物理化学学报2012，Vol.28Issue(5)：1189-1196,8.DOI:10.3866/PKU.WHXB201202292
空间高速粒子捕获用密度梯度气凝胶的热学与力学特性
Thermal and Mechanical Properties of Density-Gradient Aerogels for Outer-Space Hypervelocity Particle Capture
摘要
Abstract
Aerogels with densities in the range 40-175 mg · cm-3 were prepared using a tetraethyl orthosilicate (TEOS) ethanol-water solution as the precursor and hydrofluoric acid as the catalyst via a sol-gel process and CO2 supercritical-fluid drying. The density-gradient aerogels were prepared using layer-by-layer gelation, sol co-gelation, and gradient-sol co-gelation methods and their gradient properties were studied systematically. The results show that aerogels with different densities all have a three-dimensional skeleton consisting of spherical particles of diameter about 40-90 nm. The lower the density is, the looser the skeleton and pore-size distributions are, and the larger the peak value of the pore size is. Gradient aerogels prepared via different methods exhibited graded, approximately gradient, or gradient distributions. Dynamic mechanical analysis indicates that the Young's moduli of the aerogels at-100 and 25 ℃ (changed from 4.6×105 to 1.9×105 Pa and from 5.0×105 to 2.1 ×105 Pa, respectively) tend to decrease with decreasing density. Thermal constants analysis shows that as the densities of the aerogels decrease, the thermal diffusion coefficients increase and the specific heat capacities decrease, but the thermal conductivities do not change monotonically.关键词
梯度/气凝胶/热学/力学/热导率/模量/低温Key words
Gradient/ Aerogel/ Thermal/ Mechanics/ Thermal conductivity/ Modulus/ Low temperature分类
化学化工引用本文复制引用
杜艾,周斌,归佳寅,刘光武,李宇农,吴广明,沈军,张志华..空间高速粒子捕获用密度梯度气凝胶的热学与力学特性[J].物理化学学报,2012,28(5):1189-1196,8.基金项目
国家自然科学基金(51102184,51172163),国家高技术研究发展(863)计划,国家科技支撑计划(2009BAC62B02)、同济大学青年优秀人才培养行动计划(2010KJ068)和教育部博士点基金(20090072110047,20100072110054)资助项目 （51102184,51172163）
