What is nickel silver? According to its composition and properties, we can say that it is an improved version of an older alloy - cupronickel, invented back in 1819. Unlike cupronickel, which consists only of copper and nickel, nickel silver also necessarily contains zinc, and in addition to it, iron and some other alloying elements.
Alloy composition options
In nickel silver, the main alloy element 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 bronze (in which other metals act as alloying elements, that is, except for nickel and zinc). Although nickel silver contains both nickel and zinc, it is still classified as a copper-nickel alloy. This fact is explained by the fact that the main contribution to the properties of the material as an alloying element is made by nickel, and not by zinc.
Percentage of nickelcan vary from 5 to 35%, zinc - from 12 to 46%. There are several specific alloy options in GOSTs.
- Nickel silver MNTs15-20. The letters in the name indicate the metals that make up the alloy (copper, nickel and zinc), and the numbers indicate the average content of metals as a percentage 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, and so on. - no more than 2%, the rest is copper. The use of nickel silver with an alloy composition of this type is quite wide: it is used to make elements of precision measuring instruments, medical instruments, sanitary equipment, technical utensils, steam and water fittings, is used in electrical engineering, and is also used for the manufacture of consumer goods (for example, cutlery).
- Lead nickel silver MNTsS16-29-1, 8. As the name suggests, here, in addition to nickel and zinc, lead plays an important role in the composition of the alloy, the content of which by weight ranges from 1.6% to 2%. Nickel occupies 15-16.7%, copper - 51-55%, the rest - zinc and no more than 1% impurities. Parts of watch movements are made from lead nickel silver.
Physical and chemical properties of the alloy
Nickel silver has a beautiful silver color. This is reflected in its 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 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. With prolonged exposure to an acidic environment, selective corrosion of zinc appears - 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 nickel silver cutlery: the environment of the digestive system is acidic, which can allow copper from the alloy to enter the body and cause heavy metal poisoning.
Mechanical properties of the alloy
Mechanical properties include such indicators as hardness, strength, elastic limits, yield strength, elastic strength, metal fatigue and some other characteristics. The addition of nickel increases the hardness and strength of the alloy, and improves its elastic properties. Materials of different properties are made from nickel silver - soft, hard, very hard products with correspondingly different mechanical characteristics.
Use of nickel silver
The composition and characteristics allow this alloy to be used in a wide range of applications. In industry, from nickel silver, first of all, they receivea number of important products: strips, tapes, rods, wire of different hardness. Heavy duty nickel silver tapes are used to make contact springs used in electrical relays.
The use of nickel silver is determined by the composition of the alloy. Due to the increased resistance to external influences of any type, it is used in shipbuilding, used in conditions of high temperatures and pressures.
Nickel silver products
At one time cupronickel cutlery was extremely popular in the Soviet Union. They were valued for their appearance, which was practically indistinguishable from silver to the eye, although the cost of the copper-nickel alloy was clearly much less than the cost of the noble metal. The use of nickel silver for the same purposes was not so widespread, although it had the same goals; in addition, cupronickel and nickel silver still needed to be plated with silver to avoid the 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 practically does not tarnish over time, and the wire from it has good mechanical properties, so they like to use nickel silver in the manufacture of jewelry.
Neusilber as coin metal
Although nickel silver has never been a popular alloy for minting coins, sometimes they resorted to it - they released commemorative, limitedor collector's series, as well as specific single editions.
An example is the 20 kopeck coins minted in 1961. The design of the coin was not complicated - it was an ordinary batch. And now, among numismatists, samples of twenty-kopeck coins of 1961 are not highly valued, despite the uncharacteristic metal.
Commemorative nickel silver coins have been minted in Ukraine and Kazakhstan in recent years. In Kazakhstan, these are a series of coins with a face value of 50 tenge dedicated to one of the topics: "Tales", "Space", "Cities", "Red Book". In Ukraine, coins of various circulations and denominations were minted: in honor of famous people, memorable dates (many belong to the Great Patriotic War), cities.
