In situ formed biphasic high-entropy silicate ceramic aerogels reinforced by Al2O3 nanorods for high-temperature thermal insulation

초록

Biphasic high-entropy ceramic aerogels offer new material pathways toward lightweight thermal-insulation and structural applications involving multicomponent rare-earth (RE) systems that operate in extreme-temperature environments. In this study, we fabricated a lightweight and mechanically robust high-entropy ceramic aerogel using a sol-gel self-assembly method followed by supercritical drying. An RE-Si-Al sol precursor was subjected to one-step calcination, which led to the in-situ formation of high-entropy rare-earth monosilicate (RE2SiO5) and garnet (RE3Al5O12) and a biphasic coexisting ceramic aerogel (RSAA) that effectively suppresses heat transport while efficiently bearing mechanical load. RSAA retained its intact three-dimensional network even after calcination at 1300 degrees C for 30 min, owing to high-entropy phonon scattering, multiscale pore-blocking effects, and load-transfer supported by Al2O3 nanorods. The aerogel exhibited an ultralow density of 0.075 g/cm3 and an exceptionally low thermal conductivity of 0.0313 W/(m & sdot;K), with a backside temperature of only 226.2 degrees C after 1200 s of butane-flame ablation at 1300 degrees C, which highlights its outstanding thermal-insulation and ablation-resistance properties. Moreover, it exhibited a compressive strength of 347 kPa at 60% strain and withstands quenching in liquid nitrogen (-196 degrees C) without cracking, highlighting its remarkable structural stability under extreme thermal conditions.

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