An ultra-hard and thick composite coating metallurgically bonded to Ti–6Al–4V

•Vacuum braze coating process prepares an ultra-hard thick composite coating on TC4.•Microstructure of the coatings is analyzed.•A metallurgical bonding between composite coatings and TC4 is obtained.•The hardness of the composite coating is significantly improved.•The composite coating has shown excellent wear properties.

The vacuum braze coating process was proposed to prepare an ultra-hard thick composite coating on titanium alloy in this paper. Mixed powders of Ti–Zr–Cu–Ni and TiC were heated to 1223 K and held for 30 min under vacuum. Microstructure and mechanical properties of the (Ti–Zr–Cu–Ni) + TiC composite coating have been systematically analyzed. The results showed that a uniform dispersion of TiC in the Ti–Zr–Cu–Ni matrix can be found for the composite coating, which is strongly bonded with TC4. Moreover, the surface hardness improved drastically after the incorporation of TiC particles, and the maximum value of surface Rockwell hardness was 66.1 HRC. The (Ti–Zr–Cu–Ni) + TiC composite coating had excellent wear resistance under sliding wear test conditions compared with the pure Ti–Zr–Cu–Ni coating, due to the high hardness of the TiC dispersoids.