Production of Colored Phosphate Coatings on Steel

Abstract

Phosphating has long been successfully used as a method of protecting metal products and structures from corrosion. The possibility of obtaining non-ferrous phosphate coatings on steel by cold method was investigated. Compositions of cold phosphating solutions for the deposition of colored phosphate coatings of green and blue colors are proposed. To obtain green phosphate films, chromium salts and procyon olive green dye were introduced into the compositions of cold phosphating solutions. To obtain phosphate films of orange color, cobalt salts were introduced into the compositions of cold phosphating solutions. To obtain blue phosphate films, methylene blue and Prussian blue were introduced into the compositions of cold phosphating solutions. It was found that colored phosphate films are worse at preventing metal corrosion. Colored phosphate coatings have a higher porosity and are less uniform compared to modified phosphate films.