Phosphate coating composition and method of applying a zinc-nickel phosphate coating

摘要

This invention relates to a method of coating metal surfaces including zinc-coated steel with zinc and nickel 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 or manganese ions in relative proportions to cause the nickel or manganese ions to form a crystalline coating on the surface in combination with the zinc and phosphate.