Growth mechanism of Mo₂C coatings on diamond particles in molten salt

Diamond has always been used for reinforcing diamond tools and thermal management materials owing to its high hardness and good thermal conductivity. However, surface inertness of diamond hinders tight bonding with the matrix, leading to significantly declined performance of diamond-reinforced composites. This can be solved by forming coatings with good wetting on diamond surface to serve as a bridge for optimizing interfacial bonding of composites. Accordingly, Mo₂C coating was prepared in this study through molten salt method. Key parameters influencing coating quality were investigated systematically by multi-scale microstructural characterizations to shed light on growth mechanism. Results revealed nucleation process of Mo₂C highly depended on different diamond surface nucleation sites controlled by reaction mechanism, while further growth of Mo₂C coating was controlled by diffusion mechanism. Affinity of as-prepared Mo₂C coating on diamond was directly verified by thermal shock tests. Overall, novel insights into nucleation process were provided, promising for further preparation and regulation of carbide coating on diamond.