Chromium-free passivate solution and process

摘要

An aqueous acidic solution and process for treating receptive metal surfaces, particularly zinc and zinc alloy surfaces, to impart a passivate film thereon imparting improved corrosion resistance thereto. The aqueous solution contains effective amounts of hydrogen ions to provide a pH of about 1.2 to about 2.5, an oxidizing agent and a combination of iron and cobalt ions present in an amount effective to activate the bath and promote the formation of a passivate film on the metal substrate. The treating solution may optionally further contain cerium ions present in an amount to further activate the bath and to impart a light-yellow color to the passivate film, halide ions and a wetting agent.