Introduction of firing technology of alumina ceramics

The most widely used heating device for firing is the electric furnace. Besides atmospheric sintering, there are also hot pressing sintering and hot isostatic pressing sintering. Although continuous hot pressing sintering increases the output, but the cost of equipment and mould is too high. In addition, because of axial heating, the length of products is limited. Hot isostatic burning adopts high temperature and high pressure gas as pressure transfer medium, and has the advantages of uniform heating in all directions, so it is suitable for sintering complicated products. Due to the uniform structure, the material properties are improved by 30 ~ 50% compared with cold pressing sintering. 10-15% higher than normal hot pressing sintering. Therefore, some high value-added alumina ceramic products or special components needed for national defense, such as ceramic bearings, reflectors, nuclear fuel and barrel products, field using heat isostatic burning method.
In addition, microwave sintering, arc plasma sintering and self-propagating sintering techniques are also being developed.
Finishing and packaging processes
Some alumina ceramic materials need to be finished after sintering. If used as artificial bone products require a high surface finish, such as mirror, to increase lubricity. Due to the high hardness of alumina ceramic material, it needs to be finished with harder polishing brick material. Such as SIC, B4C or diamond, etc. Usually from coarse to fine abrasive step by step grinding, final surface polishing. Generally, Al2O3 micropowder <1 m micron or Diamond paste can be used for grinding and polishing. In addition laser and ultrasonic machining grinding and polishing methods may also be used.

Alumina ceramic strengthening process
In order to strengthen alumina ceramics and improve their mechanical strength, a new alumina ceramics strengthening process is introduced abroad. This process is novel and simple, the technical means adopted is on the surface of alumina ceramics, using electron ray vacuum coating, sputtering vacuum coating or chemical vapor deposition method, coated with a layer of silicon compound film, heating treatment at 1200℃ ~ 1580℃, aluminum oxide ceramics toughened.
The mechanical strength of the strengthened alumina ceramics can be greatly increased on the original basis and the alumina ceramics with ultra-high strength can be obtained.