Aerogel composites have some unique properties,such as high porosity,large specific surface area and low thermal conductivity,etc.To enhance its mechanical property,the material is often doped with reinforced fibers in the in-plane direction.Due to the limitations of measurement method and material preparation process,most of the previous studies were focused on the out-of-plane thermal conductivity,and less attentions were paid on the in-plane thermal conductivity.In this paper,the out-of-plane thermal conductivity of aerogel composites is measured by a"sandwich"structure based on the steady-state method,the apparent effective thermal conductivity of aerogel composites is measured by the Hot Disk thermal constant analyzer based on the transient plane source(TPS)method,and the in-plane thermal conductivity is obtained indirectly from the above two values.In addition,the thermal insulation performance is also compared at high temperature by the infrared heating of quartz lamp.The results show that out-of-plane and in-plane thermal conduc-tivity increases rapidly with the increment of temperature,and effective thermal conductivity in the Logarithmic coordinates shows an"S"variation with the increment of gas pressure,alumina aerogel composites has better high-temperature insulation performance than silica aerogel composites.
aerogel compositesthermal conductivityanisotropyhigh temperature and variable gas pressureexperimental study
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