Changes of alumina ceramics before, during and after sintering
Changes of alumina ceramics before, during and after sintering
Sintering is one of the processes in the production of alumina ceramics. So what changes will occur in alumina ceramics before sintering, during sintering, and after sintering?
1. Changes before sintering alumina ceramics.
In this process, the temperature control of alumina ceramics is very important and critical. As the temperature continues to rise, the embryo body will gradually shrink, but the change in density and strength is actually not very large. And in the microstructure, the ratio of crystal grains does not change, but cracks are more likely to occur, because the moisture and binder are completely eliminated, so temperature control is very important.
2. Changes in the sintering process of alumina ceramics:
At this time, the sintered alumina ceramics will have a relatively small change in temperature, and the volume will continue to shrink, and the change in density will also become larger. Although the change in crystal grains is not large on the microscopic level, the particles are There is no longer a phenomenon of thick spot joints, pores are also decreasing, and the volume of the embryo body will be reduced a lot due to sintering, so the deformation and cracking of the embryo body will occur.
3. Changes in the late sintering period of alumina ceramics:
There is a significant rise in temperature, the changes related to alumina ceramics will become larger, and the density and intensity have reached the limit and will not change. In the microstructure, the change in the ratio of crystal grains is very significant, and the pores are also smaller. , Are not connected to each other, and more isolated pores appear.
However, some alumina ceramic pores will still remain inside the crystal, but because it is the late stage of sintering, there will be many different undesirable phenomena in the growth of crystal grains. In order to reduce the occurrence of such undesirable phenomena, the most common solution is Yes, add an appropriate amount of additives to control the growth of crystal grains.
