Carbon fiber-reinforced high-entropy carbide ceramics (Cf/HECs) are considered promising candidates for ultrahigh-temperature structural applications. The fiber–matrix interface plays a crucial role in determining the overall performance of these materials. This study proposes a novel interface design strategy inspired by the traditional Chinese mortise–tenon joint. In this design, microscale carbon spheres are deposited on the surface of carbon fibers to function as the “tenon”, while the matrix serves as the corresponding “mortise”. Furthermore, a TiC interfacial layer is introduced to improve the interfacial bonding through atomic diffusion. Owing to this distinctive interface structure, the resulting Cf/(TiZrHfNbTa)C–SiC composite exhibits excellent mechanical properties, with a flexural strength of 1053.33 MPa and a fracture toughness of 9.77 MPa·m^1/2. Additionally, the composite demonstrates remarkable thermal shock resistance, with a critical thermal shock temperature difference (ΔT_c) of 802  °C. It also displays superior ablation resistance, characterized by a linear ablation rate of 3.27 μm·s⁻¹ and a mass ablation rate of 0.05 mg·s⁻¹.

To meet the emerging demands for thermal protection materials for hypersonic aircraft, developing porous ultrahigh-temperature ceramics with both robust mechanical properties and superior thermal insulation performance is a critical challenge. Herein, we report novel porous (Ta_0.2Nb_0.2Ti_0.2Zr_0.2Hf_0.2)C high-entropy carbide (PHEC) ceramics fabricated by a self-foaming method using commercially available metal chloride and furfuryl alcohol (FA) as precursors. The PHEC ceramics are constructed of microspheres with a size of 2 µm, leading to a high porosity of 91.3% and an interconnected frame. These microspheres consist of high-entropy carbide grains (20 nm), resulting in abundant interfaces and nanosized pores in the PHEC ceramics. Due to its unique hierarchical structure, the prepared PHEC ceramics have outstanding compressive strength (28.1±2 MPa) and exceptionally low thermal conductivity (κ_T, 0.046 W·m⁻¹·K⁻¹) at room temperature. This makes it a promising thermal insulation materials for ultrahigh temperature applications. This work provides a cost-effective and facile strategy for producing porous ultrahigh-temperature ceramics.