Progress in Zinc Phosphate Conversion Coatings: A Review

Phosphating is one of the most widely used surface treatments of ferrous and non-ferrous materials due to its low-cost, easy production, good corrosion resistance and good adhesion with paint. Many researchers have tried to explore the different applications of the phosphating processes in various fields including automobile and aerospace. Recently, the zinc phosphate conversion coatings on magnesium alloys and alluminium alloys and the role of nano structured materials on the development and corrosion resistance of zinc phosphate coatings have been intensively studied. This paper reviews the state-of-the-art of phosphate conversion coatings on materials , in terms of past and present developments in the process of phosphatization, coating characteristics, evaluation of coatings, evolution of nano coatings and environmental impact. Keywords— phosphating, corrosion, electrochemical