Abstract:
TiN coatings were prepared by physical vapor deposition on surfaces of TC4 titanium alloy manufactured by laser powder bed fusion (LPBF-TC4 titanium alloy) and by traditional process (CP-TC4 titanium alloy). The microstructure was observed. The dry reciprocating sliding wear tests under different loads (2, 6 N) were carried out, and the wear resistance and wear morphology evolution were studied. The results show that the thickness of the TiN coating was approximately 2.5 μm, it adhered closely to the surface of the TC4 titanium alloy substrate, and the structure was dense. The wear rate of coated samples was lower than that of the titanium alloy substrate, and the protective effect of the coating on the substrate under 2 N load was stronger than that under 6 N load. The difference in substrate hardness led to different fracture characteristics of the two coating samples. Under 2 N load, the coating of the TiN coating/LPBF-TC4 titanium alloy sample thinned at 2 219 s, with a thickness less than 1 μm. The coating started to fail from the middle of the wear scar, forming a scratch band. The failure width expanded over time to be the same as the wear scar width. The TiN coating /CP-TC4 titanium alloy samples began to fail at 2 401 s. The coating thinned, with a thickness of less than 1 μm. The local coating was pressed into the substrate by wear debris and cracks occurred.