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
  • C23C22/364—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 manganese cations
  • C23C22/365—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 manganese cations containing also zinc and 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
  • C23C22/17—Orthophosphates containing zinc cations containing also organic acids
• • 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

Definitions

• the invention relates to a method for applying phosphate coatings on metal surfaces with the aid of phosphating solutions based on zinc phosphate, which additionally contain nickel and formic acid, and its use in dipping to produce phosphate coatings on steel, galvanized steel and / or galvanized steel, in particular as preparation for Metal surfaces for electro dip painting.
• phosphate coatings on surfaces of steel, galvanized steel or alloy-galvanized steel with the aid of phosphating solutions which belong to the zinc / nickel-phosphate system. If the surfaces to be treated consist of so-called composite metals such as steel and galvanized steel and / or alloy-galvanized steel, the use of phosphating solutions from the zinc / nickel / manganese-phosphate system has become established.
• the phosphate coatings produced by these processes increase the corrosion resistance of the treated metal surfaces and the adhesion of a subsequently applied paint, especially if the paint is applied by electrocoating.
• the effect of the nickel in the above-mentioned phosphating systems is, in particular, to increase the corrosion resistance after subsequent painting, that of the manganese, and to increase the alkali resistance required for the improvement of the cationic electrocoating.
• the presence of manganese also improves the so-called wet grip.
• the abovementioned phosphating systems contain accelerators, which can in particular be nitrate ions, chlorate ions, nitrite ions and / or nitrobenzenesulfonic acid.
• the phosphating solutions are generally used at temperatures in the range from 30 to 60 ° C., immersion processes, spraying processes or combined immersion-spraying processes are customary.
• the object of the invention is to provide a phosphating process for the treatment of metal surfaces which leads to phosphate coatings of high quality, in particular high corrosion resistance, and which is responsible for excellent wet adhesion of the subsequently applied lacquer film, and which can nevertheless be carried out in a simple manner.
• the object is achieved by designing the method of the type mentioned at the outset in accordance with the invention in such a way that the metal surfaces are brought into contact with a phosphating solution which contains 0.3 to 5 g / l of formic acid (calculated as HCOO).
• the formic acid or formate content can be brought about by adding formic acid as such or salts of formic acid, such as alkali metal formate, alkaline earth metal formate, ammonium formate or heavy metal formates to the phosphating solution.
• formic acid such as alkali metal formate, alkaline earth metal formate, ammonium formate or heavy metal formates
• Particularly suitable compounds are sodium formate, potassium formate, calcium formate, barium formate, ammonium formate, nickel formate, cobalt formate, iron (III) formate and manganese formate.
• concentrations in the range from 0.3 to 5 g / l are important insofar as, when added in accordance with a concentration ⁇ 0.3 g / l, the effect with regard to the deposition of nickel ions on the metal surface to be treated is inadequate, whereas with additives An increase in the effect of more than 5 g / l is practically no longer achievable. It is particularly advantageous to measure the addition of formic acid or formate in such a way that a concentration of 1.0 to 3.0 g / l results.
• a preferred embodiment of the invention provides for the metal surfaces to be brought into contact with a phosphating solution which contains 0.5 to 2 g / l of zinc.
• a phosphating solution which contains 0.5 to 2 g / l of zinc.
• Zn3 (PO4) 2. 4 H2O) in the phosphate coating rises and thus the latter Suitability as a primer for subsequent electro-dip painting decreases.
• Particularly favorable results are achieved if the zinc content in the phosphating solution is 0.7 to 1.5 g / l.
• the metal surfaces should be brought into contact with phosphating solution which contain 0.5 to 3.0 g / l of nickel.
• phosphating solution which contain 0.5 to 3.0 g / l of nickel.
• concentration of less than 0.5 g / l there is a risk that, despite the presence of the reducing formic acid or the reducing formate, the amount of nickel deposited is insufficient, so that the corrosion resistance of the phosphate coating and its adhesion imparted to a subsequently applied lacquer film is insufficient not achieve the optimum. If a concentration of 3 g / l is exceeded, an additional increase in the quality of the phosphate coating produced can no longer be achieved. A concentration of 2 g / l nickel is usually sufficient.
• the addition of manganese ions which is responsible for increasing the alkali resistance of the phosphate coating and the wet adhesion of the subsequently applied paint, in particular in the case of partially galvanized or alloy-galvanized steel, should be in the range from 0.3 to 1.5 g / l lie. If the concentration is higher than 1.5 g / l, the properties of the phosphate coating can deteriorate, particularly with regard to the corrosion resistance. As a rule, it is sufficient if the manganese content of the phosphating solution is 1 g / l. At concentrations of the manganese ions below 0.3 g / l, the desired effect can no longer be achieved to the required extent.
• FIG. 1 Further advantageous embodiments of the invention consist in bringing the metal surfaces into contact with a phosphating solution containing 10 to 25 g / l phosphate (calc. As PO4) or 0.5 to 2.0 g / l simple and / or complex fluoride (calculated as F) contains.
• the fluoride ions can be used as hydrofluoric acid or as complex fluorides, for example in the form of fluorosilicate or fluoroborate.
