High alumina refractory bricks are refractory products
having an AL2O3 content of 48% or more in an aluminosilicate refractory. High alumina refractory brick manufacturer
divide high alumina refractory products into mullite-corundum,corundum-mullite, mullite,and corundum according to the composition of the main minerals in the product.According to the level of AL2O3,the high-aluminum bricks for general use are classified into three grades,namely,the first grade AL2O3 is >65%; the second grade AL2O3 is =55%-65%; the third grade AL2O3 is =48%-55%.
(1) The refractoriness of high alumina refractory bricks is relatively high in the silicate refractories.As the AL2O3 content in the products increases,the refractoriness increases, generally not less than 1750℃ to 1790℃.For corundum products with an AL2O3 content greater than 95%,the refractoriness can be as high as 1900℃ -2000℃.
(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 refractory bricks is 1420℃-1530℃.Corundum products with AL2O3 content greater than 95% have a load softening temperature of over 1600℃.
(3) The slag resistance of high alumina refractory bricks is highly resistant to erosion by acidic or alkaline slag due to its high AL2O3 content and neutrality in the product.
(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 at 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 time for firing is sufficient,then the volume is stable and the change in the reheating line is small.Conversely,due to recrystallization inside the product,residual shrinkage is caused.