Sunrise Refractory Casting corundum brick slow cooling treatment
2019-10-18
The cast-cast corundum brick is subjected to slow cooling and cooling treatment immediately after casting to prevent cracks in the product during cooling. The effect of slow cooling is to reduce the solidification speed of the melt, so that the melt of the compensation riser has enough time to fill the mold, so that the shrinkage holes are concentrated as much as possible into the riser. Minimize the internal and external temperature difference of the product to prevent the product from cracking due to the difference in thermal stress.
There are two methods for slow cooling and cooling: one is to use the slow cooling box method; the other is to use the tunnel slow cooling kiln cooling method.
(1) Slow-cooling box method: an upper-opening slow-cooling box that can be lifted by steel plate and section steel. The size of the slow cooling box depends on the size of the product, and is generally not less than 1.5 m3. Fill the slow cooling box with 400 ~ 500mm high-temperature and heat-insulating granular expanded vermiculite. Place the cast product together with the mold in the middle of the slow box. It is still buried with expanded vermiculite around it and at the top. Let it cool naturally.
Replacing the expanded vermiculite with aluminum oxide hollow spheres or synthetic lightweight aggregates can increase the service life and effectively reduce the splash of dust.
(2) Slow cooling method for tunnel kiln: Removable assembly molds should be used for slow cooling and cooling in tunnel kiln to reduce demoulding time. The mold was removed from the kiln car and the kiln car was immediately pushed into the high temperature part of the tunnel kiln. Incubate at 1300 ~ 1400 °C for 2 ~ 4h, then cool down at 15~60 °C / h, and take natural cooling below 800 °C. The casting rate of α-β corundum bricks can be controlled to achieve a cooling rate of over 80%.
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