Fused zirconium corundum

Fused zirconium corundum
Electric fused zirconium corundum is commonly known as white iron brick or fused cast high corundum brick. It is the most important refractory to ensure the normal operation of the glass furnace. At present, the improvement of melting rate, extension of furnace life and reduction of fuel consumption of glass furnaces at home and abroad are mainly due to the use of this refractory.
1、 Irregular changes in thermal expansion.
The expansion curve of fused zirconium corundum brick has an anomaly near 1000 ° C. The ZrO2 crystal inside the brick undergoes reversible crystal transformation with large volume change. Therefore, the products containing ZrO2 should not be at the position where the temperature often fluctuates sharply at about 1000 ° C. When baking the furnace, the temperature change at 900-1150 ° C shall not be too large, generally not more than 15 ° C/h, and the temperature shall rise steadily. Some parts of the kiln shall be protected from blowing cold air with other bricks to prevent cracking.
2、 Casting method
1. Common casting, inclined casting. Shrinkage holes often appear at the casting mouth during molten casting. There are many air holes and poor density of the brick here. Therefore, when building the wall of the glass melting pool, the shrinkage holes are all directed towards the inside of the kiln. If the casting mouth is facing outward, when the brick is eroded to a very thin thickness, the leakage of liquid glass will occur. When used in the upper flame space of the tank furnace, the service life is very long, and there is no problem of glass leakage, so the casting mouth is used outward to extend the service life.
2. Casting without shrinkage cavity. Since the shrinkage cavity is cut off completely after the casting is cooled and formed, the bricks are all dense. Now most of the tank walls of kilns use non shrinkage bricks.
3、 Precautions.
Electric fused zirconium corundum bricks are laid in contact with clay and siliceous refractory bricks, which will produce co melting phenomenon at 1300 ° C. Therefore, when selecting refractory materials, it is necessary to avoid contacting two refractory materials with serious co melting phenomenon. For example, silicon bricks are most vulnerable to erosion of electric fused zirconium corundum bricks when contacting electric fused zirconium corundum bricks, so zircon bricks are sandwiched between the two refractory materials.