| Steel and aluminum as two kinds of metals of the most usage in the world, their service time and service quality had become increasing concerns. Steel easily occurred oxidation and failure in high temperature environment. The corrosion resistance of aluminum was enhanced after anodic oxidation, but its corrosion resistance was slightly insufficient in seawater or acidic environment. Therefore, study how to improve the high temperature oxidation resistance of steel and how to enhance the corrosion resistance of aluminum anodic film were greatly significant.ZrO2, Al2O3coatings and ZrO2-Al2O3composite coatings were prepared on the stainless steel by a sol-gel method in the paper. Microstructure morphology indicated that surface of all coatings were smooth and free-crack. The thickness of ZrO2and Al2O3coatings prepared by a single dipping process were about11nm and19nm respectively. Their phase composition were Zr0.92Y0.08O1.96of quartet structure and γ-Al2O3of cubic structure respectively. The results of high temperature oxidation showed that the high temperature oxidation resistance of ZrO2and Al2O3coatings were both enhanced with their increasing thicknesses. ZrO2-Al2O3composite coatings, which combined the merit of high thermal expansion coefficient for ZrO2coatings and the merit of low oxygen diffusion coefficient for Al2O3coatings, performed better resistance to high temperature oxidation than pure ZrO2and Al2O3coatings. Under the same total dipping times, ZrO2-Al2O3composite coatings showed a rule of firstly enhanced and then weaken with the increase of dipping times of ZrO2coatings or the decrease of dipping times of Al2O3coatings. Under the same dipping times of ZrO2and Al2O3coatings, the high temperature oxidation resistance of ZrO2-Al2O3composite coatings were gradually enhanced with the increase of dipping times of adjacent ZrO2or Al2O3coatings.The sol-gel technology were also used to seal the aluminum anodic films in the paper. Microstructure morphology indicated that aluminum anodic films were free-crack after sealing treatment. The phase composition of anodic films sealed with ZrO2and Al2O3sol were Zr0.92Y0.08O1.96of quartet structure and γ-Al2O3of cubic structure respectively. The results of Electrochemical impedance spectroscope(EIS) and exfoliation corrosion indicated that the corrosion resistance of anodic films sealed with ZrO2or Al2O3sol were enhanced, and performed a rule of firstly enhanced and then tends to be stable with the increase of sealing times. Under the identical sealing process, corrosion resistance of the anodic films sealed with Al2O3sol performed a little batter than with ZrO2sol.In the paper, a sol-gel method was applied to prepared coatings on the stainless steel, and seal the aluminum anodic film. The rules of high temperature oxidation resistance of coatings were studied with the increase thicknesses of coatings and the change of ways of permutation and combination. The influence of sealing times was studied on the corrosion resistance of anodic films. The above research had certain reference significant to high temperature oxidation of coatings and sealing of anodic films. |
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