Powder preparation: The incoming alumina powder is prepared into powder materials according to different product requirements and different molding processes.

The powder particle size is below 1μm. If high-purity alumina ceramic products are manufactured, in addition to the purity of alumina at 99.99%, it is also necessary to ultra-finely grind and make the particle size distribution uniform.

When using extrusion molding or injection molding, binders and plasticizers need to be introduced into the powder, generally thermoplastics or rosin with a weight ratio of 10-30%. Organic binders should be evenly mixed with alumina powder at 150-200 degrees to facilitate molding operations.

Powder materials molded by hot pressing do not need to add binders.

If semi-automatic or fully automatic dry pressing molding is used, there are special process requirements for the powder. It is necessary to use spray granulation to process the powder and make it spherical, so as to facilitate the adjustment of powder flowability and automatic filling and wall touching during molding.

In addition, in order to reduce the friction between the powder and the wall, 1-2% lubricant, such as stearic acid, and binder PVA need to be added.

When dry pressing is required, the powder needs to be spray granulated, and polyvinyl alcohol is introduced as a binder.

In recent years, a research institute in Shanghai, China has developed a water-soluble paraffin wax as a binder for Al2O3 spray granulation, which has very good fluidity under the condition of blasting. The powder after spray granulation must have good fluidity, loose density, and the flow angle friction temperature is less than 30℃. The particle size ratio is ideal, etc., in order to obtain a larger green body density.