Sinterability of Magnesium Oxide Powder with Magnesium Phosphate Addition Prepared by Coprecipitation Technique

II. Changes in Microstructure during Sintering

Abstract

Changes in microstructure of magnesium oxide compact containing magnesium phosphate equivalent to 0.50mol% P₂O₅ were investigated at a heating rate of 10°C·min^-1 up to 1400°C and by isothermal 5 h-heating at 1200°, 1300° and 1400°C. The microstructure changed with densification, which was caused by an increase in the liquid volume formed above 1100°C. Between 1100° and 1300°C, the densification took place along with rapid grain growth. Thus, Ostwald ripening is operative in the presence of a liquid phase. From 1300° to 1400°C, the grain growth continued, although the densification was slowed down.