Quick Facts about Copper


Copper - (L. cuprum, from the island of Cyprus), Cu; atomic weight 63.546(3); atomic number 29; Melting Point 1084.62 deg C; boiling point 2562 deg C; specific gravity 8.96 (20 deg C); valence 1 or 2. The discovery of copper dates from prehistoric times. It is said to have been mined for more than 5000 years. It is one of man's most important metals. Copper is reddish colored, takes on a bright metallic luster, and is malleable, ductile, and a good conductor of heat and electricity (second only to silver in electrical conductivity). The electrical industry is one of the greatest users of copper. Copper occasionally occurs native, and is found in many minerals such as cuprite, malachite, azurite, chalcopyrite, and bornite. Large copper ore deposits are found in the U.S., Chile, Zambia, Zaire, Peru, and Canada. The most important copper ores are the sulfides, oxides, and carbonates. From these, copper is obtained by smelting, leaching, and by electrolysis. Its alloys, brass and bronze, long used, are still very important; all American coins are now copper alloys; monel and gun metals also contain copper. The most important compounds are the oxide and the sulfate, blue vitriol; the latter has wide use as an agricultural poison and as an algicide in water purification. Copper compounds such as Fehling's solution are widely used in analytical chemistry in tests for sugar. High-purity copper (99.999 + %) is available commercially. Natural copper contains two isotopes. Twenty five other radioactive isotopes and isomers are known.
Chile is the world's largest producer of copper, accounting for an estimated 33% of world supply.

Copper is one of the most important metals. Copper is reddish with a bright metallic lustre. It is malleable, ductile, and a good conductor of heat and electricity (second only to silver in electrical conductivity). Its alloys, brass and bronze, are very important. Monel and gun metals also contain copper. Apparently the reason that policemen in the USA are nicknamed "cops" or "coppers" is to do with their uniforms which used to have copper buttons.


Physical Properties of Copper


Like gold and silver, copper is malleable. That is, it can be bent and shaped without cracking, when either hot or cold. It can be rolled into sheets as thin as 1/500 of an inch.

Copper also is ductile, that is, it can be drawn out into thin wire. A copper bar 4 inches thick can be heated, rolled, then drawn into a round wire so thin that it is thinner than a human hair. This wire is 20 million times longer than the original bar!

Industry valued copper for these properties. Copper is second only to silver in its ability to conduct elecricity, but silver is too expensive for this sort of use. Bronze and brass, however, do not conduct electricity as well as pure copper.

Besides electricity, copper also is an excellent conductor of heat, making it an important metal in cookware, refrigerators, and radiators.

Copper is resistant to corrosion, that is, it will not rust. If the air around it often is damp, it will change from its usual reddish orange color to reddish-brown. Eventually, it is coated with a green film called a "patina" that stops all further corrosion.

The melting point of copper is 1083.4 degrees Centigrade. Liquid copper boils at 2567 degrees Centigrade.

Specific Properties of Copper:

• Chemical Symbol: Cu
• Atomic Number: 29
• Atomic Weight: 63.54
• Density: 8960 kg m(-3)
• Melting Point: 1356K
• Specific Heat at 293K: 0.383kJkg(-1)K(-1)
• Thermal Conductivity: 394W m(-1) K(-1)
• Electrical Conductivity (%International Annealed Copper Standard): 100%
• Electrical Resistivity: 1.673x10(-8) ohm-m
• Crystal Structure: Face Centered Cubic

Forms of Copper:

Copper is shipped to fabricators mainly as cathode, wire rod, billet, cake (slab), or ingot. Through extrusion, drawing, rolling, forging, melting, electrolysis, or atomization, fabricators can form wire, rod, tube, sheet, plate, strip, castings, powder, and other shapes. These copper and copper-alloys are then shipped to manufacturing plants that make products to meet society's needs.


The Ancient History of Copper


Copper was the first metal mined and crafted by man, and has been the most important one in the oldest times of history, because it was available in great quantities and was initially extractable almost at the surface of ground. In addition, it was suitable to craft weapons and tools, art objects and ornaments.

Very likely the original center of metallurgy was on Iran highlands, where copper was easily found. Archaelogical excavations proved that copper crafting was known in Iran, and by Sumerians, since the beginning of Neolithic era. At the end of the fourth millennium B.C., copper working had reached high technical levels in Iran, Mesopotamia and Egypt.

From its original center, metallurgy spread both around the northern edge of the "fertile Crescent", finally reaching the Mediterranean coasts, and to the West reaching, through Anatolia, the Trojan site. During the third millennium B.C., Troy became very important in metallurgy history, as metal craftsmen, merchants and traders established there their activity. From here the technical knowledge and the materials for metal working reached the Aegean islands and beyond. In particular, Crete influence spread to the Mediterannean islands, like Sicily and Sardinia, and along the European coasts to Spain.

Since about 2000 B.C. copper crafting was widely diffused in Europe, where the Bronze Age began soon after with the development of several and important trading routes.

The discovery of the process needed to obtain copper from its ores was a very important event in our history: an event which gave birth to metallurgy and laid the grounds for the development of our great industries, not only copper industry, but indirectly iron and steel industries.

