镁合金材料表面处理技术研究新动态

New Development Trend of Surface Treatment Technology for Magnesium Alloys

对镁合金材料近年来在表面微弧氧化、表面超疏水膜层、激光表面改性以及溶胶-凝胶涂层四个方面的研究动态进行了简要综述。镁合金材料采用双极性和混合(单极和双极的组合)电流模式微弧氧化处理的膜层生长速率较快,膜层更致密且硬度更高,膜层的耐磨性和耐腐蚀性能更好。在高浓度苛性碱为主的强碱性溶液中添加适量的添加剂,经短时间(~3 min)微弧氧化处理,即可获得中性盐雾试验达200 h以上的致密耐腐蚀膜层。采用水热法、电化学刻蚀、微弧氧化和电沉积等方法,可在镁合金材料表面形成具有微纳米多级结构的粗糙表面,再用低表面能物质对粗糙表面进行修饰,可在镁合金表面获得超疏水膜层,从而提高镁合金的耐腐蚀性能。镁合金材料激光表面改性处理可改善其表面成分,细化晶粒,使组成相分布更均匀以及提高表层的固溶度极限,从而提高镁合金材料的耐腐性能、摩擦磨损抗力和疲劳强度。溶胶-凝胶有机/无机杂化涂层与镁合金基材良好的附着力,不仅可提高镁合金的耐腐蚀性能,还可以使镁合金具有抗氧化、耐磨损、防水性以及其他性能。

The research trends of magnesium alloy were briefly reviewed in terms of micro-arc oxidation, super-hydrophobic film, laser surface modification and sol-gel coating. The growth rate was faster, the film was denser, the hard-ness was higher, and the wear resistance and corrosion resistance of the magnesium alloy were better provided with micro-arc oxidation in bipolar and mixed （single and bipolar） current modes. The dense corrosion resistant film resisting to neutral salt spray test for over 200 hours could be obtained after micro-arc oxidation for a short time （-3 min） by adding suitable additives in the strong alkali solution mainly composed of high concentration caustic alkali. The micro-nano multi-level structure, roughened surface, could be formed on the surface of magnesium alloy by adopting hydrothermal method, electrochemical etching, micro-arc oxidation and electrodeposition. Then the surface was modified by low surface energy substances to obtain super-hydrophobic film layer and improve corrosion resistance of the magnesium alloy. The laser surface modification of magne- sium alloy could improve the surface composition, refine the grain size, generate uniform phase distribution and improve solid solubility limit of the surface, thereby improving corrosion resistance, friction and wear resistance and fatigue strength of the magnesium alloy. Sol-Gel organic/inorganic hybrid coatings showed good adhesion to magnesium alloy substrate. They could not only improve the corrosion resistance of magnesium alloys, but also entrust oxidation resistance, wear resistance, water proofness and other properties to magnesium alloys.