Bioinert TiC ceramic coating prepared by laser cladding: Effect of SiO2 on microstructural evolution, wear resistance, and cytocompatibility of the coating

Bioinert ceramic coatings prepared by laser cladding (LC) offer an effective means to enhancing the wear resistance of titanium alloy implants. However, the application of such ceramics is often limited by their poor flow characteristics and high melting points. The preplaced powder layer was also loose and porous, which often results in issues such as poor surface quality and insufficient microstructural density in the resulting ceramic coatings. To further improve the quality of TiC ceramic coating prepared by LC, SiO 2 particles were introduced as a liquid-phase additive into TiC preplaced powders. The effect of SiO 2 content (10-30 wt.%) on the surface quality, microstructure, phase composition, wear resistance, and cytocompatibility of TiC ceramic coating was systematically investigated. Microstructural evolution of the coating and the function mechanism of SiO 2 liquid phase were thoroughly analyzed. The results showed that increasing SiO 2 content promoted an evolution in TiC from dendritic to cellular crystal and finally to cellular dendrite morphology. In-situ formed Ti 5 Si 3 phase exhibited oriented nano-lamellar structures and conical nano-column structures with a high-aspect-ratio. The SiO 2 liquid phase promoted heat and mass transfer in the molten pool, facilitating the rearrangement of TiC nanoparticles and the densification of the ceramic coating via the mechanism combining the liquid phase sintering and the complete melting/solidification. The preferred TiC-20SiO 2 coating exhibited a dense microstructure, with a wear volume of 13.28% of that of Ti6Al4V. Cell culture tests with MG-63 osteoblasts confirmed its good cytocompatibility. This work provides a viable strategy for preparing high-quality ceramic coatings via LC.