Alloy of copper that contains nickel
Cupronickel or copper-nickel ( CuNi ) is an admixture of copper that contains nickel and strengthening elements, such as iron and manganese. The copper content typically varies from 60 to 90 percentage. ( Monel is a nickel-copper debase that contains a minimum of 52 percentage nickel. ) Despite its high copper message, cupronickel is silver in color. Cupronickel is highly immune to corrosion by salt water, and is consequently used for pipe, heating system exchangers and condensers in seawater systems, vitamin a well as for marine hardware. It is sometimes used for the propellers, propeller shafts, and hulls of high-quality boats. other uses include military equipment and chemical, petrochemical, and electrical industries. [ 1 ] Another park modern use of cupronickel is silver-coloured coins. For this use, the typical debase has 3:1 copper to nickel proportion, with very small amounts of manganese. In the past, true ash grey coins were debased with cupronickel.

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name [edit ]

apart from cupronickel and copper-nickel, several early terms have been used to describe the material : the tradenames Alpaka or Alpacca, Argentan Minargent, the registered french terminus cuivre blanc, and the romanize yue term Paktong, 白銅 ( the French and yue terms both meaning “ white copper ” ) ; cupronickel is besides occasionally referred to as hotel silver, plata alemana ( spanish for “ german ash grey ” ), German silver, and Chinese silver. [ 2 ]

Applications [edit ]

Marine engineering [edit ]

Cupronickel alloys are used for marine applications [ 3 ] due to their immunity to seawater corrosion, estimable fabricability, and their effectiveness in lowering macrofouling levels. Alloys ranging in composition from 90 % Cu–10 % Ni to 70 % Cu–30 % Ni are normally specified in heating system exchanger or condenser tubes in a wide-eyed kind of marine applications. [ 4 ] authoritative marine applications for cupronickel include :

  • Shipbuilding and repair: hulls of boats and ships, seawater cooling, bilge and ballast, sanitary, fire fighting, inert gas, hydraulic and pneumatic chiller systems.[5][6]
  • Desalination plants: brine heaters, heat rejection and recovery, and in evaporator tubing.[7]
  • Offshore oil and gas platforms and processing and FPSO vessels: systems and splash zone sheathings.[8]
  • Power generation: steam turbine condensers, oil coolers, auxiliary cooling systems and high pressure pre-heaters at nuclear and fossil fuel power plants.[9]
  • Seawater system components: condenser and heat exchanger tubes, tubesheets, piping, high pressure systems, fittings, pumps, and water boxes.[10][11]

coinage [edit ]

Cupronickel Five swiss francs The successful use of cupronickel in coinage is due to its corrosion resistance, electric conduction, lastingness, malleability, low allergy risk, relief of stamping, antimicrobial properties and recyclability. [ 12 ] In Europe, Switzerland pioneered the nickel billon coinage in 1850, with the addition of silver. In 1968, Switzerland adopted the far cheaper 75:25 copper to nickel proportion then being used in Belgium, the United States, and Germany. From 1947 to 2012, all “ argent ” neologism in the UK was made from cupronickel, but from 2012 onwards the two smallest cupronickel denominations were replaced with lower-cost nickel-plated steel coins. In part due to silver roll up in the Civil War, the United States Mint first base used cupronickel for circulating neologism in three-cent pieces starting in 1865, and then for five-cent pieces starting in 1866. Prior to these dates, both denominations had been made lone in silver in the United States. Cupronickel is the cladding on either slope of United States half-dollars ( 50¢ ) since 1971, and all quarters ( 25¢ ) and dimes ( 10¢ ) made after 1964. Currently, some circulate coins, such as the United States Jefferson nickel ( 5¢ ), [ 13 ] the swiss franc, and the confederacy korean 500 and 100 won are made of solid cupronickel ( 75:25 proportion ). [ 14 ]

early use [edit ]

