Composition and process for treating surfaces of light metals and their alloys

摘要

An aqueous bath for treating the surfaces of light metals and light metal alloys that does not contain hexavalent chromium or produce any other highly polluting effluent and that forms a highly corrosion-resistant and highly paint-adherent conversion coating has a pH from 1.0 to 7.0 and contains from 0.01 to 50 g/L of permanganic acid and/or salt(s) thereof and 0.01 to 20 g/L of at least one water soluble compound of titanium or zirconium.