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refractories

Sintered High Alumina

High Alumina Series is generally supposed to be aluminium silicate product with high content of Al2O3 (48%). It is batched according with a certain proportion of both aggregate and powder, and produced with high temperature combustion of more than 1350-1560℃.

In China, there are 4 kinds of high alumina products being commonly defined, according to different contents of Al2O3:

A2204—Al2O3 standard content: ≥80%;
A2203—Al2O3 standard content: 75% ;
A2202—Al2O3 standard content: 65%;
A2201—Al2O3 standard content: 55%.

Sintered High Alumina

Physical and Chemical Indicators

Sintered High Alumina
Item CodeA2204A2203A2202A2201
Al2O3%80756555
Fe2O322.52.52.6
B.D g/cm32.62.52.42.3
C.C.SMPa80706050
R.U.L 1550151014601420
Refractoriness1790179017701770
A.P%21222324
Linear Change Rate-0.2-0.3-0.4-0.4
Application

The series is mainly used in flues, regenerator, outside wall and other parts of glass furnace. And it can also be applied to the lining of metallurgy blast furnace, hot blast furnace, top of electric furnace , blast furnace, reverberatory furnace and rotary furnace.

Characteristics

High alumina series has good refractoriness, high refractoriness under load and its slag resistance is obviously improved with an increasing content of Al2O3. More specifically, high alumina product has following properties:

  1. Refractoriness
    High alumina product is supposed to be a high-grade refractory material. Its refractoriness (1750-1790℃) is higher than that of clay products and semi-silica products.With an increasing of Al2O3 content as well as a decreasing of impurities content, the refractoriness will be improved.
  2. Refractoriness Under Load
    Because of a high content of Al2O3 with lower impurities in the series, the quantity of vitreum which can be easily melted is quite low. Therefore, its refractoriness under load is higher than that of clay series. However, its temperature of refractories under load is still lower than that of silicon series due to a lack of network structure formed by mullite crystallization.
  3. Thermal Conductivity
    Thermal conductivity of high alumina product is better than that of clay product. Because, in high alumina series, the quantity of glass phase which owns a lower thermal conductivity is very low. Besides, the increase of quantities of mullite and corundum crystal which owns good thermal conductivity obviously improves the capacity of heat transmission of high alumina series.
  4. Thermal Shock Resistance
    Thermal shock resistance of high alumina series is between that of clay and silicon. The times of water cooling cycle at 850℃ can reach to 35. The main reason is thermal expansibility of corundum is higher than mullite and no crystal can be transformed.
  5. Slag Resistance
    High alumina series contains a good proportion of Al2O3 and is very close to neutral refractory materials. It can resist the corrosion of acid slag as well as alkaline slag. Due to the content of SiO2, the resistance of alkali slag is a little weaker than that of acid sla
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