Influence of 0.2% fe addition on zirconium conversion coating on aluminium alloy

Abstract

Conversion coating on aluminium/0.2%Fe alloy developed from a zirconium nitrate/fluoride solution has been examined with scanning electron (SEM) and transmission electron microscopes (TEM) with attached energy dispersive X-ray (EDX) facilities. Zirconium-rich islands of thicker sections were observed in the SEM. The thin sections from the transmission micrographs revealed undulating metal/coating and coating/solution interfaces. This is consistent with anode/cathode reactions in the formation and growth of conversion coatings on metals, especially aluminium alloys. The coating comprises of zirconium rich surface which is contaminated or otherwise with aluminium and other species from the coating solution.