纳米SiC对AZ91D镁合金微弧氧化膜微观结构及性能的影响

摘要

Ceramic coating incorporated with nano-SiC was obtained on AZ91D magnesium alloy during MAO by adding nano-SiC into the silicate−aluminate-based composite electrolyte. The microstructure, thickness, phase analysis, element composition and hardness of the coatings were respectively investigated by scanning electron microscopy(SEM), film thickness meter, X-ray diffraction (XRD), energy disperse spectroscopy(EDS) and Vickers hardness tester. The wear resistance of Mg alloy and coatings were evaluated by friction and wear apparatus, while the corrosion resistance of Mg alloy and coatings were evaluated by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The results show that after adding nano-SiC into the electrolyte, both the striking voltage and final voltage decrease, the size and number of the micropore on the surface of the coating decrease, the thickness and hardness of the coating increase, both the wear resistance and corrosion resistance of the coating raise.%通过向Na2SiO3−NaAlO2复合电解液体系中添加纳米SiC，经过微弧氧化处理后在AZ91D镁合金表面制备含纳米SiC的复合陶瓷层。利用SEM、膜层测厚仪、XRD、EDS和维氏硬度计分别研究膜层的微观形貌、厚度、相结构、元素组成及硬度。采用摩擦磨损试验机对镁合金基体和膜层的干滑动磨损行为进行研究，运用动电位极化曲线试验和交流阻抗法测量镁合金基体和膜层在3.5% NaCl溶液中的耐蚀性能。结果表明：向电解液中添加纳米SiC后，微弧氧化的起弧电压和终止电压均下降。经纳米SiC复合处理后，微弧氧化膜层的孔径减小，致密性提高；与未添加纳米SiC的膜层相比，其厚度和硬度都得到提升，耐磨性与耐蚀性均增强。