金属复合材料微弧氧化研究进展

Research Progress of Micro-arc Oxidation on Metal Composite

微弧氧化是一种在阀金属(Al、Mg、Ti等)及其合金表面原位生成陶瓷膜的表面处理技术。利用微弧氧化技术获得的膜层与基体结合力强,能改善材料的耐磨、耐蚀、耐热冲击以及绝缘性等性能。以微弧氧化的发展和成膜机理作为切入点,比较了单一合金与金属复合材料微弧氧化处理的异同,发现机理的研究主要围绕电击穿理论展开,具有阀金属特性的第二相有助于复合材料微弧氧化的进行,而其他的第二相则会阻碍微弧氧化成膜,使机理研究变得复杂。综述了电解液及添加剂、电压、电流密度、频率和占空比、温度和处理时间等对金属复合材料微弧氧化过程,及膜层微观结构、相组成、厚度、硬度以及耐磨、耐蚀性能的影响。最后指出了复合材料微弧氧化目前存在的问题,提出了需要从加强机理研究、优化工艺的参数、改进微弧氧化设备以及与其他技术相结合等研究方向着手,以进一步加快金属基复合材料微弧氧化处理及改善陶瓷膜的性能,推进微弧氧化技术的应用。

Micro-arc oxidation is a surface-treatment technology to in-situ form ceramic coatings on surfaces of valve metals including Al, Mg and Ti and corresponding alloy. The coatings obtained by micro-arc oxidation are closely adhesive to metal substrates and can improve wear resistance, corrosion resistance, thermal shock resistance and insulativity of materials. With development and formation mechanism of micro-arc oxidation as anentry point, similarities and differences between single al-loy and metal composite were compared. It was found that the formation mechanism was mainly based on electric breakdown theory. The micro-arc oxidation will be accelerated if second phase of the metal composite was valve metal. The micro-arc oxidation will be hindered if the second phase was formed by other metal elements（other than valve metals）, which made the mechanism complicated. Effects of electrolyte, additives, voltage, current density, frequency, duty cycle, temperature and treatment time on micro-arc oxidation process of metallic composite, coating microstructure, phase composition, thickness, hardness, wear resistance and corrosion resistance were summarized. Finally, current problems in micro-arc oxidation of the metal composite were put forward. It was proposed to strengthen the mechanism research, optimize the process parameters, improve micro-arc oxidation devices and combine with other technologies in order to improve accelerate micro-arc oxidation, improve performance of ceramic membrane and promote application of micro-arc oxidation technology.