Microstructure and Properties of Reactive Plasma Sprayed TiN Composite Coating on ZL104 Alloy

NiCrAl alloy adhisive coating and TiN composite coating were in turn deposited by reactive plasma spraying on ZL104 alloy substrate. The phase composition, microstructure, bonding strength, micro-hardness and wear resistance of the coating were studied by X-ray diffraction, structure observation, hardness test and tensile and wear test, and the wear mechanism was also discussed. The results show that the composite coating consisted of TiN, TiN_0.3 and a small amount of TiO₂ phases, and its structure was dense with a few cavities and microcracks. The coating and ZL104 alloy was well bonded, and the bonding strength was 17.7 MPa. The average hardness of the TiN composite coating was 1 330 HV, which was about 22 times of the substrate; the wear mass loss of the TiN composite coating increased with the load, and was much smaller than that of the substrate. The wear mechanism of ZL104 alloy was micro-cutting abrasive wear and micro-fatigue wear, while that of the TiN composite coating was micro-cutting abrasive wear.