What is nickel silver? By its composition and properties, we can say that it is an improved version of an older alloy - cupronickel, invented back in 1819. Unlike nickel silver, which consists only of copper and nickel, the nickel silver also necessarily contains zinc, and besides it - iron and some other alloying elements.
Alloy Composition Options
In nickel silver, the main element of the alloy is copper. In general, copper alloys are divided into three large groups: brass (copper with zinc), copper-nickel alloys (the second element is obvious from the name) and bronzes (in which the remaining metals are alloying elements, that is, except nickel and zinc). Although nickel and zinc are present in the nickel silver alloy, it is nevertheless referred to as copper-nickel alloys. This fact is explained by the fact that nickel, not zinc, makes the main contribution to the properties of the material as an alloying element.
In percentage, the amount of nickel can range from 5 to 35%, zinc - from 12 to 46%. In GOST there are several specific options for the alloy.
- Neysilber MNTs 15-20. The letters in the name indicate the metals that make up the alloy (copper, nickel and zinc), and the numbers indicate the average metal content in percent by weight. In this version of the alloy, the nickel content varies from 13.5% to 16.5%, zinc - from 18% to 22%, impurities in the form of other metals - silicon, antimony, etc. - no more than 2%, the rest is copper. The use of a nickel silver with an alloy composition of this type is quite widespread: elements of precision measuring instruments, medical instruments, sanitary equipment, technical utensils, steam and water fittings are made of it, used in electrical engineering, and also used for the manufacture of consumer goods (for example, cutlery) .
- Nickel silver lead ISTC 16-29-1.8. As the name implies, here, in addition to nickel and zinc, lead plays an important role in the alloy composition, the content of which varies by mass from 1.6% to 2%. Nickel occupies 15-16.7%, copper - 51-55%, the rest is zinc and not more than 1% of impurities. Parts of clockworks are made of lead nickel silver.
Physico-chemical properties of the alloy
The nickel silver has a beautiful silver color. This was reflected in his name - in a literal translation from German, nickel silver means "new silver." Despite the fact that copper - the main metal of the alloy - is reddish in color, nickel “interrupts” it, giving the alloy a white color, sometimes with a blue tint.
By the nature of the bonds, nickel silver is a solid solution that forms copper with nickel.
One of the most important properties of the nickel silver is its high resistance to corrosion. Copper and nickel as metals themselves are resistant to corrosion, the addition of zinc increases this resistance by forming a protective oxide film - corrosion is about 0.5-30 × 10 - 4 mm per year. When it is in an acidic environment for a long time, selective corrosion of zinc is manifested - it undergoes oxidation and leaves the alloy, thus protecting the remaining components from destruction, although they also gradually corrode. Therefore, direct contact of copper alloys is undesirable for a person, for example, when using cutlery made of nickel silver: the environment of the digestive system is acidic, which can allow copper to enter the body and cause poisoning by heavy metals.
The mechanical properties of the alloy
The mechanical properties include indicators such as hardness, strength, elastic limits, yield strength, tensile strength, metal fatigue and some other characteristics. The addition of nickel increases the hardness and strength of the alloy, and also improves its elastic properties. Materials of various properties are made from nickel silver - soft, hard, very hard products with correspondingly different mechanical characteristics.
The use of nickel silver
The composition and characteristics allow the use of this alloy in a wide range of directions. In industry, from nickel silver, first of all, a number of important products are obtained: strips, tapes, rods, wire of different hardness. High strength nickel silver tapes are used to make contact springs used in an electric relay.
The application of a nickel silver by alloy composition is determined. Due to the increased resistance to external influences of any type, it is used in shipbuilding, used in conditions of high temperatures and pressures.
Products from nickel silver
At one time, cutlery made of cupronickel was extremely popular in the Soviet Union. They were valued for their appearance, which was almost indistinguishable from silver by eye, although the cost of a copper-nickel alloy was definitely much less than the cost of a noble metal. The use of nickel silver for the same purposes was not so widespread, although his goals were the same; in addition, instruments from both nickel silver and nickel silver still had to be coated with silver to avoid a characteristic metallic taste.
For the same properties and characteristics, nickel silver is also very popular with jewelers. It looks like silver and is cheap, but, unlike silver, it does not fade over time, and the wire from it has good mechanical properties, which is why nickel silver is used to make jewelry.
Nickel silver as coin metal
Although nickel silver was never a popular alloy for minting coins, they sometimes resorted to it - they produced anniversary, limited or collection series, as well as specific single runs.
An example is the coin of 20 kopecks minted in 1961. The design of the coin was not difficult - it was an ordinary party. And now, for numismatists, samples of twenty-cent coins of 1961 are not very highly valued, despite the uncharacteristic metal.
In recent years, commemorative nickel silver coins have been minted in Ukraine and Kazakhstan. In Kazakhstan, this is a series of coins with a face value of 50 tenge dedicated to one of the topics: "Tales", "Space", "Cities", "Red Book". Coins of different circulation and denomination were minted in Ukraine: in honor of famous people, memorable dates (many belong to the Great Patriotic War), cities.