Mullite Brick is high alumina refractory whose main crystalline phase is mullite(3Al2O3·2SiO2). The alumina content of mullite brick is around 65%~75. The refractoriness of mullite brick is up to 1790℃ good thermal stability. Mullite bricks are be divided into two kinds, sintered mullite brick and electric cast mullite brick. Mullite refractory bricks are commonly applied in smelting industry, like in the top of hot blast stove,blast furnace shaft, furnace bottom, etc. Any need of mullite brick? Come and find Rongsheng Kiln Refractory Company! Quote RS to get the best price!
Mullite Brick Definition
Mullite brick is made of synthetic mullite as raw material. The main crystalline phase of mullite brick is mullite. The average content of alumina is between 65% and 75%. In addition to mullite, the lower alumina contained a small amount of vitreous phase and calcite.Higher alumina content also contains a small amount of corundum. Mullite brick is widely used in various parts of thermal furnaces in iron and steel, chemical industry, glass, ceramics and other industrial sectors. The refractoriness of mullite brick is higher than 1790℃. The softening of load starts at 1600~1700℃. The compressive strength at normal temperature is 70 ~ 260MPa. The thermal shock resistance ability is good. There are sintered mullite brick and electric mullite brick two kinds of mullite brick.
Mullite Brick Properties
- High refractoriness(above 1790℃).
- RUL is 1600~1700℃.
- Cold crushing strength is 70~260MPa.
- Good thermal shock resistance.
- Good performance at high temperature.
- Good creep-resisting property.
- Good wear resistance.
- Strong acid and alkali slag resistance ability.
- Low thermal expansion.
Mullite Brick Composition
- Synthetic mullite.
- A small amount of cristobalite.
- A small amount of glass phase.
- A little corundum.
Mullite Brick Application
On the one hand, mullite brick is usually applied in electronics and optimal industries. And on the other hand, mullite brick is mainly used in high temperature industry, such as in the roof of hot blast stove, blast furnace stack, furnace bottom, glass furnace regenerator, ceramic sintering kiln, oil cracking system dead angle lining and so on.
Mullite Brick Classification
According to synthetic methods, they are two types of mullite bricks.
- Sintered mullite brick
- Electric cast mullite brick.
Sintered Mullite Brick
Sintered Mullite Brick Components
Sintered mullite bricks are made from high alumina clinker, with a small amount of clay or raw bauxite as the binding agent through molding and firing.
Sintered Mullite Brick Formulas
- Natural bauxite+kaolin
- Industrial alumina+clay(kaolin or wax stone)
- Industrial alumina+silica
- Industrial alumina+bauxite(or sillimanite concrete)
Sintered Mullite Brick Process Technology
1.Purity of sintered mullite brick raw materials.
The mullite brick production process requires high purity of raw materials, a small amount of impurities will reduce mullite content. The most harmful thing is R2O, which leads to decomposition of mullite at high temperature. Fe2O3 can delay the formation process of mullite. When a small amount of TiO2 exists, some Ti ions can enter the mullite crystal lattice and form a limit solid solution, thus promoting mullite formation and crystal growth. When the content of TiO2 is too much, it acts as a flux.
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2.Fitness of sintered mullite brick raw materials.
The sintering synthesis of mullite brick mainly depends on the solid phase reaction between Al2O3 and SiO2. The increase of the subdivision of raw materials will accelerate the process of solid phase reaction. Especially, the particles smaller than 8um play a great role in the formation and sintering of mullite. According to some data, the sintering temperature of synthetic mullite depends on the proportion of 4um particulates. When the particle size is below 4um, the material density is the highest.
3.Calcination temperature of sintered mullite brick.
Synthetic mullite usually forms at the beginning temperature 1200 C and terminates at 1650 C. The crystallization is well developed when the temperature is over 1700. The calcinating temperature of mullite brick should be more than 1700 degrees C. When natural raw materials are prepared, the calcination temperature is slightly lower due to a small amount of impurities in the raw materials. When the proportion of alumina in the mix is slightly lower than the theoretical composition of mullite, the calcining temperature is 1630~1650 C and the heat preservation time is 6~8 hours, the good mullite clinker with more than 90% mullite content can be obtained.
Electric Cast Mullite Brick
The electric cast mullite brick is made of high alumina, industrial alumina and refractory clay as raw materials, adding charcoal or coke fine-grained as reducing agent. After forming, electric cast mullite brick is formed by reduction electrofusion method. The crystallization of fused mullite is larger than that of sintered mullite, and its thermal shock resistance is better than that of sintered products.
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Electric cast mullite brick can be used to prepare mullite fragments, used as cast iron sand, packing sand, fluidized bed roasting sand, and can also be used as filter material. Far infrared emitting ceramics made from mullite ceramics can be used to purify and intensify water to facilitate fish breeding. Mullite fibers can be used as heat resistant filler materials and heat-resistant sealing materials for automotive engines.
Mullite Brick Manufacturer
Zhengzhou Rongsheng Kiln Refractory Company is one of the famous mullite brick manufacturers in the world who can produce both sintered mullite brick and electric cast mullite brick. Rongsheng Refractory mullite brick manufacturer has advanced refractory production technology and satisfactory after-sales service. Any need of zirconia mullite bricks, corundum mullite bricks or silica mullite bricks? Don’t be hesitated to quote from Rongsheng! RS Refractory Company will offer you the best price!