Silica aerogels are gaining significant importance and have attracted considerable interest due to their extraordinary properties and numerous applications. Silica aerogels are highly porous with high surface area and very low density and thermal conductivity. Usually they are prepared and synthesized via sol-gel technique, which involves making a sol containing a precursor, a solvent and a catalyst. The properties possessed by the final product depend upon numerous factors such as ratio of precursor to solvent and the drying method employed. Due to the flexibility of synthesis methods and the production of aerogels with tailored properties, silica aerogels have found numerous commercial applications and are being investigated of their suitability in several areas, such biomedical and aerospace engineering. Despite having exceptional properties, silica aerogels come with drawbacks such as brittleness and low mechanical strength, which can be resolved by fabricating composites extending the potential applications. This paper reviews the synthesis of silica aerogels via sol-gel technique, and the applications where this extraordinary material has shown promising results. The different materials used for the fabrication of composites to improve and enhance the physical and chemical properties of silica aerogels are also presented.

二氧化硅气凝胶正变得越来越重要，并且由于其非凡的性能和众多应用而引起了相当大的兴趣。二氧化硅气凝胶是高度多孔的，具有高表面积和非常低的密度和导热性。通常它们是通过溶胶-凝胶技术制备和合成的，该技术包括制备含有前体、溶剂和催化剂的溶胶。最终产品所具有的特性取决于许多因素，例如前体与溶剂的比例以及所采用的干燥方法。由于合成方法的灵活性和具有定制特性的气凝胶的生产，二氧化硅气凝胶已经发现了许多商业应用，并且正在研究它们在多个领域的适用性，例如生物医学和航空航天工程。尽管拥有非凡的属性，二氧化硅气凝胶具有脆性和机械强度低等缺点，可以通过制造复合材料扩展潜在应用来解决这些缺点。本文回顾了通过溶胶-凝胶技术合成二氧化硅气凝胶，以及这种非凡材料显示出有希望的结果的应用。还介绍了用于制造复合材料以改善和增强二氧化硅气凝胶的物理和化学性能的不同材料。