Common alumina ceramics also known as precision ceramics, special ceramics, or high-tech ceramics, it is the use of highly selected raw materials, according to the special manufacturing process production, can accurately control the chemical composition and excellent performance of ceramics.
It is widely used in high technology and industry, such as microelectronics, nuclear reactor, aerospace, magnetohydrodynamic power generation, artificial bone and artificial joint, etc.
Alumina ceramics are very different from ordinary ceramics in composition and manufacturing process. Ordinary ceramics are made by three processes: raw material preparation, blank forming and kiln firing. Alumina ceramics are mostly made by powder sintering.
In terms of forming technology, due to the extremely high hardness of ceramics, it is difficult to cut and process, especially for non-opposable products with complex shapes, they are finished products after forming and sintering, and no further processing is required.
In order to meet this requirement, people imitate the injection molding technology of polymer material industry to produce plastic parts and process alumina ceramics, and obtain satisfactory results.
Ceramic injection molding technology is to add thermoplastic resin, thermosetting resin, plasticizer and friction reducer into ceramic powder to make it become viscous elastomer. Then, the slurry after heating and mixing is injected into the metal mold from the nozzle, and then it is formed by cooling and curing.
The injection molding principle of alumina ceramics is basically the same as that of plastics. In order to achieve a compact and uniform injection form, the ceramic powder concentration is higher. But too high will make the forming performance worse.
In order to improve the fluidity of mixed billet, the viscosity of dispersant polymer system should be reduced. As a pretreatment, it is very important to improve the dispersion of ceramic powder. In order to improve the fluidity of polymer, it is necessary to add appropriate plasticizer and lubricant.
Alumina ceramic raw material size is generally 1 m, add binder (or called additive), after fully mixing, stirring. In the stirring process, the ceramic powder is wetted and coated by the binder, and all become uniform composite before injection molding.
After cooling, drying and grinding, the particles suitable for funnel feed of injection molding machine can be obtained.