Rigid silica xerogel/alumina fiber composites and their thermal insulation properties

Mechanically robust silica xerogel/alumina fiber composites were successfully prepared by a cost-effective ambient pressure drying route. Microstructure investigation shows that the alumina fibers embed into the silica xerogel matrix as reinforcements, which improves the strength of the composites greatly. As the alumina fibers volume increases to 4.0%, the compressive and flexural strength value of the composite is 0.96 MPa and 2.53 MPa, while the thermal conductivity at room temperature slightly changes between 0.051 and 0.059 W/mK. The composite is hydrophobic and keeps water repellent until 300 °C as shown by the TG–DSC result. After being heated at 800 °C for 25 min, the composite remains structurally intact demonstrated good thermal resistant property. The above characteristics indicate that the as prepared composite has great potential application as thermal insulation material in energy-saving area.