The color of silica mullite brick has a certain relationship with the firing temperature, but the most important thing is the firing atmosphere. During the firing process, the reducing atmosphere is most suitable for the firing of silica mullite refractory bricks.
If the firing temperature is in an oxidizing atmosphere, the brick will oxidize, the surface layer will not reflect silicon carbide, and the strength will also decrease. silica mullite bricks are characterized by wear resistance and good seismic stability, and are mostly used in the transition zone before and after cement rotary kilns.
1. silica mullite bricks has a dense structure
This silica series bricks have a dense structure, stable mullite and SiC crystals, and can prevent erosion by gases and molten materials. However, silicon carbide has high thermal conductivity, small thermal expansion coefficient, and good thermal and shock resistance, so the bricks are not easy to break and peel off. The performance of silica mullite bricks used in cement rotary kilns is relatively better than anti-flaking high-alumina bricks and phosphate high-alumina bricks with better wear resistance.
2. The firing atmosphere of this brick is different from that of high alumina brick.
However, in many cases, the firing atmosphere of silica mullite bricks is different from that of high alumina bricks or magnesia bricks, because carbon silicide is suitable for firing in a reducing atmosphere. In an oxidizing atmosphere, silicon carbide is oxidized, and the use effect will be greatly improved. reduce. Some manufacturers will add a certain proportion of metal aluminum powder to adjust the oxidation of silicon carbide in the production process. However, during the firing process, the firing atmosphere must be well controlled. The silicon carbide effect of silica mullite bricks fired in a reducing atmosphere makes the appearance reaction obvious. And when used as a lining in a cement rotary kiln, it can prevent the melt from forming.
It should be noted that the amount of silicon carbide added also affects the color reflection of the silica mullite bricks. When the amount of silicon carbide added is small, the reaction on the brick surface is relatively small. When the amount is less than 8%, the brick surface basically reacts little. , just a layer of slight discoloration. No surface glaze appears. If the temperature is too high, the surface reaction will not change much. But the most critical thing is the influence of the firing atmosphere on the color of silica molybdenum bricks. Of course, performance will also be reduced during use.
