High alumina refractory brick is a refractory product with an AL2O3 content of 48% or more in an aluminum silicate refractory. According to the composition of the main minerals in the product, the high-aluminum refractory products are divided into four types: mullite-corundum, corundum-mullite, mullite, and corundum. According to the level of AL2O3, the high-aluminum bricks for general use are divided into three grades, namely, the first grade AL2O3>65%; the second grade AL2O355%～65%; the third grade AL2O348%～55%.
(1) The refractoriness of high-aluminum refractory bricks is relatively high in the silicate refractories. As the content of AL2O3 in the products increases, the refractoriness increases, generally not less than 1750 to 1790 °C. For corundum products with an AL2O3 content greater than 95%, the refractoriness can be as high as 1900-2000 °C.
(2) The load softening temperature of high alumina refractory bricks decreases with the increase of SiO2 and metal oxide content in the product. Generally, the load softening temperature of high alumina brick is 1420-1530 °C. The corundum product with an AL2O3 content greater than 95% has a load softening temperature of 1600 ° C or higher.
(3) The slag resistance of high alumina refractory bricks, because of the high content of AL2O3 in the products and neutral, it has strong anti-erosion ability to acidic or alkaline slag.
(4) The thermal shock resistance of high alumina refractory bricks, in which there are two crystals of corundum and mullite, and the linear expansion coefficient of corundum is larger than that of mullite, so it changes in temperature. When the stress concentration is caused by the difference in the expansion of the product, the thermal shock resistance of the high alumina brick is poor, and the number of water cooling is generally only 3 to 5 times.
(5) The change of the re-firing line of the high-alumina refractory brick depends on the degree of firing of the product. If the firing temperature is sufficient and the sufficiency is sufficient at the time of firing, the volume is stable and the change in the reburning line is small. Conversely, due to recrystallization inside the product, residual shrinkage is caused.
In view of the above characteristics of high-aluminum refractory bricks, it is mainly used for the construction of coke oven combustion chamber burners and the bottom of the carbonization chamber, but it is not suitable for use as carbonization chamber wall tiles, because it will produce curling and warping at high temperatures. and many more.
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