High alumina brick is a kind of refractory material, in which the content of Al2O3 reaches 55%~75%, and the refractoriness is above 1770℃. The refractoriness of high alumina bricks is higher than that of clay bricks and semi-silica bricks, and they belong to advanced refractory materials. However, compared with high-temperature kilns that require a use temperature of more than 2000°C, their refractoriness is still far from enough. If they continue to be used, they will have the effect of over-temperature use, and the consequences will be very serious.
High alumina brick physical and chemical index:
After high-alumina bricks are used at high temperature, if the temperature is within the softening temperature of the physical and chemical indexes, the other constants of the physical and chemical indexes will not change. If it exceeds the range of the load softening temperature, other physical and chemical index constants will increase or decrease accordingly. Mainly manifested in the following aspects:
1. Refractoriness. High-alumina brick products are advanced varieties of aluminum silicate refractory products. Its refractoriness increases with the increase of Al2O3 content, generally not lower than 1750~1790℃. For example, corundum bricks with Al2O3 content greater than 95%, the refractoriness can be as high as 1900~2000℃.
2. Load softening temperature. The load softening temperature of high alumina brick products decreases with the increase of the content of silica and alkali metal oxides, but it is higher than that of clay brick products, about 1420-1530°C.
3. Slag resistance. Due to the neutrality and high content of aluminum oxide in high alumina brick products, similar materials are resistant to corrosion by acid and alkali slag.
4. Thermal shock stability. In high-alumina brick products, when the temperature of the refractory brick changes, the stress is concentrated due to the difference in expansion. Therefore, the thermal shock stability of high-alumina brick products is worse than that of clay products. Generally, the number of water cooling is only 3 to 5 times.
5. The reburning line changes. If the firing temperature of high alumina brick products is sufficient, If the firing time is sufficient, the volume will be stable and the refire line will change little; on the contrary, it will produce residual shrinkage like clay brick products, which is also caused by recrystallization.
From this, it can be seen that the kiln has high requirements for high alumina bricks. If the temperature of the product itself does not reach the temperature required by the kiln itself, over-temperature will occur. This phenomenon must be avoided. Otherwise, it will not only increase the cost and temperature, but also cause the danger of casualties due to the collapse of the furnace.
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