Reheating linear change means that the size of refractory products is irreversible changed when the refractory products are heating on high temperature. A positive value indicates expansion which is called expansion of reheating linear change; negative value indicates contraction which is called contraction of reheating linear change.
Due to corundum brick is used at high temperature and maybe further sintered and phase changed which will cause the change of volume, then produce expansion or contraction of reheating linear change. It is also an aspect to express the high temperature volume stability and an important quality index of zircon brick. For instance, if the contraction of reheating linear change of the upper blocks in a glass furnace is too big, this will cause the refractory brick shedding and the roof collapsing. So reheating linear change of corundum brick has great significance to discriminate its high temperature volume stability which can ensure stability of furnace, reduce gap of masonry, improve the tightness and corrosion resistance, and avoid the destruction of the whole structure of glass furnace.
Factors affecting the reheating linear change of refractory bricks:
1. Chemical mineral composition and microstructure
It will expanse when the density of the reaction product is less than the density of the reactants. Otherwise, it will shrink.
2. Sinter
Sintering is an important process in process of reheating, which is the important reason for linear change on reheating. The porosity, liquid phase, liquid phase composition and grain size of refractory can greatly affect the sintering.
3. Manufacturing technology
It can shorten the distance between the refractory material and the thermodynamic equilibrium state when improve the sintering temperature and prolong the holding time of the products, which will reduce the reheating linear change.
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