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

ABSTRACT 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 HfO 2 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.