超级绝热型防火材料的研究进展及其在城市地下空间的应用展望

超级绝热型防火材料,是一种具有纳米孔隙结构及超低导热系数的无机材料,可分为溶胶-凝胶法气凝胶复合材料和气相法氧化物纳米粉末基材料两种.其基础组成氧化物为SiO₂和更高熔点的Al₂O₃、ZrO₂,且研究发现合适的复合组元比单组元在火灾温度下具有更好的耐热稳定性.红外遮光剂是显著降低材料高温导热系数的关键组分,通过比红外消光系数测定以及基于Mie散射理论等的数值计算为红外遮光剂的合理选择提供了依据.超级绝热型防火材料,具有高效防火的特点,只要很小的厚度就能达到较高的耐火等级.随着气凝胶材料从超临界干燥向常压干燥的发展,以及超级绝热型防火材料总体生产成本的降低,这种材料将在城市地下空间被动防火系统中发挥重要的作用.

Status and development of fire protection materials based on super thermal insulator and their application prospect in urban underground space

Fire-protective super thermal insulator is an inorganic material with a nanopore structure and super-low thermal conductivity. It can be classified as either a sol-gel aerogel-based composite or a fumed oxide-based composite. The matrix oxides are investigated from SiO₂ to oxides with higher melting temperatures, including Al₂O₃ or ZrO₂. It was found that the complex component oxides with the appropriate ratios exhibit better thermal stability than single oxide when exposed to fire. The infrared opacifier is a key component to this material that can significantly reduce its high-temperature thermal conductivity. The appropriate selection of opacifiers becomes possible by determining the specific infrared extinction coefficient and performing a numerical calculation based on Mie scattering theory. This fire protection material has high fireproof efficiency while also being very thin and is rated as having high fire resistance. With the development of ambient pressure drying for aerogel-based composite from supercritical drying, this fire protection material can be manufactured at low overall cost and will play an important role in passive fire protection systems in urban underground spaces.