Novel high‐temperature‐resistant Y₂SiO₅ aerogel with ultralow thermal conductivity

Abstract

A novel Y 2 SiO 5 ternary aerogel was prepared from tetraethoxysilane and yttrium chloride hexahydrate via the sol-gel method followed by high-temperature calcination.The effects of different calcination temperatures on the microstructure, mechanical and thermal stability of the Y 2 SiO 5 aerogels were investigated. The aerogels exhibited low densities of 0.33-0.62 g/cm 3 , low thermal conductivities of 0.029-0.05 W/ (m·K), and a relatively high strength of 0.16-56.47 MPa. Moreover, compared with the Al 2 O 3 -SiO 2 aerogel, the Y 2 SiO 5 aerogel has higher thermal stability and more excellent high-temperature insulation, which has potential applications as a thermal protection material in hypersonic vehicles. K E Y W O R D S aerogel, insulation, thermal propertiesHow to cite this article: Gu H, Hou X, Zhang R, Fang D. Novel high-temperature-resistant Y 2 SiO 5 aerogel with ultralow thermal conductivity. Int J Appl Ceram

In Situ Formation of the TiCN Phase in SiBCN Ceramic Aerogels Enabling Superior Thermal and Structural Stability up to 1800 °C

“…The compressive strength of TiCN/SiBCN-1-1 is up to 2.16 mPa after pyrolysis at 1000 °C and remains at 2.04 mPa after pyrolysis at 1400 °C, which is higher than the oxide-based aerogels and even some fiber/whisker-reinforced aerogels (Table S4). − Moreover, the specific compressive strength of the TiCN/SiBCN aerogels is 7.9–10.9 mPa·cm 3 /g, which is close to the ZrC/C aerogels and much higher than the oxide-based aerogels (Figure S5), further indicating the superiority of mechanical properties of the aerogel as the thermal insulation material. ,− The superior mechanical properties of the TiCN/SiBCN aerogel should be attributed to its homogeneous porous structure, high interparticle connection, and strong chemical bonding. , …”

SiO2 Nanostructure-Based Aerogels with High Strength and Deformability for Thermal Insulation

“…Thereinto, the average pore sizes of H2F-SA-0.214, H2F-SA-0.252, and H2F-SA-0.334 are close to or lower than the average free path of air molecules (about 70 nm), which can effectively suppress the convective heat transfer. Usually, thermal conduction and thermal convection at room temperature are the main causes of thermal conductivity, and the thermal radiation is negligible. , For aerogel materials with high porosities, the thermal convection occupies a major part of the thermal conductivity. , Therefore, the thermal conductivities of H2F-SA-0.214, H2F-SA-0.252, and H2F-SA-0.334 are relatively low (Figure d). Although H2F-SA-0.334 has an lower average pore size, a higher density results in a higher solid-phase thermal conduction, resulting in a higher thermal conductivity than that of H2F-SA-0.252.…”

“…Usually, thermal conduction and thermal convection at room temperature are the main causes of thermal conductivity, and the thermal radiation is negligible. 3,28 For aerogel materials with high porosities, the thermal convection occupies a major part of the thermal conductivity. 29,30 Therefore, the thermal conductivities of H2F-SA-0.214, H2F-SA-0.252, and H2F-SA-0.334 are relatively low (Figure 3d).…”

Synthesis mechanism and phase stability analysis of z‐Y2Si2O7 by sol‐gel process

“…When the temperature rises to 300 • C, the sharp decrease of the weight is associated with the decomposes of nitrate, while presents an endothermic peak (P 3 ) on the DTA curve. 20,27,28 These decomposition processes continue to about 500 • C. Besides, there was a unignorably exothermic peak (Tc) at 887 • C of the DTA curve, which can be explained by the formation of yttrium silicate crystals from the precursor. 29 The DTA curves of yttrium silicate precursors with different concentrations are shown in Figure 3.…”