The Main Factors Affecting The Creep Rate Of Refractory Bricks Under High Temperature Working Environment

The main factors affecting the creep rate of refractory bricks under high temperature working environment

The creep of refractory bricks is a function of temperature, stress, time, and material structure. The higher the temperature at which refractory bricks are placed, the greater the stress they can withstand, and the longer the time, the higher the creep rate.

When refractory bricks are entirely composed of crystals, creep is mainly controlled by vacancy diffusion, dislocation movement, grain boundary slip, and the bonding state between grains, in addition to being affected by the bond strength of crystals related to crystal elasticity. The fewer crystal defects, fewer grain boundaries, and stronger interpenetration between grains, the less likely severe creep is to occur.
When refractory bricks contain glass phase Especially when the glass phase is a continuous phase, the creep of refractory bricks is controlled by the glass phase. The more glass phase there is and the lower the viscosity, the more viscous flow can occur in refractory bricks under low stress, resulting in more severe creep at high temperatures. When refractory bricks contain impurities that may form a liquid phase at high temperatures, the more liquid phase impurities are formed, such as the creep of clay bricks, which is relatively large. The faster the viscosity decreases with increasing temperature, the more severe the creep.

Pores or cracks at the grain boundaries in refractory bricks can directly cause slip at the grain boundaries. In addition, at high temperatures, the liquid phase in refractory bricks can penetrate into the pores in the same phase, especially into the medium and small pores below 25 μ m. Therefore, the existence of pores also affects creep through the migration of transitional phases. So, the pores of refractory bricks have a significant impact on creep. Increasing the porosity of refractory bricks can actually increase their creep rate.