Since the cast refractories used in the invention, both output and varieties have been tremendous development.
Early refractory castable alumina cement (or even ordinary portland cement) a combination of aluminum silicate castable cement to join the most 15-35%. Alumina cement calcium oxide is quite high, castable calcium oxide content of 3-11%, the calcium oxide castable A1203, and SiO2 reaction anorthite (CaO · A12O3 · 2SiO2) and aluminum yellow feldspar (2CaO · A1O2 · SiO2) of low-melting, greatly reducing the high temperature properties of aluminum silicate castable refractoriness and high temperature strength, anti-erosion and anti-erosion performance degradation, makes this castable only at 1300 ℃ be used. In addition, this castable Maintenance strength depends on the cement binding agent in a variety of hydrates to form a gel, dehydration and hydration when heated to between 800 ° C and 1000 ° C so that the strength is reduced, resulting castable structure regional damage, this for common castable performance is extremely harmful.
60 years before and after the development of a low-calcium aluminate cement and Calcium Aluminate Cement their minerals to the CaO 2A12O3, and mainly, the CaO content is reduced to 21-25% from 33 to 35% calcium aluminate cement, This allows the preparation of castable high alumina aggregate and corundum aggregate use temperature up to 1450-1600 ° C by 1300 ℃.
But with low calcium aluminate cement and calcium aluminate cement, there is still a certain amount of CaO into the refractory castable, high temperature structural strength and other high-performance A. Therefore, over the past decade, some scholars at home and abroad dedicated to research and development of low cement, ultra low cement or no cement castable, castable calcium aluminate cement added in an amount from 15 to 35% down to 5-7% (low cement castable), 1-3% (ultra-low cement castable) and 0% (no cement castable, chemical binding and cohere).
