Abstract: The increasing flight velocities of hypersonic vehicles require breakthroughs in active cooling technology to ensure the oxidation and ablation resistance of key thermal structures such as nose cones and windward surfaces. To achieve such a goal, we pioneered the active cooling approach by introducing arranged active cooling channels in the C_f/HfB₂-SiC composite, through which the temperature of the C_f/HfB₂-SiC composite could be significantly reduced under high heat flux tests. Intriguingly, with the increase of heat flux, the amplitude of temperature reduction exhibited a significant increasing trend. Specifically, under the heat flux of 4 MW/m², the surface temperature of the C_f/HfB₂-SiC composite was reduced from exceeding 2000 to 1500 °C, achieving a temperature reduction of over 500 °C. The composite sample also maintained excellent structural integrity under 2-4 MW/m² heat flux over a test time of 300 s. These results not only highlighted the substantial advantages of the aligned channel active cooling strategy but also provided a new avenue for developing ceramic matrix composites and structures in extreme environmental applications.

Key words: Active cooling, C_f/HfB₂-SiC composite, Aligned channels, Oxidation and ablation resistance