Effect of ZrO2 on the densification behavior and properties of Indian magnesite

Natural magnesite is the primary source for magnesia-based refractory materials. India has vast deposits of magnesite in Salem and Almora regions. However, due to the presence of large amount of impurities which forms low-melting compounds at elevated temperature, its high-temperature application is restricted. Raw magnesite was evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, and phase assemblage. Zirconia (1-5 wt %) was added to Indian natural magnesite of Salem region to minimize the low-melting phase formation at high temperatures. Samples were sintered in the temperature range of 1550-1700 degrees C. Sintered samples were characterized in terms of densification, mechanical and thermo-mechanical properties, phase assemblage, and microstructure. It was found that the addition of zirconia reduced the formation of detrimental phases like monticellite and thereby improved the high-temperature mechanical properties.