EFFECT OF POLYETHYLENEIMINE ON PHOSPHATE COATINGS ON MILD-STEEL

The interposition of a phosphate layer between a metal substrate and i ts paint finish has become a well known method of improving adhesion b etween them. This paper describes efforts to improve the protective an d paint-base properties of phosphate coatings, through the incorporati on of polymeric compounds as additives in phosphating compositions. In the present study, a high molecular weight, water-soluble polymer, po lyethyleneimine (PEI), was evaluated as an additive in an optimized Ca -Zn cold phosphating formulation. The incorporation of PEI in the bath resulted in the formation of coatings having desirable properties and good corrosion resistance.