodiments of the present invention will be described below.

As has been described above, the content of the electrochemical reaction of the thin film forming reaction of the embodiment of the present invention is different from the prior art method. As shown in the cathodic electrolytic treatment reaction (Table 4), the content of the electrochemical reaction according to the embodiment of the present invention mainly contains an "electrolytic reaction between electrodes".

But the prior art, including Japanese Unexamined Patent Application Publication No. 5-822481, does not exhibit this type of "electrolytic reaction between electrodes". The object of Japanese Unexamined Patent Application 5-822481 is to provide an electrolytic reaction to enhance the electrochemical reaction in the prior art non-electrolytic phosphate chemical treatment.

The non-electrolytic treatment liquid mainly contains "an electrolytic reaction between the object to be treated (solid) and the treatment liquid (liquid) on the same metal surface". The differences between the present invention and the non-electrolytic treatment are summarized in Table 6.

Table 6 Differences between electrolytic reactions Non-electrolytic treatment Electrolytic treatment (the present invention) response content Electrochemical reaction system Electrochemical reaction between the workpiece to be treated (solid) and the treatment liquid (liquid) on the same metal surface There is mainly an electrochemical reaction between the electrodes in the treatment solution Electrolytic reaction of solvent (water) No have Effect on Thin Film Phosphate Crystal Formation Mechanism Phosphate deposition (oxidation reaction, anodic reaction) corresponding to the reduction reaction (cathodic reaction) of the accelerator (NO ^2- ) Deposition due to electrochemical reaction between electrodes Metal deposition with charge exchange There are no general rules. But in the case of film formation on iron, a slight reduction and deposition of nickel (cathodic reaction) is observed on the iron interface accompanied by dissolution of iron (anodic reaction) have. Deposition through electrochemical reactions between electrodes can occur throughout the film formation process. It is also possible that this deposition reaction does not occur.

The thin film characteristics of the present invention can be said to be mainly produced by the electrochemical reaction between the electrodes. That is, the thin film is formed by obtaining a large amount of electrochemical energy as compared with the thin film obtained from non-electrolytic treatment.

Embodiments of the present invention will be presented below. The procedures of Examples and Comparative Examples are shown in Table 7.

The degreasing process includes immersing in an alkaline degreasing agent of specified concentration and temperature for 4 to 5 minutes. The pickling process is to immerse in 10% hydrochloric acid solution for 5-10 minutes. The surface finish was dipped in 0.2% of PL-ZT manufactured by Nihon Parkerizing Co., Ltd. The cleaning process performed until the degreasers and other chemicals have been completely removed from the piece to be treated. Electrodeposition coating was performed using Power Top U-56 manufactured by Nippon Paint Co., Ltd., so that the coating thickness after baking was 20-25 μm.

The process of Table 7 embodiment and comparative embodiment

(○ means the process is in progress, - means the process is not in progress) process Skim → cleaning → Pickling → cleaning→ Surface Finishing→ Phosphate Chemical Treatment → cleaning→ Process after chemical treatment Example 1 ○ ○ - - - ○ ○ Cleaning with pure water→electrodeposition coating→cleaning with pure water→baking (190°C, 25 minutes) Comparative Example 1 ○ ○ - - ○ ○ ○ Example 2 ○ ○ - - ○ ○ ○ Dip in 5% sodium stearate solution (85°C, 5 minutes) → cold forging Comparative Example 2 ○ ○ ○ ○ ○ ○ ○ Example 3 ○ ○ - - - ○ ○ Cleaning with pure water→electrodeposition coating→cleaning with pure water→baking (190°C, 25 minutes) Comparative Example 3 ○ ○ - - - ○ ○ Example 4 ○ ○ - - - ○ ○ Cleaning with pure water→electrodeposition coating→cleaning with pure water→baking (190°C, 25 minutes) Example 5 ○ ○ - - - ○ ○

Table 8 shows the compositions and electrochemical conditions of the phosphate chemical treatment solutions of the examples and comparative examples.

Table 8 Composition and electrochemical conditions of phosphate chemical treatment solution Composition of treatment liquid (g/l) Chemical analysis value of treatment liquid Electrochemical conditions of the treatment solution Phosphate ion Nitrate ion Nickel ions Zinc ions sodium ion Total acidity (Pt) Accelerator concentration (Pt) pH ORP(mV)Ag/AgCl electrode potential EC(mS) temperature °C Example 1 7.6 12 5.5 0.4 0 20 0 0.5 270 15.3 27.6 Comparative Example 1 7 20 0.5 3 6.4 12 5 3.05 520 - 28 Example 2 21.2 20.2 0.25 17.1 0 44 0 2.17 399 twenty one 32.4 Comparative Example 2 Nihon Parker Ltd.'s Palbond3500 treatment solution, non-electrolytic treatment solution (80°C), immersion for 15 minutes 50 2.5 - - - 80 Example 3 4.3 17.1 6 0.8 0 28 0 1.2 275 20.9 30.4 Comparative Example 3 7 19 4.5 2.5 0.6 twenty one 0 2.77 356 24.5 36.4 Example 4 2.8 10.1 3.8 0.4 0 18 0 2.09 338 9.1 28.7 Example 5 2.9 11 3.9 0.4 0 18 0 2.18 318 8.7 27.7

Table 9 shows the electrolytic treatment conditions of Examples and Comparative Examples. Except for Comparative Example 2, the phosphate chemical treatment liquid was filtered and circulated so that the treatment liquid was not decomposed and cloudy due to the formation of deposits. The film of Comparative Example 2 is a thick film used for lubricating treatment for cold forging. In order to obtain a thick film by non-electrolytic treatment, it is necessary to heat the treatment liquid and keep the treatment liquid at 80°C.

