Growth and characterization of anodic films on aluminum alloys in 5-sulfosalicylic acid solution

Anodic oxide film was grown on aluminum alloy in 5-sulfosalicylic acid electrolyte. The corrosion resistance of the oxide film formed at different electrolyte temperatures and concentrations was studied using electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results obtained indicate that the growth of oxide film on aluminum alloys greatly improved the corrosion resistance. The best corrosion resistance was obtained by oxide film growth with 0.5 M solution at relatively low temperature (4 °C). Hardness value was also increased as the electrolyte temperature decreased due to the formation of dense oxide film. At low bath temperature (near 0 °C) the microhardness reaches its maximum value and slightly decreases as the film thickness increases. According to EIS and hardness measurements, 5-sulfosalicylic acid is a suitable electrolyte for anodic film growth of aluminum surface.