Phosphating is the application of a porous crystalline
Phosphate coating can be defined as the process in which the phosphate coating solution forms an insoluble phosphate layer on a metal surface by dipping, spraying or any other method. For the formation of this type of coating the content of the prepared solution must contain hydrogen ion (H+), phosphate anion (PO4-3) and at least one metal cation in order to obtain surface pickling on the metal and proper pH.
Phosphating of metals is one of the most important of surface treatment methods and a number of modern metal finishing procedures would not be possible without it.
Coating usually applied to ferrous-based materials, the process is non-electrolytic with the phosphate layer being produced by catalytic action between the component material and the Phosphating solution, this catalytic action producing an exceptionally strong bond of the phosphate layer to the component surface.
The coating produced is crystalline and