The Firing Process of Mullite Brick

Mullite brick is characterized by good high temperature resistance and good thermal shock resistance, which comes into being mullite through calcine with clay, high alumina materials and ceramics.

The firing process of mullite brick can be divided into three stages. 

1) The formation of mullite brick starts at 1200℃ and ends at 1650℃. This is the first stage. At this stage, the solid phase reaction that forms mullite and the sintering process of mullite bricks happens at the same time. With the increase of temperature, the content of mullite increases. The bulk density increases and the porosity decreases. There is almost no glass phase formed at this stage close to the pure solid phase reaction. 

2) At 1650~1700℃, the content of mullite is substantially constant, but the mullite grains grow with the increase of the temperature. The glass phase increases too. At 1700℃, the apparent porosity of clinkers is lowest and the bulk density is highest. This is the second stage and there is liquid phase in this firing process.  

3) At 1700℃, this is the last stage of the firing process. The firing process is slow and even stagnant. With the increase of the temperature, it will be counterproductive. The porosity may increase and the bulk density decreases.