Swedish chemist Georg Brandt (1694–1768) is credited with isolating cobalt sometime between 17. Cobalt has been detected in Egyptian sculpture and Persian jewelry from the third millennium BC, in the ruins of Pompeii (destroyed AD 79), and in China dating from the Tang dynasty (AD 618–907) and the Ming dynasty (AD 1368–1644). The 60Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favour in the Western world where linacs are common.Ĭobalt compounds have been used for centuries to impart a rich blue colour to glass, glazes, and ceramics. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. The 60Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. It is used in industrial radiography to detect structural flaws in metal parts.Ĭo-60 is useful as a gamma ray source partially because it can be produced - in known quantity, and very large amounts - by simply exposing natural cobalt to neutrons in a reactor for a given time.Ĭobalt-60 (Co-60 or 60Co) is a radioactive metal that is used in radiotherapy.It is used in radiation treatment of foods for sterilization (cold pasteurization).Cobalt-60 has multiple uses as a gamma ray source:.Pigments ( cobalt blue and cobalt green).Drying agents for paints, varnishes, and inks.Electroplating because of its appearance, hardness, and resistance to oxidation.Catalysts for the petroleum and chemical industries.Cemented carbides (also called hard metals) and diamond tools.Superalloys, for parts in gas turbine aircraft engines. Metallic cobalt commonly presents a mixture of two crystallographic structures hcp and fcc with a transition temperature hcp→fcc of 722 K.Ĭommon oxidation states of cobalt include +2 and +3, though +1 is also seen. Cobalt has a relative permeability two thirds that of iron. Cobalt-60, an artificially produced radioactive isotope of cobalt, is an important radioactive tracer and cancer-treatment agent. Mammals require small amounts of cobalt salts. It is frequently associated with nickel, and both are characteristic ingredients of meteoric iron. The Curie temperature is of 1388 K with 1.6~1.7 Bohr magnetons per atom. Its compounds are used in the production of inks, paints, and varnishes.Ĭobalt is ferromagnetic with atomic number 27. It is found in various ores, and is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Cobalt ( IPA: /ˈkəʊbɒlt/) is a hard, lustrous, silver-gray metal, a chemical element with symbol Co.
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