The electrolytic treatment condition of table 9 embodiment and comparative example Quantity processed (piece/mass) Volume of treatment tank (L) Electrolysis conditions Anodized Cathode treatment Ni electrode Fe electrode Zn electrode Example 1 8 200 9.6V×28A×cleaning for 4 seconds, hanging for 6 seconds (electrode surface area = 380cm ² /piece) --- 17.7V×51A×cleaning for 4 seconds, hanging for 105 seconds (electrode surface area=380cm ² /piece) --- Comparative Example 1 --- 25 Without electrolysis (non-electrolytic treatment: 3 minutes) Example 2 5 25 2.9V×0.01A×cleaning for 30 seconds (electrode surface area=20cm ² /piece) --- 2.9V×0.01A×cleaning for 2 minutes, passivation for 11 minutes (electrode surface area = 20cm ² /piece) 5.5V×2.5A×cleaning for 3 minutes, hanging for 10 minutes (electrode surface area = 20cm ² /piece) Comparative Example 2 --- 1000 Without electrolysis (non-electrolysis treatment: 15 minutes) Example 3 8 200 20V×20A×cleaning for 4 seconds, hanging for 6 seconds (electrode surface area=75cm ² /piece) --- 17.7V×51A×cleaning for 4 seconds, hanging for 105 seconds (electrode surface area=75cm ² /piece) --- Comparative Example 3 1 25 2.5V×1.2A×cleaning for 10 seconds, passivation for 2 seconds (electrode surface area=100cm ² /piece) --- 3V×1.3A×cleaning for 10 seconds, hanging for 10 seconds×8 passivation (electrode surface area=100cm ² /piece) --- The above anodic treatment → cathodic treatment was repeated three times Example 4 8 200 18V×19A×cleaning for 1 second, hanging for 6 seconds (1) 18V×31A×(passivation for 1 second→cleaning for 2 seconds)×13 times (2) 9V×8A×cleaning for 15 seconds, hanging for 58 seconds (electrode surface area=90cm ² /piece) (1) Passivation for 42 seconds (2) 11V×8A×cleaning for 20 seconds, hanging for 50 seconds (electrode surface area = 40cm ² /piece) --- Example 5 8 200 18V×19A×cleaning for 1 second, hanging for 6 seconds (1) 18V×30A×(passivation for 1 second → cleaning for 2 seconds)×13 times (2)7V× (1) Passivation for 2 seconds (2) 15V×16A×cleaning for 20 seconds, hanging for 50 seconds (electrode surface area = --- 0.4A×cleaning for 15 seconds, hanging for 58 seconds (electrode surface area=90cm ² /piece) 40cm ² /piece)

Example 1

The automotive air-conditioning components (clutch, stator shell) shown in the accompanying drawings are used as the parts to be treated. The stator case of FIG. 4 including a disc formed with a flat surface portion 20 (pressure foot portion) and a case formed with an outer cylindrical portion 21 (pressure formed portion) were welded and subjected to a coating evaluation test. The shell formed by the outer cylindrical portion is made by subjecting a flat plate to irregular deformation through press working. With the large amount of deformation in the process of pressure processing, part of the lubricating oil is seriously attached to the surface of the large deformation. As a result, during the surface treatment, such a phenomenon occurs that part of the lubricating oil adheres to the surface due to its large deformation. Therefore, this part has the chemical activity of blocking (hindering) the metal surface, resulting in a decrease in the performance of the surface treatment. In the example of Fig. 4, the corrosion resistance of the plating film is lowered.

Under the conditions of Tables 8 and 9, carry out phosphate chemical treatment according to the process of Table 7. In addition, the ORP values shown in Table 8 refer to potentials (mV) using an Ag/AgCl electrode as a reference electrode. When the potential of the Ag/AgCl electrode as the reference electrode is to be converted to the standard electrode potential of hydrogen as the reference, add 210mV to the value.

Conduct electrodeposition coating on the workpiece to be treated according to the initial chemical treatment process in Table 7. According to the electrodeposition coating, the anti-corrosion evaluation test of the coating is carried out on the workpiece to be treated. The corrosion resistance evaluation test of the coating film was carried out by making a scratch with a knife on the coating film on the surface of the planar part and the outer cylindrical part of the article to be treated so as to extend to the substrate and immersing it in 55°C 5 % sodium chloride solution for 240 hours. After 240 hours of immersion had elapsed, the pieces to be treated were washed with water. After allowing at least 2 hours to dry, apply the adhesive tape to the coated surface scratched with a knife and peel it off vigorously. As a result of peeling off the tape, the coating was peeled off, and the width of the peeled coating was measured and used to evaluate the corrosion resistance of the coating. The smaller the peeling width, the better its corrosion resistance. The evaluation results of corrosion resistance are compared with Comparative Example 1 and shown in Table 10.

Comparative Example 1

The same to-be-processed piece as in Example 1 was used. The process was the same as in Example 1 except that a surface modification step was added and a non-electrolytic phosphate chemical treatment process was carried out. Phosphate chemical treatment by non-electrolytic treatment, the method used is shown in Tables 8 and 9. The corrosion resistance evaluation of the coating was carried out in the same manner as in Example 1. The evaluation results of corrosion resistance are compared with Example 1 and shown in Table 10.

