通过微弧氧化-溶胶凝胶复合表面处理技术来提高铝合金的耐腐蚀性能,分析了多层凝胶层对6061铝合金耐腐蚀性能的影响。采用扫描电镜（SEM）、X射线衍射仪（XRD）和电化学分析等方法对膜层的表面形貌、化学组成、结构以及耐腐蚀性能进行了表征。研究表明：TiO2溶胶渗入微弧氧化陶瓷膜的微孔以及裂纹中,能有效阻挡腐蚀介质的扩散和渗透;复合处理后的试样较仅微弧氧化处理更平滑、致密;膜层除了γ-Al2O3相外,经高温退火处理后出现TiO2锐钛矿,并形成较好的晶相结构;在3.5%NaCl溶液中的室温电化学行为中,复合处理较微弧氧化处理后的试样自腐蚀电位上升最高约400 mV,自腐蚀电流密度最高减小约3个数量级,极化电阻明显增大;随着凝胶层厚度的增加耐腐蚀性能逐渐增强,但当凝胶层数大于4时,膜层龟裂现象严重,并导致耐腐蚀性能开始下滑。
The compound surface treatment of micro-arc oxidation（MAO） and sol-gel with different layers was used to enhance the corrosion resistance of 6061 aluminum alloy.The microstructure,composition,phases and corrosion resistance of the coatings were investigated by means of SEM,XRD and electrochemical tests.The results show that TiO2 particles infiltrate into the pores and cracks of MAO ceramic coating after sol-gel treatment,which can block the corrosive media out of the coating.The coatings treated by the composite technique are more smooth and dense than that treated by MAO only.In addition to γ-Al2O3,the TiO2 films are mainly composed of anatase after annealing treatment.Room temperature electrochemical behavior in NaCl（w=3.5%）solution of the ceramic coatings was studied,the corrosion resistance of the composite coatings is better than that of MAO coatings,whose corrosion current density is reduced by over 3 orders of magnitudes and the corrosion potential increases 400 mV in positive direction,also,the polarization resistance increases significantly.The corrosion resistance of the coatings increases with increasing gel layers,however,when the gel layers are more than 4,the layer cracks seriously,leading to the decrease of corrosion resistance.
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