Jan 6, 2014

Posted by Shanell Calloway in Business | Comments Off on What Is Cupro-Nickel?

What Is Cupro-Nickel?

Cupro-nickel, otherwise known as copper-nickel is an alloy of two base metals, copper and nickel. This alloy is extremely resistant to the corrosion that is endemic in a marine environment as well as biofouling. The addition of nickel to copper results in an alloy which is stronger and more resistant to corrosion but it retains its excellent ductility.

Although there are a number of cupro-nickel alloys the two most popular are 90/10 and 70/30. These numbers represent the percentage of each material in the alloy; 90 percent copper and 10 percent nickel, etc. Copper and nickel mix in their molten state so the percentage of each base metal is not confined to any specific limit, the alloy is available with as little as 2 percent nickel and as high as 45 percent. The alloy with the highest percentage of nickel is the strongest and the most resistant to oxidation. The better of the two common alloys is 70/30 as it is stronger and exhibits greater resistance to sea water corrosion. Although this is the superior alloy, 90/10 is used in most applications and is somewhat less expensive. Although the definition seems to indicate that the alloy is strictly copper and nickel, there are small amounts albeit important amounts of iron and manganese which enhance the metals resistance to flowing salt water and also to enhance even more its corrosion resistance.

Cupro-nickel is used extensively for piping systems, heat exchangers and condensers in salt water environments. It is often used for propellers and crankshafts of boats. For the average individual, he or she may not realize it but they come in contact with the material every day as it is used in coins. The US half dollar, quarters and dimes all are clad with the alloy. Another application which is found everyday is the silver-plated knives, forks and spoons.

As well as its well known resistance to sea water corrosion, the alloy is well suited as a material for fabricated assemblies. Both of the common alloys are easily welded by the majority of available techniques but a weld consumable is needed which eliminates oxy-acetylene. Not only can Cu-Ni be joined to itself, it can easily be welded to steel which adds to its potential uses.

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