The influence of sodium tungstate concentration and anodizing conditions on microarc oxidation (MAO) coatings for aluminum alloy

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• 作者：Chun-Chieh Tseng^a ; Jeou-Long Lee^b ; ^{ljl@mail.lhu.edu.tw} ; Tzu-Hsuan Kuo^b ; Shien-Nan Kuo^b ; Kuo-Hui Tseng^a
• 关键词：Microarc oxidation ; Sodium tungstate ; Current density ; Aluminum alloy
• 刊名：Surface and Coatings Technology
• 出版年：2012
• 期刊代码：106_02578972
• 类别：ms
• 出版时间：15 April, 2012
• 卷：206
• 期：16
• 页码：3437-3443
• 文件大小：1382 K

摘要

Microarc oxidation (MAO) coatings on 5052 aluminum alloy are prepared in silicate-hypophosphite electrolytes with sodium tungstate. The effects of sodium tungstate concentrations and current density on the surface morphology, phase composition and properties of the coatings are investigated. With the addition of sodium tungstate in the electrolyte and increase of current density, the final voltage at the microarc discharge process increases. The results also show that the MAO coatings are composed mainly of 伪-Al₂O₃ and 纬-Al₂O₃ and the proportion of 伪-Al₂O₃ and 纬-Al₂O₃, pore size, surface roughness as well as thickness of the coatings strongly depend on the sodium tungstate concentration and current density. Thus, the hardness, friction coefficient and corrosion resistance of the coatings are significantly influenced by the magnitude of the current density and sodium tungstate concentration. These oxide films on aluminum were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thickness gage, and polarization curves, respectively.