Although the gel injection molding process can achieve the preparation of complex-shaped ceramic products with near-net size, the process has high requirements for molds. When preparing complex large-sized parts, molds need to be designed and manufactured, which increases the time cost and mold cost, and to a certain extent restricts the application of this process in the mass production of ceramic structural parts. On the other hand, for some ceramic parts with high dimensional accuracy requirements, the gel injection molding process cannot meet their dimensional accuracy requirements.
Different from the traditional “bottom-up” moldless molding process, the ceramic blank machining process (Green ceramic machining, GCM) is a “top-down” process. Its principle is similar to the processing process of metal materials or wood, such as turning, milling, planning, grinding, etc. It uses CNC machining technology to perform three-dimensional processing on ceramic block blanks to directly obtain the required structure, which can realize the rapid manufacturing of ceramic products, especially suitable for multi-variety and small-batch production of structural ceramics.
In the ceramic blank prepared by the gel injection molding process, the ceramic particles are combined by a three-dimensional gel network, and the bonding force between the particles is small. During the processing, the ceramic particles or particle agglomerates are easily peeled off and removed under the action of the tool. The material removal is mainly brittle peeling, which is different from the plastic removal method of metal material processing, and the brittle fracture of particles and the micro-crushing removal of grain boundaries are non-existent. Using diamond tools and CNC machine tools to efficiently and accurately process the ceramic blank, the preparation of silicon carbide ceramic products with complex shapes can be realized. The silicon carbide ceramic products prepared by this process have high dimensional accuracy and high surface finish.