nickel silver

 

name for various alloys of copper, zinc, and nickel, sometimes also containing lead and tin. They were originally named for their silver-white color, but use of the term silver is now prohibited for alloys not containing that metal. German silver varies in composition, the percentage of the three elements ranging approximately as follows: copper, from 50% to 61.6%; zinc, from 19% to 17.2%; nickel, from 30% to 21.1%. The proportions are always specified in commercial alloys. German silver is extensively used because of its hardness, toughness, and resistance to corrosion for articles such as tableware (commonly silver plated), marine fittings, and plumbing fixtures. Because of its high electrical resistance it is used also in heating coils. It was discovered (early 19th cent.) by a German industrial chemist, E. A. Geitner.

Nickel silver is a metal alloy of copper with nickel and often but not always zinc. It is named for its silvery appearance, but contains no elemental silver. Other common names for this alloy are German Silver ( a term which may also refer to 0.800 fine silver), Paktong, New Silver and Alpacca (or Alpaca).

Composition

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. A representative industrial formulation, Alloy No. 752, is 65% copper, 18% nickel, and 17% zinc. In metallurgical science, such alloys would be more properly termed nickel brass. The white alloy of 75% copper and 25% nickel used in coins, such as the United States nickel, is better known as copper-nickel, cupro-nickel or cupronickel.

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

Nickel silver alloys are commonly named by listing their percentages of copper and nickel, thus "Nickel Silver 55-18" would contain 55% copper, 18% nickel, and 27% other elements, most probably entirely zinc. A two-element alloy may be named for its nickel content alone, thus NS-12 is 88% copper and 12% nickel.

Uses

Nickel silver first became popular as a base metal for silver plated cutlery and other silverware, notably the electroplated wares called EPNS (Electro-plated Nickel Silver).

It is used in zippers, better quality keys, costume jewellery, for making musical instruments (e.g., cymbals), and is valuable for electrically powered model railway layouts as its oxide is conductive. Also, after about 1920, its use became widespread for pocketknife bolsters, due to its machinability and corrosion resistance. Prior to this point, most common was iron.

It is widely used in the production of coins (e.g. GDR marks, Portuguese escudo).

Its industrial and technical uses include marine fittings and plumbing fixtures for its corrosion resistance, and heating coils for its high electrical resistance.

It was used in the construction of the early tricone resophonic guitar. It is also used to produce the tubes (called staples) onto which oboe reeds are tied. Guitar frets are made from it, as well on mandoline, banjo, bass, etc.

Musical instruments, including the flute, saxophone, and french horn can be made of nickel silver. For example, some leading saxophone manufactuers such as Selmer, P.Mauriat, Yanagisawa, and Yamaha offer saxophones made of nickel silver which possess a bright and powerful sound quality; an additional benefit is that nickel silver does not require a lacquer finish.

Toxicity

According to the Merck Manual 17th edition p56, prolonged contact of copper alloys with acidic food or beverages (including boiling milk) can leach out the copper and cause toxicity. Long term, low doses can lead to cirrhosis. It should be of interest that cadmium is known to cause renal failure.

History

Nickel silver is first known in China, and was known in the west from imported wares called Paktong or Pakfong (白銅, literally "white copper") where the silvery metal colour was used to imitate sterling silver. It was discovered to be a copper-nickel-zinc alloy in the 18th century. In 1770 the Suhl (Germany) metalworks were able to produce a similar alloy and in 1823 a competition was initiated to perfect the production process by creating an alloy that possessed the closest visual similarity to silver. The brothers Henniger in Berlin and A. Geitner in Schneeberg independently achieved this goal. Alpacca became a widely known name in northern Europe for nickel silver after it was used as a trademark brand by the manufacturer Berndorf. A form of German Silver was also invented in Birmingham, England in 1832.

Nickel silver became widely used after 1840 with the development of electroplating, as it formed an ideal strong and bright substrate for the plating process. It was also used unplated in applications such as cheaper grades of cutlery.

See also

• Cupronickel
• Britannia metal

External links

• National Pollutant Inventory - Copper and compounds fact sheet
• Nickel Silver, German Silver and related alloys
• Products made of alpaca silver

Donate to Wikimedia