Characteristics of laser clad α-Ti/TiC+(Ti,W)C1−x/Ti2SC+TiS composite coatings on TA2 titanium alloy

Abstract

TiC reinforced Ti matrix composite coating with Ti2SC/TiS lubricant phases in-situ synthesized were prepared on TA2 titanium alloy by laser cladding with different powder mixtures: 40%Ti-19.5%TiC-40.5%WS2, 40%Ti-25.2%TiC-34.8%WS2, 40%Ti-29.4%TiC-30.6%WS2 (wt%). The phase compositions, microstructure, microhardness and tribological behaviors and wear mechanisms of coatings were investigated systematically. Results indicate that the main phase compositions of three coatings are all continuous matrix α-Ti, reinforced phases of (Ti,W)C1−x and TiC, lubricant phases of Ti2SC and TiS. The microhardness of the three different coatings are 927.1HV0.5, 1007.5HV0.5 and 1052.3HV0.5, respectively. Compared with the TA2 titanium alloy (approximately 180HV0.5), the microhardness of coatings have been improved dramatically. The coefficients of friction and the wear rates of those coatings are 0.41 and 30.98×10−5mm3N−1m−1, 0.30 and 18.92×10−5mm3N−1m−1, 0.34 and 15.98×10−5mm3N−1m−1, respectively. Comparatively speaking, the coating fabricated with the powder mixtures of 40%Ti-25.2%TiC-34.8%WS2 presents superior friction reduction and anti-wear properties and the main wear mechanisms of that are slight plastic deformation and adhesive wear.