Low-temperature synthesis of six-principal-component high-entropy transition-metal carbide aerogel thermal insulator

High-entropy transition-metal (IVB–VIB) carbide (HETMC) ceramics consisting of multiple principal components generally correspond to higher configuration entropy, and exhibit better overall performance. However, they also present certain synthesis challenges, for example, in the synthesis of a three-dimensional six-principal-component HETMC aerogel. In the present work, as an example a novel (Ti_0.167Cr_0.167V_0.167Mo_0.167Nb_0.167Ta_0.167)C aerogel was prepared at a relatively low temperature of 1773 K by an in-situ carbothermal reduction/partial sintering technique following the successful preparation of (Ti_0.2V_0.2Mo_0.2Nb_0.2Ta_0.2)C and (Ti_0.2Cr_0.2Mo_0.2Nb_0.2Ta_0.2)C five-principal-component HETMC aerogels. The synthesized 6-HETMC aerogel exhibited a homogeneous microstructure with grain phases and pores of 100–300 nm and 0.2–10 μm, respectively, a density of 0.45 g cm⁻³, a high porosity and compressive strength of 94.5% and 0.8 MPa, respectively, a low thermal conductivity of 0.128 W (m K)⁻¹ at 298 K, and a good high-temperature stability at least up to 1673 K in Ar. This research provided a novel strategy for future development of HETMC ceramic aerogels for high-temperature applications.