Patent ID: 6179934
Filing Date: 2001-01-30
Classification: C23C

Abstract:
A liquid composition suitable for forming a zinc phosphate conversion coating on a metal surface by contact and reaction therewith, said liquid composition comprising water and the following dissolved components:(A) a concentration of 5 to 50 g/L of phosphate ions;(B) a concentration of 0.2 to 10 g/L of zinc ions;(C) a hydroxylamine source in a quantity that provides a concentration of 0.5 to 4.0 g/L stoichiometric equivalent as hydroxylamine; and(D) at least one of components (D.1) and (D.2) as follows:(D.1) a concentration of 0.01 to 5.0 g/L in total of at least one substance selected from the group consisting of polycarboxylic acids, salts thereof, and starch phosphate;(D.2) a concentration of zinc ions that is at least 2.0 g/L and has a ratio to the concentration of phosphate ions in the same liquid composition that is not greater than 0.27:1.0.