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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.
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.
Electric matches before, during and after ignition. An electric match is a device that uses an externally applied electric current to ignite a combustible compound.. Electric matches use a bridgewire consisting of a heating element to ignite a pyrogen, which is a quantity of readily ignited pyrotechnic initiator composition.
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 ...
The mechanism is similar to transfer of momentum of balls in a Newton's cradle [11] but the rapid propagation of an electric energy along a wire is not due to the mechanical forces, but the propagation of an energy-carrying electromagnetic field guided by the wire. Most metals have electrical resistance.
For heating, resistance wire must be stable in air when hot. Kanthal FeCrAl alloy forms a protective layer of aluminium oxide (). [1]Aluminium oxide has high thermal conductivity but is an electrical insulator, so special techniques may be required to make good electrical connections.
The wire drawing process is quite simple in concept. The wire is prepared by shrinking the beginning of it, by hammering, filing, rolling or swaging, so that it will fit through the die; the wire is then pulled through the die. As the wire is pulled through the die, its volume remains the same, so as the diameter decreases, the length increases.