A manganin resistor made in 1900 at the Bushy House physic laboratory.
|Tensile strength (?t)||300-600 MPa|
|Elongation (?) at break||<50%|
|Izod impact strength||107 J/m|
|Melting temperature (Tm)||1020 °C|
|Thermal conductivity (k) at||22 W/(m·K)|
|Linear thermal expansion coefficient (?)|
|Specific heat capacity (c)||0.097 cals/gm|
|Volume resistivity (?)||43-48 cm|
Manganin foil and wire is used in the manufacture of resistors, particularly ammeter shunts, because of its virtually zero temperature coefficient of resistance value and long term stability. Several Manganin resistors served as the legal standard for the ohm in the United States from 1901 to 1990. Manganin wire is also used as an electrical conductor in cryogenic systems, minimizing heat transfer between points which need electrical connections.
Manganin is also used in gauges for studies of high-pressure shock waves (such as those generated from the detonation of explosives) because it has low strain sensitivity but high hydrostatic pressure sensitivity.
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In 1887 Edward Weston discovered that metals can have a negative temperature coefficient of resistance, inventing what he called his "Alloy No. 2." It was produced in Germany where it was renamed "Constantan".
In 1892 Weston had finally completed his discovery of an alloy of copper, nickel, and manganese prepared by a complicated series of heat-treatments. In May, 1893, he received a basic patent on the composition, manufacture, and use of the material for electrical resistors. Production was carried out in Germany, and it became known as "Manganin". The availability of a practical conductive metal with an extremely constant resistance over the range of ordinary temperatures was a great advance in electrical technology and equipment design, but Weston did not receive general recognition for this.
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|Temperature [°C]||coefficient of resistivity|
|AWG||ohms per cm||ohms per ft|