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Nichrome (also known as NiCr, nickel-chromium or chromium-nickel) is a family of alloys of nickel and chromium (and occasionally iron [1]) commonly used as resistance wire, heating elements in devices like toasters, electrical kettles and space heaters, in some dental restorations (fillings) and in a few other applications.
Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures, up to 1,400 °C (2,550 °F). When used as a heating element, resistance wire is usually wound into coils.
Nichrome 80/20 is one of the most commonly used resistance heating alloys because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time. Material beneath this layer will not oxidize, preventing the wire from breaking or burning out.
Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators. Alternatively, a heat pump can achieve around 150% – 600% efficiency for heating, or COP 1.5 - 6.0 Coefficient of performance , because it uses electric power only for ...
Usually a thin nichrome wire is used. Some applications also use platinum - silver alloy; other bridgewire materials in use are platinum , gold , silver , tungsten , etc. Care has to be taken when selecting the material as it is in direct contact with the pyrotechnic composition and should not undergo corrosion in such conditions.
Manganin wire as we know it was developed by Weston's assistant John Forrest Kelly. [7] In May 1893, Weston received a patent [citation needed] for the material and its use for resistors. While Manganin represented a significant advance in technology -- the material was a conductive metal with constant resistance over a wide range of working ...
When perfected, the new alloy was 300 times stronger than other types at that time. Chromel is made of 80% nickel and 20% chromium (though other ratios are used for special purpose nichrome applications). The US patent was granted February 1906, in Marsh's name, and later sold to Hoskins Manufacturing.
Chromel is made from nickel and chrome and it is also known as nichrome. This wire was then coiled into a spiral and wrapped around a ceramic body. When heated to high temperatures it forms a protective layer of chromium oxide which protects the wire from burning and corrosion, and causes the element to glow. [5]