Industrial Phosphating Services

The process of phosphating aluminum and steel parts is typically listed as a conversion coating because the process involves metal removal as part of the reaction. However, it is not like anodizing or black oxide in that the phosphate  coating is actually a precipitation reaction. The final surface is a layer of very fine phosphate crystals adhering to the surface of the metal. For paint and powder coatings, a phosphate coating has two main functions. First, the coating provides improved paint and powder coating adhesion since the phosphate crystals act as organic coating anchoring sites. Second, the phosphate layer acts as a corrosion barrier should the organic coating get  scratched. In rust creep testing, the rust creep is reduced when phosphate is present under the paint  layer or powder coat layer compared to no conversion layer under the organic coating.