Ceramic Injection Molding (CIM) is a new process for preparing ceramic components that combines polymer injection molding methods with ceramic preparation processes. The manufacturing process of ceramic precision injection molding mainly includes four steps: (1) Preparation of injection feed: Mixing, drying, and granulating suitable organic carriers with ceramic powder at a certain temperature to obtain injection feed; (2) Injection molding: The mixed injection mixture is heated in the injection molding machine and transformed into a viscous melt. It is injected into the metal mold at a certain temperature and pressure at high speed, cooled and solidified into the desired shape of the billet, and then demolded; (3) Degreasing: By heating or other physical and chemical methods, the organic matter inside the injection molded body is eliminated; (4) Sintering: Densify and sinter the degreased ceramic blank at high temperature to obtain the required appearance, dimensional accuracy, and microstructure of dense ceramic components.
The ceramic injection molding process has a series of outstanding advantages: (1) high degree of mechanization and automation in the molding process, high production efficiency, short molding cycle, high billet strength, convenient management and control in the production process, and easy to achieve large-scale production; (2) It can form various small ceramic components with complex geometric shapes and special requirements in a near net manner, so that sintered ceramic products do not require machining or less processing, thereby reducing expensive ceramic processing costs; (3) The formed ceramic products have high dimensional accuracy and surface smoothness. Therefore, this technology has been widely studied and applied both domestically and internationally, especially for the large-scale production of ceramic products with high dimensional accuracy and complex shapes. The use of ceramic powder injection molding is the most advantageous.
In the 1980s, in order to meet the needs of ceramic engine development and the preparation of high-temperature ceramic components such as turbine rotors, the focus of ceramic injection molding research was on non oxide high-temperature ceramic components such as silicon nitride and silicon carbide, especially the injection molding preparation of Si3N4, SiC turbine rotors, blades, and sliding bearings for engines. At the same time, many high-performance and complex shaped high-temperature structural ceramic products were successfully prepared, Ceramic turbine rotors have been used in racing and military armored vehicles in Japan and the United States. At present, ceramic injection molding has been widely used for the molding of various ceramic powders and engineering ceramic products. Various precision ceramic components prepared through this process have been used in fields such as aviation, automotive, machinery, energy, optical communication, and life medicine.
In recent years, new technologies for micro injection molding of ceramics have emerged. Due to the excellent mechanical, chemical, and high-temperature resistance properties of structural ceramics, many micro components (ranging from tens of micrometers to 1000 micrometers) in the microelectronics industry and microelectromechanical systems require the use of structural ceramic materials. Compared to other microfabrication technologies, using micro injection molding to form ceramic or metal powders into various shapes of billets in one go has lower manufacturing costs and higher efficiency, making it the most promising advanced microfabrication manufacturing technology. At present, some micro ceramic components of alumina, zirconia, silicon nitride, lead zirconate titanate, barium titanate, hydroxyapatite, and aluminum nitride have been formed by low-pressure micro injection molding method, with a forming temperature of 60-100 ℃ and an injection pressure of 3-5 MPa.
It can be foreseen that with the continuous improvement and development of ceramic injection molding technology, it will become the most advantageous preparation technology in precision ceramic components.