二氧化硅气凝胶及其在保温隔热领域应用进展

Silica aerogel and its application in the field of thermal insulation

二氧化硅气凝胶是目前已知最轻的固体材料,具有热导率低、孔隙率高和比表面积大等优点,被誉为新型超级保温隔热材料。然而,二氧化硅气凝胶自身存在力学性能差和制备成本高的问题,大大限制了其在保温隔热领域大规模推广应用。本文简述了二氧化硅气凝胶合成技术和力学性能增强方法,从制备过程控制、老化条件优化、热处理、纤维复合和高分子聚合物复合等方面分析了其对气凝胶性能和工艺的影响,重点介绍了近年来二氧化硅气凝胶保温隔热材料应用在航空航天、军工领域、工业管道、建筑保温以及新能源汽车等领域的研究进展,总结了其在各领域应用的技术挑战。指出未来需进一步拓展二氧化硅气凝胶的使用温区,利用共前体和化学交联等方法增强高温下的隔热性能,同时解决气凝胶纤维复材“掉粉”和微米级粉体分散不均匀等难题,尤其是新能源汽车等新兴应用领域发展迅猛,未来仍需针对新的应用需求对其合成技术进行设计和优化。

Silica aerogel,as the lightest solid material,is known as a new type of super thermal insulation material with the advantages of low thermal conductivity,high porosity and high specific surface area.However,silica aerogel suffers from poor mechanical performance and high cost,which significantly hamper its widespread applications in thermal insulation.This paper reviews the synthesis technologies and mechanical properties enhancement methods of silica aerogel,and their effects on the aerogel performance are analyzed from the aspects of preparation process control,aging conditions optimization,heat treatment,fiber and polymer composite.Emphasis is put on the silica aerogel’s thermal insulation application in aerospace,military industry,industrial pipelines,building insulation,new energy vehicles and other fields in recent years,and analyzes the technical challenges.It is pointed out that in the future,it is necessary to further expand its operation temperature range,consider co-precursor and chemical cross-linking methods to enhance the thermal insulation performance at high temperature,and at the same time solve the problems of“powder loss”of aerogel gel fiber composite and uneven dispersion of micron powder,particularly the rapid development of emerging application fields such as new energy vehicles.The silica aerogel’s synthesis technologies need to be further designed and optimized for new application requirements.