Silica brick is an acid refractory material with good resistance to acid slag erosion. The softening temperature under load is as high as 1640-1670℃, and the volume is relatively stable in long-term use at high temperature.
Silica brick main data:
Acidic refractory mainly composed of tridymite, cristobalite and a small amount of residual quartz and glass phases. The silica content is more than 94%. The true density is 2.35g/cm3. It has resistance to acid slag erosion. Higher high temperature strength. The starting temperature of softening under load is 1620-1670°C. Long-term use at high temperatures will not deform. Low thermal shock stability (1 to 4 times of heat exchange in water). Natural silica is used as raw material, and an appropriate amount of mineralizer is added to promote the transformation of quartz in the green body into tridymite. It is slowly fired at 1350-1430°C in a reducing atmosphere. When heated to 1450 ℃, the total volume expansion is about 1.5~2.2%. This residual expansion will make the slits close and ensure the masonry has good air tightness and structural strength.
What’s important for silica brick
The properties and process of silica bricks are closely related to the crystal transformation of SiO2. Therefore, the true specific gravity is an important quality indicator of silica bricks. The general requirement is below 2.38, and the high-quality silica brick should be below 2.35. The true specific gravity is small, which reflects that the amount of tridymite and cristobalite in the brick is large, and the amount of residual quartz is small, so the residual linear expansion is small, and the strength drop in use is also small.
The raw material for making silica bricks is silica. The higher the SiO2 content of the silica raw material, the higher the refractoriness. The most harmful impurities are Al2O3, K2O, Na2O, etc., which seriously reduce the refractoriness of refractory products. Silica bricks are made of silica with a SiO2 content of not less than 96%, adding mineralizers (such as iron scale, lime milk) and binders (such as molasses, sulfite pulp waste liquid), and then kneading, molding, drying and firing. and other procedures.
Silica brick main usage:
It is mainly used for the partition walls of the carbonization chamber and the combustion chamber of the coke oven, the regenerator and the slag chamber of the steel-making open-hearth furnace, the soaking furnace, the refractory material of the glass melting furnace and the firing kiln of the ceramics, etc. load bearing part. It is also used for high temperature load-bearing parts of hot blast stoves and acid open hearth furnace tops.
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