Decent ablative resistance, enhanced thermal conductivity and high mechanical properties of high-entropy (Hf, Zr, Ti, Ta)C-W composites

High entropy carbides (HECs) ceramics are promising candidates for high-temperature ablation-resistance materials. However, the limited thermal conductivity and mechanical properties still impede its capability to survive in extreme ablation environment. Here, we design the high entropy carbide Hf_0.5Zr_0.3Ti_0.1Ta_0.1C, denoted as HZTTC, integrated with refractory tungsten mesh. This composite remains intact subjected to ablation at 2500 °C. Its linear ablation rate (LAR) and mass ablation rate (MAR) achieve decent values of −1.75 μm·s⁻¹ and −0.149 mg·s⁻¹·cm⁻². This decent ablation performance is characteristic of various ablation resistant oxides with unique morphologies, such as lamellar, flocculent, needlelike, and rod-shaped oxides. Surprisingly, the composite still reveals attractive ablation properties with the LAR of −0.75 μm·s⁻¹ and the MAR of −0.072 mg·s⁻¹·cm⁻², even when the ablation temperature goes up to 2700 °C for 600 s. Moreover, the ceramic-metal composite achieves a high thermal conductivity of 25.72 W·m⁻¹·K⁻¹, demonstrating a 16.7 % enhancement to that of the pure HZTTC ceramic. Moreover, this composite also reveals a high hardness of 22.21 GPa and a fracture toughness of 5.64 MPa·m^1/2. This decent ablation performance, high thermal conductivity and peculiar mechanical properties enable this composite to be a potential alternative for protecting hypersonic aircraft severing in extreme environments.