SiO_2溶胶配比对气凝胶隔热复合材料力学性能的影响

以无机陶瓷纤维为增强体,与SiO2溶胶混合,经超临界干燥制备了SiO2气凝胶隔热复合材料,研究了SiO2溶胶配比对气凝胶及其复合材料微观结构和力学性能的影响。结果表明,随着SiO2溶胶中乙醇含量的增大,SiO2气凝胶的密度逐渐降低,平均孔径增大,气凝胶中含有的大孔、连孔数量增加,网络骨架结构强度降低。纤维与SiO2气凝胶复合后,气凝胶充满了纤维间的孔隙,形成较好的界面结合。当乙醇/正硅酸乙酯(EtOH/TEOS)摩尔比由2∶1增加到20∶1时,SiO2气凝胶基体传递载荷能力逐渐减弱,材料的力学性能逐渐降低,其拉伸强度、弯曲强度和压缩强度分别由1.9 MPa、2.7 MPa、1.73 MPa(10%应变)降低到0.17 MPa、0.12 MPa、0.04 MPa(10%应变)。

Effect of SiO2 sol proportion on the mechanical properties of aerogel insulation composites

SiO2 aerogel insulation composites were prepared by impregnating inorganic ceramic fiber with SiO2 sols results via supercritical drying. The effect of SiO2 sol on mechanical properties of the composites was investigated. The results show the higher the ethanol (EtOH) content in sol, the lower the density of aerogel, the bigger the average pore size, the less the cross-linking between the clusters and the lower the network strength of aerogel. The inorganic ceramic fibers are dispersed within the aerogel and closely packed by aerogels, thus a well interface is formed. With increasing the EtOH/TEOS molar ratio from 2 to 20, the load transfer capability of SiO2 aerogel is weakened, therefore, the mechanical properties of the aerogel composites decrease. The tensile, bending and compressive strengths of the composites decrease from 1.9MPa, 2.7MPa, 1.73MPa (10% strain) to 0.17MPa、 0.12MPa、 0.04MPa (10% strain), respectively.