Preparation of silica aerogels with high temperature resistance and low thermal conductivity by monodispersed silica sol
Preparation of silica aerogels with high temperature resistance and low thermal conductivity by monodispersed silica sol
复制标题
DOI：
10.1016/j.matdes.2020.108640
复制
发表时间：
2020-06-01
影响因子：
8.4
通讯作者：
Feng, Junzong
中科院分区：
文献类型：
--
作者：
Cai, Huafei;Jiang, Yonggang;Feng, Junzong
首次采用单分散硅溶胶制备了不同粒径的二氧化硅气凝胶。系统研究了SiO2气凝胶在常温和高温下的性能。在四种不同粒径的气凝胶中，SA-2样品由20.31 ± 1.21 nm的颗粒组成，具有窄的粒径分布，具有高的耐温性和低的热导率。与传统的酸碱两步法制备的SiO2气凝胶相比，单分散SiO2气凝胶在保持较低热导率（0.02723 W.m（-1）.K-1）的同时，显著提高了SiO2气凝胶的耐温性。由大颗粒相互连接形成的坚固骨架结构可以有效地抑制气凝胶颗粒之间的粘性流动，避免骨架破坏引起的孔塌陷，其可以保持稳定的结构直到900 ℃，并且在1000 ℃下保持相对完整的结构，热处理2 h后仅约35%的体积收缩。在1100 ℃下，气凝胶颗粒之间的粘性流动和孔塌陷不能得到有效抑制，纯二氧化硅气凝胶只能在1100 ℃下短时间内使用。研究结果对耐高温、低导热系数的超级绝热材料的设计具有一定的指导意义。(C)2020年，任作家。爱思唯尔有限公司出版
Silica aerogels with different particle size were prepared by monodispersed silica sol for the first time. The properties of the silica aerogels under normal and high temperature were systematically studied. Among the four different particle size aerogels, the SA-2 sample consisted of 20.31 +/- 1.21 nmparticles with narrow size distribution had high temperature resistance and low thermal conductivity. Compared with the traditional acid-base two-step prepared silica aerogels, the monodisperse silica aerogels can significantly increase the temperature resistance while maintaining a low thermal conductivity (0.02723 W.m(-1).K-1). The sturdy skeleton structure formed by the interconnection of large particles can effectively inhibit the viscous flow between aerogel particles and avoid pore collapse caused by skeleton failure which can maintain a stable structure until 900 degrees C and retain a relatively complete structure at 1000 degrees C with only about 35% volume shrinkage after 2 h heat treatment. At 1100 degrees C, the viscous flow between aerogel particles and pore collapse cannot be effectively suppressed, and the pure silica aerogels can only be used during a short period at 1100 degrees C. The results will be meaningful for the design of super thermal insulation materials with high temperature resistance and low thermal conductivity. (C) 2020 The Authors. Published by Elsevier Ltd.