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
  • C23C22/362—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 also zinc 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
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/14—Orthophosphates containing zinc cations containing also chlorate anions

Definitions

• the invention relates to a process for phosphating metals, in particular iron and steel, with aqueous acidic oxidizing agent-containing zinc phosphate solutions, and to the use thereof for preparing the metal surfaces for electrocoating.
• the reduced zinc content compared to the usual phosphating baths leads to improved thin and uniform phosphate coatings on metal surfaces, especially on iron and steel. These coatings are very adhesive and durable and are particularly suitable as a basis for the subsequent electrocoating.
• the object of the invention is to provide a process which avoids the known disadvantages, in particular those mentioned with reference to DE-OS 22 32 067, and leads to phosphate layers which, while maintaining the very good properties of the layers, e.g. as the basis for a subsequent painting, which shows the desired wet corrosion resistance of the phosphate layers.
• iron and steel are treated with the method according to the invention.
• it is also suitable for the phosphating of zinc and aluminum materials and for steel with coatings made of zinc, zinc alloys, Aluminum and aluminum alloys.
• the metal surfaces can be treated by spraying, flooding and also immersion. However, it is also possible with combined working methods, e.g. Spray-dive-spray, flood-dive and the like are applicable.
• the contact times for the phosphating solution with the metal surface are in the usual range and can e.g. for spraying 45 seconds to 3 minutes, for diving 2 to 5 minutes and for spray-immersion spraying 20 seconds spraying, 3 minutes diving, 20 seconds spraying.
• the bath temperatures are usually 40 to 70 ° C, preferably 50 to 60 ° C. If the contact times are extended, however, they can also be reduced to 30 ° C and below.
• the phosphating bath essentially only contains alkali metal ions, in such an amount as is necessary to adjust the ratio of free to total P 2 0 5 required for the phosphating.
• This acid ratio is usually between 0.04 and 0.09, and it increases with increasing bath temperature, increasing total concentration and increasing amount of zinc in relation to P 2 0 5 .
• small quantities may also be present; these include in particular ammonium, calcium, manganese, copper and cobalt.
• nickel to the bath has a favorable effect on the rate of phosphating, the formation of layers on steel surfaces that are difficult to phosphate and on the phosphating of zinc surfaces.
• the nickel concentration is no more than 1.5 times the zinc concentration.
• the known advantage of the weight ratio of Zn to P 2 0 5 should lie in particular in the fact that, compared to phosphating processes based on zinc phosphate, in which the ratio of Zn to P 2 0 5 is higher, a zinc phosphate coating with a higher iron content is formed, which is more acid-resistant is. This reduces the amount of phosphate coating detachment that occurs, for example, when the pH value at the interface decreases during electrocoating. As a result, smaller amounts of layers get into the lacquer film, so that the associated disadvantageous influence on the film is significantly reduced. Since the solutions according to the invention lead to uniformly fine coatings with a low layer weight, the electrical resistance at the interface is lower, so that the lacquer film is deposited in a particularly adhesive manner.
• the concentration is between 50 and 500 mg / l, with the low to medium concentrations preferably at work temperatures of 50 to 60 0 C are used, while the higher contents are used at lower bath temperatures.
• nitrobenzenesulfonate e.g. is used in concentrations between 200 and 2000 mg / l. The best results are generally found at levels of 300 to 700 mg / l.
• the baths can contain SiF 6 - , for example in amounts up to 1.5 g / l, and / or F - , for example in amounts up to 0.8 g / l. It is also possible to use other complex fluorides, eg BF 4 - .
• the phosphate layers produced with the method according to the invention are in principle suitable for all types of use of the phosphate layers known to date. In particular, however, they have proven themselves as a preparation for electrocoating, the best results being achieved in connection with cathodic electrocoating.
• the method according to the invention finds practical application e.g. for the phosphating of car bodies.
• Sheet steel test specimens degreased with mildly alkaline aqueous spray and dip cleaner at 60 ° C. and for 3 minutes were rinsed in water, then firstly sprayed for 20 seconds and then treated with the following phosphating bath at 55 ° C. for 180 seconds:
• This bath has the following titration data:
• test specimens were then rinsed with water, rinsed with a rinse solution containing chromium and dried.
• the phosphate layers were uniformly gray opaque, extremely fine crystalline and had a weight per unit area of 1.8 g / m 2 . This also applied to the surfaces of the test specimen, which were not hit by the spray jet due to the special form of treatment, but were only treated in diving. The test specimens could be exposed to the nitrous gas-containing vapor space above the phosphating bath significantly more than 1 min after the phosphating, without rusting the surface. Test specimens which had been phosphated in the claimed amounts without the addition of N0 3 and C10 3 proved to be particularly sensitive to rust, particularly in the places accessible only by immersion treatment.

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• 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)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Catalysts (AREA)
• Saccharide Compounds (AREA)
• Glass Compositions (AREA)
• Laminated Bodies (AREA)
• Materials For Medical Uses (AREA)
• Secondary Cells (AREA)
• Manufacture And Refinement Of Metals (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Cited By (3)

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Citations (2)

• 1980
  • 1980-04-30 DE DE19803016576 patent/DE3016576A1/de not_active Withdrawn
• 1981
  • 1981-03-13 AT AT81200286T patent/ATE5332T1/de not_active IP Right Cessation
  • 1981-03-13 DE DE8181200286T patent/DE3161398D1/de not_active Expired
  • 1981-03-13 EP EP81200286A patent/EP0039093B1/fr not_active Expired
  • 1981-04-28 GB GB8113014A patent/GB2074611B/en not_active Expired
  • 1981-04-28 ES ES501701A patent/ES501701A0/es active Granted
  • 1981-04-29 PT PT72944A patent/PT72944B/fr unknown
  • 1981-04-29 IT IT8121425A patent/IT1207959B/it active
  • 1981-04-29 BR BR8102619A patent/BR8102619A/pt unknown

Patent Citations (2)

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