During the processing of zirconia ceramics, pure zirconia ceramics sinter and crack. Zirconia made by slurry injection is naturally air-dried for 3 days and then put into a high-temperature furnace. The temperature is raised to 1450℃ at 3℃/min and 5℃/min respectively, and the temperature is kept for 4 hours. After cooling out of the furnace, cracks appear. So do you know what causes zirconia ceramics to crack? Here are some introductions for you:
The causes of zirconia ceramics cracking are as follows:
1. Volume
Since zirconia ceramics will undergo a large change in volume when the monoclinic phase is converted to the tetragonal phase, and after cooling, the volume changes in the opposite direction, it is easier to cause zirconia ceramics to crack, which has a certain impact on the product in the field of high-temperature use, but adding appropriate additives can improve it.
2. Sintering
Sintering at 1800-1840 degrees in a neutral or oxidizing atmosphere. The phase change of zirconia ceramics has a large volume change, which absorbs or releases energy. We can find the univariate phase diagram of zirconia and look at the phase change point, which may be the main reason for cracking. Moreover, many phase changes of zirconia ceramics are suppressed by doping. For example, YSZ or SSZ, which are often used in high-temperature fuel cells, stabilize a certain phase to room temperature by doping. Generally, Y oxide or other materials are doped to suppress the phase change of zirconia. If you do not add any inhibitors, cracking during the sintering process is inevitable.
In summary, these are the reasons for the cracking of zirconia ceramics. If you encounter cracking during the processing of zirconia ceramics, you can analyze the causes and solve them as described above.
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