Improvement in the high-temperature oxidation resistance of stainless steel and the corrosion resistance of the anodic oxide films of aluminum alloys by sol-gel technology

A sol-gel method was applied to prepare ZrO₂ and Al₂O₃ coatings on stainless steel(SS304) substrates and to seal the anodic oxidation films of an aluminum alloy. The high-temperature oxidation resistance of as-prepared ZrO₂ and Al₂O₃ coatings was investigated by cyclic high-temperature oxidation tests. The corrosion resistance of the sealed anodic films was investigated by electrochemical impedance spectroscopy(EIS) and exfoliation corrosion method. The experimental results indicate that the high-temperature oxidation resistance of the ZrO₂ and Al₂O₃ coatings is improved with the increasing of coating thickness,and the corrosion resistance of the sealed anodic films is also improved with the increasing times of sealing processes. However,the impedance value and corrosion degree of the sealed anodic films change slightly after more than 8 times of sealing processes. The corrosion resistance of the anodic films sealed with Al₂O₃ sol performs a little better than those with ZrO₂ sol with the same times of sealing processes.