CHEMICAL PREPARATION AND PHASE-STABILITY OF CA2SIO4 AND SR2SIO4 POWDERS

A process has been developed to produce high surface area Ca2SiO4 and Sr2SiO4 powders using colloidal silica for the silicon precursor. This method was relatively straightforward and avoided the use of precipit ation techniques and unstable alkoxides. Calcium carbonate and stronti um carbonate were identified as intermediate compounds, and the silica tes appeared to form by a low-temperature solid-state reaction. The ef fect of resin content and calcination conditions on the phase distribu tion and physical properties of the powders was examined. Finally, the sodium content of the colloidal silica was found to have a significan t effect on the phase stability of beta-Ca2SiO4 after calcination at 1 400-degrees-C.