[Corrosion resistance evaluation results of coating]

Table 10 shows the evaluation results of the corrosion resistance of the plating film. Comparing Example 1 and Comparative Example 1, Example 1 clearly has better corrosion resistance. Also, in Example 1, although the flat surface portion showed better corrosion resistance when comparing the flat surface portion with the outer cylindrical portion, the difference was very small. However, in Comparative Example 1, there was a large difference in its corrosion resistance between the planar surface portion and the outer cylindrical surface portion. As mentioned above, this difference is the result of the reduction of the chemical treatment reaction of the metal surface during the non-electrolytic treatment due to the influence of pressure working. Since Example 1 is an example of electrolytic treatment, a large amount of electrochemical energy can be used for the electrolytic reaction. Therefore, there is no influence of pressure working, and the formed chemical film of phosphate leads to satisfactory corrosion resistance.

Table 10 Corrosion resistance evaluation results (maximum spalling width) Peeling width after salt water immersion (mm) flat surface outer cylinder Embodiment 1 (electrolytic treatment) 0 1 or less Comparative Example 1 (non-electrolytic treatment) 5 Peeling off the entire surface

[Analysis of the Phosphate Chemically Treated Thin Film Formed]

Analysis was performed between electrolytic and non-electrolytic treatments to determine differences in the films. The phosphate chemical thin films of Example 1 and Comparative Example 1 were analyzed by using energy dispersive X-ray analysis (EDX) and glow discharge analysis (GDS). The analysis is carried out on the planar surface part and the outer cylindrical part. The results are shown in Table 11.

Table 11 Some results of film analysis (chart) Thin Film Analysis (EDX) Thin Film Analysis (GDS) flat surface outer cylinder flat surface outer cylinder Example 1 Figure 5 Figure 6 Figure 9 Figure 10 Comparative Example 1 Figure 7 Figure 8 Figure 11 Figure 12

First, analyze the results of EDX. EDX gives information about surface composition elements. The thin film analysis from Fig. 5 to Fig. 8 was carried out under the same conditions.

The EDX curves of Example 1 ( FIGS. 5 and 6 ) and Comparative Example 1 ( FIGS. 7 and 8 ) were compared on the same part of the piece to be treated. Compare the flat parts. In FIG. 5 (electrolytic treatment), although the peak value of Ni is higher than that of Zn, in FIG. 7 (non-electrolytic treatment), the peak value of Zn is higher than that of Ni. This trend is also observed when comparing the outer cylindrical parts (Figs. 6 and 8).

The atomic number density analysis results of the thin films are shown in Table 12, obtained from EDX analysis under the same conditions as in FIGS. 5 to 8 . Although the atomic number density obtained from the EDX analysis results includes carbon (C) and gold (Au), since they are not thin film components, carbon and gold will be omitted in the following discussion.

(The presence of carbon is due to the use of organic solvents when cleaning the film before analysis, while gold is used to fix the test piece in the analytical instrument.) The ratio of the film composition elements is determined by calculating the ratio of each The ratio of the atomic number density of this element to the phosphorus (P) always contained in the phosphate film is determined.

Thin films are discussed in terms of the following two cases of atomic number density ratios of metal elements.

(1) Ratio of metal (Ni) not converted into phosphate/phosphorus (P) in phosphate

(2) Ratio of metal not converted to phosphate (Ni)/metal as matrix material (substrate) and metal converted to phosphate (Fe)

Table 12 The results of thin film analysis by energy dispersive X-ray analyzer (EDX) Element type Atomic density (%) Ratio of atomic number density to P Atomic Number Density Ratio C o P Fe Ni Zn Au P o Fe Ni Zn Ni/Zn Ni/Fe Zn/Fe Example 1 flat 69.4 15.3 2.9 3.3 6.1 1.9 1.2 1 5.3 1.2 2.1 0.64 3.28 1.81 0.56 cylinder 65.6 16.7 3.2 5.3 6.1 1.8 1.4 1 5.3 1.7 1.9 0.56 3.39 1.15 0.34 Comparative Example 1 flat 61.6 17.9 3.8 10.4 0.04 4.7 1.5 1 4.7 2.7 0.01 1.24 0.008 0.004 0.46 cylinder 72.4 0.9 1.6 13.3 0.2 3.2 1.3 1 5.5 8.2 0.12 1.38 0.09 0.15 0.17 Example 2 76.6 11.7 3.1 0.96 -- 5.5 2.1 1 3.8 0.3 -- 1.76 0 -- 5.68 Comparative Example 2 70.1 16.5 3.8 5.2 -- 3.3 1.1 1 4.4 1.4 -- 0.88 0 -- 0.63

(1) Ratio of metal (Ni) not converted into phosphate/phosphorus (P) in phosphate

From the atomic number density ratio of Ni/P, although the Ni density in the surface of the planar part and the outer cylindrical part of Example 1 is as high as 2.1 and 1.9, but in the surface of the planar part of Comparative Example 1 and the Ni density of the outer cylindrical part The densities of P are 0.01 and 0.12, respectively. This means that the film produced by the electrolytic treatment contains a large amount of metal that has not been converted into phosphate (Ni). On the other hand, in the case of non-electrolytic treatment, the formed film mainly contained phosphate, and the results of Comparative Example 1 can illustrate this fact. These results indicate that the metal thin film containing a large amount without forming phosphate (Ni) is suitable for surface coating treatment and improves corrosion resistance.

In addition, in Comparative Example 1, phosphorus was contained in a larger amount in the planar surface portion than in the outer cylindrical portion. The reason for this is that it is difficult to form a film on the outer cylindrical portion, and this is consistent with the fact that the phosphate chemical film is not easy to form and that the phosphate content of the main component of the film is very little.

