Research progress in carbon aerogels for thermal insulations
The continuous development of new high-speed space vehicles has put forward an urgent demand for high-temperature resistant,lightweight and high-efficiency thermal insulations. Carbon aerogel not only has the excellent characteristics of low density,high porosity,high specific surface area and low thermal conductivity due to its nanoscale structure,but also has the advantages of ultra-high temperature resistance under inert atmosphere and high infrared specific extinction coefficient. Therefore,it has significant advantages in its application as a thermal insulation for the thermal protection of ultrahigh-temperature parts. In this paper,the research status of the thermal insulation properties of carbon aerogel from the aspects of aerogel density and microstructure (pore size,particle size) based on heat transfer theory were summarized firstly. Then,the researches on the preparation technologies and properties optimization of carbon aerogels for thermal insulations in recent years,which mainly included four major aspects of mechanical property enhancement,ablative resistance/oxidation resistance,low-cost,and superlight and superelastic were reviewed,and the advantages and disadvantages of the four aspects were also summarized. Finally,the future research directions of low-cost and high-performance carbon aerogel thermal insulations are proposed,and its development and application in civil and other special fields are prospected.
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