Abstract:The TiC particles reinforced Ni-based alloy composite coatings were prepared by plasma spray. The microstructure and tribological properties of the composite coatings were investigated. The results show that the composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃ and TiC. A transition layer of 9.4 μm in thickness forms at the interface, indicating the metallurgy bond between the composite coating and the substrate. When the content of TiC particles is 30% in volume fraction, both of the friction coefficient and wear rate of the composite coatings reach the lowest values. The friction coefficient is 0.33 which is reduced by 30% compared with the pure Ni-based alloy coating; the wear rate is 0.3×10^-3 mm³/m which is about 1/3 that of latter. Under the load of 6-10 N, the composite coatings are in a slight wear stage and their wear mechanisms are mainly adhesive wear. Under the high load of 12 N, the composite coatings suffer from severe wear, and the wear mechanisms change into the desquamation of the hard phases and the delamination of the transferred layer.

Key words: plasma spray; composite coatings; TiC particle; Ni-based alloy; friction and wear