物理化学学报 >> 2012, Vol. 28 >> Issue (05): 1189-1196.doi: 10.3866/PKU.WHXB201202292

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空间高速粒子捕获用密度梯度气凝胶的热学与力学特性

杜艾, 周斌, 归佳寅, 刘光武, 李宇农, 吴广明, 沈军, 张志华   

  1. 同济大学, 上海市特殊人工微结构材料与技术重点实验室, 上海 200092
  • 收稿日期:2011-11-21 修回日期:2012-02-07 发布日期:2012-04-26
  • 通讯作者: 周斌 E-mail:zhoubin863@tongji.edu.cn
  • 基金资助:

    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

Thermal and Mechanical Properties of Density-Gradient Aerogels for Outer-Space Hypervelocity Particle Capture

DU Ai, ZHOU Bin, GUI Jia-Yin, LIU Guang-Wu, LI Yu-Nong, WU Guang-Ming, SHEN Jun, ZHANG Zhi-Hua   

  1. Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092, P. R. China
  • Received:2011-11-21 Revised:2012-02-07 Published:2012-04-26
  • Contact: ZHOU Bin E-mail:zhoubin863@tongji.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51102184, 51172163), National High Technology Research and Development Program of China, National Key Technology Research and Development Program of China (2009BAC62B02), Program for Young Excellent Tatents in Tongji University (2010KJ068), and Doctoral Fund of Ministry of Education of China (20090072110047, 20100072110054).

摘要: 采用正硅酸四乙酯(TEOS)的乙醇-水溶液为前驱体, 氢氟酸为催化剂, 结合溶胶-凝胶过程与CO2超临界流体干燥工艺, 一步反应获得了密度为40-175 mg·cm-3的单元气凝胶. 以上述工艺为基础, 通过逐层凝胶法、溶胶共凝法和梯度溶胶共凝胶法分别制备了三种密度梯度气凝胶样品, 并研究了其功能梯度特性. 结果表明: 不同密度的气凝胶均具有粒径约为40-90 nm球形颗粒构成的三维骨架结构, 密度越低, 骨架越疏松, 峰值孔径越大, 孔径分布也更为分散; 三种方法制备的样品均具有明显的密度梯度, 梯度特性由不连续到连续. 动态热机械性能测试表明, 随着密度的降低, 气凝胶在低温(-100 °C)和常温(25 °C)下杨氏模量均有减小的趋势, 其范围分别约为4.6×105-1.9×105 Pa和5.0×105-2.1×105 Pa. 热学测试表明, 随着密度的降低, 气凝胶的热扩散系数增高, 单位体积热容降低, 而热导率则不成单调变化.

关键词: 梯度, 气凝胶, 热学, 力学, 热导率, 模量, 低温

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 threedimensional 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 °C (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.

Key words: Gradient, Aerogel, Thermal, Mechanics, Thermal conductivity, Modulus, Low temperature

MSC2000: 

  • O643