Trivalent chromium passivate solution and process

Abstract

An aqueous acidic solution and process for treating metal surfaces, particularly zinc and zinc alloy surfaces, for depositing a passivate film of improved clarity and hardness and to impart improved corrosion resistance thereto. The solution contains effective amounts of chromium ions substantially all of which are in the trivalent state, hydrogen ions to provide a pH of about 1.2 to about 2.5, an oxidizing agent, a bath soluble and compatible organic carboxylic acid or metal salts thereof present in an amount to impart increased initial hardness and improved clarity to the passivate film and at least one additional metal ion selected from the group consisting of iron, cobalt, nickel, molybdenum, manganese, lanthanum, cerium, lanthanide mixtures as well as mixtures thereof. The treating solution may optionally further contain halide ions and a wetting agent.

Dependencies are inferred from the claim text.