Sliding friction behaviors of TiCN/Cr3C2-NiCr and TiCN/WC-CoCr duplex coatings fabricated by combining HVOF and HT-CVD procedures

Abstract

Hard films play essential roles in the wear protection of metal moving components. In this study, the TiCN/Cr3C2-NiCr and TiCN/WC-CoCr duplex coatings were designed and fabricated by utilizing the high-velocity oxygen fuel and the high-temperature chemical vapor deposition processes. The effects of two cermet interlayers on the microstructure, mechanical characteristics, stress distribution, and sliding wear behavior of the top TiCN films were thoroughly explored. Results evidenced that the TiCN/WC-CoCr duplex coating had a smoother surface than the TiCN/Cr3C2-NiCr duplex coating. The load-bearing capacity and fracture toughness of TiCN/WC-CoCr duplex coating were superior to TiCN/Cr3C2-NiCr duplex coating due to WC-CoCr coating possessing higher hardness, elastic modulus and high-temperature stability. The TiCN/WC-CoCr duplex coating also exhibited lower Von Mises stress compared to TiCN/Cr3C2-NiCr duplex coating, and the stress concentration zone was further away from the interface between the TiCN film and the cermet interlayer. The wear resistance of TiCN/WC-CoCr duplex coating was approximately 2 and 1.5 times that of the single TiCN film and TiCN/Cr3C2-NiCr duplex coating under 20 N load. Moreover, the wear mechanisms of the duplex coatings involved abrasive wear, adhesive wear and oxidative wear. This work significantly enhanced the wear resistance of TiCN films, which will broaden the application of TiCN film in non-load-bearing metal moving components.