The chemical formula of mullite is 3Al2O3.2SIO2, and the theoretical composition is 71.8% Al2O3 and 28.2% SiO2. The synthetic mullite is usually sintered and fused. The synthetic mullite is a high-quality refractory raw material with the characteristics of uniform expansion, good thermal shock stability, high load softening temperature, small high-temperature creep value, high hardness and good chemical corrosion resistance
The raw materials used for the synthesis of mullite by sintering method include industrial alumina, pyrogem, kaolin, silica and bauxite. The synthesis process is to put the batch into a ball mill for common grinding and mixing, press the ball or blank, and then burn it in a rotary kiln or tunnel kiln. The raw materials for synthesizing mullite by electrofusion method include industrial alumina, bauxite and silica. The electrofusion process is to crush silica and bauxite to less than 1.5mm, mix them evenly with other powdered materials, and then melt them in the electric furnace. The reducing atmosphere is maintained in the electric furnace to remove impurities such as iron oxide, TiO2, CaO, R2O, etc
