Aluminum content 38, silicon content 55 What refractory bricks?
The mineral composition of the high alumina brick is determined by the bauxite used. The mineral composition of the clinker is usually mullite, corundum and glass. The theoretical composition of mullite is Al2O371.8%, SiO2 28.2%, and its melting decomposition temperature is 1840 DEG C. With acicular crystal, network cross structure, high temperature state showed better strength. Corundum in the form of alpha -Al2O3, melting point of 2050 degrees, hardness of Mohs 9, showing a granular and columnar crystal, has good chemical stability, acid, alkaline slag have a certain resistance. Based on the composition of mullite minerals, the phase composition of high alumina brick can be judged according to the content of Al2O3.
When the bricks are below Al2O3 71.8%, the base of the composition is mullite and SiO2, such as grade LZ-48 bricks. Because it contains a large number of SiO2 formed in the liquid phase under high temperature is 20% ~ 30%; brick in Al2O3 more than 71.8%, the excess Al2O3 formed corundum crystal under high temperature, while generating 2 high temperature phase, eutectic temperature rise by the low content of Al2O3 brick 1595 C to 1840 C, such as grade LZ-75 brick. In fact, it is impossible to produce a complete phase equilibrium in the process of production, but the glass phase is very small, and there is no more than 10% in the partial gap of the Yu Jing phase
Semisilica brick: the content of Al2O3 is 15% ~ 30% of aluminium silicate refractory products. Manufacturing products are semi silica quartz containing impurities or native clay kaolin, refractory clay or kaolin beneficiation tailings and the pyrophyllite
