Effect of SiO2 Content on The Morphology and Phase Transformation of CaSiO3 Prepared by Wet Milling Method

Abstract

This study aimed to synthesize wollastonite (CaSiO₃) from calcium oxide (CaO) and silicon dioxide (SiO₂) powders using a wet milling method. Wollastonite synthesis involves dispersing CaO and SiO₂ powder in distilled water at different ratios (i.e. 45:55, 50:50, and 55:45). The dispersions are then milled by a high-energy planetary mill at 500 rpm for 5 h. The resulting mixtures were dried in the oven and crushed into a powder. Subsequently, the dried ceramic mixtures were sintered at 950 °C for 3 h. An increase in SiO₂ content resulted in significant changes in the properties of the synthesized CaSiO₃. The effects of varying SiO₂ content on the resulting CaSiO₃'s morphology and phase transformation were investigated using SEM and XRD, respectively. An increasing SiO₂ content resulted in peak broadening in the XRD spectra, indicating the formation of a solid solution. Notably, a high-intensity peak signifying the formation of β-CaSiO₃ was observed at 55 wt.% SiO_2. This suggests a higher degree of crystallinity in the resulting material. The SEM observation indicated a pronounced blocky morphology for CaSiO₃ when the SiO₂ content was at 55 wt.%. This highlights the role of SiO₂ content in shaping the morphology of the synthesized material.