In Situ Formation of the TiCN Phase in SiBCN Ceramic Aerogels Enabling Superior Thermal and Structural Stability up to 1800 °C

Ceramic aerogels show excellent thermal insulation and functional performance for their unique nanoporous structure. However, conventional ceramic aerogels often undergo structural collapse and performance deterioration in high-temperature environments due to sintering, crystallization, and/or phase transition. Here, we designed a TiCN/SiBCN ceramic aerogel in which the TiCN phase was in situ formed through a carbothermal reaction during pyrolysis. Benefiting from its unique pearl-necklace-like structure, the TiCN/SiBCN aerogel exhibits a high specific surface area (248 m 2 /g), a low thermal conductivity (0.08 W/m·K), and a considerable compressive strength (2.2 MPa). The formation of a stable TiCN phase endows the aerogel with significant resistance to thermal decomposition and crystallization up to 1800 °C. Moreover, the TiCN/SiBCN aerogel retains high surface area and low thermal conductivity after thermal treatment, indicative of the stability and reliability of the nanoporous structure. The TiCN/SiBCN ceramic aerogel with superior thermal and structural stability is an ideal candidate for structural and functional applications in high-temperature environments.