According to different product requirements and different molding processes, the alumina powder entering the factory is prepared into powder materials. The particle size of the powder is below 1μm. If the purity of the high-purity alumina ceramic products is 99.99%, it needs ultrafine crushing and uniform particle size distribution. When extrusion molding or injection molding is used, the binder and plasticizer need to be introduced into the powder. Generally, the thermoplastic or resin organic binder with a weight ratio of 10-30% should be at a temperature of 150-200 with the alumina powder. Mix uniformly to facilitate the molding operation.
The powder raw material formed by the hot pressing process does not need to add a binder. If semi-automatic or fully-automatic dry-press molding is used, there are special process requirements for the powder, and the spray granulation method is required to treat the powder to make it spherical, which is beneficial to improve the fluidity of the powder and facilitate automatic filling of the mold during molding wall. In addition, in order to reduce the friction between the powder and the mold wall, it is necessary to add 1 to 2% of lubricants, such as stearic acid, and binder PVA.
