Mullite Insulation Bricks are made of high-quality and high-purity refractory materials. According to the specific gravity of the product, organic composite fillers are added, vacuum extrusion molding, and high temperature sintering to synthesize light mullite products. With its light weight and excellent thermal insulation properties, lightweight mullite bricks are widely used in the hot surface refractory lining or insulation layer of a variety of thermal equipment, creating conditions for improving the energy efficiency of the equipment. High-alumina refractories with mullite as the main crystal phase generally have an alumina content between 50% and 75%.
The refractory temperature of mullite lightweight brick can reach above 1790℃. The starting temperature of load softening is 1600-1700℃. Pressure resistance at room temperature is slightly 70-260MPa. Good thermal shock resistance. There are two types of sintered mullite bricks and fused mullite bricks. Sintered mullite bricks are made of high-alumina bauxite clinker as the main raw material, adding a small amount of clay or raw bauxite as a binding agent, and forming and firing.
Fused mullite bricks use high alumina bauxite, industrial alumina and refractory clay as raw materials, add charcoal or coke fine particles as reducing agents, and are manufactured by reduction fusion method after molding. The crystallization of fused mullite is larger than that of sintered mullite, and its thermal shock resistance is better than that of sintered products. Their high temperature performance mainly depends on the content of alumina and the uniformity of mullite phase and glass distribution. A high-alumina refractory with mullite (3Al2O3·2SiO2) as the main crystal phase.
Generally, the alumina content is between 65% and 75%. In addition to mullite, the mineral composition with lower alumina also contains a small amount of glass phase and cristobalite; the higher alumina contains a small amount of corundum. Lightweight mullite bricks can be directly used for the lining of high-temperature kilns, and have been widely used in shuttle kilns, roller kilns, glass and petrochemical kilns.
Features of Lightweight Mullite Bricks:
1. Low thermal conductivity, with good thermal insulation effect;
2. Low thermal melting, due to low thermal conductivity, mullite series light insulation bricks accumulate very little heat energy, which has obvious energy saving effect in intermittent operation;
3. Low impurity content has very low iron box alkali metal and other oxide content, therefore, high refractoriness; high aluminum content makes it maintain good performance in a reducing atmosphere;
4. High compressive strength in hot state;
5. Accurate appearance and size, speed up the masonry, reduce the amount of refractory clay used, ensure the strength and stability of the masonry, thereby extending the life of the lining;
6. It can be processed into special shapes to reduce the number of bricks and joints. Lightweight mullite bricks can be used as refractory lining or thermal insulation layer of hot surface working layer.
