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Low‐temperature preparation of high‐performance porous ceramics composed of anorthite platelets
Author(s) -
Han Lei,
Huang Liang,
Dong Longhao,
Zhang Haijun,
Pei Yuantao,
Li Faliang,
Jia Quanli,
Zhang Shaowei
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17265
Subject(s) - anorthite , porosity , materials science , ceramic , mineralogy , sintering , composite material , chemistry
Platelet‐like anorthite based porous ceramics with improved mechanical strength were fabricated via direct gelcasting and firing at 1223‐1473 K using CaCO 3 , Al(OH) 3 , and SiO 2 powders as the raw materials, along with H 3 BO 3 and melamine sintering/crosslinking agents. Based on density functional theory calculations, H 3 BO 3 promoted the formation of platelet‐like anorthite at a relatively low temperature via covering the {130} facet of anorthite and reducing the corresponding adsorption energy, which led to the preferential growth along the a ‐ and b ‐axes. The optimal amount of H 3 BO 3 for the anorthite platelet formation was 0.9 wt%. The porous anorthite sample with an original solid content of 22.0 wt%, after firing at 1373 K, contained 71.0% porosity and exhibited a compressive strength as high as 5.7 MPa, which were comparable or even superior to those of porous anorthite ceramics prepared previously at a much higher temperature (1573‐1723 K), indicating that the preparation strategy reported in this paper is feasible in fabricating high‐performance porous anorthite ceramics at a much milder condition. The thermal conductivity of the porous anorthite sample at 1073 K was as low as 0.266 W/(m·K), much lower than that (0.645 W/(m·K)) of the control sample, suggesting that the former could be potentially used for thermal insulation at high temperatures.