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
  • C23C22/22—Orthophosphates containing alkaline earth metal 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
  • C23C22/34—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
  • C23C22/367—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 alkaline earth metal cations

Definitions

• the present invention relates to a method for phosphating metal surfaces, in particular the zinc-calcium phosphating of surfaces made of iron, steel, zinc and / or aluminum as a pretreatment for cold forming.
• Zinc phosphating baths can contain, for example, monozinc phosphate, free phosphoric acid, zinc nitrate and oxidizing agents as main components.
• the pH of such solutions is usually in the range between 2.8 and 3.4.
• the process sequence consists of two reactions, the pickling reaction and the formation of a zinc phosphate layer on the surface to be phosphated.
• the alkali phosphating processes clean and degrease the metal surface and form a corrosion-protective cover layer, which mainly consists of iron phosphate.
• the layer formation is initiated by a pickling reaction in which a small amount of the base metal is removed.
• the majority of the dissolved surface material reacts with the phosphate ion of the solution to form poorly soluble phosphates, which deposit as a firmly adhering coating on the surface.
• the layer-forming cation originates from the base metal itself.
• iron phosphate layers with a low layer weight of around 0.2 to 0.4 g / m2 and iron phosphate layers with higher basis weights from 0.6 to 1.2 g / m2.
• the thin phosphate layers are particularly suitable for painting; they ensure excellent paint adhesion, offer good rust protection, electrical insulation, reduction of sliding resistance and facilitate cold forming.
• phosphate layers with a layer weight of up to 40 g / m2 are usually deposited.
• the metal soaps are known to be produced.
• Aluminum, calcium, lithium, zinc and magnesium stearates are water-repellent and, as solid lubricants in wire drawing, result in lower coefficients of friction at higher surface pressures than conventional alkali soaps.
• Metal soaps have the advantage over alkali soaps that they hardly absorb moisture from the air, remain unchanged in their lubricating effect due to their high compressive strength and allow higher overall cross-sectional decreases, while with alkaline soaps the lubricating effect can decrease significantly due to moisture absorption.
• EP-PS 0 045 110 describes a process for the production of phosphate coatings on iron or steel surfaces by immersion or flooding with an aqueous acidic zinc phosphate solution, the surfaces being brought into contact with a solution which, in addition to Zn2+, PO43 ⁇ , NO3 ⁇ or contains an equivalent iron (II) non-oxidizing accelerator in which the weight ratio Zn: PO4 is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which one by suitable measurement of ClO3 ⁇ or an equivalent Iron (II) to iron (III) oxidizing accelerator sets an iron (II) content of 0.05 to 1 wt .-%.
• the object of the present invention was to provide an improved method for phosphating metal surfaces, in particular surfaces made of iron, steel, zinc and their alloys, as well as aluminum as a pretreatment for cold forming.
• the objects of the present invention are achieved by the improved phosphating process based on zinc-calcium-phosphate layers.
• the phosphating solution with which the surfaces to be coated are brought into contact can Zn2+ and Ca2+ ions in a weight ratio of 1: 0.5 to 1: 1.5 and preferably in a ratio of 1: 1.
• preferred embodiments of the present phosphating solution contain further cations of transition metal ions in addition to the above Ca2 und and Zn2+ cations.
• Ni2+ ions are particularly preferred at this point.
• the phosphating solutions contain Ni2+ ions, an amount of 0.01 to 10 g / l of Ni2+ ions is preferred.
• phosphating solutions according to the invention can contain further additional anions.
• simple and / or complex fluorides can be used as further anions, if appropriate. These can be used in the phosphating solutions in particular in amounts of 0.01 to 10 g / l.
• a preferred embodiment of the present invention is to set the temperature range in the range from 50 to 70 ° C. and to bring the metal surfaces into contact with the phosphating solutions.
