Neisilber: what kind of metal is it and how to distinguish it from cupronickel?

On sale you can find a variety of dishes or jewelry made of metal resembling silver. Many do not even suspect that they are made of nickel silver.

Nickel silver that translated from German into Russian means "new silver"is not a specific metal. It is a three-component alloy based on copper, zinc and nickel. The percentage of these metals is very different. The main element is copper, it can contain up to 60%. The nickel content is from 5 to 35%, zinc - from 13 to 45%.

The percentage of these metals determines the color of the nickel silver, and it may have a bluish or greenish color. The components included in its composition give it certain qualities. Nickel provides a silver tint to nickel silver, increases its resistance to corrosion, enhances chemical resistance: the alloy does not have the ability to dissolve in organic acids.

Copper adds qualities such as ductility and ductility, which improves its forging ability. Good plastic properties allow both hot and cold processing.

The presence of zinc provides high resistance to electric current. Also, the zinc content makes it cheaper compared to cupronickel, with which nickel silver has a similar appearance and some mechanical properties.

Neysilber appeared thanks to cupronickel. This alloy was invented in China in the VIII century BC. Cupronickel possessed unique characteristics, became a substitute for silver, but was cheaper than precious metal. Therefore, Chinese scientists kept its formula secret. Later, items made of nickel silver were distributed in Europe.

They became so popular that European metallurgists tried to reveal its formula in order to independently produce this alloy. Soon, according to the Europeans, they determined its composition. Scientists mistakenly believed that cupronickel contains copper, zinc and nickel. However, the percentage of components remained unrevealed.

Only in the 19th century, German scientists obtained an alloy very similar to silver. But it was not nickel silver. The new metal with a lower cost compared to cupronickel and silver is called nickel silver. The resulting metal had higher strength and stability: its decomposition is observed only in hydrochloric and sulfuric acids heated to boiling.

Nickel silver is produced in accordance with GOST 5187-2003, which determines the chemical composition, all its mechanical characteristics. It has alphanumeric marking: ISC and ISTC. The letters respectively indicate copper, nickel, zinc, lead. Digital marking indicates the average permissible percentage of elements, and the amount of copper is not indicated: it accounts for the remainder. Since the percentage can be very different, there are about 50 brands of nickel silver.

In industry, the following brands are most often used.

• ISC 15-20. This brand may contain nickel in the range of 13.5-16.5%, zinc - 18-22%, the rest - copper. The inclusion of such additives as antimony, silicon and others is also allowed. Their share is insignificant and does not exceed 2%.
• ISTC 16-29-1.8. In this version of the nickel silver, in addition to the required elements, lead is present. The nickel content is from 15 to 16.7%, zinc is about 29%, copper is from 51 to 55%, lead is up to 1.8%. Other impurities account for about 1%, but not more.

There are other options: ISC 12-24, ISC 18-27, ISC 18-20 and others. As additives are used such elements: iron, which gives hardness, vanadium to give greater density.

Often added to the composition lead, which increases the softness of the alloy, its ductility, thereby it acquires the ability to stretch, bend, twist, and it can be processed by a press. At the same time, lead reduces brittleness at low temperature, and at high, on the contrary, it increases it.

The constituent elements of the nickel silver determine it chemical, physical and mechanical properties. The alloy is produced in various forms and one of them is wire, which is widely used in various industries. Metal and all its forms of release, including wire, have certain properties.

The material is characterized by such chemical characteristics.

1. It has a very high degree of corrosion resistance in any environment - both acidic and alkaline. This is especially true for acids of organic origin.
2. It also shows excellent resistance to negative environmental phenomena: it does not oxidize in air and does not react with it even at a temperature of +250 degrees.
3. It does not chemically interact with salts.

The mechanical parameters of the alloy are characterized by such indicators.

• Strength. From other copper-nickel alloys, nickel silver is distinguished by higher strength. This is because nickel silver is alloyed with zinc. Its strength is from 38 to 45 kg / sq. mm Deformation occurs at a force action of 10 kg / sq. mm
• Elasticity. She is not distinguished by a high rate.The modulus of longitudinal elasticity (Young's modulus) is only 14,000 kg / sq. mm, while conventional steel - 20,000 kg / sq. mm
• Plastic. In an alloy, this parameter is very high. The relative elongation in tension is from 25 to 45%, and in narrowing - up to 32%. Good ductility is preserved in the material in the cold and hot state, which provides excellent ability to various types of processing, such as embossing, broaching, stamping.
• Hardness the alloy according to the mineralogical 10-point Mohs scale is only 3 points. Therefore, it can easily be scratched on its surface.
• Melting Point Temperature - 1080 degrees, and the final melting occurs at 1200 degrees.

The color of the nickel silver depends on the percentage of nickel, and with a high proportion (up to 30%), the alloy has a whitish-silver color. With a lower amount of nickel (up to 10%), the alloy has a white color with a yellowish tinge. The nickel silver is distinguished by such physical characteristics:

• the density of the alloy is 8700 kg / cu. m;
• specific gravity - 7.5 g / cu. cm;
• electrical conductivity is low due to the content of zinc and nickel;
• electrical resistance is characterized by a high indicator - up to 0.26 Ohm, which exceeds the corresponding indicator of copper by 30 times;
• thermal conductivity is also low - from 0.06 to 0.085 cal / cm;
• the alloy retains its shape when heated: the linear expansion coefficient is negligible - at +100 degrees the expansion is only about 16.6 microns.

