High-thermal-conductivity C/C-HfC-SiC composites with enhanced ablation resistance for oxidative environments above 3000 °C

Next-generation hypersonic vehicles operate in extreme high-temperature oxidative environments exceeding 3000 °C, imposing stringent requirements on the thermal management and ablation resistance of thermal protection materials. Herein, a material design strategy is proposed to reduce the surface thermal response temperature by constructing a high-thermal-conductivity architecture. A high-thermal-conductivity C/C-HfC-SiC composite was fabricated via reactive melt infiltration using mesophase pitch-based carbon fibers and a highly graphitized carbon matrix as a continuous heat-conduction framework. The composite exhibits a maximum room-temperature thermal conductivity of 218 W·m −1 ·K −1 , together with a high ultra-high-temperature ceramic phase content (>18 vol%) and a low open porosity (<6%). Oxyacetylene ablation tests show that the surface temperature is reduced by approximately 200 °C compared with low-thermal-conductivity counterparts, with a linear ablation rate of 3.33 × 10 −3 mm/s. After 300 s exposure in a plasma wind tunnel at 9.5 MW·m −2 , the composite exhibits a measured linear ablation rate of −6.6 × 10 −4 mm/s and a mass ablation rate of 3.3 × 10 −3 g/s. The extremely low ablation rates indicate its potential for hypersonic thermal protection applications.