Characterization of microarc oxidation coatings formed on AM60B magnesium alloy in silicate and phosphate electrolytes

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• 作者：Jun Liang ; Litian Hu ; Jingcheng Hao
• 关键词：Magnesium alloy ; Microarc oxidation ; Oxide coating ; Friction and wear ; Corrosion resistance
• 刊名：Applied Surface Science
• 出版年：2007
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：15 March 2007
• 卷：253
• 期：10
• 页码：4490-4496
• 文件大小：1074 K

摘要

Microarc oxidation coatings on AM60B magnesium alloy were prepared in silicate and phosphate electrolytes. Structure, composition, mechanical property, tribological, and corrosion resistant characteristics of the coatings was studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness analyses, and by ball-on-disc friction and potentiodynamic corrosion testing. It is found that the coating produced from the silicate electrolyte is compact and uniform and is mainly composed of MgO and forsterite Mg₂SiO₄ phases, while the one formed in phosphate electrolyte is relatively porous and is mainly composed of MgO phase. The thick coating produced from a silicate electrolyte possesses a high hardness and provides a low wear rate (3.55 × 10⁻⁵ mm³/Nm) but a high friction coefficient against Si₃N₄ ball. A relatively low hardness and friction coefficient while a high wear rate (8.65 × 10⁻⁵ mm³/Nm) is recorded during the testing of the thick coating produced from a phosphate electrolyte. Both of these types of coatings provide effective protection for the corrosion resistance compared with the uncoated magnesium alloy. The coating prepared from the silicate electrolyte demonstrates better corrosion behavior due to the compacter microstructure.