(1) Ratio of metal not converted to phosphate (Ni)/metal as matrix material (substrate) and metal converted to phosphate (Fe)

Fe is an element that, in addition to being used as a matrix material (substrate), can also form a thin film with phosphate crystals. The Ni/Fe ratio represents the ratio of Ni to Fe in the film if the film is easy to form, and it represents the ratio of Ni to the base material when the film is not easily formed.

Although the ratio of Ni/Fe in both the planar surface and the outer cylindrical portion was 1 or higher in Example 1, the ratio of Ni/Fe in both the planar surface and the outer cylindrical portion was 1 or higher in Comparative Example 1. lower. These results also indicate that the Ni content affects the corrosion resistance of the coating.

GDS is to analyze the elements excited from the film with the glow discharge of the film, and can obtain information such as film composition elements and film strength. For this reason, GDS provides information about (1) the distribution of elements in the film and (2) the bond strength of the film. "The distribution state of elements in the film" can be read directly from the GDS curve. Furthermore, "film strength" can be obtained by comparing the amount of time to reach the iron substrate when analyzed under the same conditions. That is, the longer the time to reach the iron substrate, the higher the film strength.

In addition, when performing GDS analysis, the applied voltage varies with different elements. For this reason, the results analyzed for each film do not yield information on the "ratio existing between elements in the film". However, the analyzes performed from Fig. 9 to Fig. 12 were carried out under the same conditions. In this way, the state of elements present in the film can be compared between each sample (film).

The GDS can also be used to compare the Example (Figures 9 and 10) and the Comparative Example (Figures 11 and 12) on the same part of the article to be treated.

First, (1) The distribution states of elements in the film are compared.

For the flat surface portion, the form of Ni etc. contained in the thin film can be analyzed by looking at the curves of FIG. 9 (electrolytic treatment) and FIG. 11 (non-electrolytic treatment). Figure 9 (electrolytic treatment) shows the distribution of Ni along the entire direction of membrane permeation. On the other hand, Figure 11 (non-electrolytic treatment) shows hardly any Ni. In addition, Figure 9 (electrolytic treatment) shows that Fe atoms gradually increased in the thin film, which is considered to be that the Fe electrode (anode) used for electrolytic treatment dissolves and forms a thin film. Since the behavior of Fe is different from that of P, the incorporation of iron atoms into thin films can be predicted in the same way as Ni. Furthermore, there is a similar phenomenon with respect to the outer cylindrical portion.

Next, the bond strength of the film will be discussed. The bond strength of the film was obtained by comparing the amount of time (A) after piercing the film until the iron substrate in the GDS analysis. Those results are shown in Table 13.

Table 13 Film depth (film strength) in GDS analysis A: Time from GDS analysis until reaching the iron substrate (seconds) flat surface part outer cylindrical part Example 1 100 (Figure 9) 95 (Figure 10) Comparative Example 1 25 (Figure 11) 30 (Figure 12)

This evaluation shows that the film strength of Example 1 is three times that of Comparative Example 1, although the chemical treatment time of the pieces to be treated is almost the same.

The above results support the fact that phosphate chemical treatment of thin films involves deposition of metal (Ni) with concomitant charge exchange by electrolytic treatment, a feature of the present invention to effectively perform its role of providing corrosion resistant coatings.

In addition, as shown in Table 8, the concentration of nitrate ions in the treatment solution of Example 1 was almost 1/2 that of Comparative Example 1. This is the only possibility by electrolytic treatment of a treatment solution that does not contain sodium ions. Since the concentration of nitric acid has been reduced, the present invention is an environmentally friendly technology.

Example 2

A part for a car starter is shown in Fig. 13, which is used as the object to be treated. This member (a tubular member having a diameter of 23mm and a length of 80mm) was formed by cold forging press working and had spline-like grooves formed therein for meshing with gear teeth. It is made of an alloy containing about 1% Cr. The phosphate chemical treatment is performed to form a lubricious base for cold forging press working. Thus, the purpose of phosphate chemically treating the film is to reduce the load during the cold forging process. In this way, the evaluation of the film is also carried out according to the load during the cold forging process.

The electrolytic treatment of the pieces to be treated was carried out by using the procedure of Table 7 and carrying out the electrolytic phosphate chemical treatment under the conditions of Tables 8 and 9. In a step following the chemical treatment of Table 7, sodium stearate was reacted with the phosphate chemically treated film to form a metallic soap film (zinc stearate). It is processed according to cold forging pressure.

Comparative Example 2

Use the same parts as in Example 2 as the object to be treated. The same procedure as Example 2 was followed except that the resurfacing step by pickling was omitted and a different phosphate chemical treatment was used. Phosphate chemical treatment was performed by non-electrolytic treatment (80° C.) according to the methods shown in Tables 8 and 9. Comparative example 2 is the treatment process method of the production equipment commonly used.

[Evaluation of cold forging press working load, etc.]

The evaluation of cold forging press working load and film analysis is summarized in Table 14.

"Cold forging press working load" in Table 14 is the pressure applied during cold forging press working. The lower the numerical value of the cold forging press working load, the better the lubrication performance. In addition, film weight analysis was performed according to the following method. "Water soluble portion" means a value obtained by measuring the difference in weight of the article to be treated before and after being immersed in water at 100° C. for 10 minutes and then dividing by the surface area of the article to be treated. "Metal soap fraction" refers to a value obtained by measuring the difference in weight of an object to be treated before and after immersion in isopropyl alcohol (IPA) at 75° C. for 20 minutes and then dividing by the surface area of the object to be treated. "Phosphate film portion" refers to a value obtained by measuring the difference in weight before and after immersion in 5% chromic acid (CrO ₃ ) at 50˜70° C. for 20 minutes and dividing by the surface area of the object.

