期刊
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
卷 39, 期 4, 页码 1344-1351出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2018.10.015
关键词
Aerogels; Mullite whiskers; Secondary-pore structure; Vapour-solid reaction; Thermal stability
资金
- Tianjin Program of Science and Technology [17YFZCGX00600]
- Tianjin Natural Science Fundation [17JCYBJC18000]
Ultralow thermal conductivity and ultralight mullite fibers/mullite whiskers composite aerogels (MF/MW) with secondary-pore structure have been prepared via vacuum impregnation and high-temperature treatment. The in-situ generation of mullite whiskers during vapour-solid reaction process and the mechanism of improving thermal stability have been discussed in detail. Under catalysis condition at 1200 degrees C, the zero-dimensional nanoparticles of SiO2-Al2O3 aerogels are guided to in-situ transform into one-dimensional mullite whiskers. The secondary-pore structure formed by the overlapped fibers and whiskers in MF/MW reduces the thermal conductivity [as low as 0.0488 W/m(-1) K-1 compared with that of MF preform (0.0698 W/m(-1) K-1)] and exhibits excellent thermal stability after 1400 degrees C heat treatment (0.0503 W/m(-1) K-1 ) due to the macropores are decreased and gaseous heat transfer being further weakened effectively. Moreover, the MF/MW exhibits good mechanical performance with high critical compressive stress of 0.2809 MPa, which is more than 317% higher than that of MF preform (0.0673 MPa) at room temperature.
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