The insulation performance of mullite insulation brick is very good, depending on the good performance of mullite brick, so we have to control the impact of mullite insulation brick performance factors.
Mullite tiles usually contain impurities such as TiO2, Fe2O3, CaO, MgO, K2O and Na2O, and the impurity content of mullite produced from natural raw materials is higher than that of synthetic raw materials. These impurity oxides play a role in mullite, reduce the temperature and viscosity of the melt, increase the amount of liquid phase, increase the dissolution rate and dissolution of the melt to the solid phase, but the impurity oxides The effect of K2O and Na2O on the liquid formation temperature is the largest, and K2O and Na2O decrease the temperature of the non-variable point by 513 ~ 724 ℃, respectively, and also decompose the effect of mullite. Among these impurity oxides, the effect of TiO2 is the smallest, and only the variable point temperature is reduced by 101 ~ 107 ℃. When the TiO2 content is less, in addition to part of the solid solution in the mullite to form a limited solid solution to promote the formation of mullite and crystal growth, there are some at high temperatures into the liquid phase to form vitreous. Fe2O3 in the high temperature of mullite and corundum in a certain solid solubility, the formation of limited solid solution. Its solid solubility in corundum is higher than that in mullite, and the lattice of mullite and corundum grows up due to the formation of solid solution. The effect of Fe2O3 on the initial melting temperature of Al2O3-SiO2 system is related to the Al2O3 / SiO2 ratio in the system. When Al2O3 / SiO2, the initial melting temperature is 1380 ℃. When Al2O3 / SiO2> 2.55, Melting temperature increased to 1460 ℃, and with its A12O3 content increased gradually increased. In the reducing atmosphere, Fe2O3 was reduced to FeO and de-dissolved into the glass phase, and the initial melting temperature of the system decreased, respectively, down to 1240 ℃ and 1380 ℃. In short, with the mullite brick Al2O3 content increased, its high temperature performance increased; and the amount of flux increased, high temperature performance. According to this, strict control of impurity oxide content, especially K2O, Na2O and Fe2O3 content, is to obtain high-performance mullite brick important measures. In the use of alkali-containing components of the slag or gas environment, the use of mullite brick have a serious erosion.