Phosphate coatings are a crystalline conversion coating for steel and other metals that is formed on a ferrous metal substrate. The process of Phosphate coating is employed for the purpose of pretreatment prior to coating or painting, increasing corrosion protection and improving friction properties of sliding components. In other instances, phosphate coatings are applied to threaded parts and top coated with oil (P&O) to add anti-galling and rust inhibiting characteristics.

Phosphating Solution Preparation A phosphating solution is prepared by dissolving manganese phosphate salts, such as manganese nitrate or manganese chloride, in water. The solution may also contain other additives such as accelerators, stabilizers, and surfactants to control the coating formation and enhance its properties.