Five special properties of high alumina bricks

October 22, 2018

Five special properties of high alumina bricks

Compared with clay bricks, high alumina bricks have the outstanding advantages of high refractoriness and refractoriness under load. 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 alumina bricks have higher refractoriness than clay bricks and semi-silica bricks, reaching 1750℃~1790℃. It is a high-grade refractory material. The refractoriness is mainly affected by the content, variety and quantity of Al2O3, increased with the increase of Al2O3 content.

2. Refractoriness under load

Because the high alumina products have high Al2O3 content, less impurities and less fusible glass body, the refractoriness under load is higher than that of the clay bricks. However, since the mullite crystal does not form a network structure, the refractoriness under load is not as high as the silica bricks.

3.Thermal conductivity

High alumina bricks have better thermal conductivity than clay bricks. The reason is that there are fewer glass phases with low thermal conductivity in high alumina products, and the number of mullite and corundum crystals with better thermal conductivity increases, which improves the thermal conductivity of the products.

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℃ 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

Al2O3 content is more in high alumina brick, close to neutral refractory products, and can resist the erosion of acid slag and alkaline slag. However, due to the presence of SiO2, the ability to resist alkaline slag is weaker than acid slag.

In addition, the slag resistance of high alumina products is also related to the stability of the products in the slag. In general, products with a lower porosity usually have higher slag resistance after high pressure molding and high temperature firing.