铝合金磷酸盐体系微弧氧化技术研究进展

铝合金具有密度低、强度高、塑性好等优点，在航空航天、机械电子、车辆船舶等领域有着广泛的应用前景，但铝合金表面硬度低、耐蚀性较差，这限制了其更广泛的应用。采用磷酸盐电解液体系对铝合金表面进行微弧氧化处理生成氧化膜层，能够有效提高铝合金表面硬度、耐蚀性等性能，是近年来热门的表面处理技术。本文概述铝合金微弧氧化研究历程以及微弧氧化的机制，总结六偏磷酸钠、磷酸二氢钠等单一磷酸盐及其复合体系下铝合金微弧氧化在表面形貌、相组成、硬度厚度、耐蚀性方面的特点，指出目前磷酸盐体系下铝合金微弧氧化中存在一些问题，如因各牌号铝合金中Si、Zn、Mn等元素含量不同而导致的电解液作用机理不同、大型铝合金件局部区域微弧氧化处理困难从而导致处理后得到的微弧氧化膜层不均匀、铝合金微弧氧化膜层在一定厚度范围内会降低基体膜层的抗疲劳性等。今后的研究还需要在磷酸盐电解液体系中各组分的作用、电解液与基体铝合金作用的机理、基体铝合金各元素对微弧氧化过程的影响等方面继续探索。

Research Progress of Micro-arc Oxidation in Aluminum Alloy under the Phosphate system

Aluminum alloy has the advantages of low density, high strength and good plasticity. It has a wide application prospect in aerospace, mechanical electronics, vehicle ships and other fields. However, aluminum alloy surface has low hardness and poor corrosion resistance, which limit its wide application. Using micro-arc oxidation under phosphate electrolytic system to form oxide coating on aluminum alloy surface, it can effectively improve the surface hardness and corrosion resistance, and is a hot surface treatment technology in recent years. In this paper, the research process and the mechanism of micro-arc oxidation are introduced. Mainly summarizes the characteristics of micro-arc oxidation of aluminum alloy under single phosphates such as sodium hexametaphosphate, sodium dihydrogen phosphate, etc on surface topography, phase composition, the coating of hardness and thickness, corrosion resistance, as well as these characteristics in its composite system. It is indicated that micro-arc oxidation of aluminum alloy under the current phosphate system has some problems, such as the differences in the mechanism of electrolyte due to the different content of Si, Zn, Mn and other factors in various grades of aluminum alloy, the difficulty in the partial micro-arc oxidation treatment in the local region of large aluminum alloy parts, so as to result in the nonuniform micro-arc oxide coating after the treatment, which can decrease the fatigue resistance of the base coating in the thickness range, and the anti-fatigue property of the substrate coating will be reduced within a certain thickness range. Future research also needs to continue to explore the effects of various components in the phosphate electrolytic liquid system, the mechanism of interaction between electrolyte and matrix aluminum alloy, and the effects of matrix aluminum alloy elements on micro-arc oxidation process.