SiC遮光剂对SiO2气凝胶复合材料热导率的影响OA

The thermal conductivity of SiO2 aerogel increases significantly at high temperatures,and the addition of occlusive agents can significantly improve its thermal insulation performance.A periodic volume element model of SiC occlusive agent-doped SiO2 aerogel composites was established using the finite element method(FEM).Periodic boundary conditions were applied to the model,and the effects of SiC occlusive agent particle size and doping amount on the gas-solid coupling thermal conductivity of SiO2 aerogel materials were analyzed.By combining with radiative thermal conductivity calculated via Mie theory,variation law of effective thermal conductivity of SiC doped SiO2 aerogel composites was investigated.The results show that gas-solid coupled thermal conductivity increases with an increase in the volume fraction of SiC opacifier,resulting into a decrease in the radiative thermal conductivity.A connection of particle size to minimum radiative thermal conductivity has been determined for the SiO2 aerogel composites,with varies of temperatures and volume fractions.And a connection of opacifier parameter to minimum thermal conductivity was also identified.