The first copper works were made by cutting, curving and hammering with a stone stroker on a stone anvil. The old blacksmiths made an important discovery: metal hardens under prolonged hammering, but can be brought back to its initial ductility by heating (re-cooking process) with no change in shape. Many ancient objects were manufactured through alternate cycles of hammering and cooking, with a final hammering to obtain the necessary hardness.

In antiquity the metal art objects were made by the blacksmith, who utilized as raw material tin metal foils, to be crafted with various techniques. For example, the simplest way to obtain a copper bowl consisted in hammering a tin copper disc placed on a wooden block hollowed to fit the profile of the required object. This is the most ancient method to manufacture bowls, dating back to the pre-dynastic age of Babilonia and Egypt. Another technique was known as "raising": a tin copper disc, having the same diameter as the pot to be obtained, was hammered to get the required shaped, using an anvil and a suitable hammer.

A method which became very popular is the embossing: hammering the metal foil upside or downside, to obtain an embossed decoration. Ancient craftsmen were masters of the mechanical methods, and also had a great control on raw material during crafting. For example, they had an excellent mastery of quenching, needed to keep the metal ductile and fit for crafting.

As metallurgy evolved, copper was then alloyed with tin to form bronze, which was certainly obtained at first by the accidental union of copper and tin minerals inside furnaces. Bronze great success in the ancient world was due to its excellence for mould casting. For this reason it was brilliantly utilized by the artists of the classical age, and then in the Middle Ages, and in the masterpieces of Renaissance and Baroque.

Copper continued to be used mainly for household objects. Working techniques remained almost unchanged over the centuries, while the shapes were continuously improved to fit with the evolution of lifestyle. Its properties, discovered and appreciated by our ancient ancestors, are still valid today.


An In-Depth Look at Copper, it's Properties and Uses

Background

Building Industry

Commercial Compositions of Copper

Applications of Copper

Structure of Copper

Key Properties of Copper Alloys

Other Properties of Copper

Melting Point of Copper

Electrical Conductivity of Copper

Corrosion Resistance of Copper

Surface Oxidation of Copper

Yield Strength of Copper

Joining of Copper

Hot and Cold Working

Temper

Copper Designations

Cast Copper Alloys

Wrought Copper Alloys

Copper Alloy Families

Coppers

High Copper Alloys

Brasses

Brass Additives

Brass Classes

Brass Families

Bronzes

Bronze Families

Other Alloy Groups

Copper-Nickel Alloys

Copper-Nickel-Zinc Alloys

Leaded Coppers

Special Alloys

Free Machining Coppers

Recycling of Copper

Background

Copper is the oldest metal used by man. It’s use dates back to prehistoric times. Copper has been mined for more than 10,000 years with a Copper pendant found in current day Iraq being dated to 8700BC. By 5000BC Copper was being smelted from simple Copper Oxides.

Copper has been mined since ancient times. The Egyptians, for example, mined copper 5,000 years ago. In the United States, significant copper mining began in 1845, when the Pittsburgh and Boston Company started a mine in Michigan's Upper Peninsula. According to Hildebrand and Mangum, there were 25 mining companies located in the Upper Peninsula by 1850. The Calumet and Hecla Mining Company, founded in 1870, quickly became a dominant copper producer. Michigan's Upper Peninsula was the only significant copperproducing region during this period. In the late 1870s, Butte, Montana, experienced a mining bonanza. The copper mines in Butte were the largest underground copper source ever found. The vast Western copper deposits eventually eclipsed the original Michigan mining operations.

Copper is found as native metal and in the minerals cuprite, malachite, azurite, chalcopyrite and bornite. It is also often a by-product of silver production. Sulphides, oxides and carbonates are the most important ores.

Copper and copper alloys are some of the most versatile engineering materials available. The combination of physical properties such as strength, conductivity, corrosion resistance, machinability and ductility make copper suitable for a wide range of applications. These properties can be further enhanced with variations in composition and manufacturing methods.

Building Industry

The largest end use for copper is in the building industry. Within the building industry the use of copper based materials is broad. Construction industry related applications for copper include:

·         Roofing

·         Cladding

·         Rainwater systems

·         Heating systems

·         Water pipes and fittings

·         Oil and gas lines

·         Electrical wiring

The building industry is the largest single consumer of copper alloy. The following list is a breakdown of copper consumption by industry on an annual basis:

·         Building industry – 47%

·         Electronic products - 23%

·         Transportation - 10%

·         Consumer products - 11%

·         Industrial machinery - 9%


Commercial Compositions of Copper

There are around 370 commercial compositions for copper alloy. The most common grade tends to be C12200 - the standard water tube grade of copper.

World consumption of copperand copper alloy now exceeds 18 million tonnes per annum.

Applications of Copper

Copper and copper alloy can be used in an extraordinary range of applications. Some of these applications include:

·         Power transmission lines

·         Architectural applications

·         Cooking utensils

·         Spark plugs

·         Electrical wiring, cables and busbars

·         High conductivity wires

·         Electrodes

·         Heat exchangers

·         Refrigeration tubing

·         Plumbing

·         Water-cooled copper crucibles

Structure of Copper

Copper has a face centred cubic crystal structure. It is yellowish red in physical appearance and when polished develops a bright metallic lustre.

