Zirconium oxide ceramics have high melting and boiling points, high hardness, are insulators below 500°, and have excellent properties such as conductivity at high temperatures. With the development of the times, zirconia ceramics are needed It has also gradually been widely used in all walks of life. Let me introduce to you the three common molding methods of zirconia ceramics:
1. Grouting
Group casting is an earlier molding method for zirconia ceramics. The molding process of slip casting includes a physical dehydration process and a chemical coagulation process. The physical dehydration passes through the porous gypsum mold. Capillary action removes moisture from the slurry. The chemical coagulation process is because the Ca2+ generated by the dissolution of CaSO4 on the surface of the plaster mold increases the ionic strength in the slurry, causing flocculation of the slurry. Under the action of physical dehydration and chemical coagulation. Ceramic powder particles are deposited on the plaster mold wall. Slip injection molding is suitable for preparing large ceramic parts with complex shapes, but the quality of the green body, including shape, density, strength, etc., is poor, the labor intensity is high for workers, and it is not suitable for automated operations.
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2. Hot die casting
For products with complex shapes, hot die casting is generally used. Hot die casting is to combine ceramic powder with a binder (paraffin wax) at a higher temperature (60-100°C). )mix. Obtain the slurry for hot die casting. The slurry is injected into the metal mold under the action of compressed air, cooled under pressure, and demolded to obtain a wax blank. The wax blank is then The blank is obtained after dewaxing under the protection of inert powder.The blank is then sintered at high temperature to become porcelain. The green body formed by hot die casting has precise dimensions, uniform internal structure, less mold wear, and high production efficiency
3. Isostatic pressing
Isostatic pressing is mainly used for zirconia structural ceramics with special shapes and large sizes. The green body formed by isostatic pressing is subjected to uniform pressure in all directions. And the pressure is high, so the molded body has high density, good uniformity, small firing shrinkage, and is not easy to deform, crack, and delaminate. This molding method can avoid delamination that easily occurs during dry pressing, especially when molding thicker zirconia. products, so this molding method is a commonly used method for producing zirconia products. However, the green body after isostatic pressing needs to be processed, so part of the raw materials will be wasted. At the same time, the green body processing is troublesome, and the processing speed is slow, which affects the production efficiency. Not high.
