화학공학소재연구정보센터
Journal of the American Ceramic Society, Vol.103, No.9, 5365-5373, 2020
Low-temperature preparation of high-performance porous ceramics composed of anorthite platelets
Platelet-like anorthite based porous ceramics with improved mechanical strength were fabricated via direct gelcasting and firing at 1223-1473 K using CaCO3, 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 thea- andb-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 center dot K), much lower than that (0.645 W/(m center dot K)) of the control sample, suggesting that the former could be potentially used for thermal insulation at high temperatures.