the insulation performance of mullite insulation brick

The mullite insulation brick usually contains impurity oxides 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 act as fluxes in mullite, reducing the formation temperature and viscosity of the melt, increasing the amount of liquid phase generated, and increasing the dissolution rate and amount of dissolution of the melt in the solid phase, but each impurity oxide The role of the intensity of the different, of which the K2O and Na2O on the liquid phase formation temperature has the greatest impact, K2O and Na2O, respectively, the temperature of its no-variable point lower 513 ~ 724 °C, but also to break down the role of mullite. Among these impurity oxides, the effect of TiO2 is minimal, and only the temperature at the no-parameter point is lowered by 101 to 107°C. When the content of TiO2 is small, in addition to forming a limited solid solution in part of the solid solution in mullite, and promoting the growth of mullite and crystal growth, some of them enter the liquid phase to form vitreous bodies at high temperatures.