A ceramic knife is a knife made out of very hard and tough ceramic, often zirconium dioxide (ZrO₂; also known as zirconia). These knives are usually produced by dry pressing zirconia powder and firing them through solid-state sintering. The resultant blade is sharpened by grinding the edges with a diamond-dust-coated grinding wheel. Zirconia ranks 8.5 on the Mohs scale of mineral hardness, compared to 6 to 6.5 for hardened steel, and 10 for diamond. This very hard edge rarely needs sharpening.

Manufacturing procedure

Water, raw powder and ceramic milling balls are fed into a mixer-like device called a mill.

To create particles of uniform size, with diameters of approximately one micrometer (1 祄 or 0.001 mm), raw materials are first mixed into a slurry ?a fluid of water and ceramic powder in which the particles are blended.

A spray dryer dehydrates the raw materials in the slurry to make a granulated powder

The granulated powder is used to fill a knife-shaped mold.

The mold is placed under high pressure ?1 ton per cm² (approx. 12,900 psi) ?to solidify the powder into the desired shape.

The material is then fired and sintered in a kiln, like conventional ceramics, but under precisely controlled temperatures

During the firing process, the ceramic blade shrinks to 75 percent of its original, unfired size, while the volume shrinks by nearly half. These shrinkage rates are carefully calculated during the design process, so the finished size matches the design specifications.

The blade is then ground with a diamond wheel to produce a razor-sharp edge.

A handle is then attached to complete the process.