钛合金表面激光熔覆NiCrBSi-TiC复合涂层的组织和摩擦磨损性能

Microstructure and Tribological Properties of NiCrBSi-TiC Laser Clad Layer on Titanium Alloy Substrate

在Ti-6Al-4V合金表面激光熔覆NiCrBSi-TiC复合涂层,利用扫描电镜和透射电镜分析了熔覆层的微观组织,测试了熔覆层在大气和真空(P=10^(-5)Pa)环境中的摩擦磨损性能。结果表明,熔覆层的组织是在γ-Ni树枝晶和γ-Ni+M_(23)(CB)_6共晶的基体上弥散地分布着未熔TiC颗粒和液析TiC。未熔TiC颗粒与基体γ-Ni之间具有外延生长的结合界面,液析TiC与基体γ-Ni结合界面干净、光滑。熔覆层在大气环境中的摩擦系数在0.3～0.4之间,磨损率比Ti-6Al-4V合金降低约一个数量级,在真空环境中的摩擦系数在0.4～0.5之间,磨损率比Ti-6Al-4V合金降低约一倍。

Laser cladding of NiCrBSi-TiC composite coatings on Ti-6Al-4V alloy substrate was carried out, and the microstructure of the clad layer was characterized by SEM and TEM. The friction and wear properties of the clad layer were examined in atmosphere and in vacuum (10-5 Pa). The results showed that in the clad layer, the dispersive undissolved TiC particles and liquid-precipitated TiC were distributed in the matrix consisting of γ-Ni dendrites and γ-Ni+M23 (CB)6 eutectics, the liquid-precipitated TiC having a clear and smooth interface with matrix. The epitaxial growth of TiC was found at the interface of undissolved TiC particles with γ-Ni matrix. In atmosphere, the friction coefficients of the clad layer were ranged from 0.3 to 0.4, and the wear rate of clad layer was a magnitude lower than that of Ti-6Al-4V alloy. In vacuum, the friction coefficients of clad layer varied from 0.4 to 0.5, and the wear rate of clad layer was half as that of Ti-6Al-4V alloy.