Synergistic evolution of carbon structure and ZrC grain growth during carbothermic reduction

Zirconium carbide was synthesized via carbothermic reduction using Zr(OPr n ) 4 and carbon black as starting materials. The phase evolution, carbon transformation, and growth mechanism of ZrC were systematically investigated with CaF 2 as a catalyst. ZrC nucleated within the carbon phase, facilitated by the formation of gaseous ZrF 4 , which shortened the diffusion distance between zirconium and carbon. The ZrC grains grew continuously and ventually forming well-defined octahedral structures as the reaction progressed. The addition of CaF 2 promoted the graphitization of the carbon source, leading to the formation of ordered carbon layers on the surface of the ZrC grains. This graphitic structure enhanced the reactivity of carbon and further accelerated the reduction reaction. This study reveals the synergistic relationship between the structural evolution of carbon black and the nucleation and growth mechanisms of ZrC, providing practical guidance for the design of high-activity ZrC powders for advanced ceramic applications.