How Are Precision Ceramics Formed

Precision ceramics, unlike everyday pottery, are advanced materials with excellent properties such as high strength, high temperature resistance, and good insulation. They are widely used in fields like electronics, medical care, and aerospace. Their forming process is similar to a sculptor meticulously crafting a work of art, involving a precise transformation from powder to precision components. The core steps include raw material preparation, forming, and sintering, among which forming technology is particularly critical.

Step 1: Refinement and shaping of raw materials

The starting point of precision ceramics is ultra-fine, high-purity ceramic powder. These powders need to be mixed with binders, plasticizers, etc., to form a "green body material" that is easy to process. Depending on the subsequent forming process, the green body material is made into powdery, slurry-like, or plastic blocks with good plasticity, preparing for forming.

Step 2: Selecting appropriate forming technologies

Forming is the process of turning the green body material into a "green body" of a specific shape. Based on the product's shape, size, and precision requirements, the following three main technologies are used:

Dry pressing: Similar to "mold die casting". Dry ceramic powder is filled into a precision mold, and high pressure (up to hundreds of megapascals) is applied through upper and lower punches to compact it into a dense green body. This method is efficient and produces uniform-sized products, suitable for manufacturing simple-shaped, mass-produced items such as ceramic seal rings or substrates. However, it is difficult to produce complex shapes or extremely thin components.

Injection molding: Borrows the "injection process" from the plastics industry. Ceramic powder is mixed with a large amount of organic binders and heated into a viscous slurry, which is then injected into a metal mold using an injection machine. After cooling, the mold is opened to release the part. This method can efficiently produce parts with extremely complex shapes and precise dimensions, such as turbine rotors or dental crowns. The drawback is that long-term heating is required afterward to remove the binders (debinding), a time-consuming process that is prone to defects.

Tape casting: Known as "ceramic papermaking". Ceramic slurry is evenly spread on a moving base tape using a doctor blade, forming an extremely thin wet film with precise thickness. After drying, a flexible ceramic film (green tape) is obtained. This is the core technology for mass-producing electronic components such as multi-layer ceramic capacitors (MLCCs) and circuit substrates. Its advantage lies in the ability to precisely control thicknesses as thin as the micrometer level.

Step 3: Sintering gives the final form life

The green body after forming has low strength and must undergo high-temperature sintering. In kilns, the green body is heated for a long time at temperatures below its melting point. Powder particles bond together through atomic diffusion, porosity decreases, and the body eventually shrinks and densifies, becoming a hard, high-performance precision ceramic component.

In summary, the forming of precision ceramics is an art that integrates materials science and precision manufacturing. Whether through pressure shaping, injection molding, or film extension, the goal is to precisely construct the required microstructure and macro shape before sintering, laying the foundation for the final excellent performance.