等离子熔覆Ni-Cr合金涂层的组织与性能研究

Microstructure and Performance of Ni-Cr Cladding Formed by Plasma Surfacing Processes

采用等离子熔覆技术在40Cr钢基材表面熔覆Ni-Cr合金涂层,研究了熔覆层的组织特征、成分和显微硬度分布特点。结果表明:等离子熔覆层与基体的结合面是由等轴晶构成的,熔覆层与基体呈现良好的冶金结合状态;熔覆层中部分布着沿逆热流方向生长的排列较规则的枝晶组织;熔覆层表层是细小的枝晶组织。能谱分析表明在结合面处Ni,Cr含量发生显著变化,等离子熔覆可以实现低稀释率。熔覆层的显微硬度呈梯度过渡到基体,熔覆层外层硬度值最高,在结合面附近硬度出现显著的变化。

The cladding of Ni-Cr alloy was coated on the surface of 40Cr alloy steel by the PTA （Plasma Transferred Arc） surfacing process. The microstructures, component and microhardness of the coating were investigated. The results show that the coating obtained is well bonded to the matrix and the interface between the cladding and the matrix consists of the isometric crystal. The microstructure varies from relatively regular dentritic crystal in the middle of the coating to fine crystal near the top of the coating. The content of Ni and Cr change markedly on the interface by the spectrum analysis, shows that the cladding has low ratio of dilution. The hardness is the largest on the surface of the cladding and is reduced sequentially to the matrix, which changes observably on the interface.