Ceramic knife

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Kyocera ceramic knife

A ceramic knife is a knife made out of very hard ceramic, often zirconium dioxide. These knives stay sharp up to ten times longer than steel knives. They are also extremely brittle and will shatter or crack when used to pry. Usually, though, the edge will merely chip when dropped.

Zirconia is very hard; it ranks 8.5 on the Mohs scale of mineral hardness, compared to 6 to 6.5 for hardened steel, and 10 for diamond. As such, they cannot be resharpened the same way as steel blades, though they normally come with a special complimentary resharpening service.

Kyocera, Asahi and Tachi Knivesalso offer a black blade made by an extra firing or sintering via hot isostatic pressing (HIP). These black knives are said to be tougher. They are used by chefs, bomb disposal squads (they are not conductive and not magnetic), divers (they will not rust in water), and people with certain allergies (as they are chemically inert).

Ceramic knives present a conceptual problem to the security industry since ceramics are not picked up by metal detectors. To solve this problem, many manufacturers of non-military knives include a quantity of metal in each knife to ensure they are detectable with standard equipment. Ceramic knives can be detected by extremely high frequency scanners, although (as of 2006) these scanners are not yet in widespread use.

Five of the worldwide or US manufacturers that produce ceramic pocket or folding knives are Kyocera, Böker, Flint Knives, Shenzhen Hetiansheng Precision Ceramics, and Tachi Knives.