纳米SiO_2添加剂对镁合金微弧氧化陶瓷层组织结构及耐蚀性的影响

Effect of Nanosilica Additive on Microstructure and Corrosion Resistance of Micro-Arc Oxidation Coatings of Magnesium Alloy

为了改善AZ31B镁合金微弧氧化陶瓷层表面疏松状况,提高其耐腐蚀性能,在其电解液中添加纳米SiO2粉末制备了微弧氧化陶瓷层。采用测厚仪、扫描电镜(SEM)、能谱仪、X射线衍射仪(XRD)、极化曲线、交流阻抗及盐雾腐蚀试验研究了纳米SiO2添加剂对微弧氧化陶瓷层的组织结构及耐腐蚀性能的影响。结果表明:纳米SiO2粉末在微弧氧化过程中能够进入陶瓷层,使得陶瓷层表面孔洞数量减少,致密度提高;纳米SiO2的添加使陶瓷层的腐蚀电流密度减小,阻抗增加,盐雾腐蚀增重减小,耐蚀性得到提高。

Micro-arc oxidation ceramic coatings were prepared on the surface of AZ31B Mg alloy by introducing SiO_2 nanoparticles into the electrolyte.The effect of nanosilica additive on the microstructure and corrosion resistance of the micro-arc oxidation coatings was investigated with a thickness gauge,a scanning electron microscope,an energy dispersive spectrometer,an X-ray photoelectron spectroscope,an electrochemical test rig and a saltspray test rig.Results showed that SiO_2 nanoparticles could be well incorporated into micro-arc oxidation coatings during the micro-arc oxidation process,thereby effectively reducing the amount of pores and holes on the surface of the micro-arc ceramic coatings and increasing their compactness.In the meantime, incorporating SiO_2 nanoparticles helped to reduce the corrosion current density and corrosion-induced weight gain of the ceramic coatings and increase their impedance,leading to significantly improved corrosion resistances of the micro-arc oxidation ceramic coatings on Mg alloy surface.