Abstract: In order to improve the wear-resistance and anti-friction properties of TC4 alloy, a titanium-based composite coating was prepared on the TC4 alloy surface by laser cladding technique with TC4+h-BN mixed powder. The macroscopic morphology and microstructure of the clad layer were studied by using XRD, SEM, EDS, etc., and the hardness of the clad layer, heat affected zone and matrix was tested by microhardness tester. The friction coefficient and the wear mass loss of the clad layer and matrix were respectively determined by friction and wear tester and electronic precision balance. The results show that the clad layer is mainly composed of rod phase TiB, Ti-B-N ternary eutectic structure and substrate α-Ti. The hardness of the clad layer is between 1000 HV0.5 and 1200 HV0.5. The wear mechanism of the clad layer and the TC4 matrix is slight abrasive wear and severe abrasive wear, respectively. The friction coefficient and the wear mass loss of the clad layer are reduced by 0.04 and by 7 mg from that of the substrate, thus the wear resistance and friction reduction performance of the clad layer are improved compared with the substrate.

Key words: laser clad layer, TC4 alloy, microstructure, microhardness, wear resistance