• the addition of fluorides serves in particular to rapidly form the phosphate coating even at low temperatures, to refine the phosphate crystals and to increase the phosphophyllite content (Zn2Fe (PO4) 2. 4 H2O) in the phosphate coating when treating steel surfaces. If the fluoride content is less than 0.5 g / l, the effect achieved may be too low, while at concentrations above 2.0 g / l an additional improvement in the effect can no longer be achieved.
• the phosphating solution used in the process according to the invention generally contains oxidizing agents which accelerate the formation of the coating.
• nitrate, chlorate, nitrite and / or nitrobenzenesulfonate ions are used as accelerators individually or in any combination. Concentrations should be 2 to 15 g / l for nitrate ions, 0.1 to 1 g / l for chlorine ions, 0.01 to 0.2 g / l for nitrite ions and 0.3 to 2.0 g for nitrobenzenesulfonate ions / l. At concentrations of the accelerators below the specified lower limits, the acceleration effect achieved is usually not sufficient, while at concentrations above the upper limit an additional accelerating effect can no longer be achieved or else adverse effects can occur as a result of the entry into the phosphate layer.
• the process according to the invention is integrated into the usual process of producing phosphate coatings by first subjecting the metal surfaces to be treated to thorough cleaning, then to activation, for example with colloidal titanium phosphate, and then to the phosphating treatment will.
• the phosphating treatment is expediently carried out at a temperature in the range from 20 to 55 ° C. for from 30 to 180 seconds.
• the method according to the invention is used in diving.
• the method can be used with particular advantage for the production of phosphate coatings on steel, galvanized steel and / or alloy-galvanized steel.
• the galvanizing can be done electrolytically as well as by hot galvanizing.
• Zinc-nickel and zinc-iron alloys are particularly suitable zinc alloys.
• the metal surfaces to be treated can be in the form of sheet metal or strip, but also as already deformed workpieces, for example as automobile bodies.
• the method according to the invention is particularly suitable for the preparation of metal surfaces for the subsequent painting, the electrocoating and in this case the cathodic electrocoating playing a special role.
• the advantage of the method according to the invention is that nickel in the phosphating solution is deposited in considerable amounts on the surface of the workpiece to be treated and this nickel acts as a crystallization nucleus for the phosphate formation.
• the result is that very fine-grained phosphate coatings are formed, which also contain a considerable amount of nickel in the phosphate layer itself.
• the rate of oxidation of the iron (II) ions leached out during the treatment of iron surfaces is reduced to iron (III) ions, with the result that a considerable proportion of phosphophyllite is incorporated into the phosphate coating.
• SPC steel sheet samples according to SPCC according to JIS-G-3141
• EC electrolytically galvanized sheet steel
• GA hot-dip galvanized sheet steel
• the free acid (F.A.) specified in the table was determined by titration of a 10 ml bath solution with 0.1N NaOH against bromophenol blue as an indicator. The required number of ml 0.1 n-NaOH corresponds to the free acid score.
• T.A. The total acidity (T.A.) was determined by titrating a 10 ml bath sample with 0.1 n-NaOH against phenolphthalein as an indicator until the color changed from colorless to pink. Again, the consumption of ml 0.1 n-NaOH is equal to the number of points.
• the individual samples were provided with a cathodic electrocoat material (Elecron 9400, manufacturer Kansai Paint Co. Ltd.) at a bath temperature of 28 ° C. and with the application of a voltage of 250 V for a period of 180 seconds.
• the thickness of the lacquer layer was 20 ⁇ m.
• a melamine alkyd paint (Amilacque N-2 from Kansai Paint Co. Ltd.) was applied as a filler by spraying. After drying for 10 to 20 minutes, the baking was carried out at 140 ° C. for 30 minutes. The thickness of the lacquer layer produced was 30 ⁇ m.
• top coat was applied by spraying using a melamine alkyd paint (Amilacque WHITE M-3 from Kansai Paint Co. Ltd.).
• a melamine alkyd paint (Amilacque WHITE M-3 from Kansai Paint Co. Ltd.).
• the stoving was carried out for 30 minutes at 140 ° C.
• the dry layer thickness was 40 ⁇ m.
• the coating treatment resulted in a total layer thickness of 90 ⁇ m.
• the lacquered sheet metal samples were first scratched to the metal surface and then immersed in a 5% saline solution at 55 ° C for 240 h. An adhesive strip was then applied to the scoring area and torn off, and the width of the paint removal from the scoring area was determined. Unit: mm
• the painted sheets were immersed in demineralized water at 40 ° C. for 240 h.
• the sheet was then cross-cut in such a way that 100 fields each with a field size of 1 x 1 mm were created.
• the number of fields remaining on the metal surface was determined by pressing and peeling off an adhesive strip.

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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)

Applications Claiming Priority (2)

Publications (1)

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Cited By (5)

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Citations (4)

• 1988
  • 1988-09-27 JP JP63241577A patent/JPH0730455B2/ja not_active Expired - Lifetime
• 1989
  • 1989-09-25 CA CA000612791A patent/CA1322147C/en not_active Expired - Fee Related
  • 1989-09-25 US US07/412,063 patent/US5000799A/en not_active Expired - Fee Related
  • 1989-09-25 NZ NZ230767A patent/NZ230767A/xx unknown
  • 1989-09-26 GB GB8921705A patent/GB2224516B/en not_active Expired - Fee Related
  • 1989-09-26 DE DE3932006A patent/DE3932006A1/de not_active Withdrawn
  • 1989-09-26 EP EP89117708A patent/EP0361375A1/de not_active Withdrawn
  • 1989-09-27 BR BR898904900A patent/BR8904900A/pt unknown
  • 1989-09-27 AU AU41770/89A patent/AU617870B2/en not_active Ceased

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