Microstructure and wear performance of gradient Ti/TiN metal matrix composite coating synthesized using a gas nitriding technology

Surface modification is an attractive method to enhance the surface hardness and wear resistance of titanium. In this paper, a continuous wave 2 kW Nd:YAG laser was used to synthesize Ti/TiN metal matrix composite coating on the surface of commercial pure titanium. The microstructure and the wear resistance of the synthesized metal matrix composite coating were investigated. The synthesized surface Ti/TiN metal matrix composite coating had a pronounced gradient microstructure through the melt depth. Good metallurgical bonding between the reinforcing phase of the metal matrix composite and the titanium matrix was observed. The hardness and wear resistance under block-on-ring dry sliding wear testing conditions of the synthesized Ti/TiN metal matrix composite coating were markedly enhanced.