AQUEOUS PHOSPHATING COMPOSITION AND PROCESS FOR METAL SURFACES

摘要

An aqueous zinc phosphate conversion coating that contains 5 to 50 g/L of phosphate ions, 0.2 to 10 g/L of zinc ions, and 0.5 to 4.0 g/L as hydroxylamine of a hydroxylamine source, and also: (1) contains 0.01 to 5.0 g/L polycarboxylic acid or salt thereof and/or starch phosphate; or (2) has a zinc ions/phosphate ions weight ratio below 0.27 and a zinc ions concentration of at least 2.0 g/L forms high quality zinc phosphating coatings on metal surfaces even if the surfaces have not been previously conditioned by contact with a dispersion of colloidal titanium.