Effect of anodizing of recycled aluminum alloy in sulfuric acid electrolyte on wetting of Nano-silica top coat

The use of sol-gel method for metallic surface pretreatment is a relatively new approach in surface engineering and corrosion protection. The present article reports a simple and convenient method for preparing a surface based on nano-silica coating. The significance of anodizing pretreatment for roughing the surface and creating a low surface energy for better bonding of silica top coat with Al substrate will be pointed. Here, Silica coating was prepared by sol-gel method. Samples were dipped in sol after anodizing process. The coating sol was prepared by keeping the constant molar ratio of Tetraethoxysilane (TEOS), Ethanol (C2H6O), water (H2O) and (HNO3) (0.1 M) as catalyst. Morphology of coated surface were characterized by scanning electron microscopy (SEM) and, wettability of silica coats were characterized by static contact angle measurements. SEM and EDX investigations on the surface of the anodized and silica coated sample showed that the silica film formed in the pores and the rough surface becomes smooth and uniform. Consequently, static water contact angel decreases.