Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
  • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
  • C23C22/368—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing magnesium cations
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/18—Orthophosphates containing manganese cations
  • C23C22/188—Orthophosphates containing manganese cations containing also magnesium cations

Definitions

• the invention relates to a process for applying phosphate coatings to workpieces made of steel with the aid of phosphating solutions containing acidic, aqueous manganese, phosphate, nitrate and possibly iron (II) ions, and to the use of the process for the treatment of sliding friction Workpieces.
• Manganese phosphate coatings have proven themselves well for various applications, for example reducing the friction of metal surfaces sliding on one another or facilitating the cold forming of metals, because of their high mechanical resistance. With the initially common manganese phosphate solutions, however, relatively thick, coarsely crystalline layers were obtained, which are particularly disadvantageous when precision mechanical parts are to be treated. Numerous proposals have therefore been made with the aim of producing thin, fine-crystalline manganese phosphate coatings. For example, it is known to obtain a refinement of the phosphate layer by adding condensed phosphates.
• phosphating solutions based on manganese phosphate are generally used at high temperatures, so that owing to the considerable hydrolysis at high temperatures, the effectiveness of the condensed phosphates quickly decreases or the condensed phosphate must be replenished continuously.
• the German Auslegeschrift 1 109 484 describes another way to achieve fine-grained phosphate coatings. Thereafter, nitrate-containing phosphate solutions are used in which the amount of nitrate exceeds the amount of phosphate. The solutions should have a ratio of nitrate to phosphate of approximately (1.5 to 4.5): 1. However, it was found that in many cases the intended effect is not achieved.
• a phosphating solution based on manganese phosphate or manganese iron phosphate in which the concentrations with respect to manganese, iron (II), phosphate and nitrate ions are within certain limits, more free P2O5 in relation to the total P2O5 to supply than the phosphating equilibrium in the working phosphating solution corresponds.
• the above measure is said to have the advantage that a significant reduction in the sludge formed in the phosphating and a reduction in the chemicals required to produce a certain amount of coating is achieved (DE-B-22 13 781).
• nickel was considered an indispensable component of the phosphating solutions.
• the advantages of nickel are that the pickling attack on the base material is evened out and the resulting improvement in the adhesion of the phosphate layer obtained.
• the nickel ion content improves the optical appearance of the phosphate layer produced owing to a generally desired darkening.
• the nickel content in the phosphating solutions and of nickel or nickel compounds in the phosphate layers formed has disadvantages insofar as nickel and nickel compounds are from the point of view of Workplace hygiene and environmental protection are to be classified as questionable.
• the object of the invention is therefore to provide a process for applying phosphate coatings to workpieces made of steel with the aid of phosphating solutions containing acidic, aqueous manganese, phosphate, nitrate and possibly iron (II) ions, which has the disadvantages of the known, in particular does not have the abovementioned processes, in particular is nickel-free, but despite the absence of nickel leads to phosphate layers, the quality of which practically equates to that which is achieved with phosphating solutions containing nickel ions.
• the above-mentioned total number of points is determined by titrating 10 ml of the phosphating solution after dilution with water to about 50 ml using phenolphthalein as an indicator until the color changes from colorless to red.
• the number of ml 0.1 n sodium hydroxide solution used for this gives the total number of points.
• Other indicators suitable for titration are thymolphthalein and ortho-cresolphthalein.
• the electrical indication with a pH of 8.5 can also be used as an end point.
• the weight ratio Mn: Mg (5 to 50): 1 achieves a maximum layer weight with a minimum of pickling removal.
• a further advantageous embodiment of the invention provides for the workpieces to be brought into contact with a phosphating solution which additionally contains complexing carboxylic acid, such as citric acid or tartaric acid, in a concentration of 0.1 to 2.0 g / l.
• the complexing agent additive in particular prevents clouding of the phosphating solution.
• the workpieces come into contact with the phosphating solution preferably at a temperature in the range from 75 to 95 ° C.
• the workpieces can be brought into contact with the phosphating solution in any way, preferably the immersion treatment.
• the treatment time is generally 1 to 15 minutes.
• phosphate coatings with a layer weight of generally 5 to 25 g / m 2 are achieved.
• the phosphate coatings produced with the invention can be painted in a manner known per se or can be provided with plastic coatings. In conjunction with anti-corrosion oils, they serve to increase rust resistance.
• the main application of the method according to the invention is, however, in the treatment of workpieces that are exposed to sliding friction.
• Gear parts made of steel were first degreased with a strongly alkaline, aqueous cleaner in immersion, then rinsed with water, then rinsed in a slurry of finely divided manganese phosphate and finally phosphated in a phosphating solution at a temperature of 80 ° C. for a period of 10 min in immersion.
• the phosphating solution contained: 11.8 g / l manganese 0.5 g / l magnesium 0.1 g / l iron (II) 36 g / l phosphate (calculated as P2O5) 4.6 g / l nitrate and 0.36 g / l citrate (calculated as citric acid).
• the total score of the phosphating solution was 80, the score of free acid 11 points (measured with 60 g concentrate per 1 liter of water). To determine the total number of points, reference is made to the explanations above.
• 10 ml bath solution after dilution to approx. 50 ml with dist. Water, possibly with the addition of K3 (Co (CN) 6) or K4 (Fe (CN) 6) to remove interfering metal cations, using dimethyl yellow as an indicator with n / 10 NaOH until pink changes titrated for yellow.
• the ml n / 10 NaOH consumed give the free acid. They are often referred to as the Free Acid Score (FS).
• FS Free Acid Score

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Materials For Medical Uses (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6533058

Family Applications (1)

Country Status (5)

Cited By (4)

Families Citing this family (3)

Citations (11)

• 1994
  • 1994-11-11 DE DE4440300A patent/DE4440300A1/de not_active Withdrawn
• 1995
  • 1995-10-10 DE DE59501279T patent/DE59501279D1/de not_active Expired - Lifetime
  • 1995-10-10 AT AT95115909T patent/ATE162232T1/de active
  • 1995-10-10 DK DK95115909.4T patent/DK0711849T3/da active
  • 1995-10-10 ES ES95115909T patent/ES2112593T3/es not_active Expired - Lifetime
  • 1995-10-10 EP EP95115909A patent/EP0711849B1/fr not_active Expired - Lifetime

Patent Citations (13)

Also Published As

Similar Documents

Legal Events