Structure and tensile/wear properties of microarc oxidation ceramic coatings on aluminium alloy  

作　　者：魏同波 阎逢元 刘维民 田军 

机构地区：[1]State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China

出　　处：《中国有色金属学会会刊：英文版》2004年第6期1162-1168,共7页Transactions of Nonferrous Metals Society of China

基　　金：Project ( 5 0 2 710 80 )supportedbytheNationalNaturalScienceFoundationofChina

摘　　要：Thick and hard ceramic coatings were prepared on the Al-Cu-Mg alloy by microarc oxidation in alkali-silicate electrolytic solution. The thickness and microhardness of the oxide coatings were measured. The influence of current density on the growth rate of the coating was examined. The microstructure and phase composition of the coatings were investigated by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Moreover, the tensile strength of the Al alloy before and after microarc oxidation treatment were tested, and the fractography and morphology of the oxide coatings were observed using scanning electron microscope. It is found that the current density considerably influences the growth rate of the microarc oxidation coatings. The oxide coating is mainly composed of α-Al2O3 and γ-Al2O3, while high content of Si is observed in the superficial layer of the coating. The cross-section microhardness of 120 μm thick coating reaches the maximum at distance of 35 μm from the substrate/coating interface. The tensile strength and elongation of the coated Al alloy significantly decrease with increasing coating thickness. The microarc oxidation coatings greatly improve the wear resistance of Al alloy, but have high friction coefficient which changes in the range of 0.70.8. Under grease lubricating, friction coefficient is only 0.15 and wear loss is less than 1/10 of the loss under dry friction.Thick and hard ceramic coatings were prepared on the Al-Cu-Mg alloy by microarc oxidation in alkali-silicate electrolytic solution. The thickness and microhardness of the oxide coatings were measured. The influence of current density on the growth rate of the coating was examined. The microstructure and phase composition of the coatings were investigated by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Moreover, the tensile strength of the Al alloy before and after microarc oxidation treatment were tested, and the fractography and morphology of the oxide coatings were observed using scanning electron microscope. It is found that the current density considerably influences the growth rate of the microarc oxidation coatings. The oxide coating is mainly composed of α-Al_2O_3 and γ-Al_2O_3, while high content of Si is observed in the superficial layer of the coating. The cross-section microhardness of 120 μm thick coating reaches the maximum at distance of 35 μm from the substrate/coating interface. The tensile strength and elongation of the coated Al alloy significantly decrease with increasing coating thickness. The microarc oxidation coatings greatly improve the wear resistance of Al alloy, but have high friction coefficient which changes in the range of 0.70.8. Under grease lubricating, friction coefficient is only 0.15 and wear loss is less than 1/10 of the loss under dry friction.

关 键 词：微电弧氧化 铝合金 陶瓷复层 电溶法 

分 类 号：TG174.453[金属学及工艺—金属表面处理]