Mullite Brick

Mullite brick is made of mullite as the main raw material through high pressure molding and high temperature sintering. The product has excellent thermal shock stability, abrasion resistance and chemical erosion resistance. The products are widely used in CFB boiler ignition system and other industrial kilns.

High alumina refractory with Mullite (3Al2O3·2SiO2) as the main crystalline phase. Generally, the alumina content is between 65% and 75%. In addition to mullite, the lower alumina also contains a small amount of glass phase and calcite. The higher alumina content also contains a small amount of corundum.

High fire resistance, up to 1790℃ above. The initial temperature of load softening is 1600~1700℃. Normal temperature compressive strength 70~260MPa. Good thermal shock resistance. The sintered mullite brick is made of high alumina clinker as the main raw material, adding a small amount of clay or raw alumina as the binder, after molding and firing. Fused mullite brick with high alumina, industrial alumina and refractory clay as raw materials, add charcoal or coke fine particles as a reducing agent, after the formation of the reductive electrofusion method to manufacture. The crystallization of fused mullite is larger than that of sintered mullite and the thermal shock resistance is better than that of sintered products. Their high temperature performance depends mainly on the content of alumina and the uniformity of distribution of mullite phase and glass.

Refractory bricks made from sintered or fused mullite may be made entirely from mullite, or partly from mullite and partly from corundum. The former is called mullite and the latter corundum refractory or corundum refractory. The production process of mullite firebrick is the same as that of high alumina brick, including mixing, forming, drying and firing. The firing temperature is related to the composition of the ingredients, the purity of the raw material and the requirements on the performance of the firebrick, usually 1500~1700C.

Mullite firebrick and corundum mullite brick have the advantages of high softening temperature under load, low creep rate under high temperature, good thermal shock resistance, etc. They are widely used in industrial furnaces such as blast furnace hot air furnace, glass melting furnace, dry quenching furnace and heating furnace. Mullite refractory brick is easily corroded by alkaline refractory brick at high temperature. Furthermore, mullite may be damaged at high temperatures by reacting with water vapor to form A1203.

Therefore, mullite refractory brick is not suitable for long-term use in the environment of high alkaline slag and high water vapor content.