• phosphating solutions according to the invention can contain 0.1 to 2.0 g of organic nitro compounds.
• Organic nitro compounds in the sense of the present invention are selected from m-nitrobenzenesulfonates and / or nitroguanidine.
• the organic nitro compounds can also be present in amounts of 0.1 to 2.0 g / l in addition to 10 to 100 g / l NO3 ⁇ ions in the phosphating solutions.
• the process for phosphating metal surfaces in particular surfaces made of iron, steel, zinc and their alloys, as well as aluminum, zinc-calcium-phosphate layers (Scholzit) with a basis weight of 3 to 9 g / m2 are produced.
• Scholzit zinc-calcium-phosphate layers
• the zinc-calcium-phosphate layers can be created on the metal surfaces by dipping, spraying and flooding as well as by combined processes.
• the surfaces to be phosphated are degreased according to the methods known in the prior art.
• Oil, grease and lubricant residues or grinding dust from previous manufacturing processes can be removed by organic solvents or aqueous cleaners.
• the chlorinated hydrocarbons are the most frequently used organic solvents because they dissolve oils and fats excellently and are not flammable. Solids and inorganic contaminants, however, are only removed inadequate. Water-based cleaners have a very high cleaning ability.
• the advantage of the present invention is that zinc-calcium-phosphate layers are suitable for producing low layer weights on the order of 3 to 9 g / m 2 on wire.
• the zinc-calcium-phosphate layers largely contain the mineral scholzite.
• a mixed soap of zinc-calcium stearate is formed in addition to zinc stearate and calcium stearate.
• zinc calcium stearate has the advantage that the durability of the drawing dies is increased many times over. Pulling tests in the technical center also showed that the wire surfaces, in particular during a subsequent polishing pull, achieve a substantially brighter and more uniform appearance than can be achieved with conventional methods operated on the accelerator side.
• Another product advantage is the fact that the new zinc-calcium phosphating process for cold working works in a temperature range of preferably 50 to 70 ° C.
• the sludge behavior in this process can be classified as particularly favorable, since even after a bath load of 1.5 m2 steel surface per liter of bath solution, only minimal quantities in the order of a few milliliters of bath sludge are produced.
• Another advantage of the present invention is that the Sales with drawing soap (sodium stearate) resulting zinc-calcium stearate mixed soaps allow a longer service life of the drawing dies due to the improved properties.
• a phosphating solution was prepared that 10.3 gl ⁇ 1 Ca2+ ions 14.0 gl ⁇ 1 Zn2+ ions 27.8 gl ⁇ 1 PO43 ⁇ ions 46.5 gl ⁇ 1 NO3 ⁇ ions contained.
• the phosphating solution had the following characteristics: pH: approx.2.6 Acid ratio: approx. 1:21 (free acid to total acid)
• the pH was 2.5 and the ratio of free Acid to total acid 1: 17.6.
• the wire coated in this way could easily be reduced to the desired size using several drawing dies connected in series.
• the result was a bright and shiny surface.

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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)
• Laminated Bodies (AREA)
• Manufacture And Refinement Of Metals (AREA)

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Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Citations (2)

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• 1988
  • 1988-01-14 DE DE3800835A patent/DE3800835A1/de not_active Withdrawn
• 1989
  • 1989-01-07 AT AT89100228T patent/ATE83509T1/de not_active IP Right Cessation
  • 1989-01-07 EP EP89100228A patent/EP0324395B1/fr not_active Expired - Lifetime
  • 1989-01-07 DE DE8989100228T patent/DE58902980D1/de not_active Expired - Fee Related
  • 1989-01-12 TR TR89/0045A patent/TR26644A/xx unknown
  • 1989-01-13 US US07/297,155 patent/US4944813A/en not_active Expired - Fee Related
  • 1989-01-13 BR BR898900148A patent/BR8900148A/pt unknown
  • 1989-01-13 AU AU28508/89A patent/AU604395B2/en not_active Ceased
  • 1989-01-13 MX MX014531A patent/MX169762B/es unknown
  • 1989-01-17 JP JP1009621A patent/JPH01219172A/ja active Pending

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