Sintering behavior and physical property of porous wollastonite ceramics on effects of Mg as a trace element

Abstract

Wollastonite is a natural ore of calcium silicate (β-CaSiO₃), which is used as a ceramic raw material. In this study, we prepared porous wollastonite ceramics by using American and Mexican wollastonite powders which contain different amounts of Mg as a trace component. We investigated sintering behavior and physical property of these porous ceramics. As a result, it was revealed that when wollastonite contains at least 0.5 mol % of Mg, phase transition temperature from β-CaSiO₃ to α-CaSiO₃ increased by about 50 °C. Additionally, temperature-dependent phase transition becomes more gradual. This would be due to a phenomenon of “phase transformation” that solid solution of Mg stabilizes β-CaSiO₃ during firing. Moreover, such transformation also affects bulk density, porosity and pore structure of porous wollastonite ceramics.