refractory

Mullite brick production methods are mainly two types: sintering synthesis of mullite brick and fused mullite brick. These two kinds of mullite brick production methods are not the same, the use of performance and quality are also very different, the following for everyone to introduce the mullite brick production process and performance:

1, sintered mullite brick production process

The production process of sintered mullite brick is the same as that of high alumina brick. It is mainly used to synthesize mullite clinker as pellets; and fine powder sometimes use synthetic mullite clinker, or by the white corundum, quartz powder and pure clay and other ingredients made with the British stone to the equivalent of Mixed powder. The pellets and fine powder in proportion with the commonly used ratio: pellets 45% to 55%, fine powder (<0.088mm) 55% to 45%. After homogeneous mixing, high pressure forming. Firing temperature of 1550 ~ l600 ℃. When the fumed synthetic mullite is used as the granular material, the firing temperature is greater than 1700 ℃, in which the purity of the raw material, the fineness of the raw material and the calcination temperature are the most important technological factors influencing the brick formation.

2, mullite brick performance

The nature of mullite brick is mainly determined by the nature of mullite. It has high refractoriness, high softening temperature, low creep rate, excellent heat shock resistance, slag resistance, high shear modulus and so on. Mullite refractory brick is widely used, mainly for high temperature hot air stove, large blast furnace hearth and bottom, steel furnace roof, ceramic industry furnace lining, kiln furniture, and glass kiln cement kiln lining.

The sintered mullite brick produced by sintering synthetic mullite as raw material has good resistance to erosion and impact resistance, and has achieved satisfactory application effect within a certain range.

The principle of fused mullite, sintered with the production of fused mullite brick is mainly used for glass kiln. The mechanical strength and load deformation temperature of this kind of brick is high, the density is large, the porosity is small, the content of the crystal phase is large, and there is no abnormal phenomenon on the thermal expansion curve. However, at high temperatures when such substances and a large number of alkali substances in contact, mullite unstable, easy to break down, which to some extent reduce the stability of such refractories. In addition, the final performance of fused mullite brick produced by fused mullite raw materials of different purity is different; even with the same chemical purity (eg, high purity) fused mullite, due to its different fusing process , The resulting refractory bricks are also different performance.

Mullite brick at 1450 ℃ above should not be in contact with alkaline substances, or mullite will break down. In more than 1370% of the reducing atmosphere, the mullite will also decompose, part of the SiO2 into the gaseous SiO2 leaves the brick body. When the temperature is higher than 1650 ° C, mullite is decomposed even at a lower oxygen partial pressure, even if it is not a reducing atmosphere. It can be seen that the combustion temperature directly affects the firing of mullite brick.