The mechanical properties, thermal stability and chemical stability of high-efficiency insulation materials are the key to ensure their safe application. Compared with traditional thermal insulation materials, ceramic aerogel's low thermal conductivity and excellent chemical stability (such as fire resistance and corrosion resistance, etc.) give it obvious advantages. However, traditional ceramic aerogels are generally composed of oxide nanoparticles, and their brittleness and structural collapse at high temperatures limit their practical applications. In recent years, the construction of ceramic aerogel materials with flexible and tough ceramic nanostructures has achieved a transition from brittleness to elasticity of ceramic aerogels. However, such materials generally have a randomly distributed pore structure and usually exhibit a low stiffness. At the same time, unlike the nanopore structure of traditional ceramic aerogels, such randomly distributed pores cannot effectively reduce heat conduction, resulting in their relatively high thermal conductivity.
In order to solve the above-mentioned problems, Prof. Wang Hongjie's research group took SiC nanowires as the basic building unit, and constructed SiC@SiO2 nanowire aerogels with anisotropic pores and multi-level thermal resistance structures through an anisotropic multi-stage pore structure design. : On the one hand, the use of anisotropic pore structure as a reinforcing rib to increase its axial specific modulus, on the other hand, the use of multi-level thermal barrier to reduce its radial thermal conductivity, the ultimate axial modulus of 24.7 kN The elastic ceramic aerogel with kg-1 and radial thermal conductivity of only 0.014 W·m-1K-1 has realized the simultaneous improvement of the mechanical properties and thermal insulation performance of the elastic ceramic aerogel.
The above results, entitled "Anisotropic and hierarchical SiC@SiO2nanowire aerogel with exceptional stiffness and stability for thermal superinsulation", were published online recently in the international authoritative journal Science Advances (impact factor: 12.804). This result is a number of achievements made by the research group in the field of elastic ceramic aerogel research (ACS Nano, 2018, 12, 3103; ACS Appl. Mater. Interfaces, 2019, 11, 15795; ACS Appl. Mater. Interfaces, 2019, 11, 45338; ACS Appl. Mater. Interfaces, 2020, 12, 8555, etc.).