A thermocouple junction is formed from a match of thermocouple conductors such as iron- constantan, copper-constantan or nickel-chromium/nickel-aluminium. The junction may be protected within a cocktail dress of copper, cupronickel or stainless steel. [ 15 ] Cupronickel is used in cryogenic applications. Its combination of beneficial ductility retention and thermal conduction at very abject temperatures is advantageous for low-temperature process and storage equipment adenine well as for heating system exchangers at cryogenic plants. [ 16 ] [ 17 ] [ 18 ] Beginning around the become of the twentieth hundred, bullet jackets were normally made from this material. It was soon replaced with gilding metal to reduce metallic element foul in the bear. presently, cupronickel and nickel silver remain the basic material for silverplate cutlery. It is normally used for mechanical and electric equipment, checkup equipment, zippers, jewelry items, and both for strings for instruments in the violin family, and for guitar frets. Fender musical Instruments used “ CuNiFe ” magnets in their “ Wide Range Humbucker “ tone arm for respective Telecaster and Starcaster guitars during the 1970s. [ citation needed ] For high-quality cylinder locks and locking systems, cylinder cores are made from wear-resistant cupronickel. Cupronickel has been used as an alternative to traditional steel brake lines, as it does not rust. Since cupronickel is much softer than steel, it bends and flares more well, and the same property allows it to form a better seal with hydraulic components .

Properties [edit ]

Cupronickel lacks a copper color due to nickel ‘s high electronegativity, which causes a loss of one electron in copper ‘s d-shell ( leaving 9 electrons in the d-shell versus pure bull ‘s typical 10 electrons ). crucial properties of cupronickel alloys include corrosion resistance, implicit in resistance to macrofouling, good tensile military capability, excellent ductility when annealed, thermal conduction and expansion characteristics amenable for heat exchangers and condensers, good thermal conduction and ductility at cryogenic temperatures and beneficial disinfectant touch open properties. [ 19 ]

Properties of some Cu–Ni alloys[20]



Thermal conductivity


Electrical resistivity

Elastic modulus

Yield strength

Tensile strength

























The alloys are :

UNS standard compositions* of wrought alloys (in at%). Maximum or range.

Alloy UNS No.

Common name

European spec

























  • These values may vary in other standards

elusive differences in corrosion resistance and lastingness settle which alloy is selected. Descending the table, the maximum permissible flow rate in worst increases, as does the tensile military capability. In seawater, the alloys have excellent corrosion rates which remain gloomy equally long as the utmost purpose flow speed is not exceeded. This speed depends on geometry and pipe diameter. They have high resistance to crevice corrosion, stress corrosion crack and hydrogen embrittlement that can be troublesome to other debase systems. Copper-nickels naturally form a flimsy protective come on layer over the foremost several weeks of exposure to seawater and this provides its ongoing resistance. additionally, they have a high built-in biofouling immunity to attachment by macrofoulers ( e.g. seagrasses and mollusk ) animation in the seawater. To use this place to its wide potential, the alloy needs to be loose of the effects of, or insulated from, any shape of cathodic auspices. however, Cu–Ni alloys can show high corrosion rates in contaminated or dead seawater when sulfides or ammonia are salute. It is authoritative, consequently, to avoid exposure to such conditions, particularly during commissioning and refit while the surface films are maturing. ferric sulfate dosing to sea water systems can provide better resistance .
Cupronickel gap in 90–10 Cu–Ni metallic home plate due to stresses during ash grey braze As bull and nickel debase with each other easily and have bare structures, the alloys are ductile and promptly fabricated. Strength and unfeelingness for each individual alloy is increased by cold working ; they are not hardened by heat treatment. Joining of 90–10 ( C70600 ) and 70–30 ( C71500 ) is possible by both welding or brazing. They are both weldable by the majority of techniques, although autogenous ( welding without weld consumables ) or oxyacetylene methods are not recommended. The 70–30 preferably than 90–10 weld consumables are normally preferred for both alloys and no after-welding heat treatment is required. They can besides be welded directly to steel, providing a 65 % nickel-copper weld consumable is used to avoid iron dilution effects. The C71640 debase tends to be used as seamless tube and expanded rather than welded into the tube plate. Brazing requires appropriate silver-base braze alloys. however, big manage must be taken to ensure that there are no stresses in the Cu–Ni being silver brazed, since any tension can cause intergranulary penetration of the brazing material, and severe stress crack ( see image ). thus, full annealing of any potential mechanical stress is necessity.