In addition, the results of analyzing the atomic number density (%) by EDX are also shown in Table 12.

Table 14 Cold forging press processing load evaluation and thin film analysis Performance evaluation (cold forging press working load) Thin film analysis (EDX curve) Film layer and gravimetric analysis (g/m ² ) water soluble part metal soap part Phosphate film part Example 2 67Kg/cm ² (average) Figure 14 10.2 11.8 14.4 Comparative Example 2 82Kg/cm ² (average) Figure 15 2.4 1.8 6.7

Evaluation of the cold forging press working load shows that Example 2 is better than Comparative Example 2. The reason for this is apparent from Table 14 "Film Layer and Gravimetric Analysis Results". According to the "Film Layer and Gravimetric Analysis Results" in Table 14, the film of Example 2 contains nearly 5 times the amount of metal soap as that of Comparative Example 2. Metal soap has a great contribution to the lubrication of cold forging and pressure processing. Thus, it is obvious that the higher the content of this component, the greater the load that reduces the cold forging press working.

Since the metal soap part is zinc stearate, a large amount of zinc must be present in the film. The amount of zinc contained in the film can be determined by EDX analysis results. When comparing the curves of FIGS. 14 and 15, except for Example 2 (FIG. 14), which is an electrolytically treated film containing a small amount of Fe, it was also confirmed that it contained a large amount of Zn. In addition, this was quantitatively compared and confirmed in the analysis results of EDX atomic number density (%) in Table 12. If the chemical structure of the phosphate chemical thin film is set to be Zn ₃ (PO ₄ ) ₂ , the atomic number density ratio of Zn to P (Zn/P) is 1.5. The atomic number density ratio of Zn/P in Example 2 calculated from Table 12 becomes 1.76, which indicates that there is an excess amount of Zn relative to Zn ₃ (PO ₄ ) ₂ . However, the ratio becomes 0.88 in Comparative Example 2, which means that the amount of Zn relative to Zn ₃ (PO ₄ ) ₂ is small.

These findings suggest that electrolytic treatment can alter the composition of the film. That is, they are considered to have an excess amount of Zn relative to Zn ₃ (PO ₄ ) ₂ and transform into thin films in the form of metallic Zn with charge exchange. This is a result that can only be produced in the electrolytic treatment of the present invention. This is also a great contribution to reducing the cold forging press working load.

In addition, the results of analysis in Table 12 show that the film of Example 2 is a film completely free of Ni, a metal that does not form phosphate. Electrolytic phosphate chemistry can also be made possible by the absence of metals that do not form phosphates in this process.

Embodiment 3 and Comparative Example 3

Example 3 and Comparative Example 3 were used to confirm that different thin films can be formed by electrolytic treatment.

The automotive air-conditioning parts used in Example 1 and Comparative Example 1 are used as the treated parts of Example 3 and Comparative Example 3, and the phosphate chemical treatment and electrodeposition coating are carried out according to the process in Table 7. Under the conditions of Tables 8 and 9, electrolytic phosphate chemical treatment was carried out. The main difference between Example 3 and Comparative Example 3 is the phosphate chemical treatment solution. Although the treatment liquid of Example 3 did not contain Na ions, the treatment liquid of Comparative Example 3 contained Na ions. Evaluation of the corrosion resistance of the coating films of Example 3 and Comparative Example 3 was carried out in the same manner as in Example 1 and Comparative Example 1. Those results are shown in Table 15.

Table 15 Evaluation results of coating corrosion resistance (maximum peeling width) The difference of treatment liquid Peeling width after salt water immersion test (mm) flat surface outer cylinder Example 3 Does not contain Na ions 0 5 Comparative Example 3 There are Na ions 1 10

The results in Table 15 show that the coating film of Example 3 has better corrosion resistance than that of Comparative Example 3.

This difference is thought to be due to the formation of different phosphate chemical films. Table 16 shows the X-diffraction pattern results of the phosphate chemical films of Example 3 and Comparative Example 3.

Table 16 X-diffraction pattern results of thin films flat surface part outer cylindrical part Example 3 No phosphate crystal diffraction peaks (see Figure 16) There is no phosphate crystal diffraction peak, but there is a Ni diffraction peak (small) (see Figure 17) Comparative Example 3 There are phosphate crystal diffraction peaks (see Figure 18) There are phosphate crystal diffraction peaks (see Figure 19)

The relevant differences of the phosphate chemistry films of Example 3 and Comparative Example 3 include the following:

(1) Presence or absence of phosphate crystal diffraction peaks

(2) Existence or absence of diffraction peaks of Ni

The results in Table 16 do not indicate that the film of Example 3 does not contain phosphate crystals. It means that the phosphate crystals are very tiny. It also indicates such a result that the combination of Ni metal and phosphate crystals is going on.

Table 17 summarizes the combination of Ni metal and phosphate crystals that was going on to form the Example 3 film.

Table 17 Elements along the film cross-section direction by EPMA (electron microprobe analysis)

Analyze photos SEM image (4000×) Elemental Analysis Photos Phosphorus (P) Zinc (Zn) Nickel (Ni) Iron (Fe) flat surface Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 outer cylinder Figure 25 Figure 26 Figure 27 Figure 28 Figure 29

The distribution state of each element in the cross section of the film as shown in the SEM photographs of Fig. 20 and Fig. 25 magnified by 4000× is shown in the analysis photographs (Fig. 21 to Fig. 24 and Fig. 26 to Fig. 29). These photographs show that each element is uniformly distributed in the film. It can also be seen from these photographs that although the film contains phosphate, its crystals are very fine (results in Table 16).

