采用溶胶-凝胶法, 以γ-环氧丙氧丙基三甲氧基硅烷(γ-GPTMS)和正硅酸乙酯 (TEOS)为前驱体, 在2A12铝合金表面制备了稀土铈盐(Ce(NO3)3)掺杂的有机－无机杂化膜, 研究了铈盐掺杂浓度和涂层固化温度等工艺条件. 通过极化曲线和电化学阻抗谱(EIS), 比较了掺杂与未掺杂有机－无机硅烷杂化膜、铬酸盐转化膜和RE转化膜在3.5%NaCl (质量分数)溶液中的耐腐蚀性能. 测试结果均表明, 铈盐掺杂硅烷杂化膜的极化电阻比掺杂前增大了约13倍,并显著高于铬酸盐转化膜和RE转化膜.
In the present work, silane-based organic-inorganic hybrid films doped with rare earth salt (cerium nitrate) were prepared by sol-gel method using γ-glycidoxypropyltrimethoxysilane (γ-GPTMS) and tetraethoxysilane (TEOS) precursors on 2A12 aluminum alloys. The electrochemical tests (such as polarization curve and electrochemical impedance spectroscopy (EIS)) were preformed to investigate the preparing process of Ce-doped organic-inorganic hybrid films (including the concentration of cerium salt doped in films and curing temperature of coatings) and characterize the performances of corrosion protection of the coatings for 2A12 aluminum alloys. At the same time, the corrosion resistance of Ce-doped coatings was compared with non-doped silane-based hybrid films, chromate conversion coating and rare earth conversion coating. The results of polarization curve tests indicated that the polarization resistance value of Ce-doped silane-based hybrid films increased by more than one order of magnitude compared with that measured for non-doped coating, and much greater than those of chromate and rare earth conversion coatings. EIS measurements gave the results in good agreement with those obtained from polarization curves, suggesting that silane-based hybrid process present promising potentialities as alternative method of chromating by improving the preparing technology of these films.