AZ91和AZ80镁合金表面含石墨纳米颗粒的PEO涂层的摩擦和腐蚀行为

摘要

The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation (PEO) coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances of the obtained coatings were investigated. A solution that contained both phosphates and silicates was used as electrolyte. Moreover, two different PEO treatment times were studied. The corrosion resistance was analyzed with potentiodynamic polarization and EIS tests; the wear resistance was investigated with a flat on ring tribometer. The results were related to the morphology, microstructure, elemental composition and thickness evaluated with SEM analysis. The presence of the graphite nanoparticles increased the thickness, produced a densification of the coating and sealed the pores on the surface, thus improving both the corrosion and wear resistance. The increase in the corrosion and wear resistances was more evident for AZ91 than for AZ80 due to the higher aluminum content.%用等离子电解氧化(PEO)法在AZ91和AZ80镁合金表面制备涂层,研究在电解液中添加石墨纳米颗粒对涂层的耐腐蚀性和耐磨性能的影响.所用电解液为含有磷酸盐和硅酸盐的碱性溶液,并采用两种不同的PEO处理时间(1 min和3 min).用动电位极化法和电化学阻抗谱(EIS)分析涂层的耐腐蚀性,用平面?盘式滑动摩擦实验测试其耐磨性能.用扫描电镜及能谱仪(SEM?EDS)观察涂层的组织形貌、微观结构、元素组成和涂层厚度.结果表明,石墨纳米颗粒增加了涂层的厚度,封闭了表面的孔隙,使涂层更致密,因此提高了其耐腐蚀性和耐磨性能.由于AZ91具有更高的铝含量,其耐腐蚀性能和耐磨性能的提高比AZ80更显著.