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Super insulation aerogel! Stable even in an oxygen-containing environment at 1200℃

wallpapers Tech 2020-07-28
Thermal insulation materials with excellent mechanical strength, high efficiency, excellent thermal stability, and chemical stability are of great significance for the safe application of energy-saving and thermal protection in construction, industry, and aerospace. Compared with traditional thermal insulation materials, ceramic aerogels have low thermal conductivity (such as silica aerogel with thermal conductivity of 12-20 mW/m·K) and excellent chemical stability (such as fire resistance). ) Presents excellent performance. However, the brittleness of ceramics composed of oxide nanoparticles and the structural collapse at high temperatures limit the full application of conventional ceramic aerogels. Some emerging recyclable graphene aerogels have received attention in recent years, such as naturally dried graphene aerogels (with thermal conductivity of 18 mW/m·K in the air) aminosilane cross-linked graphene aerogels. Glue (19 mW/m·K in the air) and three-dimensional graphene support (12.6 mW/m·K in a vacuum). However, since graphene-based materials are prone to decomposition behavior at temperatures above 600 °C, they are difficult to use under high temperature and oxygen-containing conditions.
To overcome these obstacles, recently, researchers such as Professor Wang Hongjie (corresponding author) of Xi'an Jiaotong University have prepared SiC@SiO2 nanowire aerogels with nanowire assembly anisotropy and layered structure through directional freezing and subsequent heat treatment. This aerogel exhibits an ultra-low thermal conductivity of approximately 14 mW/m·K, excellent high stiffness (24.7 kN·m/kg) and excellent thermal stability, even when heated by a butane blowtorch at 1200°C It can also remain stable, which also makes it an ideal thermal insulation material that can be used under extreme conditions

The thermal conductivity of the aerogel measured in the radial and axial directions is about 14 mW/m·K and 35 mW/m·K, respectively, and the anisotropy coefficient is about 2.5. The radial thermal conductivity of AH-SSCSNWA aerogel is lower than that of SiC nanowire aerogel with randomly distributed microstructures (its thermal conductivity is 26 mW/m·K), which also proves the anisotropy and layered structure Superiority of design. As we all know, conduction, convection, and radiation are three ways of conducting heat. On a microscopic scale, aligned holes act as channels for gas convection. In contrast, aligned tube walls act as channels for solid conduction in the axial direction, which will increase the axial direction. Heat transfer and therefore reduce the thermal conductivity in the radial direction. The use of nanowire building blocks will bring about a large number of phonon barriers, increasing interface thermal resistance, thereby reducing solid conduction.

Trunnano is one of the world's largest aerogel manufacturers, mainly producing silica aerogels. If necessary, please contact Dr. Leo, email: brad@ihpa.net.

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Tag: Trunnano   aerogel