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摘要
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 (Ti0.167Cr0.167V0.167Mo0.167Nb0.167Ta0.167)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 (Ti0.2V0.2Mo0.2Nb0.2Ta0.2)C and (Ti0.2Cr0.2Mo0.2Nb0.2Ta0.2)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.(#br)(Ti0.167Cr0.167V0.167Mo0.167Nb0.167Ta0.167)C six‐principal‐component high‐entropy transition‐metal carbide (6‐HETMC) ceramic aerogels were successfully synthesized via in‐situ carbothermal reduction/partial sintering by using transition‐metal oxides and chitosan powders as raw materials. They contained 94.5% porosity had a compressive strength of 0.8?MPa, and exhibited a homogeneous microstructure (with pore size 0.2–10?μm) formed mainly by the release of CO gas and the neck sintering of particles on firing. Thanks to their highly porous structure and the higher configuration entropy, the as‐prepared 6‐HETMC ceramic aerogels exhibited a much lower thermal conductivity than the conventional 5‐HETMC materials prepared previously.
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