High-density zirconia mullite refractory brick for glass furnace

Sintered zircon mullite brick is a general sintered AZS product containing zircon. The firing temperature determines whether the zircon particles are completely decomposed and whether the surface is slightly decomposed or not decomposed at all. Sintered zirconium mullite refractory has good high-temperature resistance and corrosion resistance. But in the temperature range of the ZrO2 phase transition, it is sensitive to thermal shock.

By introducing ZrO2 into the Al2O3-SiO2 series brick to improve the structure of mullite, it can improve the chemical corrosion resistance, and thermal shock resistance and reduce the expansion coefficient of mullite. This ZrO2-containing mullite brick, commonly known as Zirconium mullite bricks are generally produced by the electrofusion method and are also produced by the sintering method. The introduction of zirconia into mullite bricks and the use of zirconia's phase transformation toughening can greatly improve the high-temperature mechanical properties of mullite materials.

Using industrial alumina and zircon as raw materials, the zirconium mullite brick made by reaction sintering is difficult to control the process because the reaction and sintering are carried out at the same time. Usually, during firing, the temperature is kept at 1450 °C to make it densified, and then the temperature is raised to 1600 °C for reaction. ZrSiO4 is decomposed into ZrO2 and SiO2 at greater than 1535 °C, wherein SiO2 and Al2O3 react to form mullite. Due to the decomposition of ZrSiO4, A part of the liquid phase appears, and the decomposition of ZrSiO4 can refine the particles and increase the specific surface area, thereby promoting sintering.

The research shows that when the addition of zircon is less than 54.7%, with the increase of the addition of zircon, the microstructure of the sintered sample is gradually transitioned from the network composed of columnar corundum to the network structure composed of columnar mullite. The high-temperature flexural strength (1400°C) of the sample also increases with the increase of zirconia content, and a larger value appears when the zirconia content is 23.7%, and then the strength decreases. The addition of zircon contributes to the improvement of thermal shock resistance.