Furthermore, these results are clearly consistent with the GDS analysis results shown in Example 1 (Table 12 and Figures 9 and 10).

The results from Table 15 show that the film obtained from the treatment solution containing no sodium ions of Example 3, in which Ni is very finely distributed in the phosphate crystals, is effective in improving the corrosion resistance of the plating film.

In addition, as an example in the prior art of electrolytic phosphate chemical treatment, the X-ray diffraction pattern of Japanese Unexamined Patent Application Publication (Saikohyo) No. 5-822481 shows a diffraction peak of phosphate.

Examples 4 and 5

Examples 4 and 5 are examples where Ni is easily formed on the substrate coated with the phosphate of the present invention, reducing a large amount of electrolytic Fe and tending to deteriorate the treatment solution as much as possible. Thus, only the electrolysis of Ni proceeds at the beginning of the cathodic electrolytic treatment, and thereafter there is simultaneous electrolysis of Ni and Fe. At that time, the amount of electrolytic Fe was 1/3-1/8 less than that of Example 3.

The automotive air-conditioning parts used in Example 3 were used as the parts to be treated in Examples 4 and 5, and the phosphate chemical treatment and electrodeposition coating were carried out according to the process in Table 6. Under the conditions of Tables 8 and 9, electrolytic phosphate chemical treatment was carried out.

Evaluation of the corrosion resistance of the coatings of Examples 4 and 5 was carried out in the same manner as in Example 1. Those results are shown in Table 18.

Table 18 Evaluation results of coating corrosion resistance (maximum peeling width) Peeling width after salt water immersion test (mm) flat surface outer cylinder Example 4 0 2 Example 5 2 4

The corrosion resistance of Examples 4 and 5 is better than that of Comparative Example 3. As explained in Example 1, in the case of non-electrolytic treatment, it is difficult to form a thin film on the outer cylindrical portion. If the electrolytic treatment of the present invention was carried out in Examples 4 and 5, even on the same surface, it was converted to a film formation, indicating that the corrosion resistance could be secured.

Next, the EDX analysis results of the phosphate chemical thin films obtained in Examples 4 and 5 are shown.

Table 19 Analysis results of thin films by using energy dispersive X-ray analyzer (EDX) elemental form Atomic density (%) Ratio of atomic number density (to P) Atomic Number Density Ratio P Fe Ni Zn P Fe Ni Zn Ni/Zn Ni/Fe Zn/Fe Example 4 flat surface 19 62.8 9.6 8.61 1 3.31 0.51 0.45 1.13 0.15 0.13 outer cylinder 9.7 77.7 7.3 5.3 1 8.01 0.75 0.55 1.36 0.09 0.07 Example 5 flat surface 19.9 51.9 15.4 12.9 1 2.61 0.77 0.64 1.20 0.30 0.24 outer cylinder 26.8 40 25.1 8.6 1 1.49 0.94 0.32 2.94 0.63 0.21

Comparing the results in Table 19 with those in Table 12, the tendency of the composition ratio of elements is not that the matrix substance (Fe) does not change. Although both Ni and P are contained in the film, they are present at a ratio (Ni/P) of 0.5 or higher in both Table 12 and Table 18, indicating that the amount of Ni present in the film is 1/4 higher than that of P . This result also shows that this film is very different from the film obtained by electroless treatment with Ni/P ratio much smaller than 0.25 (see Table 12).

The examples of Examples 4 and 5 show examples of cathodic electrolytic treatment using two electrodes of Fe and Ni. They also show that this approach works.

Claims (38)

1. one kind has on pending the surface of electroconductibility by electrolysis treatment, form and contain a kind of phosphoric acid salt and a kind of electrolytic phosphate chemical treatment method that does not form the film of said phosphatic metal at least, this method is, said pending is contacted with a kind of phosphate chemical treatment solution, and described phosphate chemical treatment solution contains phosphate anion and phosphoric acid at least, nitrate ion, form the metal ion of complex compound with phosphate anion in the said phosphate chemical treatment solution, and be dissolved in the described phosphate chemical treatment solution, and its be reduced and with the sedimentary current potential of metallic forms more than or equal to the current potential of the anode electrolysis of water solvent reaction or more than or equal to the metal ion of-0.83V; The method is characterized in that:

The content of other metal ion in the said phosphate chemical treatment solution except those thin film compositions is 0～400ppm, and does not contain the solid that influential film forms reaction in the treatment solution fully; With

By in said phosphate chemical treatment solution, using following metallics to carry out electrolysis treatment to pending:

Can with phosphate anion in the said phosphate chemical treatment solution form complex compound metallics and

It is dissolved in current potential that the metal ion in the said phosphate chemical treatment solution reacts more than or equal to the anode electrolysis of water solvent with metallic forms reduction and sedimentary current potential or more than or equal to the metallics of-0.83V.

2. the described electrolytic phosphate chemical treatment method of claim 1 is characterized in that in the said phosphate chemical treatment solution, the content of other metal ion except those thin film compositions is 0～100ppm.

