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Latest Achievements in Ceramic Aerogels
Release time:
2021-09-03 16:32
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Ceramic aerogels are considered ideal thermal insulation materials because of their low density, low thermal conductivity and excellent fire resistance and corrosion resistance. However, the brittle nature of ceramics and the behavior of high temperature crystallization make ceramic aerogels show serious strength degradation and even structural collapse in thermal shock or long-term high temperature exposure. Therefore, excellent mechanical properties and thermal stability have become a prerequisite for the further development and application of ceramic aerogels in the field of thermal insulation. In this paper, we report a ceramic aerogel material of polycrystalline boron nitride (hBNAGs) and silicon carbide (β SiCAGs) with a hyperbolic, double-walled microstructure, which has the characteristics of negative Poisson's ratio and negative thermal expansion, and has four characteristics: ultra-light, ultra-elastic, high thermal stability and excellent thermal insulation.
Based on the previous three-dimensional graphene aerogel research and using multi-scale structural design, the research team prepared and synthesized hBN and beta SiC ceramic aerogel materials by template-free chemical vapor deposition. This kind of ceramic material is composed of nano-layered double-walled pore structure, and the whole presents a hyperbolic structure. These special "superstructure" designs give the material negative Poisson's ratio (-0.25) and negative linear thermal expansion (-1.8 × 10-6/K) characteristics, so that the material can still exhibit excellent deformability while maintaining thermal stability. Such materials exhibit excellent thermal stability with almost zero loss of strength during severe thermal shock testing (about 275°C/s) and long-term high temperature oxygen-free exposure. At the same time, the double-walled substructure of the material effectively reduces the thermal conductivity of the skeleton and reduces the air heat conduction and heat convection, so that it can achieve ultra-low thermal conductivity lower than that of air (about 2.4 mW/m • K in vacuum and about 20 mW/m • K in air). The research results are highly reviewed.
Ultra-light, super-elastic, structural and thermal stability of ceramic aerogels
Aerogel, ceramic aerogel, ceramic aerogel material, graphene aerogel
