Cupronickel or copper-nickel or "cupernickel" is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Cupronickel is highly resistant to corrosion in seawater, because its electrode potential is adjusted to be neutral with regard to seawater. Because of this, it is used for piping, heat exchangers and condensers in seawater systems as well as marine hardware, and sometimes for the propellers, crankshafts and hulls of premium tugboats, fishing boats and other working boats.
A more familiar common use is in silver-coloured modern circulation coins. A typical mix is 75% copper, 25% nickel, and a trace amount of manganese. In the past, true silver coins were debased with cupronickel. Despite high copper content, cupronickel is silver in colour.
Cupronickel, any of an important group of alloys of copper and nickel; the alloy containing 25 percent nickel is used by many countries for coins. Because copper and nickel mix readily in the molten state, the useful range of alloys is not confined within any definite limits. Additions of from 2 percent to 45 percent of nickel to copper provide a series of alloys that are stronger and more resistant to oxidation at high temperatures than is pure copper. An alloy containing 30 percent nickel, the most important, is widely used for condenser tubes in steam-power plants.
Cupronickel was first utilized for coins in 1860 by Belgium; it became widely used thereafter, replacing silver in British coinage, for example, in 1947. The 75:25 ratio was adopted by the United States for the “nickel” 3-cent piece (1865–89) and the “nickel” 5-cent coin (from 1866); since 1965 it has formed the two outer layers of the 10-cent and 25-cent pieces, with a layer of copper sandwiched between. An 88:12 composition was used briefly for the American cent (1857–64).
Easily worked hot or cold, cupronickel has numerous applications, with 20 percent nickel, for example, in exposed automobile parts.
| Cupro Nickel Product list |
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| Chemical Composition |
Cu-Ni 90/10 |
Cu-Ni 70/30 |
| Element |
Percentage % |
Element |
Percentage % |
| Nickel |
9-11 % |
C |
29-33 % |
| Lead |
max 0.05% |
Mn |
max 0.05% |
| Iron |
max. 1% |
Si |
max. 1% |
| Zinc |
max. 1% |
P |
max. 1% |
| Manganese |
max. 1% |
S |
max. 1% |
| Sulfur |
max. 0.02% |
Cr |
max. 0.02% |
| Phosphorus |
max. 0.02% |
Mo |
max. 0.02% |
| Copper |
remainder |
Ni |
remainder |
| |
| Physical Properties |
Thermal Conductivity |
BTU/ (sq ft-ft-hr-F) |
17 |
| Specific Heat |
BTU/lb/ºF @ 68F |
.09 |
| Thermal Expansion |
Per °F from 68 F to 572 F |
.0000090 |
| Density |
lb/cu in @ 68 F |
.323 |
| Electrical Conductivity* (Annealed) |
% IACS @ 68 F |
4.6 |
| Modulus of Elasticity (Tension) |
KSI |
22,000 |
| Applications |
- Chemical processing, transport and storage
- Oil and gas exploration and offshore rigs
- Oil and gas refining
- Marine environments
- Pollution control equipment
- Pulp & paper manufacturing
- Chemical process plant
- Heat Exchangers,
- Oil Coolers,
- Radiators,
- High Capacity Power Plants,
- Ship Building & Ship Repairs,
- Condensers,
- Offshore Oil rigs,
- Distiller Tubes,
- Evaporators,
- Ferrules etc.
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