The type and essence of the main crystalline phase, as well as the fusion form between the main crystalline phase and the sub crystalline phase.

The essence and number of matrices, as well as the relationship between the main phase or main phase and sub crystalline phase, as well as the diffusion form.

3. Sealing and porosity status of refractory bricks. When the refractory brick is completely composed of single-phase polycrystals, the refractory property of the refractory brick is consistent with the melting point of the crystalline phase. For example, high-purity refractory bricks composed of high melting point crystals have high fire resistance. The softening temperature of high-purity sintered corundum bricks during loading can reach 1870 ° C.

When the high-temperature melting point crystals in refractory bricks intersect or interweave into a sturdy network structure, their flame retardancy will definitely be higher. In contrast, when the high-temperature melting phase is isolated, the fire resistance of refractory bricks is definitely lower. For example, the phase composition of silica bricks is mainly composed of flake like crystals and less clay like crystals. The scale like crystals in the brick form a network structure with crisscrossed double crystals on the front, so the flame retardancy is usually high. The initial softening temperature exceeds 1650 ℃, and some reach as high as 1680 ℃ or higher, exceeding the melting point of the scale like crystals (1670 ℃), just like ordinary magnesium bricks. Among them, the melting point of the main crystalline phase magnesium is as high as 2800 ℃, but due to the single-phase nature of the main crystalline phase, the initial unloading temperature is only 1550 ℃.

When refractory bricks have a high melting point crystalline phase outer matrix, the matrix is easily transformed into a melt in the tropics, and the viscosity of the melt is easily reduced with temperature, as well as the quantity and diffusion of the matrix. D It has a significant impact on fire resistance. For example, clay refractory bricks and high alumina refractory bricks with low Al2O3 content are the main crystalline phases of Molite, therefore they contain more SiO2 rich glass matrix, where Molite crystals are distributed separately, and the matrix may begin to soften at temperatures below 1000 ° C. Therefore, the initial deformation softening temperature is lower, and the content ratio of mullite to matrix can be reduced as the matrix content increases.

In addition, due to the slow decrease in viscosity of the matrix with increasing temperature, the boundary of deformation temperature is wider. Compared to ordinary magnesium bricks, the main crystalline phase of magnesium grains is mainly deposited by the matrix, which is composed of fusible silicate crystals. The fire resistance of refractory bricks is regulated by the vertical movement of the matrix, so it is lower. After the matrix melts, its viscosity is very low, so the sample is prone to sudden decomposition. Another example is high-temperature soft loaded silica bricks, which not only consist of flake crystals and other skeletal components, but also have high viscosity glass phases related to the matrix. Refractory bricks have a high porosity, which can reduce the starting point for load reduction.