Alumina ceramic firing technology

The technical method of densifying a granular ceramic body and forming a solid material is called sintering. Sintering is to remove the voids between the particles in the body, remove a small amount of gas and impurity organic matter, and make the particles grow and combine with each other to form a new substance.

An electric furnace is most widely used for heating devices used for firing. In addition to normal pressure sintering, that is, pressureless sintering, there are also hot press sintering and hot isostatic pressing. Although continuous hot press sintering increases the yield, the cost of equipment and mold is too high, and the length of the product is limited due to the axial heat. The hot isostatic pressing uses high-temperature and high-pressure gas as the pressure transmission medium, and has the advantages of uniform heating in all directions, and is suitable for sintering of complicated shapes. Due to the uniform structure, the material properties are improved by 30 to 50% compared to cold press sintering. It is 10-15% higher than ordinary hot press sintering. Therefore, some high-value-added alumina ceramic products or special parts required for national defense military, such as ceramic bearings, mirrors, nuclear fuel and barrels, and other fields, use hot isostatic pressing.

In addition, microwave sintering, arc plasma sintering, and self-propagating sintering are also being developed.