Preparation and Structural Evolution of ZrB2–HfC–SiC/Dicyanobenzene Hybrid Ultra-High-Temperature Materials Moulded at 250 °C/2 h

Ultra-high-temperature materials (UHMs) are indispensable for extreme thermal environments (e.g., temperatures exceeding 2000 °C); however, their practical implementation remains severely constrained by demanding processing conditions, including extreme sintering temperatures, prolonged cycles, densification barriers and high equipment cost. In order to meet the low-cost and ablation-resistant requirements of aircraft nose cones, a facile organic–inorganic hybrid strategy is proposed to fabricate ZrB2–HfC–SiC composites using a high-char-yield 1,2-dicyanobenzene (DCB) binder, enabling low-temperature moulding at merely 250 °C (2 h; 20 MPa). Upon high-temperature oxidative exposure, the DCB matrix undergoes in situ pyrolysis and synergistic co-sintering with the ceramic powders, producing a multi-layered, self-protective structural architecture. A comprehensive structure–temperature map correlating temperature-dependent phase evolution with flexural strength and thermal conductivity is established, thereby elucidating the underlying self-healing and ablation-resistance mechanisms. The hybrid material in this work exhibits excellent flexural strength, ablation resistance and thermal stability. This study successfully reconciles the long-standing contradiction between low-temperature processability and ultra-high-temperature (2600 °C) service durability, offering a scalable route for next-generation thermal protection systems.