Constructing secondary-pore structure by in-situ synthesized mullite whiskers to prepare whiskers aerogels with ultralow thermal conductivity

Thermal Radiation Shielding and Mechanical Strengthening of Mullite Fiber/SiC Nanowire Aerogels Using In Situ Synthesized SiC Nanowires

“…The wavelength of thermal radiation is mainly concentrated at 1–8 μm at high temperatures [ 31 ]; in this band, SiC NWS are able to effectively reduce the infrared transmittance, giving rise to the decrease in radiation thermal conduction. Moreover, after the in situ synthesis of SiC NWS, both the decline in pore size and the formation of hierarchical pore structures contributed to the decreasing collision frequency of gas molecules inside the pores of MF/SiC NWS, which is beneficial for restraining the thermal conduction of the gases [ 12 ]. Therefore, the high-temperature thermal conductivity of MF/SiC NWS decreased significantly after in situ synthesized SiC NWS.…”

“…[ 3 , 4 , 5 , 6 , 7 , 8 ]. Despite these merits, the practical application of traditional ceramic nanoparticles aerogel is impeded by its inherent brittleness, poor high-temperature structural stability, and high radiation heat transfer [ 9 , 10 , 11 , 12 ]. Fiber-reinforced aerogels, with fibers that act as an effective skeleton, are beneficial to declining the volume shrinkage of aerogel at high temperatures by confining the aerogel to the internal pore structure formed by the adjacent fibers.…”

“…In recent years, a new kind of ceramic aerogel with fibers as matrix and nanostructured materials as reinforcement is being developed [ 12 , 28 , 29 , 30 ]. Micro and nano fibers interlace together to form porous structure similar to traditional aerogels, but overcome the brittleness of traditional aerogel, which exhibits higher heat resistance and compressive strength.…”

“…On the basis of this, many mullite-fiber-based aerogels have been reported. For instance, Zhao and Yi et al [ 12 , 28 , 29 ] in situ synthesized mullite whiskers in the porous mullite fiber ceramic. This micro/nano-ceramic fiber aerogel with a secondary-pore structure exhibited good mechanical performance and low thermal conductivity at room temperature.…”

“…Similarly, one-dimensional SiC nanostructures have been shown to have a high infrared reflection and absorption capacity and exhibited an infrared thermal radiation shielding effect [ 41 , 42 ]. In addition, in situ synthesis of nanowires and whiskers in ceramic fibrous insulation materials with high porosity has been widely used owing to its characteristics of flexibility and low thermal conductivity [ 12 , 30 , 43 ]. It is expected to overcome the brittleness of traditional ceramic insulation fibers, and prepare high effective thermal insulation materials with excellent mechanical properties.…”