Mechanical strengths and thermal properties of titania-doped alumina aerogels and the application as high-temperature thermal insulator

Alumina (Al 2 O 3 )-based diphasic aerogels have better physical properties than those of pure Al 2 O 3 aerogel according to previous studies. In the present research, we focused on an alumina–titania (Al 2 O 3 -TiO 2 ) diphasic aerogel. A series of Al 2 O 3 aerogels were synthesized and studied with and without minor TiO 2 dopants (up to 10 mol%). We found that the pure Al 2 O 3 aerogel, which had the fiber-like particles, was stronger than those with TiO 2 dopants that possessed the sphere-like particles. However, the sphere-like particles make the TiO 2 -doped Al 2 O 3 aerogel (with 3 mol% TiO 2 ) possessing the largest specific surface area (SSA) of 650 m 2 /g, much larger than that of the pure Al 2 O 3 aerogel (326 m 2 /g). This work proved that fiber-like particles enhance strength but reduce SSA of Al 2 O 3 aerogel. At last, ceramic fibers reinforced Al 2 O 3 aerogel composites with the sizes of 20 cm width × 20 cm length × 1 cm thickness were fabricated. The aerogel composites possessed a thermal conductivity of 0.136 W/m K at 1000 °C, better than those of the ceramic fiber blankets itself (0.30 W/m K), indicating potential application as high-temperature thermal insulator.