Production technology of alumina ceramic tube
The aluminum oxide powder in the factory is prepared into powder materials according to different product requirements and different molding processes. The particle size of the powder is less than 1μm, if the manufacture of high-purity alumina ceramic products in addition to the purity of alumina in 99.99%, but also need to ultrafine grinding and make its particle size distribution uniform. When extrusion molding or injection molding is used, binders and plasticizers need to be introduced into the powder, generally thermoplastics or resins with a weight ratio of 10-30%. The organic binder should be evenly mixed with the alumina powder at 150-200 temperature to facilitate the molding operation. The powder material formed by hot pressing process does not need to add binder. If semi-automatic or automatic dry pressing molding is used, the powder has special process requirements, and it is necessary to use spray granulation method to treat the powder and make it appear spherical, so as to improve the fluidity of the powder and facilitate the automatic filling of the mold wall in the molding. In addition, in order to reduce the friction between the powder and the mold wall, it is necessary to add 1 to 2% of the lubricant, such as stearic acid, and the binder PVA.
Alumina ceramic tube
To dry press molding, powder spray granulation is required, in which polyvinyl alcohol is introduced as a binder. A research institute in Shanghai developed a water-soluble paraffin wax as a binder for Al203 spray granulation, which has good fluidity under heating. The powder after spraying granulation must have good fluidity, loose density, and flow Angle friction temperature less than 30℃. In order to obtain higher density of blank, the ratio of particle size is ideal.
Forming method
The forming methods of alumina ceramic products include dry pressing, grouting, extrusion, cold isostatic pressing, injection, casting, hot pressing and hot isostatic pressing. In recent years, at home and abroad have developed a filter molding, direct solidification injection molding, gel injection molding, centrifugal injection molding and solid free molding technology. Different product shapes, sizes, complex shapes and precision products require different molding methods.
