Refractory material especially in the high temperature when subjected to below its ultimate strength under a certain stress will produce plastic deformation, deformation along with the load increasing, and even lead to the failure of materials. This external force generated by the 
deformation increased with time phenomenon called creep. Creep refractories are its stress compression under certain temperature and pressure effect after certain time generated to represent the creep. Sometimes often to achieve individual variables of time, can also be directly to the deformation or strain rate versus time curve description. The compressive stress strain measuring results is not easy to be keen reflected inside the material phase change, so often in the bending creep or creep (torsional shear creep) said.
deformation increased with time phenomenon called creep. Creep refractories are its stress compression under certain temperature and pressure effect after certain time generated to represent the creep. Sometimes often to achieve individual variables of time, can also be directly to the deformation or strain rate versus time curve description. The compressive stress strain measuring results is not easy to be keen reflected inside the material phase change, so often in the bending creep or creep (torsional shear creep) said.
Creep refractory material is a function of stress, temperature, time and material structure. Material at higher temperature, stress is bigger, the longer, the greater the creep rate. When the refractory material completely by the crystal structure, creep in addition to bond strength by the relevant and crystal elastic effects of crystal, crystal body is mainly controlled by vacancy diffusion, dislocation movement, the control with the state grain boundary sliding and grain. Crystal defects, grain boundaries are less and less grain combine is strong, not easy to produce serious creep.
When the material containing glass phase, especially when the glass phase as continuous ![04-2[1]](https://123yilong.files.wordpress.com/2014/03/04-211.jpg?w=300&h=300)
phase, material creep by glass phase control. The higher the amount and viscosity of the glass phase is low, material under low stress can produce viscous flow, so in the high temperature creep is more serious. When the refractory materials containing high temperatures may form an impurity liquid phase, the formation of the impurity quantity of the liquid phase, the viscosity decreases with the increase of the temperature is faster, the more serious the creep.
phase, material creep by glass phase control. The higher the amount and viscosity of the glass phase is low, material under low stress can produce viscous flow, so in the high temperature creep is more serious. When the refractory materials containing high temperatures may form an impurity liquid phase, the formation of the impurity quantity of the liquid phase, the viscosity decreases with the increase of the temperature is faster, the more serious the creep.
The grain boundary of the refractory material in the pores or cracks can be directly caused by grain boundary sliding. In addition, in the high temperature materials in liquid phase to solid phase permeable pores in, especially to the infiltration of 25 mu m or less, in the small pores, thus holes exist, through the liquid phase migration also influence of creep. Therefore, the material porosity has great influence on the creep. Improve the porosity, actually can increase the creep rate.
没有评论:
发表评论