Production Technology
Corundum mullite brick bodies are formed by a 300 t friction press with a density of 2.7 g/cm3. The billets are dried in a tunnel dryer: the inlet temperature is 40-50 deg C, the maximum drying temperature is 130 deg C, the drying time is 48 h, and the water content of the body is not more than 1.5 percent. The product is fired in the tunnel kiln at a firing temperature of 1550 deg C with a holding time of 10 h.
Forming Methods
(1) Refractory products with complex shape and large size are rammed with an air hammer or formed by vibration. (2) Ordinary products or standard specifications can be formed by semi-dry high-pressure molding. (3) Special-shaped pure or special products need designed molds and isostatic pressing.
Physical Properties
The high-temperature main crystalline phases of corundum mullite brick are corundum and mullite. The corundum crystals are short columns and barrels, which are not interspersed and interlaced in the resistant material structure. The corundum crystals are interlaced with mullite columnar crystals, which can effectively prevent the sliding of corundum crystals and obtain a stable structure. Because the crystal structure is more stable, the excellent performance of mullite or mullite and corundum is supported: the melting point of mullite is 1870 deg C, corundum 2050 deg C, and the high fusion temperature of the two is 1840 deg C, which is conducive to the improvement of the high-temperature performance of the material.
Advantages and Characteristics
(1) High temperature resistance: high refractoriness and high load softening temperature. (2) Chemical erosion resistance: strong resistance to acidic solution or slag. (3) Oxidation resistance: not easy for O2, H2, CO and other gases to react chemically. (4) Good thermal stability and high-temperature volume stability: not easy to expand or shrink. (5) Good thermal shock resistance: resistant to thermal cycling without flaking. (6) High compressive strength at room temperature: not easy to wear during handling or unloading.
Frequently Asked Questions
What are the main phases of corundum mullite brick? Corundum and mullite, interlaced to form a stable structure.
What is the firing temperature? 1550 deg C with a 10 h holding time.
Why is the brick thermal-shock resistant? The interlaced corundum-mullite structure and stable high-temperature phases resist cracking under thermal cycling.
