A Biomimetic Bifunctional Composite Enabling Integrated Thermal Protection and Insulation for Ultra-High-Temperature TPS

The rapid development of advanced aircraft has heightened the demand for high-performance thermal protection systems (TPS), yet existing materials struggle to balance ultra-high-temperature ablation resistance and thermal insulation. Inspired by the hair of polar bears, a biomimetic bifunctional composite with a “surface ablation resistance—inner thermal insulation” partitioned structure is designed and fabricated. This architecture comprises a dense ablation-resistant layer composed of HfC nanoparticles / Carbon microspheres@HfC (HfC-n/CMs@HfC) and a porous insulation layer consisting of monodisperse HfC hollow microspheres (HfC-HMs, a material innovation synthesized herein). The composite with a mere 4 mm thickness withstands ablation at 2500°C for 1000 s with a 1638°C front-back temperature difference, and maintains a 1724°C difference at 2600°C for 100 s. The excellent performance stems from the in-situ formation of a dense HfO₂ layer by HfC-n and CMs@HfC, which blocks heat and oxygen, coupled with HfC-HMs suppressing gas conduction through the Knudsen effect within the hollow microstructure and diminishing solid conduction by phonon scattering at the nanoscale shells. Additionally, the composite exhibits a high compressive strength of 201.44 MPa. This work demonstrates that a composite can balance ablation resistance and thermal insulation, and offers a novel design strategy for next-generation ultra-high-temperature TPS.