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Please clarify Cupronickel vs. Nickel Silver

I know, I know, don't trust Wikipedia. But it is so damn convenient.

The Wikipedia entry on Cupronickel says: "Cupronickel is an alloy of copper, nickel and strengthening impurities, such as iron and manganese. Cupronickel does not corrode in seawater, because its electrode potential is adjusted to be neutral with regard to seawater. Because of this it is used for marine hardware..."

The entry for Nickel silver says: "Nickel silver is a metal alloy of copper with nickel and often but not always zinc. It is named for its silvery appearance..."

And later:

"Many alloys fall within the general term of "nickel silver". All contain copper and nickel, while some formulations may additionally include zinc, antimony, tin, lead or cadmium."

"Some nickel silver alloys, especially those containing high proportions of zinc, are stainless (corrosion-resistant)."

So, some questions:

If nickel silver is defined as copper plus nickel plus just about anything else, why isn't cupronickel included?

The cupronickel article implies that (some) copper nickel alloys do not corrode in seawater. The US nickels in my pocket confirm that the 75% copper 25% nickel alloy does not corrode in sweat, skin oil, and numerous trips through washing machines. So why does "Nickel silver" need lots of zinc in order to be "stainless"?

Reply to
Paul Ciszek
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Paul:

If you look at the Copper Development Association web site you will find a clearer discussion of nickel silver alloys versus copper nickels at:

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Copper nickels are defined as : "...alloys with nickel as the principal alloying element, with or without other designated alloying elements." Conversely, copper-nickel-zinc alloys are defined as: "... known commonly as 'nickel silvers,' these are alloys which contain zinc and nickel as the principal and secondary alloying elements, with or without other designated elements."

If you look at the Copper Development Association web site you also will find a discussion of nickel silver alloys and their microstructures at:

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"Nickel silvers are alloys that contain copper, nickel, and zinc. They are also called nickel brasses, the silver refers to their attractive silver luster.".... "The wrought nickel silvers contain between 7 and

20% nickel, and 14 and 46% zinc."....

Nickel silver makes nice track for model railroads. I don't believe that it is stainless in salt water. Both copper nickel and nickel silver have a long history in coinage. For example, see: "Trends of nickel in coins":

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As for Wikipedia, you can find a half dozen hilarious Sheldon comic strip comments on it between December 9 and 14 of last year. The best is:
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Pittsburgh Pete

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Reply to
metalengr

Thank you. It sounds like the primary flaw in the Wiki article is implying that you can have a nickle silver witout zinc. It sounds like zinc is not only de regure, but should make up more of the alloy than nickel, i.e., the statement that nickel is the *secondary* alloying element. Or can you have a nickel silver than has more nickel than zinc?

Reply to
Paul Ciszek

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