Foam-gelcasting preparation, microstructure and thermal insulation performance of porous diatomite ceramics with hierarchical pore structures

Hierarchically pore-structured porous diatomite ceramics containing 82.9 similar to 84.5% porosity were successfully prepared for the first time via foam-gelcasting using diatomite powder as the main raw material. Sizes of mesopores derived from the raw material and macropores formed mainly from foaming were 0.02 similar to 0.1 p.m and 109.7 similar to 130.5 p.m, respectively. The effect of sintering temperature, additive content and solid loading of slurry on pore size and distribution, and mechanical and thermal properties of as-prepared porous ceramics were investigated. Compressive strength of as-prepared porous ceramics increased with sintering temperature, and the one containing 82.9% porosity showed the highest compressive strength of 2.1 +/- 0.14 MPa. In addition, the one containing 84.5% porosity and having compressive strength of 1.1 +/- 0.07 MPa showed the lowest thermal conductivity of 0.097 +/- 0.001 W/(m-K) at a test temperature of 200 degrees C, suggesting that as-prepared porous ceramics could be potentially used as good thermal insulation materials. (C) 2017 Elsevier Ltd. All rights reserved.