海泡石纤维增强二氧化硅气凝胶的制备及性能

Preparation and Properties of Sepiolite Fiber Enhanced Silica Aerogel

溶胶-凝胶法常压制备二氧化硅(SiO_(2))气凝胶的产率与性能不足问题限制了其工业化规模应用。本工作以海泡石纳米纤维作为增强体,正硅酸四乙酯作为硅源前驱体,三甲基氯硅烷作为改性剂,采用溶胶-凝胶法、常压干燥制备了海泡石纤维/二氧化硅气凝胶块体材料,测试了力学性能、热性能、火安全性等,并进行了孔隙结构、红外光谱与微观形貌的分析表征。海泡石的纤维骨架可抑制气凝胶块体收缩开裂;纤维在溶胶形成阶段具有异相形核作用,使颗粒细化并提高气凝胶的比表面积,改变孔隙结构;纤维的引入提高了气凝胶的力学性能、高温与烧蚀稳定性和火安全性,降低了导热系数。块体海泡石纤维/二氧化硅气凝胶导热系数可达0.0128 W/(m·K),抗压强度最高为1.20 MPa,阻燃均为V-0级,1300℃烧蚀后形状保持稳定,综合性能优异。

The efficiency and performance of silica(SiO_(2))aerogel prepared by sol-gel method under atmospheric pressure are insufficient,which limits its industrial scale application.In this work,sepiolite nanofibers were used as enhancement,tetraethyl orthosilicate was used as silicon source precursor,and trimethylchlorosilane was used as modifier.Sepiolite fiber/silica aerogel bulk materials were prepared by sol-gel method and atmospheric drying.The mechanical properties,thermal properties and fire safety properties were tested,and the pore structure,infrared spectrum and micro-morphology were analyzed and characterized.The fiber skeleton of sepiolite can inhibit the shrinkage and cracking of aerogel block.Fibers have heterogeneous nucleation in the sol formation stage,which refines the particles,increases the specific surface area of aerogels and changes the pore structure.The introduction of fiber improves the mechanical properties,high temperature and ablation stability and fire safety properties,and reduces the thermal conductivity.The thermal conductivity of mass sepiolite fiber/silica aerogel can reach 0.0128 W/(m·K),the compressive strength is 1.20 MPa,the flame retardancy is V-0,the shape remains stable after ablation at 1300℃,and the comprehensive performance is excellent.