A method and composition for forming a zinc phosphate coating on a metal
surface utilizes an aqueous solution of zinc, phosphate, nitrate, nickel,
a compound containing a group IV-B element, and a fluosurfactant. The
method involves contacting the metal surface with such a bath under
process conditions such that a coating is formed on the metal surface.
Preferably, the compound containing a group IV-B element is a fluoacid of
titanium, zirconium, or hafnium. More preferably, the fluoacid is
fluotitanic acid. The fluosurfactant may be any compatible fluosurfactant
but preferably is an amine perfluoroalkyl sulfonate or a non-ionic,
fluorinated alkyl polyoxethylene ethanol or a combination of both. The
coating serves to improve the ability of the metal to retain a lubricant
on its surface (for cold working of the metal), to improve corrosion
resistance, and to improve paint adhesion.