Zirconium Mullite Brick

Apparent Porosity％：≤17

Bulk Density g/cm3：≥3.15

Cold Crushing Strength Mpa：≥90

20-1000℃ Thermal Expansion % (x 10-6)：0-0.6

Pyrometric Cone Equivalent ℃ SK：31

Application of zirconium mullite brick: sintered zirconium mullite refractory has good high temperature resistance, corrosion resistance, mainly used for long life mouth ring, tank bottom, tank upper structure.

Sintered zircon mullite brick is a general sintered AZS product containing zircon, which is made by sintering (or electromelting) mullite or corundum calcined bauxite coarse particles and zircon stone in arbitrary proportion, plus binder firing. The firing temperature determines the total decomposition of zircon particles, slight decomposition on the surface or no decomposition at all. Sintered zirconium mullite refractory has good high temperature resistance and corrosion resistance. However, in the temperature range of ZrO2 phase transition, it is sensitive to thermal shock.

By introducing ZrO2 into Al2O3-sio2 bricks to improve the structure of mullite, can improve the chemical erosion resistance of mullite, heat resistance and reduce the expansion coefficient, this Zro2-containing mullite brick, known as zirconium mullite brick, is generally obtained by electric melting method, but also useful sintering method production. Sintered zirconium mullite brick is a special refractory made by using industrial alumina and zircon concentrate as raw materials and introducing zirconia into mullite matrix by reaction sintering process. The high temperature mechanical properties of mullite can be greatly improved by introducing zirconia into mullite brick and using the phase transformation toughening of zirconia. Zirconia can promote the sintering of mullite material, and the addition of ZrO2 can accelerate the densification sintering process of ZTM material due to the production of low melting point and the formation of vacancy. When the mass fraction of ZrO2 is 30%, the relative theoretical density of the billet sintered at 1530℃ reaches 98%, the strength reaches 378MPa, and the toughness reaches 4.3MPa•m1/2.

It is difficult to control the process of zirconium mullite brick made of industrial alumina and zircon by reaction sintering because the reaction and sintering are carried out simultaneously. Generally, during the sintering process, it is first held at 1450℃ to densitize, and then heated to 1600℃ for reaction. ZrSiO4 is decomposed into ZrO2 and SiO2 at a temperature greater than 1535℃, in which SiO2 and Al2O3 react to produce mullite. Due to the decomposition of ZrSiO4, some liquid phase appears. Moreover, the decomposition of ZrSiO4 can refine the particles and increase the specific surface area, thus promoting sintering.

The results show that when the addition of zircon is less than 54.7%, the microstructure of the sintered sample is gradually changed from columnar corundum to columnar mullite with the increase of the addition of zircon. The high temperature flexural strength of the sample (1400. C) It also increases with the increase of zirconia content, and a large value appears when the zirconia content is 23.7%, and then the strength decreases. The addition of zircon helps to improve the thermal shock resistance.

JIYGO REFRACTORY & ABRASIVE LIMITED