Al_2O_3含量对Al_2O_3-Al复合涂层组织和摩擦磨损性能的影响

Effect of Al_2O_3 contents on microstructure and tribological properties of Al_2O_3-Al composite coatings

通过改变喷涂粉末中Al2O3和Al的比例,在AZ91D镁合金表面制备不同Al2O3含量的等离子喷涂Al2O3-Al复合涂层。对复合涂层的显微组织、硬度和摩擦磨损性能进行表征,研究Al2O3含量对涂层组织和磨损性能的影响。结果表明,涂层组织为带状Al2O3分布在致密的Al基体上,Al2O3内可见细微的片层结构,且层与层间存在一定的孔隙。复合涂层中Al平均硬度62HV,Al2O3平均硬度达1380 HV。摩擦磨损实验证实,复合涂层具有较小的摩擦系数和较低磨损量,大大改善了镁合金表面的抗磨损性能。涂层中Al2O3体积少于Al时,Al2O3增加使涂层的抗磨效果增强。涂层中Al2O3体积超过Al后,涂层的孔隙增多、涂层变脆,其耐磨损性能下降。

Al2O3-Al composite coatings were fabricated on AZ91 D magnesium alloy by plasma spraring with Al2O3 and Al mixed powders.Microstructure,microhardness and wear resistance of the coatings were examined and the effect of Al2O3 contents on the microstructure and tribological properties of the coatings was investigated. The results showed that in these composite coatings Al2O3 distributed in the compacted Al matrix. The microstructure of the coatings is banded structure and consisted of many tiny lamella with some pores. The hardness of Al is about 62 HV and that of Al2O3 is up to 1380 HV. The wear test results show that Al2O3-Al composite coatings have lower friction coefficient and less mass loss,and improved the wear resistance of AZ91 D magnesium alloy greatly. When the volume fraction of Al2O3 is lower than that of Al,wear resistance of the coatings increases with increasing Al2O3. When the volume fraction of Al2O3 is higher than that of Al,wear resistance of the coatings decreases.