Last issue we introduced additives performance and ignition loss of light weight mullite fire bricks. This issue we will continue to introduce performance of light weight mullite fire brick water reducer.
3. Performance of water reducer
The forming method of light mullite fire bricks is wet plastic forming, the moisture content of the mud is high, the shrinkage of green body during the drying process is large, and the green body is prone to cracks and uneven shrinkage. The addition of water reducer effectively reduces the amount of water added, and avoids the above problems.
Generally, the alumina content of light weight mullite fire bricks is between 65% and 75%. In addition to mullite, in bricks with lower alumina, it contains a small amount of glass phase and cristobalite. In bricks with higher alumina, it contains a small amount of corundum. The refractoriness is high, which can reach above 1790 ℃. Softening temperature under load 1600 ～ 1700 ℃. Compressive strength is 70 ～ 260MPa. Good thermal shock resistance. There are two kinds of mullite bricks, sintered mullite bricks and fused mullite bricks. Sintered mullite bricks are made of high-alumina bauxite clinker, with a small amount of clay or raw bauxite as a binding agent, and are made by molding and firing. The fused mullite bricks are made of high alumina, industrial alumina and refractory clay, with fine particles of charcoal or coke as reducing agents, and are manufactured by reducing electric melting after molding. The crystal of fused mullite is larger than that of sintered mullite, and its thermal shock resistance is better than that of sintered products. Their high temperature performance mainly depends on the content of alumina and the uniformity of the distribution of mullite phase and glass phase.
They are mainly used on hot blast stove top, blast furnace body and bottom, glass melting furnace regenerator, ceramic sintering kiln, oil cracking furnace inner corner lining, etc.
