镁合金在大气中的腐蚀行为及其表面防护技术

Atmospheric corrosion behavior of magnesium alloys and surface protection technique

镁合金由于密度小,比强度高,作为结构材料在汽车工业和电子产品领域受到广泛关注。限制镁合金进一步扩大应用的主要障碍是其差的耐腐蚀性能。镁合金主要的服役环境是在大气条件下,大气湿度、腐蚀性污染物是影响镁合金腐蚀的主要因素。在含有氯化物的环境中,镁合金呈现强的腐蚀敏感性。对于镁合金在大气环境下的腐蚀行为及其研究进展进行了综述。为了提高镁合金的耐腐蚀性能,在镁合金表面覆盖防护性膜层是有效方法。介绍了化学转化膜、阳极氧化膜、金属镀层等几种典型的镁合金表面防腐蚀处理方法。由于六价铬致癌,传统的铬酸盐表面处理工艺逐渐被限制和取缔。开发环境友好型的镁合金表面腐蚀防护技术并在工程上应用是发展趋势。

Magnesium alloys have gained extensive attention as a structure material in automobile industry and electronic products because of low density and high weight-to-strength ratio. The further spread use of magnesium alloys is mainly limited by their poor anti-corrosion performance. Magnesium alloys mostly served in atmospheric environment, where atmospheric humidity and corrosive contamination are the main influence factor for the corrosion, and magnesium alloys show strong corrosive sensitivity in the circumstance containing chloride. In this paper, atmospheric corrosion behavior of magnesium alloys is reviewed. In order to improve the anti-corrosion performance, overlaying protective layer on the surface of magnesium alloy is an effective method. A number of typical methods of surface treatment for magnesium alloys such as chemical conversion coating, anodizing film as well asmetal plating, are introduced. Because hexavalent chromium causes cancer, traditional chromate salt surface treatment processing will gradually he limited and banned. Opening up environment friendly surface protection technology and applying in engineering is the developing trend.