Abstract
Preparation of the porous ceramics from the mixtures of natural zeolite including clinoptilolite and allophane composed mainly of amorphous alumina silica gel has been studied. The mixtures were pressed at 12.25 MPa and fired at a temperature between 1000°C and 1150°C for 40 min. The properties of the obtained porous ceramics are as follows :
They had very few cracks. The shrinkage increased with an increase in the firing temperature, and decreased with an increase in the amount of allophane. The coefficient of water absorption was from 12.8% to 26.9% (1000°C to 1150°C, R =85 (Natural zeolite 85 wt%/Allophane 15 wt%)). The porous ceramic prepared at the temperature of 1150°C had the highest bending strength of 20.97 MPa and the surface hardness of 45 at R =85. In addition, the specific surface area was 0.15 m2g-1 at R =85, the total cumulative volume was 185 mm3g-1 and the average pore radius was 0.473 nm at R=85.
The results indicated that the porous ceramics are expected to use as materials for molds, building such as water permeability plate or water-holding plate, and filters.
