Investigation of thermal insulation performance of glass/carbon fiber-reinforced silica aerogel composites

Silica aerogels have been widely used as thermal insulators, but their fragility has hindered the potential applications. In this work, a novel way of improving aerogel skeletal structure was proposed where composites were reinforced by three functional layers of glass fiber (GF)/ carbon fiber (CF). Heat insulation performance of fiber-reinforced aerogel composites was also investigated in a simulated solar radiation system. Composites composed of three layers of fiber were prepared by a sol-gel process under ambient pressure drying. The results showed that, as three layers were all GF blankets, the composite heat conductivity increased with increasing glass fiber content. Flexural strength increased initially and reached a maximum at 20% glass fiber content before decreasing. To find a balance between promoting heat insulation performance and strengthening the composite structure, two layers of 5% glass fiber blankets were used as structure strengthening layers and one carding 5% carbon fiber as the heat insulation layer were recommended. Under these conditions, the composite showed extremely low thermal conductivity (0.031 W/m K), almost comparable to that of pure aerogel (0.036 W/m K) while maintaining high flexural strength (2.846 MPa), superior than previous studies. Composites with other ratios of glass/carbon fibers with sandwiched alignments also demonstrated better flexural strength and lower thermal conductivity than GF aerogel composites. This work provided an alternative way to prepare robust and sustainable heat insulation aerogel composites for practical uses. Highlights Heat insulation performance of silica aerogels composited with different ratios of glass fiber and carbon fiber was investigated. The flexural strength increased with increased glass fiber loading, and reached its highest value when glass fiber content was 20%. 5% carbon fiber inserted between the two 5% glass fiber layers was found the most ideal condition in terms of flexural strength (2.846 MPa) and thermal conductivity (0.031 W/m K).