汽车发动机缸体用AZ91合金的表面改性与耐磨耐蚀性能

Surface modification and wear and corrosion resistance of AZ91 alloy for automotive engine cylinder

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 for automotive engine was modified by surface plasma cladding. The microstructure and phase composition of AZ91 alloy substrate,TiB2-Al2O3 and Al∶（TiB2-Al2O3） modified layers were analyzed,and the hardness,wear resistance and corrosion resistance of the modified layer were studied. The results show that with the increase of distance from the surface,the overall micro hardness of the modified layer are gradually reduced,and microhardness of the modified layers are higher than that of the AZ91 alloy substrate（ 98 HV0. 1）,and that of the TiB2-Al2O3 layer is the highest. Microhardness of the modified layers shows gradually decreases trend with the increase of Al content. The wear and corrosion resistance of the modified layer are improved compared with those of AZ91 alloy substrate,and the Al∶（ TiB2-Al2O3） = 1∶2 modified layer has the best wear and corrosion resistance.