1. Creep
The structural parts of alumina ceramics will be subjected to external forces at high temperatures, and with time, plastic changes will continuously and slowly happen . This phenomenon can be called creep. When the structural parts of alumina ceramics creep, there is a great relationship between the stress and the temperature. In addition, when the stress increases or the temperature continues to rise, the rate of creep will also increase.
2. Graphitization and spheroidization
Since graphite is relatively low in strength and mainly presented in flakes, it will cause the material to decrease a lot in strength, and the brittleness will increase accordingly, so we call it graphitization. Also under high temperature conditions, the internal structure of alumina ceramics will contain a large amount of cementite. Because of its acquisition of greater energy, aggregation or migration will occur, which will transform into coarse-grained cementite. And it will be directly mixed in the ferrite. The most important thing is that the cementite will gradually change from the sheet to the spherical shape, so we call it spheroidization.
3. Thermal fatigue performance
If the structural parts of alumina ceramics are kept under the working condition of alternating cold and heat for a long time, the error of the material itself will change due to the effect of thermal stress, and tiny cracks will gradually appear, which will eventually lead to serious cracking. Therefore, in the case of large temperature fluctuations, thermal fatigue needs to be considered for the structural parts of alumina ceramics.