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
  • C23C22/07—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
  • C23C22/182—Orthophosphates containing manganese cations containing also zinc cations
  • C23C22/184—Orthophosphates containing manganese cations containing also zinc cations containing also nickel 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
• • 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

Definitions

• the invention relates to a process for phosphating metals, in particular iron and steel, with aqueous acidic, chlorate-containing zinc phosphate solutions at temperatures from 30 to 60 ° C. 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, which are very adhesive and durable and are particularly suitable as a basis for the subsequent electrocoating. In this process, it has proven to be very advantageous to additionally use nitrite in order to achieve the desired results.
• DE-OS 30 04 927 discloses a process for phosphating metals which are subsequently electroplated, in which acidic aqueous zinc phosphate solutions are also used.
• the solutions contain nitrite ions and / or aromatic nitro compounds as accelerators.
• the phosphating is carried out in a special immersion / spray process.
• the preferred embodiment of the process also provides for baths containing nitrite to be used.
• nitrite which is preferably used leads to the formation of nitrous gases which are known to be toxic and have an unpleasant smell. Suction measures are therefore essential to ensure occupational safety.
• the object of the invention is to provide a method which does not have the disadvantages of the known methods, requires little heating energy because of the low application temperatures and is simple to carry out.
• the method according to the invention is intended in particular for the treatment of iron and steel. However, it is also suitable for the phosphating of zinc and aluminum materials as well as for steel with coatings made of zinc, zinc alloys, aluminum and aluminum alloys produced using a wide variety of processes.
• the metal surfaces can be treated by spraying, flooding and also immersion. However, it is also with combined working methods, e.g. B. splash-dip-spray, flood-dive and the like applicable.
• the contact times for the phosphating solution with the metal surface are in the usual range and can, for. B. for spraying 45 sec to 3 min, for diving 2 to 5 min and for syringe diving 20 sec spraying, 3 min diving.
• the bath temperatures are 30 to 60 ° C. The lower the bath temperature, the longer i. a. the contact time.
• the addition of nickel to the bath generally has a favorable effect on the rate of phosphating, the formation of layers on steel surfaces that are difficult to phosphate, on the phosphating of zinc surfaces and on the corrosion protection properties.
• the ratio of free P 2 O 5 to total P 2 O 5 in the bath must be kept between (0.005 to 0.06): 1 in order to produce uniformly covering phosphate layers.
• the phosphating rate becomes slower, at the same time the quality of the phosphate layers decreases.
• a Falling below the specified values leads to excessive precipitation of zinc phosphate sludge and is undesirable for this reason alone.
• the low values of the ratio of free P 2 O 5 to total P 2 O 5 (acid ratio) in the range according to the invention apply to the lower bath temperatures (low Zn / P 2 0 5 ratio and low total concentration); the higher acid ratios relate to higher bath temperatures (higher Zn / P 2 0 5 ratios and higher total concentrations).
• the optimal acid ratio for a particular bath of the invention can easily be estimated or determined by experiment.
• the weight ratio of free P 2 O 5 to total P 2 O 5 is preferably set to (0.005 to 0.03): 1, in particular (0.005 to 0.027): 1 for the temperature range from 30-45 ° C. and to (0, 03 to 0.06): 1 set for the temperature range of 45-60 ° C.
• One embodiment of the invention consists in bringing the metal surfaces into contact with solutions which contain 0.8 to 1.2 g / l of Zn.
• phosphating solutions which contain up to 0.7 g / l, in particular 0.2 to 0.5 g / l, of Mn.
• the use of manganese has proven to be particularly beneficial in phosphating in the low temperature range.
• the layer formation can be improved by adding simple and / or complex fluorides.
• the solutions for reducing the phosphate layer weight can also contain compounds known per se, such as hydroxycarboxylic acids (e.g. tartaric acid, citric acid), polyphosphates (e.g. tripolyphosphate, hexametaphosphate).
• hydroxycarboxylic acids e.g. tartaric acid, citric acid
• polyphosphates e.g. tripolyphosphate, hexametaphosphate.
• the necessary acid ratio is essentially set only with alkali metal ions.
• Other cations e.g. B. calcium, copper and cobalt, however, should only be present in minor amounts.
• the weight per unit area of the phosphate layers produced by the process according to the invention is generally in the range between 0.8 and 4 g / m 2 .
• activating agents e.g. B. on titanium phosphate basis, in the pre-rinse bath or in / the last cleaning stage.
• the phosphate layers produced by the method according to the invention are suitable in principle for all types of use of the phosphate layers known to date.
• the layers bring about an unusually strong improvement in the resistance of the coating film against the infiltration of the coating in the event of corrosive stress and a significant increase in the adhesion of the coating to the metallic substrate.
• the sheets were rinsed with water, rinsed with a rinse solution containing chromic acid and then coated with anodic and cathodic electrocoat.
• the application tests such as salt spray test, condensation test, rockfall text and outdoor exposure, led to very good results.

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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)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Paints Or Removers (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 1981
  • 1981-01-22 DE DE19813101866 patent/DE3101866A1/de not_active Withdrawn
  • 1981-11-03 EP EP81201244A patent/EP0056881B1/de not_active Expired
  • 1981-11-03 AT AT81201244T patent/ATE17955T1/de not_active IP Right Cessation
  • 1981-11-03 DE DE8181201244T patent/DE3173781D1/de not_active Expired
  • 1981-12-21 CA CA000392764A patent/CA1183430A/en not_active Expired
• 1982
  • 1982-01-08 US US06/337,916 patent/US4389260A/en not_active Expired - Lifetime
  • 1982-01-19 PT PT74310A patent/PT74310B/pt unknown
  • 1982-01-20 ES ES508885A patent/ES508885A0/es active Granted
  • 1982-01-21 IT IT19228/82A patent/IT1190666B/it active
  • 1982-01-22 GB GB8201900A patent/GB2093075B/en not_active Expired

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