Effect of zirconia on densification and properties of natural Indian magnesite

• Indian magnesite contains significant amount of CaO, SiO2, and Fe2O3 as impurities.
• ZrO2 addition reduces the amount of low melting phases in sintered magnesite.
• Periclase grain shape changed from rounded to subrounded in presence of zirconia.
• ZrO2 significantly improves the high temperature flexural strength of sintered magnesite.

Indian magnesite mineral has substantial amount of impurities like CaO, SiO2 & Fe2O3. During sintering at elevated temperature these impurities react to form low melting phases like monticellite (CMS), which can degrade the high temperature properties of magnesite. In the present study, ZrO2 was added to reduce the formation of low melting phase in order to improve the hot strength. Amount of additive was varied between 2 and 6 wt.% with respect to raw magnesite. It was observed that addition of ZrO2 reduces the formation of low melting CMS at higher temperature and improves the flexural strength at 1200 °C. Periclase grain shape also changed from rounded to subrounded in the presence of zirconia.