Influence of different pore-forming agents on wollastonite microstructures

Abstract

In this study, highly porous macro- and micro-cellular wollastonite-based ceramics was synthesized. Ceramic precursor, methylhydrocyclosiloxane, together with micro-sized CaCO3, was used as starting material. After 20 min of ultrasound treatment, and calcination at 250 oC for 30 min, different pore-forming agents were added to the as-obtained powders. Differential thermal analysis was used to determine characteristic temperatures of processes occurring within powders during heating. Based on the obtained results, sintering regime was set up. Prepared mixtures were pressed into pallets and sintered at 900 oC. During the sintering regime, highly porous wollastonite-based ceramics was obtained. The phase composition of the sintered samples as well as microstructures was analyzed by the means of X-ray diffraction method and SEM. Two-phase system was detected in all samples, CaSiO3 wollastonite and Ca2SiO4 larnite, and their ratio varied with each pore-forming agent. It was observed that addition of different pore-forming agent resulted in significantly different microstructures.