Processing and properties of water-absorbing zeolite-based porous ceramics

Abstract

Zeolite-based porous ceramics were developed using inexpensive natural zeolite powder with B2O3, Bi2O3, and SiO2 additives and sintered at low temperatures (500–600 °C) compared to those in previous studies (800–1300 °C). The effects of sintering temperature on the porosity, microstructure, flexural strength, thermal conductivity, and water absorption capacity were investigated. As the sintering temperature increased from 500 to 600 °C, the porosity of the zeolite-based porous ceramics decreased from 49.6 to 45.7%, which is attributed to improved densification at high temperature via viscous flow of the glass phase. The flexural strength and thermal conductivity increased from 5.4 to 11.9 MPa and from 0.19 to 0.30 W/mK, respectively, with increasing sintering temperature. The samples sintered at 550 and 600 °C were highly stable in water, with high absorption capacities of 37.6 and 34.1 wt%, respectively. The typical flexural strength, thermal conductivity, and water absorption capacity of the zeolite-based porous ceramic sintered at 550 °C (~ 46% porosity) were 8.4 MPa, 0.24 W/mK, and 37.6%, respectively.