3. the described electrolytic phosphate chemical treatment method of claim 1, the concentration that it is characterized in that said nitrate ion in the said phosphate chemical treatment solution be that 6～140g/l, said phosphate anion and concentration of phosphoric acid are 0.5～60g/l, the concentration that forms the metal ion of complex compound with phosphoric acid salt in said phosphate chemical treatment solution is 0.5～70g/l and be dissolved in the said phosphate chemical treatment solution, be 0～40g/l with the concentration of metallic forms reduction and deposited metal ions.

4. the described electrolytic phosphate chemical treatment method of claim 3 is characterized in that said phosphate chemical treatment solution does not contain the acid of dissociation constant greater than the dissociation constant of said phosphate anion.

5. the described electrolytic phosphate chemical treatment method of claim 1 is characterized in that forming with metal ion at least a metal ion in a group below being selected from of said phosphate anion formation complex compound in said phosphate chemical treatment solution: Zn ion, Fe ion, Mn ion and Ca ion.

6. the described electrolytic phosphate chemical treatment method of claim 1 is characterized in that describedly being dissolved in the said phosphate chemical treatment solution and being reduced and being made up of at least a metal ion that is selected from following a group with the metallic forms deposited metal ions: Ni ion and Cu ion.

7. the described electrolytic phosphate chemical treatment method of claim 1, wherein said phosphate chemical treatment method is that catholyte is handled, use said pending to carry out electrolysis as negative electrode, it is characterized in that comprising a kind of circulation, this circulation comprises a kind of electrolysis treatment, adopt in the described electrolysis treatment be dissolved in said phosphate chemical treatment solution in and be reduced the metallics identical with deposited metal ions and/or with a kind of conducting material of said phosphate chemical treatment solution that is not dissolved in as anode; Subsequently, carry out another kind of electrolysis treatment, wherein use with the metallographic phase that in said phosphate chemical treatment solution, forms complex compound with metallics as anode; And this circulation is carried out once at least.

8. the described electrolytic phosphate chemical treatment method of claim 1, wherein said phosphate chemical treatment method is that catholyte is handled, use said pending to carry out electrolysis as negative electrode, it is characterized in that, electrolysis is being carried out in as the anodic electrolyzer with a kind of conducting material that is not dissolved in the phosphate chemical treatment solution and is being carried out electrolysis with a kind of metal that can form complex compound in said phosphate chemical treatment solution in as the anodic electrolyzer respectively.

9. one kind has on pending the surface of electroconductibility by electrolysis treatment, form the electrolytic phosphate chemical treatment method that contains a kind of phosphatic film at least, this method is, said pending is contacted with a kind of phosphate chemical treatment solution, described phosphate chemical treatment solution contains phosphate anion and phosphoric acid, nitrate ion at least and forms the metal ion of complex compound with phosphate anion in the said phosphate chemical treatment solution, it is characterized in that:

The content of other metal ion of said phosphate chemical treatment solution except those are said thin film composition is 0～400ppm, and does not contain the solid that influential film forms reaction in the treatment solution fully; With

By using the metallics that can form complex compound to carry out electrolysis treatment to said pending with the phosphate anion in the said phosphate chemical treatment solution.

10. the described electrolytic phosphate chemical treatment method of claim 9 is characterized in that in the said phosphate chemical treatment solution, and the content of other metal ion except those form the composition that contains phosphatic film at least is 0～100ppm.

11. the described electrolytic phosphate chemical treatment method of claim 9, the concentration that it is characterized in that said nitrate ion in the said phosphate chemical treatment solution are 6～140g/l, said phosphate anion and concentration of phosphoric acid is that the concentration that phosphoric acid salt in 0.5～60g/l, the said and phosphate radical chemical pretreatment solution forms the metal ion of complex compound is 0.5～70g/l.

12. the described electrolytic phosphate chemical treatment method of claim 9 is characterized in that said phosphate chemical treatment solution does not contain the acid of dissociation constant greater than the dissociation constant of said phosphate anion.

13. the described electrolytic phosphate chemical treatment method of claim 12 is characterized in that be nitric acid in said dissociation constant greater than the acid of the dissociation constant of said phosphate anion.

14. the described electrolytic phosphate chemical treatment method of claim 9 is characterized in that forming with metal ion at least a metal ion in a group below being selected from of said phosphate anion formation complex compound in said phosphate chemical treatment solution: Zn ion, Fe ion, Mn ion and Ca ion.

15. claim 1 or 9 described electrolytic phosphate chemical treatment methods is characterized in that adopting said pending to carry out electrolysis as anode.

16. claim 1 or 9 described electrolytic phosphate chemical treatment methods is characterized in that adopting said pending to carry out electrolysis as negative electrode.

17. claim 1 or 9 described electrolytic phosphate chemical treatment methods is characterized in that adopting said pending to carry out electrolysis as anode, adopt said pending to carry out electrolysis as negative electrode subsequently.

18. claim 1 or 9 described electrolytic phosphate chemical treatment methods, during wherein catholyte is handled, the electrolysis of said phosphate chemical treatment method is to use said pending to carry out as negative electrode, comprising at least a electrolysis in the following electrolysis:

With be dissolved in the said phosphate chemical treatment solution and be reduced with the same metallics of sedimentary metal as anode, or be not dissolved in conducting material in the said phosphate chemical treatment solution as the anodic electrolysis with a kind of; With

Can in the phosphate chemical treatment solution, form the metallics of complex compound with a kind of as the anodic electrolysis.

19. the described electrolytic phosphate chemical treatment method of claim 18, it is characterized in that, said be dissolved in said phosphate chemical treatment solution in, form by at least a metal that is selected from following a group with the metallic forms reduction metallics identical with deposited metal ions: Ni and Cu.

