电流密度对铝合金微弧氧化膜物理化学特性的影响

利用微弧氧化(MAO)技术，在LYl2铝合金上沉积了显微硬度达42.14GPa的超硬陶瓷膜.采用x射线衍射仪和显微硬度计研究了阳极电流密度j_a和阴极、阳极电流密度比j_c/j_a对MAO膜相构成和力学特性的影响.此外，利用扫描电子显微镜和恒电位仪分别对膜的微结构和抗点腐蚀特性进行了分析.结果表明，高j_a制备的膜主要含α-Al₂O₃相，低j_a制备的膜主要含γ-Al₂O₃相.显微硬度测试表明，这类膜有较高的硬度，但以j_a=15A/dm²和j_c/j_a=0.7制备的陶瓷膜硬度最高.抗点腐蚀测试表明，j_c/j_a对陶瓷膜的微结构有很强的影响.关键词：微弧氧化显微硬度电流密度抗点腐蚀

Effect of current density on physical and chemical properties of microarc oxidation coatings of aluminium alloy

Ultra-hard ceramic coatings with microhardness of 42.14GPa have been synthesized on the Al alloy substrate by microarc oxidation (MAO) technique. The effects of anodic current density j_a and the ratio of cathodic to anodic current density j_c/j_a on the mechanical property and phase composition of MAO coatings have been studied by microhardness test and x-ray diffraction, respectively. In addition, the microstructure and corrosion resistance of the coatings were analyzed by scanning electron microscopy and pitting corrosion test, respectively. The results show that the samples prepared at high anodic current density consist mainly of α-Al₂O₃, while the samples fabricated at low anodic current density are composed almost entirely of γ-Al₂O₃. Microhardness test shows that these kinds of samples have high hardness, and the microhardness of the coating prepared at j_a=15A/dm² and j_c/j_a=0.7 is t highest of all coatings prepared. Pitting corrosion test shows that the structure of coatings is strongly influenced by the variation in j_c/j_a.