Sintered High Alumina Refractories

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Introduction of Sintered High Alumina Refractories

high alumina refractories

High Alumina refractory bricks are a kind of alumina silica fire bricks that contain more than 48% Al2O3 content. High alumina refractory bricks have properties of high thermal stability and refractoriness, and good slag resistance. They can be used to build electric furnaces for steel making, glass furnaces, and lining rotary kilns.

Mineral Composition and Structure of Sintered High Alumina Refractories

The mineral composition of high-alumina refractories varies with the content of Al203 in the raw material. Generally, according to the different content of Al203 in high-aluminum bricks, it can be divided into three levels of high-aluminum bricks: the first grade contains Al203 greater than 75%; Level 2 is 75-60%; Level 3 is 60-48%. Therefore, according to the chemical composition and mineral composition of high-alumina bricks, high-alumina bricks can be divided into mullite bricks, mullite-corundum bricks, corundum-mullite bricks, and corundum bricks.

high alumina refractories
high alumina refractories

Classification of High Aluminum Refractories

Level 1 High Alumina Refractory

level 1 high aluminum refractories

Level 1 high aluminum refractory is a neutral refractory material with an alumina content of not less than 75%. It is formed and calcined from bauxite or other raw materials with a high alumina content. High thermal stability, refractory above 1770 °C. It is mainly used for masonry blast furnaces, hot blast furnaces, electric furnace roofs, reverberation furnaces, and rotary kiln lining. In addition, high-aluminum bricks are also widely used as plug heads and spout bricks for pouring systems.

Level 2 High Alumina Refractory

level 2 high aluminum refractories

Level 2 high aluminum refractory is a kind of aluminum silicate refractory with an alumina content of not less than 60%. Suitable for thermal boilers, glass kilns, cement kilns, fertilizer gas furnaces, blast furnaces, hot blast furnaces, coking furnaces, electric furnaces, bricks for casting and pouring steel, etc.

Level 3 High Alumina Refractory

level 3 high aluminum refractories

Level 3 high aluminum refractory brick refers to an aluminum silicate refractory with an aluminum oxide content of not less than 48%. Level 3 high aluminum refractory bricks are mainly used for electric furnace lids (furnace roof), blast furnace (furnace body), hot blast furnace partition walls, ladle lining, smelting-pot car, cement kiln, glass kiln, and other thermal kiln linings. Widely used in ironmaking, steelmaking, chemical, cement, and other industries.

Characteristics of Level 3 high aluminum refractory brick
  • High thermal stability
  • The fire resistance temperature is above 1600 °C
  • refractoriness under load can reach above 1350°C
  • Good slag resistance
  • Good thermal shock stability
  • Anti-acid, anti-alkali
  • Low creep rate at high temperatures

Sintered High Alumina Refractory Application

High Alumina Fire Bricks can be used in many kinds of industrial furnaces or kilns, such as blast furnaces, hot blast furnaces electric furnaces for steel making, and molten steel ladles as the furnace top and wall. High alumina bricks also can be used for checkerwork of regenerative chambers, reverberatory furnaces, and rotary kilns.

High Aluminum Special-shaped Refractory Bricks

Special-shaped refractory bricks are customized according to user requirements to meet the use of different environments, and refractory bricks of different materials can be selected according to indicators.

high aluminum special shaped refractory bricks

High Alumina Fire Bricks Properties

  • Refractoriness
    High Alumina Fire Bricks Products are high-grade alumina-silicate refractory. Their refractoriness will increase with the increase of Al2O3 content, which generally is not lower than 1750~1790℃. When the Al2O3 content reaches up to 95%, it is the corundum bricks that can resist high refractoriness of 1900~2000℃.
  • Refractoriness Under Load
    High Alumina Fire Bricks Products’ refractoriness under load will reduce with the increasing of SiO2 content and alkali metal oxide content, which is higher than fireclay bricks’ refractoriness under a load of 1420~1530℃. Corundum bricks’ refractoriness under load reaches up to 1600℃.
  • Slag Resistance
    As the high alumina fire bricks contain much high neutral Al2O3 content, this kind of refractory product has strong alkali furnace slag erosion resistance.
  • Thermal Shock Stability
    In the high alumina fire bricks products, there are two types of crystals of corundum and mullite existing. As the corundum’s thermal expansion coefficient is higher than mullite’s. When the temperature change happened to the refractory bricks, the thermal expansion difference results from the stress concentration. High alumina fire bricks products’ thermal shock stability is worse than fireclay bricks products’.
  • Reheating Linear Change
    If the firing temperature and time of high alumina bricks products are enough, the volume is stable and the reheating linear change is low. Or, the recrystallization will cause the linear after contraction of fireclay bricks.
high aluminum refractories

Sintered Type of High Aluminum Refractory

According to the material form, sintered can be divided into solid-phase sintered and liquid-phase sintered. According to the process, there are many sintered methods, new methods are still emerging, the most common methods are the following:

  • Isothermal sintered is sintered under constant temperature conditions.
  • Non-isothermal sintered.
  • Hot press sintered is the sintered of the sintered mass under pressure.
  • In hot isostatic pressing sintered, the block is subjected to sintered under high isostatic pressing conditions, and the block is subjected to uniform pressure from all directions.
  • Reaction sintered, sintered carried out in the same process as a chemical reaction.
  • Activation sintered. This is a term with a broad meaning. According to international standards, all accelerated sintered is called activated sintered.
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