Bioinert TiC ceramic coating prepared by laser cladding: Microstructures, wear resistance, and cytocompatibility of the coating

Recent advance in biological applications such as artificial joint replacement are focused towards fabricating reliable bearing surface to extend their service life. Given this perspective, incremental attempts have been made to enhance the wear resistance of titanium alloys used widely in artificial joint and mechanical reliability of brittle TiC ceramic, but plan often don't go along with reality. It is proposed that both high mechanical reliability and wear resistance can be hold if a thin TiC ceramic coating is formed onto high toughness Ti6Al4V alloy used widely in biological applications. In this paper, bioinert TiC ceramic coating was fabricated on Ti6Al4V substrate surfaces through laser cladding using preplaced TiC nanoceramic powders on the substrate surfaces. The microstructural characteristics of the TiC ceramic coating were investigated in detail. Further, the rapid melting mechanism of the TiC nanoparticles and the microstructural formation mechanism of the coating were revealed. Moreover, the wear mechanism and cytocompatibility of the coating were identified. The results showed that the original TiC nanoparticles completely melted and solidified to form dendritic TiC ceramic coating owing to the small size effect of the nanoparticles and the thermodynamic effect of the high-energy laser beam. The wear resistance of the TiC ceramic coating fabricated by laser cladding was three times higher than that of the Ti6Al4V substrate, and the coating had the same good cytocompatibility as that shown by Ti6Al4V. Microstructure-phase-property relationships in TiC ceramic coating were revealed and discussed according to our research findings. The designed TiC coating and Ti alloy hybrid might be potential application in artificial joint surfaces and other implants with strong wear-resistance requirements.