Technical Description

Five special properties of high alumina bricks

Compared with clay bricks high alumina bricks have the outstanding advantages of high refractoriness and load softening temperature. With the increase of Al2O3 content the slag resistance performance is significantly improved. In particular high alumina bricks have the following properties.

(1) Refractoriness
The high-aluminum brick has higher refractoriness than clay bricks and semi-silica bricks reaching 1750~1790 °C which is a high-grade refractory material. The degree of refractoriness is mainly affected by the content and type and quantity of Al2O3 and the refractoriness increases with the increase of Al2O3 content.

(2) Load softening temperature
Because the high aluminum product has high Al2O3 low impurity content and less fusible glass body the load softening temperature is higher than clay brick but the mullite crystal does not form a network structure so the load softening temperature is still not high.

(3) Thermal conductivity
High alumina bricks have better thermal conductivity than clay bricks. The reason is that the glass phase of the high aluminum product has a low thermal conductivity and the number of mullite and corundum crystals with better thermal conductivity increases which improves the thermal conductivity of the product.

(4) Thermal shock resistance
The thermal shock resistance of high alumina bricks is between clay products and siliceous products. The water cooling cycle at 850 ° C is only 3 to 5 times. This is mainly due to the fact that the thermal expansion of corundum is higher than that of mullite and there is no crystal transformation. At present the thermal shock resistance of the product can be improved by improving the granular structure of the product reducing the content of the fine powder and increasing the critical particle size and particle gradation of the clinker.

(5) slag resistance
High alumina bricks contain more Al2O3 close to neutral refractory materials and can resist the erosion of acid slag and alkaline slag. Because of the SiO2 content the ability to resist alkaline slag is weaker than that of acid slag. In addition the slag resistance of high aluminum products is also related to the stability of the product in the slag. In general articles having a lower porosity have a higher slag resistance after high pressure molding and high temperature firing.