Phosphate coating composition and method of applying a zinc-nickel-manganese phosphate coating
AssigneeChemfil Corporation
InventorsThomas W. Cape, Harry R. Charles
Life of this patent
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Abstract
This invention relates to a method of coating metal surfaces including zinc-coated steel with zinc, nickel and manganese phosphate crystals for the purposes of improving paint adhesion, corrosion resistance, and resistance to alkali solubility. Potassium, sodium, or ammonium ions present as a phosphate salt are combined with zinc ions and nickel and manganese ions in relative proportions to cause the nickel and manganese ions to form a crystalline coating on the surface in combination with the zinc and phosphate.
Claims7
A method of phosphate conversion coating metallic substrates selected from the group consisting of steel, zinc-coated steel, and aluminum comprising the steps of:
- cleaning the surface of the substrates with an alkali cleaner;
- conditioning the surface of the substrates with a titanium-containing aqueous solution;
- coating the surface of the substrates with a solution consisting essentially of an aqueous solution of the constituents A, B, and C combined in the ratio of about 4 to 40 parts by weight A:2 parts by weight B:2 to 13 parts by weight C, and B is provided at a concentration of between about 300 and 1,000 ppm, wherein:
- A is selected from the group consisting of potassium, sodium and ammonium ions present as a phosphate salt;
- B is zinc ions;
- and
- C is nickel and manganese;
- applying said coating composition to the surface of the substrates at a temperature of between about 100.degree. F. and 140.degree. F. for between 30 and 300 seconds;
- rinsing said substrate by applying a chromate rinse to the substrate and rinsing the substrate with water.
Dependencies are inferred from the claim text.