Densification control and analysis of outer shell of new high-temperature vacuum insulated composite

Three-Dimensional Reticulated, Spongelike, Resilient Aerogels Assembled by SiC/Si3N4 Nanowires

“…In view of the intrinsic thermal conductivity of SiC as 490 W/(m K), the thermal conductivity of the aerogels with a bulk density of 10.67 mg/cm 3 has been characterized to be as low as 23.19 mW/(m K), displaying a distinct advantage over SiC foams, SiC aerogels, and other aerogels such as AlBSi-bonded SiO 2 fibers or ZrO 2 nanowire assembled aerogels (Figure e, Table S2). ,,,,− ,,,,,− It is found that SiC aerogels possess excellent thermal stability below 850 °C, and weight gain of 27.17% occurred when the temperature increased to 1400 °C (Figure S5), which could be attributed to the oxidation of SiC and Si 3 N 4 . Moreover, thermal conductivity dependent on testing temperature exhibiting the reverse trend has been observed (Figure S6), i.e., lower thermal conductivity at high test temperature, mainly due to the decrease of phonon mean-free-path caused by their elevated vibration velocity and collision frequency according to the phonon scattering processes. ,, The superiority of SiC aerogels on thermal insulation and stability could be further proven by the morphology after heat treatment at 1088 °C for 30 min, maintaining excellent independence for each single nanowire despite the interlaced form with each other, as illustrated in Figure f.…”

“…(c) Infrared image of the back side taken from the sample at different times. (d) Temperature variation curve depending on the time taken from the marked section from part c. (e) Comparison of thermal conductivity values of this work and the referred SiC foams/aerogels as well as other aerogels. ,,,,− ,,,,,− (f) SEM images of the front side after heat treatment for 30 min.…”