Preparation and Properties Study of Lanthanum Modified Mullite

Mullite materials exhibit distinctive physical and chemical characteristics at elevated temperatures, making them key refractory materials in high-temperature applications. However, the cost of sintering mullite synthesis is extremely high, as it requires temperatures up to 1700 ℃.This not only results in significant energy consumption but also necessitates more stringent equipment specifications. The results of this study show that doping coal gangue raw material with La₂O₃ can significantly reduce the preparation temperature of mullite materials, effectively minimize quartz-phase impurities formed during the sintering process, and enhance the density of the resulting mullite. When the doping amount of La₂O₃ is 5% (mass fraction), the synthesis temperature of mullite can be reduced from 1700 ℃ to 1560 ℃, and the compressive strength of the modified material at 1200 ℃ reaches 27.3 MPa, the flexural strength is 8.1 MPa, and the coefficient of thermal expansion is 7.03×10⁻⁶. This study presents a novel approach for the low-temperature fabrication of high-quality mullite materials.