Changes of alumina ceramic structural parts under high temperature conditions
Changes of alumina ceramic structural parts under high temperature conditions
1.The first is creep. At high temperature, when the structure of alumina ceramics is subjected to external force, due to the increase of time, plastic deformation will occur continuously and slowly, so we can call it creep. When the structural parts of alumina ceramics creep, no matter it is related to stress or temperature. When the stress increases, or the temperature continues to rise, the rate of creep will continue to increase.
2.Graphitization and spheroidization. Under the action of high temperature, the cementite contained in the alumina ceramic structural parts will be aggregated or migrated due to the acquisition of greater energy, and will be transformed into cementite with coarse grains, and is mixed in In ferrite, and cementite will gradually transform from flake to spherical, which we can call spheroidization. Because graphite is very low in strength, and mainly in the form of flakes, the strength of the material is greatly reduced, and the brittleness will increase accordingly, so it can be called graphitization.
3. Thermal fatigue performance. If the structural parts of alumina ceramics are alternated between cold and heat for a long time, the change in the internal temperature difference of the material will cause continuous expansion and tiny cracks due to the effect of thermal stress, and eventually serious cracks will appear. Therefore, when working under fluctuating temperature conditions, the fatigue performance of its structural parts should be considered.