Despite the resemblance, both alloys have differences. The most important difference is their composition. Cupronickel does not consist of 3 main components, like nickel silver, but of 2 - copper (up to 80% of it), nickel (up to 18%) and minor additives in the form of iron and manganese. In cupronickel there is no zinc.

Neusilber compared to cupronickel It also has slightly greater strength and resistance to temperature extremes and external influences. Cupronickel objects in humid air quickly acquire a dark shade. The nickel silver does not darken for a long time, so it does not need frequent care, like cupronickel.

In appearance, the nickel silver does not differ from cupronickel: both alloys look like silver. It is possible to determine which alloy a particular product is made of only by marking. Cupronickel objects are marked with 2 letters MN (copper-nickel) or "chalk", as well as similar markings in a foreign language.

The use of nickel silver is largely determined by its technical characteristics. Nickel, neutralizing the red color of copper during melting, gives the alloy a glossy texture with a white, whitish-blue or greenish tone. After adding lead, the luster becomes dull and takes on a shade of gray.

The alloy is used to make billets in the form of ingots, tapes, wire, rods, pipes, which are then processed in various ways. The alloy is easily exposed heating, cooling, it can be minted and forged.

Nickel silver is processed by the method cutting and molding. For the manufacture of appliances or electrical equipment, the metal is polished to a shine.

Apply nickel silver in the following areas.

After removing impurities, a pure nickel silver (with a content of other metals of not more than 0.1%) is used for the manufacture of relays, plates for the housing, springs. Due to its high anti-corrosion properties and polishing purity, it is one of the main metals in the manufacture of measuring instruments: dials and scoreboards are made of it. The divisions on the scale of such devices are usually made of nickel silver wire.

After gilding, a metal so similar to silver is used for making awards. Some countries use minting alloys coins of daily circulation. In addition, nickel silver is often used. for the release of anniversary copies, limited and collection designs.

In this area apply alloy ingots, sheets and ribbons, but the most important thing in production is wire. It is used mainly when creating various kinds of jewelry, frames, or bases for jewelrywhich are then gilded.

Especially popular is considered brand wire ISC 15-20. This brand has a melting point of about 1050 degrees, light weight and the possibility of reuse without loss of original properties. It is environmentally friendly and resistant to aggressive environments. Therefore it is her used, for example, in the manufacture of men's jewelry accessories: cufflink, tie barrettes, corporate badges. In addition, they create and from wire women's jewelry: beautiful chains and fasteners, earrings and bracelets, brooches, pendants and pendants.

In this area, the alloy is not used as widely as nickel in the composition can cause allergies in humans. So, the alloy is no longer used in dentistry for the manufacture of instruments and dental prostheses. However, some are still made from it. individual elements of medical equipment and instruments, since the alloy tolerates disinfection well and does not react with acids and alkalis.

Various alloys are made crockery and cutlery. And since the products acquire a metallic taste in direct contact with the nickel silver, the products are necessarily coated with gilding or silver.

Neisilber ware is made according to a special standard from the brand ISC 15-20authorized by health authorities, by GOST 492-2006. The standard coating must not be less than 24 microns for spoons and forks and 18 microns for knife handles.

The dishes are characterized by high functional and decorative properties. It can be considered as a jewelry and art product, since precious metals are used as a coating, and in the manufacturing process, such complex finishing methods as stamping, chasing and filigree, carving and engraving, enamel are used.

The range of such items is very wide: sugar bowls and coffee pots, teapots, vases for sweets and fruits, trays, dishes of various shapes and much more. Neisilber ware has high hygienic and aesthetic qualities.

This metal has found application in watch industry: watch cases, relay springs for mechanisms, and also bracelets for watches are made of it.

Applied nickel silver and in architecture: for interior design, alloy wire is used; for the decoration of iron castings and ornaments of exterior and interior decoration, tape is widely used.

In art craft it makes decor on the frames of wall clocks, on photo frames, and is used to create enamels and filigree. Artists and restorers often use nickel silver foil in their work.

Due to the high level of resistance to environmental influences, the alloy has found application in shipbuilding. Sheet metal is used in the manufacture of parts working in conjunction with an aqueous medium or steam: for water valves and taps, pipe fittings.

From nickel silver make pins and needles, elements of string and wind musical instruments, and fishing gear and even bullets for small arms.

In accordance with its characteristics, the metal itself does not need any special care and storage conditions. However, jewelry and gilded cutlery still need to be looked after. To maintain an aesthetic appearance and extend the life of products, you should adhere to such care rules.

1. Items must be stored in a separate box or box with a lid to protect them from direct sunlight and dust.
2. In order not to damage the product, it is not recommended to try to bend it, checking the strength.
3. If necessary, items made of nickel silver wire can only be cleaned with a natural bristle brush.
4. A layer of special colorless varnish should be applied to the award signs (medals, orders) to protect them from scratches.
5. If the metal has darkened, then the product must be cleaned with a napkin designed specifically for the care of jewelry. Dark spots that have appeared can also be removed with warm vinegar, and then rinse the product well with running water. To clean the dishes, you can still use toothpaste or powder, soda and cleaning products for washing dishes.
6. Products with a shiny polished surface must be wiped with felt cloth every month, and jewelry and cutlery are cleaned twice a month.
7. Alloy jewelry should not be worn on a daily basis, and should be removed during stays in spas and saunas.
8. In the event of a jewelry breakdown, it should be attributed to the jewelry master, and not try to repair it yourself.

For more information on the characteristics of metal nickel silver, see the next video.