Applications for Cu–Ni alloys have withstood the test of clock, as they are hush widely used and range from seawater system pipe, condensers and heat exchangers in naval vessels, commercial embark, multiple-stage flash desalination and power stations. They have besides been used as splash zone cladding on offshore structures and protective facing on boat hulls, ampere well as for solid hulls themselves .

fabrication [edit ]

due to its ductility, cupronickel alloys can be readily fabricated in a wide diverseness of product forms [ 21 ] and fittings. Cupronickel tube can be promptly expanded into tube sheets for the fabricate of blast and tube heat exchangers. Details of lying procedures, including general handling, cutting and machine, shape, estrus treatment, preparing for welding, weld preparations, append weld, welding consumables, welding processes, paintina, mechanical properties of welds, and tube and pipe bending are available. [ 22 ]

Standards [edit ]

ASTM, EN, and ISO standards exist for ordering ferment and hurl forms of cupronickel. [ 23 ] Thermocouples and resistors whose resistance is stable across changes in temperature contain admixture constantan, which consists of 55 % copper and 45 % nickel .

history [edit ]

chinese history [edit ]

Cupronickel alloys were known as “ ashen bull ” to the taiwanese since about the third gear hundred BC. Some weapons made during the Warring States period were made with Cu-Ni alloys. [ 24 ] The theory of chinese origins of Bactrian cupronickel was suggested in 1868 by Flight, who found that the coins considered the oldest cupronickel coins yet discovered were of a identical similar alloy to chinese paktong. [ 25 ] The author-scholar, Ho Wei, precisely described the process of making cupronickel in about 1095 AD. The paktong debase was described as being made by adding minor pills of naturally occurring yunnan ore to a bathtub of melt copper. When a crust of slag formed, potassium nitrate was added, the alloy was stirred and the ingot was immediately shed. Zinc is mentioned as an component but there are no details about when it was added. The ore used is noted as entirely available from Yunnan, according to the floor :

“ San Mao Chun were at Tanyang during a famine class when many people died, so taking certain chemicals, Ying projected them onto flatware, turning it into gold, and he besides transmuted iron into silver – frankincense enabling the lives of many to be saved [ through buy grain through this fake silver and gold ] Thereafter all those who prepared chemical powders by heating and transmuting copper by projection called their methods “ Tanyang techniques ”. [ 25 ]

The deep Ming and Qing literature have very little information about paktong. however, it is first base mentioned specifically by name in the Thien Kung Khai Wu of circa 1637 :

“ When lu kan shih ( zinc carbonate, hemimorphite ) or wo chhein ( zinc metallic element ) is shuffle and combined with chih thung ( copper ), one gets ‘yellow bronze ‘ ( ordinary brass ). When phi shang and other arsenic substances are heated with it, one gets ‘white bronze ‘ or white copper : pai thong. When alum and potassium nitrate and other chemicals are mix together one gets ching thung : greens bronze. ” [ 25 ]

Ko Hung stated in 300 ad : “ The Tanyang copper was created by throwing a mercuric philosopher’s stone into Tanyang copper and heated- gold will be formed. ” however, the Pha Phu Tsu and the Shen I Ching describing a statue in the western provinces as being of silver, tin, lead and Tanyang bull – which looked like aureate, and could be forged for plating and inlaying vessels and swords. [ 25 ] Joseph Needham et al. argue that cupronickel was at least known as a alone alloy by the Chinese during the predominate of Liu An in 120 BC in Yunnan. furthermore, the Yunnanese State of Tien was founded in 334 BC as a colony of the Chu. Most probable, modern paktong was unknown to Chinese of the day – but the naturally occurring Yunnan ore cupronickel alloy was probably a valuable inner trade commodity. [ 25 ]

Greco-Bactrian neologism [edit ]

In 1868, W. Flight discovered a Greco-Bactrian coin comprising 20 % nickel that dated from 180 to 170 BCE with the broke of Euthydemus II on the obverse. Coins of a alike alloy with busts of his younger brothers, Pantaleon and Agathocles, were minted around 170 BCE. The musical composition of the coins was late verified using the traditional wet method acting and roentgenogram fluorescence spectroscopy. [ 25 ] Cunningham in 1873 proposed the “ Bactrian nickel hypothesis, ” which suggested that the coins must have been the result of overland trade from China through India to Greece. Cunningham ‘s theory was supported by scholars such as W. W. Tarn, Sir John Marshall, and J. Newton Friend, but was criticized by E. R. Caley and S. van R. Cammann. [ 25 ] In 1973, Cheng and Schwitter in their new analyses suggested that the Bactrian alloy ( copper, lead, cast-iron, nickel and cobalt ) were close alike to the chinese paktong, and of nine know asian nickel deposits, alone those in China could provide the identical chemical compositions. [ 25 ] Cammann criticized Cheng and Schwitter ‘s paper, arguing that the decline of cupronickel currentness should not have coincided with the opening of the Silk Road. If the Bactrian nickel theory were true, according to Cammann, the Silk Road would have increased the supply of cupronickel. however, the end of Greco-Bactrian cupronickel currentness could be attributed to other factors such as the end of the House of Euthydemus. [ 25 ]

european history [edit ]

