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对汽车发动机缸体用AZ91合金表面进行了等离子熔覆改性处理,对比分析了AZ91合金基体、TiB_2-Al_2O_3和三种不同比例的Al∶(TiB_2-Al_2O_3)改性层的显微组织和物相组成,并对改性层的硬度、耐磨性和耐腐蚀性能进行了研究。结果表明,随着距离改性层表面距离的增加,显微硬度整体呈逐渐降低的趋势,不同配比的改性层的显微硬度都高于AZ91合金基体(98 HV0.1),TiB_2-Al_2O_3改性层的显微硬度最高,随着熔覆材料中Al含量的增加,改性层显微硬度呈现逐渐降低的趋势;经过等离子熔覆TiB_2-Al_2O_3和Al∶(TiB_2-Al_2O_3)改性处理后的发动机缸体的耐磨性与耐腐蚀性均有所提高,其中Al∶(TiB_2-Al_2O_3)=1∶2改性层的耐磨性及耐腐蚀性能最好。
The surface of AZ91 alloy was modified by plasma cladding. The microstructure and properties of AZ91 alloy substrate, TiB_2-Al_2O_3 and three different proportions of Al: (TiB_2-Al_2O_3) modified layer were analyzed. Phase composition, and modified layer hardness, wear resistance and corrosion resistance were studied. The results show that the microhardness decreases gradually as the distance from the surface of the modified layer increases. The microhardness of the modified layers with different proportions is higher than that of AZ91 alloy (98 HV0.1), TiB_2- The microhardness of Al 2 O 3 modified layer is the highest. With the increase of Al content in the cladding material, the microhardness of the modified layer tends to decrease gradually. After plasma cladding TiB 2 -Al 2 O 3 and Al: (TiB 2 -Al 2 O 3) After treatment, the wear resistance and corrosion resistance of engine block are improved, among which the wear resistance and corrosion resistance of Al: (TiB 2 -Al 2 O 3) = 1: 2 modified layer are the best.