20. the described electrolytic phosphate chemical treatment method of claim 18 is characterized in that, the metallics at least a metal in a group below being selected from that forms complex compound in said phosphate chemical treatment solution is formed: Zn, Fe, Mn and Ca.

21. claim 1 or 9 described electrolytic phosphate chemical treatment methods, it is characterized in that said pending not with situation that said phosphate chemical treatment solution contacts under, with a metallics as negative electrode, described metallics is being used as in the electrolysis treatment of negative electrode as anode pending, and a material that is not dissolved in the said phosphate chemical treatment solution is used as anode, and between said anode and said negative electrode, apply a 5V or lower voltage.

22. claim 1 or 9 described electrolytic phosphate chemical treatment methods, it is characterized in that said pending not with situation that said phosphate chemical treatment solution contacts under, with a metallics as negative electrode, described metallics is being used as in the electrolysis treatment of negative electrode as anode pending, and with a material that is not dissolved in said phosphate chemical treatment solution as anode, and between said anode and said negative electrode, apply one and make the complete undissolved voltage of said negative electrode.

23. claim 1 or 9 described electrolytic phosphate chemical treatment methods, it is characterized in that from the groove that fills said phosphate chemical treatment solution, taking out a part of said phosphate chemical treatment solution, make the energy state of this portion phosphate chemical pretreatment solution reach Thermodynamically stable, and subsequently said part is turned back in the said groove.

24. the described electrolytic phosphate chemical treatment method of claim 23, it is characterized in that from the groove that fills said phosphate chemical treatment solution, taking out a part of said phosphate chemical treatment solution, and will form the solid that is deposited in the reaction process in the said phosphate chemical treatment solution at film and remove, and said part will be turned back in the said groove.

25. the described electrolytic phosphate chemical treatment method of claim 23, it is characterized in that in the time will replenishing the composition of said phosphate chemical treatment solution, the said phosphate chemical treatment solution of a part is removed, and will replenish liquid and join in the said phosphate chemical treatment solution, and have at least a kind of concentration of composition to be higher than the concentration of this composition in the said phosphate chemical treatment solution in the composition of the treatment solution that described additional liquid contained.

26. electrolytic phosphate chemical treatment method, wherein use pending to carry out electrolysis treatment as negative electrode, it is characterized in that, comprising a kind of reaction, in this reaction, be dissolved in the phosphate chemical treatment solution, and it is reduced with metallic forms and sedimentary current potential is reduced and is deposited on said pending the surface from the positively charged ion state by electrolysis treatment more than or equal to the current potential of the anode electrolysis of water solvent reaction or more than or equal to the metal ion of-0.83V, and a kind of reaction, wherein with the phosphate chemical treatment solution in the metal ion of phosphate anion complexing deposit with phosphate crystal, correspondingly, phosphate anion generation dehydrogenation reaction.

27. the described electrolytic phosphate chemical treatment method of claim 26 is characterized in that said and the metal ion phosphate anion complexing is at least a metal ion that is selected from following a group: Fe ion, Zn ion, Mn ion, Ca ion and Mg ion.

28. the described electrolytic phosphate chemical treatment method of claim 26 is characterized in that the said metal ion that is dissolved in the said phosphate chemical treatment solution is made up of at least a metal ion that is selected from following a group: Ni ion, Cu ion, Fe ion and Zn ion.

29. claim 1, one of 9 and 26 described electrolytic phosphate chemical treatment methods, it is characterized in that when carrying out electrolysis treatment, the composition of treatment solution is such, with the ratio of the concentration (g/l) of the metal ion of phosphate anion complexing and phosphate anion and concentration of phosphoric acid (g/l) be 0.1～100.

30. claim 1, one of 9 and 26 described electrolytic phosphate chemical treatment methods, wherein use said pending to carry out electrolysis treatment as negative electrode, it is characterized in that, in the initial stage of said electrolysis treatment, the voltage that is applied between anode that is made of metallics and negative electrode changes with impulse form.

31. the lip-deep laminated film at steel is characterized in that, it does not form phosphatic metal and a kind of phosphate compounds is formed by a kind of, and the metal of wherein said formation film and phosphate compounds are to be dispersed in the whole film.

32. the lip-deep laminated film at steel is characterized in that, it does not form phosphatic metal and a kind of phosphate compounds is formed by a kind of, wherein has at least in the outermost of film surface a kind ofly not form phosphatic metal and exist.

33. lip-deep laminated film at steel, it is characterized in that, it does not form phosphatic metal and a kind of phosphate compounds is formed by a kind of, and wherein said film other diffraction peak do not occur except inevitable phosphoric acid salt diffraction peak in X one x ray diffraction analysis x.

34. lip-deep laminated film at steel, it is characterized in that, it does not form phosphatic metal and a kind of phosphate compounds is formed by a kind of, and the atomicity that does not wherein form phosphatic metal is to form 0.25 times of the phosphorus atom number of phosphate crystal or higher.

35. the described laminated film of one of claim 31 to 34 is characterized in that, does not saidly form phosphatic metal and is selected from following one group of metal: Ni, Cu, Fe and Zn.

36. the described laminated film of one of claim 31 to 34 is characterized in that, the metal of described formation phosphate compounds is selected from following one group of metal: Fe, Zn, Mn, Ca and Mg.

37. the described laminated film of one of claim 31 to 34 is characterized in that, when with the total amount of steel during as 100% weight, said steel contains the iron of 95% weight at least.

38. the described laminated film of claim 33 is characterized in that, said X-ray diffraction analysis is analyzed by ESCA or EDX and is carried out.

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