20% Al2O3-SiO2(sf)/AZ91D镁基复合材料微弧氧化陶瓷层电化学腐蚀性能

Electrochemical Corrosion Property of Microarc Oxidation Ceramic Coatings on 20vol% Al2O3-SiO2(sf)/AZ91D Magnesium Matrix Composite

摘要:

在磷酸盐体系电解液中，对20%(体积分数)硅酸铝短纤维(Al2O3-SiO2)增强AZ91D镁基复合材料进行微弧氧化表面处理获得陶瓷层。利用扫描电子显微镜(SEM)和X射线衍射(XRD)仪分析陶瓷层的表面形貌、截面组织和相组成，采用动电位极化和电化学阻抗谱(EIS)测试评价微弧氧化陶瓷层的电化学腐蚀性能。结果表明，该陶瓷层主要由MgO和MgAl2O4相组成。陶瓷层的腐蚀电流密度比镁基复合材料基体低3个数量级，电化学阻抗大幅升高，耐腐蚀性能明显高于复合材料基体

Abstract:

Ceramic coatings were prepared on 20vol% Al2O3-SiO2(sf)/AZ91D magnesium matrix composites by microarc oxidation (MAO) technique in a phosphate electrolyte. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were employed to analyze the surface morphology, cross-section microstructure and phase composition of the coated composites. The electrochemical corrosion property of coatings was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results show that the ceramic coating mainly consists of MgO and MgAl2O4. The corrosion current density of ceramic coating decreases nearly by three orders of magnitude compared with magnesium matrix composite substrate while its electrochemical impedance increases greatly. The magnesium matrix composites treated by microarc oxidation display good corrosion resistance