Reactive ZrB ₂ -induced oxidation resistance and kinetics in (Zr,Ti,W)C-based ceramics at 1000°C–1100°C

This study systematically investigates the high-temperature oxidation behaviour of (Zr,Ti,W)C-Me x B y multiphase ceramics fabricated by spark plasma sintering, focusing on their performance in static air at 1000°C – 1100°C (operating temperature range for divertor components in nuclear fusion devices). The oxide layers consist predominantly of t-TiO 2 , m-ZrO 2 and (Ti, Zr)O 2 /(Zr,Ti)O 2 solid solutions. At 1000°C, oxidation follows parabolic kinetics, suggesting diffusion-controlled growth. At 1100°C, linear kinetics prevail as enhanced volatilisation of WO 3 and B 2 O 3 leads to porous microstructures. The outer oxide layer develops voids due to WO 3 sublimation, while the inner layer remains dense owing to B 2 O 3 filling the pores and cracks. The multiphase oxide structure, comprising (Zr,Ti)O 2 and (Ti,Zr)O 2 solid solutions along with dispersed ZrO 2 and TiO 2 particles, substantially enhances the oxidation resistance. The incorporation of ZrB 2 significantly increases the apparent activation energy of oxidation from 13.3641 kJ/mol (TW) to 47.4178 kJ/mol (TW60ZB), representing a 355% improvement in oxidation resistance. The key mechanisms include prolonged oxygen diffusion paths due to low-diffusivity ZrO 2 regions, grain boundary pinning by interphase boundaries and microstress fields at TiO 2 /ZrO 2 interfaces that deflect microcracks. These results demonstrate the promising potential of (Zr,Ti,W)C-Me x B y ceramics for high-temperature applications such as nuclear fusion divertor components.