Structure and performance of Tianyang refractory fused mullite brick

The mullite brick is a silicon-aluminum system refractory product mainly composed of mullite crystal phase. Since the main crystal phase of mullite brick is mullite, the refractory degree of mullite is about 1850 ° C, the load softening temperature is high, the high temperature creep rate is low, the thermal shock resistance is good, and the acid corrosion is resistant.

 

The electric fused mastic brick is made of high alumina bauxite and the different bauxite is composed of mullite (3Al2O3·2SiO2, the mass percentage is 72% of Al2O3 and 28% of SiO2). It is melted at about 2300 ° C, cast in a sand mold at 1850 ° C, and then annealed to eliminate stress. The main crystal phase is mullite and corundum, and the glass phase is filled between the crystal phases. Its resistance to vitrification is stronger than sintered refractories, but not as good as other fused refractories. Adding a small amount (7%~8.5%) of zirconia can make the mullite crystals smaller, the brick structure compact, and the mullite amount increased to 60%~70%, which relatively reduces the content of the glass phase, and Reduced cracks in the product. The electric melting mullite brick has low thermal expansion coefficient, good thermal shock resistance and strong resistance to glass liquid.

When the fused mullite brick is manufactured, the corundum crystal is first precipitated during the cooling process, and then the mullite crystal is precipitated. A small amount of SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, etc. remains as a glass phase. The glass phase accounts for 25% of the bricks. It contains many low-melting substances, so the corrosion resistance is worse than other electric melting bricks. Bubbles and reducing substances are also present in the glass phase, which can contaminate the glass when used.