Phosphating is a process that uses an acid to remove parts of the metal substrate and re-deposit a layer of material that is a combination of the phosphate, metal substrate, and other metals. The new material sticks to the surface of the metal and provides a good coating base.
The surface created firmly adheres to the metal, provides better corrosion inhibition, increases surface area, and ensures that the powder coating will stick. With phosphating, the good coating base extends the working life of the piece.