The debase seems to have been rediscovered by the West during chemistry experiments. notably, Andreas Libavius, in his Alchemia of 1597, mentions a surface-whitened copper aes album by mercury or silver. But in De Natura Metallorum in Singalarum Part 1, published in 1599, the same term was applied to “ tin ” from the East Indies ( contemporary Indonesia and the Philippines ) and given the spanish mention, tintinaso. [ 25 ] Richard Watson of Cambridge appears to be the first to discover that cupronickel was an alloy of three metals. In attempting to rediscover the unavowed of white-copper, Watson critiqued Jean-Baptiste Du Halde ‘s History of China ( 1688 ) as confusing the terminus paktong’., He noted the Chinese of his day did not form it as an alloy but rather smelted readily available unprocessed ore:

“ … appeared from a huge series of experiments made at Peking- that it occurred naturally as an ore mined at the region, the most extraordinary bull is pe-tong or white copper : it is white when dig out of the mine and even more white within than without. It appears, by a huge numeral of experiments made at Peking, that its color is owing to no mix ; on the reverse, all mixtures diminish its beauty, for, when it is rightly managed it looks precisely like silver and were there not a necessity of mixing a little tutenag or such alloy to soften it, it would be so much more the extraordinary as this classify of copper is found no where but in China and that merely in the Province of Yunnan ”. Notwithstanding what is here said, of the color of the copper being owing to no concoction, it is certain the chinese white copper as bring to us, is a mixt [ sic : desegregate ] metallic element ; so that the ore from which it was extracted must consist of versatile metallic substances ; and from such ore that the natural orichalcum if it always existed, was made. ” [ 25 ]

During the acme european import of chinese white-copper from 1750 to 1800, increased care was made to its discovering its constituents. Peat and Cookson found that “ the darkest proved to contain 7.7 % nickel and the lightest said to be identical from silver with a characteristic bell-like resonance when strike and considerable immunity to corrosion, 11.1 % ”. Another trial by Andrew Fyfe estimated the nickel subject at 31.6 %. Guesswork ended when James Dinwiddie of the Macartney Embassy brought back in 1793, at considerable personal risk ( smuggling of paktong ore was a capital crime by the Chinese Emperor ), some of the ore from which paktong was made. [ 26 ] Cupronickel became widely understand, as published by E. Thomason, in 1823, in a meekness, by and by rejected for not being raw cognition, to the Royal Society of Arts. Efforts in Europe to precisely duplicate the taiwanese paktong failed due to a general lack of needed building complex cobalt-nickel-arsenic naturally occurring ore. however, the Schneeberg district of Germany, where the celebrated Blaufarbenwerke made cobalt blue and other pigments, entirely held the needed complex cobalt-nickel-arsenic ores in Europe. At the lapp time, the prussian Verein zur Beförderung des Gewerbefleißes ( Society for the Improvement of Business Diligence/Industriousness ) offered a loot for the command of the process. Unsurprisingly, Dr E.A. Geitner and J.R. von Gersdoff of Schneeberg won the loot and launched their “ german silver ” mark under the trade names Argentan and Neusilber ( modern silver ). [ 26 ]

In 1829, Percival Norton Johnston persuaded Dr. Geitner to establish a foundry in Bow Common behind Regents ‘ Park Canal in London, and obtained ingots of nickel-silver with the writing 18 % Ni, 55 % Cu and 27 % Zn. [ 26 ] Between 1829 and 1833, Percival Norton Johnson was the first person to refine cupronickel on the british Isles. He became a affluent world, producing in excess of 16.5 tonnes per year. The alloy was chiefly made into cutter by the Birmingham firm William Hutton and sold under the trade-name “ Argentine ”. Johnsons ‘ most dangerous competitors, Charles Askin and Brok Evans, under the brilliant chemist Dr. EW Benson, devised greatly improved methods of cobalt and nickel suspension and marketed their own mark of nickel-silver, called “ british Plate ”. [ 26 ] By the 1920s, a 70–30 copper-nickel degree was developed for naval condensers. Soon afterwards, a 2 % manganese and 2 % iron debase immediately known as debase C71640 was introduced for a UK power station which needed better erosion resistance because the levels of entrain sandpaper in the seawater. A 90–10 alloy first became available in the 1950s, initially for seawater piping, and is nowadays the more wide used alloy .

See besides [edit ]

References [edit ]

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