Effect of Two-step Anodizing on Corrosion and Adhesion Resistance of A5052 Aluminum Alloy

In order to fabricate multi-materials such as joining between aluminum alloy and engineering plastics for the purpose of lightening the weight of automobiles, this study investigated surface treatments to improve the adhesion and corrosion resistance of A5052 aluminum alloy. The two-step anodizing process of phosphoric acid anodizing + sulfuric acid formed a two-layer film with a phosphoric acid treated film on the upper layer and a sulfuric acid treated film on the lower layer. In this two-layer coating, the sulfuric acid-treated film on the lower layer improves the corrosion resistance, and the phosphoric acid-treated film on the upper layer improves adhesion, showing excellent adhesion and corrosion resistance.