Preparation of alumina powder

Preparation of alumina powder

Prepare the incoming aluminum oxide powder into powder materials according to different product requirements and forming processes.

The particle size of alumina powder is below 1 μ m micrometer. To manufacture high-purity alumina ceramic products, in addition to alumina purity of 99.99%, ultrafine grinding and uniform particle size distribution are also required.

When using extrusion molding or injection molding, binders and plasticizers need to be introduced into the powder, usually thermoplastic plastics or resins with a weight ratio of 10-30%? The organic binder should be evenly mixed with the alumina powder at a temperature of 150-200 to facilitate the molding operation.

The powder raw materials formed by hot pressing process do not require the addition of binders.

If semi-automatic or full-automatic dry pressing is adopted, there are special process requirements for the powder, and the powder needs to be treated by spray granulation method to make it spherical, so as to improve the powder fluidity and facilitate the automatic filling of mold wall during molding.

In addition, to reduce the friction between the powder and the mold wall, 1-2% lubricants such as stearic acid and adhesive PVA need to be added.

For dry pressing, the powder needs to be spray granulated, in which polyvinyl alcohol is introduced as the binder.

A water soluble paraffin developed by a research institute in Shanghai is used as the binder for Al203 spray granulation, which has good fluidity under heating. The powder after spray granulation must have good fluidity, loose density, and flow angle friction temperature less than 30 ℃.

Ideal particle size ratio and other conditions are required to obtain a higher green density.

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