| Manganin | |
| Type: | Copper-manganese alloy |
| Tensile Strength: | 300–600 MPa |
| Elongation: | <50% |
| Izod Impact Strength: | 107 J/m |
| Melting Point: | 1020 °C |
| Thermal Conductivity Note: | at |
| Thermal Conductivity: | 22 W/(m·K) |
| Specific Heat: | 0.097 cals/gm |
| Volume Resistivity: | 43–48 μΩ⋅cm |
| Footnotes: | Source[1] |
Manganin is a trademarked name for an alloy of typically 84.2% copper, 12.1% manganese, and 3.7% nickel. It was first developed by Edward Weston in 1892, improving upon his Constantan (1887).
Manganin foil and wire is used in the manufacture of resistors, particularly ammeter shunts, because of its virtually zero temperature coefficient of resistance value[2] and long term stability. Several Manganin resistors served as the legal standard for the ohm in the United States from 1901 to 1990.[3] 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.[4]
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".[5] Five years later, after experimenting with alloys of copper, nickel, and manganese, he developed Manganin. In May 1893, Weston received a patent 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 temperatures, Weston did not receive wide recognition at the time.[6]
Electrical Properties
Mechanical Properties
| Temperature [°C] | coefficient of resistivity | |
|---|---|---|
| 12 | +.000006 | |
| 25 | .000000 | |
| 100 | −.000042 | |
| 250 | −.000052 | |
| 475 | .000000 | |
| 500 | +.00011 |
| AWG | ohms per cm | ohms per ft | |
|---|---|---|---|
| 10 | .000836 | 0.0255 | |
| 12 | .00133 | 0.0405 | |
| 14 | .00211 | 0.0644 | |
| 16 | .00336 | 0.102 | |
| 18 | .00535 | 0.163 | |
| 20 | .00850 | 0.259 | |
| 22 | .0135 | 0.412 | |
| 24 | .0215 | 0.655 | |
| 26 | .0342 | 1.04 | |
| 27 | .0431 | 1.31 | |
| 28 | .0543 | 1.66 | |
| 30 | .0864 | 2.63 | |
| 32 | .137 | 4.19 | |
| 34 | .218 | 6.66 | |
| 36 | .347 | 10.6 | |
| 40 | .878 | 26.8 |