Oxide aerogel materials are prone to crystal transformation and particle sintering in high temperature areas (>1000℃), and their temperature resistance is relatively poor, but they have low thermal conductivity in medium and high temperature areas (<1000℃). Oxide aerogel materials mainly include SiO2, Al2O3, TiO2, ZrO2, CuO, etc.
1) SiO2 aerogel materials
SiO2 aerogel is currently the most studied and more mature high-temperature resistant aerogel in the field of thermal insulation. Its porosity is as high as 80%~99.8%, the typical size of the pores is 1~100nm, the specific surface area is 200~1000m2/g, and the density can be as low as 3kg/m3, and the room temperature thermal conductivity can be as low as 12m.W/(m〃K). SiO2 aerogel materials are usually compounded with infrared sunshades and reinforcements to improve the thermal insulation and mechanical properties of SiO2 aerogels, making them both practical nanoporous super thermal insulation materials and having good thermal insulation and mechanical properties. They are mainly used in thermal insulation in aerospace, military, electronics, construction, home appliances and industrial pipelines. Common infrared sunshades include silicon carbide, TiO2 (rutile and anatase), carbon black, potassium hexatitanate, etc.; common reinforcement materials include ceramic fiber, alkali-free ultrafine glass fiber, polycrystalline mullite fiber, aluminum silicate fiber, zirconium oxide fiber, etc.
2) ZrO2 aerogel materials
Compared with SiO2 aerogel materials, ZrO2 aerogels have lower high-temperature thermal conductivity and are more suitable for thermal insulation applications in high-temperature sections. They have great application potential as high-temperature thermal insulation materials. The pore size of ZrO2 aerogel material is smaller than the mean free path of air molecules. There is no air convection in the aerogel, the porosity is extremely high, and the volume ratio of solids is very low, which makes the thermal conductivity of the aerogel very low. At present, there are relatively few reports on the application of ZrO2 aerogel in the field of thermal insulation. Researchers are mainly committed to the research of ZrO2 aerogel preparation process.
3) Al2O3 aerogel material
Alumina aerogel material has a nanoporous structure, which makes it lighter and smaller in volume to achieve equivalent thermal insulation effect. At the same time, it has high porosity, high specific surface area and open woven structure, and has potential application value in catalysts and catalytic carriers. Alumina aerogel can also be used as high-voltage insulation material, substrate material for high-speed or ultra-speed integrated circuits, isolation medium for vacuum electrodes and supercapacitors.

1.3.2. Carbon aerogel and carbide gel materials
The biggest feature of carbon aerogel is its temperature resistance of up to 2000℃ in an inert and vacuum atmosphere. After graphitization, its temperature resistance can even reach 3000℃. In addition, the carbon nanoparticles in carbon aerogel have excellent absorption properties for infrared radiation, thus producing an effect similar to that of infrared sunscreen, so its high-temperature thermal conductivity is low. However, under aerobic conditions, carbon aerogel oxidizes above 350℃, which greatly limits its application in the field of high-temperature thermal insulation. With the development of highly resistant coatings such as SiC, MoSi2, HfSi2, and TaSi2, a dense resistant coating is applied on the surface of carbon aerogel materials to prevent further diffusion of oxygen, which will give the material great application prospects.
Carbide materials have excellent antioxidant properties, but their own thermal conductivity is high. Making them into aerogels with a three-dimensional network structure can greatly reduce the thermal conductivity of the material and further improve the thermal insulation performance of the material. At present, there is relatively little research on carbide aerogels at home and abroad, especially the research on block carbide aerogels with good formability is still in the initial stage. The research on it as a high-efficiency thermal insulation material is also relatively scarce, and is limited to the preparation and characterization of the material.