Freeze-drying method of mullite porous ceramics

Using protein clay as the main material and as a pore-forming agent can effectively increase the porosity of mullite ceramics, reduce the amount of binder, and improve the strength of the product. A freeze-drying method for preparing mullite porous ceramics by a vacuum freeze dryer comprises the following steps:

1. Put the modified protein soil, α-alumina and sintering aids into an agate ball mill, and use a planetary ball mill to ball mill at 300 rpm for 2 h to obtain uniformly mixed powder;

2. Mix the uniform powder with water to prepare a ceramic slurry with a starch content of 6vol%-10vol%;

3. Quickly pour the prepared ceramic slurry into a mold of a certain shape for casting, and vacuum degassing to remove air bubbles in the slurry, and then place the sample in a low-temperature refrigerator to completely freeze the sample and demould;

4. Put the sample into a vacuum freeze dryer with a temperature of -30°C and a vacuum degree of 10 Pa for 36 hours;

5. Sintering and cooling to obtain mullite porous ceramics.