AZ31镁合金的SiO2（Mg）涂层的组织及性能研究

采用机械合金化的方法在AZ31镁合金表面涂覆SiO₂（Mg）涂层。通过XRD、显微硬度计、扫描电镜等测试手段对表面涂层的微观形貌结构、涂层的显微硬度进行分析，利用电化学工作站对涂覆前后的AZ31镁合金的耐蚀性能进行检测。结果表明:SiO₂涂层被成功地涂覆到AZ31镁合金表面；同时，随着球磨时间的增加，涂层的显微硬度呈增加趋势，且随着球料比的增加，显微硬度亦增加，最高达到370.6HV，较基体提高了15.2%；涂层的厚度也呈现先增加后趋于稳定的趋势，但球磨时间过长，涂层内部出现裂纹；当球料比为15:1、球磨时间为15 h时，所制备涂层厚度为148μm，涂层致密且与基体结合较好；所对应的自腐蚀电流密度较基体降低了一个数量级，对应的腐蚀电压提高了6.5%，耐腐蚀性能得到明显改善。 

Microstructure and Performance Study on SiO2 (Mg)Coating on AZ31 Magnesium Alloy

SiO₂(Mg) coating was applied on the surface of AZ31 magnesium alloy by mechanical alloying. The microstructure and microhardness of the surface coating were analyzed by XRD, microhardness tester and scanning electron microscope. The corrosion resistance of AZ31 magnesium alloy before and after being coated was tested by electrochemical workstation. The results showed that SiO₂ was successfully coated on the surface of AZ31 magnesium alloy. At the same time, with the increase of milling time and ball-to-material ratio, the microhardness increased, which could be up to 370.6 HV, 15.2% higher than that of the substrate. The thickness of the coating also showed a trend of increasing first and then stabilizing. However, if the ball milling time was too long, cracks would appear in the coating. When the ball-to-material ratio was 15:1 and the ball milling time was 15 h, the thickness of the prepared coating was 148 μm, the coating compact and the bond between the film and substrate excellent. The corresponding self-corrosion current density was reduced by 1 magnitude and the corresponding corrosion current increased by 6.5% compared with those of the substrate. The corrosion resistance was obviously improved.