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Refractoriness for refractory brick

September 14, 2018

Refractoriness for refractory brick

Refractory bricks are subjected to high temperature heat load during the actual use process. Therefore, the use properties of refractory bricks are essentially characterized by their resistance to high temperature heat load but also by other chemical, physical and chemical and mechanical effects and not easy to damage the performance. So these properties of refractory bricks can be used not only to judge the quality of materials, but also to directly test their applicability at high temperatures according to the working conditions at the time of use. The use properties of refractory bricks can be classified into refractoriness, refractoriness under load and reheat linear change.

Refractory brick refractoriness refers to the temperature at which the refractory brick reaches a certain degree of softening under high temperature, and characterizes the material's resistance to high temperature. The meaning of refractoriness is different from the melting point. The melting point is the temperature at which the liquid phase and the solid phase of the crystal are in equilibrium. Refractoriness is the temperature at which a poly phase reaches a certain degree of softening. For most ordinary refractory bricks, they are multi-phase heterogeneous materials, without a certain melting point, and the liquid phase to complete melting is a gradual process. In a fairly wide range of high temperatures, the solid and liquid phases coexist. Therefore, the characteristics of softening and melting of such materials at high temperatures can only be measured in terms of refractoriness.

Refractoriness of refractory products is an important technical indicator for evaluating refractory materials. However, it cannot be used as an upper limit for the temperature at which the product is used. For refractory bricks composed of single-phase poly-crystals, the degree of refractoriness is generally lower than the melting point of the crystal. But some refractory bricks, like that when the viscosity of the liquid phase formed is high, the refractory bricks may have a higher degree of refractoriness than the melting point.

Therefore, it can be considered that the degree of refractoriness of the refractory brick is mainly controlled by the chemical and mineral composition of the material, in addition to the measurement conditions, particularly the particle size composition and temperature rise rate of the test cone and the fact that certain materials are related to the measurement atmosphere. For refractory brick refractories composed of various single components, it depends mainly on the melting point of the compound. As for a refractory brick refractory composed of multiple components, it depends on the ratio of the main component to the other components. Impurities can seriously reduce the refractoriness of the material. Therefore, in order to improve the refractoriness of the refractory brick refractory, it is necessary to increase the amount of the main component and the main crystal phase and to reduce the impurities as much as possible.