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Common Molding Method Of Alumina Ceramics

Aug. 27, 2018

Alumina ceramics are widely used in industry nowadays. We often have Accurate Dimension Ceramic Mosaic Tiles, alumina ceramic tube and so on. Next, let Wear-resistant Alumina Supplier introduce several common alumina ceramic molding methods.

1. Dry-pressing: Alumina ceramics dry-pressing technology is limited to simple shape and inner wall thickness of more than 1 mm, length and diameter ratio is not greater than 4:1 objects. The forming method is uniaxial or bidirectional. There are two types of press, hydraulic and mechanical, which can be semi-automatic or fully automatic. The maximum pressure of the press is 200Mpa. The output can reach 15~50 pieces per minute. Because the stroke pressure of hydraulic press is uniform, the height of pressing parts is different when powder filling is different. However, the applied pressure of mechanical press varies with the amount of powder filling, which easily leads to the difference of size shrinkage after sintering and affects the product quality. Therefore, the uniform distribution of powder particles during dry pressing is very important for mold filling. The accuracy of filling quantity has great influence on the dimensional accuracy control of alumina ceramic parts. The maximum free flow effect can be obtained when the powder particles are larger than 60 micron and between 60 and 200 meshes, and the best pressure forming effect can be obtained.

2, grouting molding method: grouting molding is the earliest molding method for alumina ceramics. Because of plaster mold, low cost and easy to shape large size, complex shape parts. The key to grouting is the preparation of alumina slurry. Usually water is used as the flux medium, and then glue release agent and binder are added. After full grinding, exhaust gas is exhausted, and then poured into the gypsum mold. The slurry is solidified in the mold due to the adsorption of water by the capillary of the plaster mold. When hollow grouting is applied, the excess slurry must be poured out when the slurry wall reaches the required thickness. In order to reduce shrinkage of billet, high concentration slurry should be used as far as possible.

Organic additives should be added to the alumina slurry to form a double electric layer on the surface of the slurry particles so as to stabilize the slurry suspension without precipitation. In addition, vinyl alcohol, methyl cellulose, alginate amine and other binders, polyacrylamide, Arabic gum and other dispersants are added to make the slurry suitable for grouting operation.

3, firing technology: the technical method of densification of granular ceramics and forming solid materials is called sintering. Sintering is a method of removing voids between grains, removing a small amount of gases and impurities, and combining the growth of grains to form new materials.

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