Copper is a ductile metal, easy to process, has electrical and thermal conductivity. To improve the performance properties, various alloying components are introduced into its composition. This article will focus on an alloy of copper and nickel, which increases its resistance to corrosion, increases strength and electrical resistance.
What does adding nickel to copper do?
Nickel is introduced into the alloy as the main alloying component. It significantly increases the hardness of copper. Metals are endowed with a rare feature, they completely dissolve in each other. When fused, depending on the proportion, homogeneous alloys of two metals change their properties as follows:
- Increases resistance to acids and alkalis.
- Increases heat resistance.
- Corrosion resistance is being developed.
- Increases elasticity and strength.
- The temperature coefficient of resistance decreases.
Classification
Using mechanical, chemical and physical properties, as well as the scope, copper-nickel alloys conditionallycan be divided into two main groups:
Structural - characterized by high corrosion resistance and high strength. These include cupronickel, containing up to 30% nickel and small amounts of other metals, nickel silver, which has excellent strength, and a special kunal alloy with aluminum additives, which is well processed by pressure
Electrical - have high electrical resistance. These include the thermoelectrode alloy kopel, which contains a high content of nickel, manganin and constantan. Used in electrical engineering for compensating wires, thermocouples and rheostats
Alloys are used for the manufacture of parts, used in devices, heat exchangers, so they are subject to stringent requirements for chemical composition and physical characteristics.
Melchior
An alloy of copper and nickel, whose name is cupronickel, can contain up to 22% of the main alloying component of nickel, about 80% of copper and no more than 0.6% of impurities. It is noted for its high strength, ductility, and corrosion resistance. The alloy lends itself well to machining, it is stamped, cut, minted, soldered, polished, pressure is applied in any form (cold and hot). Melchior is produced in the form of tapes, strips and pipes. The metal is silver in color. It is used in the production of condenser pipes, air conditioner parts, and is used in instrument making.
In addition, fromalloys make medical products, inexpensive jewelry, coins and dishes. To improve the appearance of products coated with a thin layer of silver.
Neusilbers
Alloys of nickel, copper and zinc contain up to 35 percent nickel and 45 percent zinc, and the rest is copper. Neusilbers (translated from German as “new silver”) have a beautiful silver color, they do not oxidize in air, they are resistant to solutions of organic acids and s alts. Due to their high corrosion resistance, non-ferromagnetic alloys are used in instrument making, used for the manufacture of medical instruments, watch mechanisms.
In the manufacture of products for the jewelry industry, deoxidizers are added to the alloys, which can reduce the amount of copper oxide, increase ductility and strength. With an increase in nickel alloy, its hardness and strength increase. With the introduction of aluminum, the alloys become dispersion-hardened, and the resistance to corrosion also increases. The presence of lead in nickel silver gives the metal elasticity and improves cutting performance.
High resistance alloys
For the manufacture of electric heaters, conductors are required material that has a high specific and low temperature coefficient of resistance. Precise resistances for devices, as a rule, are made from manganins - an alloy of copper, nickel and manganese. It consists of 86% copper, manganese 13% and nickel about 3%. Forstabilization in manganins introduce a small amount of iron, silver and aluminum. Alloys have a high melting point, which is 960 degrees, the average density is slightly more than 8 g / cm3. and orange color.
Manganins are little dependent on the temperature of the electrical resistance, which is very important for their use in electrical measuring devices with a high degree of accuracy. Another advantage of the alloys is a very small thermal EMF paired with copper. Manganin is artificially aged to stabilize electromechanical properties. The wire is heated in a vacuum to 400 degrees for about two hours, after which it is kept at room temperature for a long time to obtain stable properties. The alloy is used for the manufacture of additional resistances, coils, shunts, high-precision measuring instruments.
Constantan
Which alloy of copper and nickel, along with manganin, belongs to the alloys of high electrical resistance? This is constantan, it contains up to 65% copper, up to 41% nickel and about 2% manganese. This alloy has a specific silver tone, an average density and a melting point of 1270 degrees. The industry produces a wire from constantan, the diameter of which is 0.02-5 millimeters. Significant thermo-EMF paired with copper limits the use of the alloy in precision electrical measuring instruments. But it finds application in thermocouples for measuring temperatures up to 300 degrees.
Constantan wire fromAn alloy of copper and nickel is subjected to a special heat treatment by heating it to 900 degrees and then cooling it. As a result, a dark gray oxide film forms on its surface, which forms an insulating layer and does not require additional protective coating. The alloy lends itself well to machining, therefore it has high technological properties. It finds application in measuring instruments, electric heating elements and rheostats with temperatures up to 400 degrees.
Conclusion
Copper-nickel alloys are used in various industries. They are plastic and have anti-corrosion properties. Of these, parts are made that have a responsible purpose, used in heat exchangers and devices. Therefore, strict requirements are imposed on alloys in terms of density and chemical composition.
