Preparation of the novel B₄C–SiC composite aerogel with high compressive strength and low thermal conductivity

A novel B₄C–SiC composite aerogel is synthesized using nano boron carbide suspension, 3-aminopropyltriethoxysilane (APTES), and resorcinol–formaldehyde (RF) as precursors through the sol–gel route and carbothermal reduction process. The effects of different B/Si molar ratios and calcination temperatures on the physical chemistry properties of B₄C–SiC composite aerogels are investigated. The addition of the B₄C phase is beneficial for improving the comprehensive properties of composite aerogel. The results show that the compressive strength of B₄C–SiC composite aerogel is as high as 3.05 MPa. The specific surface area can reach 692.81 m²/g, which ensures that it has a thermal insulation capacity under elevated temperatures. After heat-treated at 1650 °C for 3 h, the thermal conductivity of carbon fiber mat reinforced composite aerogel is 0.058 W/m K (25 °C). This composite aerogel material has great application prospects in the field of high temperature insulation.