Key Properties of Copper Alloys

Copper is a tough, ductile and malleable material. These properties make copper extremely suitable for tube forming, wire drawing, spinning and deep drawing. The other key properties exhibited by copper and its alloys include:

·         Excellent heat conductivity

·         Excellent electrical conductivity

·         Good corrosion resistance

·         Good biofouling resistance

·         Good machinability

·         Retention of mechanical and electrical properties at cryogenic temperatures

·         Non-magnetic

Other Properties of Copper

·         Copperand copper alloys have a peculiar smell and disagreeable taste. These may be transferred by contact and therefore Copper should be kept clear of foodstuffs.

·         Most commercially used metals have a metallic white colour. Copper is a yellowish red.

Melting Point of Copper

The melting point for pure Copper is 1083ºC.

Electrical Conductivity of Copper

The electrical conductivity of Copper is second only to silver. The conductivity of Copper is 97% that of silver. Due to its much lower cost and greater abundance, Copper has traditionally been the standard material used for electricity transmission applications.

However, weight considerations mean that a large proportion of overhead high voltage power lines now use aluminum rather than copper by weight, the conductivity of of Copper.

All copper alloys resist corrosion by fresh water and steam. In most rural, marine and industrial atmospheres copper alloys also resistant to corrosion. Copper is resistant to saline solutions, soils, non-oxidising minerals, organic acids and caustic solutions. Moist ammonia, halogens, sulphides, solutions containing ammonia ions and oxidising acids, like nitric acid, will attack Copper. Copper alloys also have poor resistance to inorganic acids.

The corrosion resistance of copper alloys comes from the formation of adherent films on the material surface. These films are relatively impervious to corrosion therefore protecting the base metal from further attack.

Copper Nickel alloys, Aluminium Brass, and Aluminium Bronzes demonstrate superior resistance to saltwater corrosion.

Surface Oxidation of Copper

Most of Copper

The yield point for copper alloys is not sharply defined. As a result it tends to be reported as either a 0.5% extension under load or as 0.2% offset.

Most commonly the 0.5% extension yield strength of annealed material registers as approximately one-third the tensile strength. Hardening by cold working means the material becomes less ductile, and yield strength approaches the tensile strength.

Joining of Copper

Commonly employed processes such as brazing, welding and soldering can be used to join most copper alloys. Soldering is often used for electrical connections. High Lead content alloys are unsuitable for welding.

Copper and Copper alloys can also be joined using mechanical means such as rivets and screws.

Hot and Cold Working

Although able to be work hardened, Copper and copper alloys can be both hot and cold worked.

Ductility can be restored by annealing. This can be done either by a specific annealing process or by incidental annealing through welding or brazing procedures.

Temper

Copper alloys can be specified according to temper levels. The temper is imparted by cold working and subsequent degrees of annealing.

Typical tempers for copper alloys are

·         Soft

·         Half-hard

·         Hard, spring

·         Extra-spring

Yield strength of a hard-tempercopper alloys is approximately two-thirds of the materials’ tensile strength.

Copper Designations

Designation systems for Copper are not specifications, but methods for identifying chemical compositions. Property requirements are covered in ASTM, government and military standards for each composition.

The method for designating copper alloys is an expansion upon the system developed by the U.S. copper and brass industry. Their old system used 3 digits, the new Unified Numbering System for Metals and Alloys (UNS) system uses five digits preceded by the letter C.

As an example the forging brass known as Copper alloy 377 is known as C37700 under the UNS system. Wrought compositions are included in the designations from C10000 through to C79900. Casting alloys are assigned numbers from C80000 through to C99900. Casting alloys are assigned numbers from C80000 through to C99900

The UNS designations are summarised in the following table:

UNS Numbers

Types

Alloy Names

C10000-C19999

Wrought

Coppers, High-Copper Alloys

C20000-C49999

Wrought

Brasses

C50000-C59999

Wrought

Phosphor Bronzes

C60600-C64200

Wrought

aluminum Bronzes

C64700-C66100

Wrought

Silicon Bronzes

C66400-C69800

Wrought

Brasses

C70000-C79999

Wrought

Copper nickels, nickel silvers

C80000-C82800

Cast

Coppers, High-Copper Alloys

C83300-C85800

Cast

Brasses

C86100-C86800

Cast

Manganese Bronzes

C87200-C87900

Cast

Silicon Bronzes and Brasses

C90200-C94800

Cast

Tin Bronzes

C95200-C95800

Cast

aluminum Bronzes

C96200-C97800

Cast

Copper Nickels, Nickel Silvers

C98200-C98800

Cast

Leaded Copper

C99300-C99750

Cast

Special Alloys

Cast Copper Alloys

The nature of the casting process means that most cast copper alloys have a greater range of alloying elements than wrought alloys.

Wrought Copper Alloys

Wrought copper alloys are produced using a variety of different production methods. These methods including processes such as annealing, cold working, hardening by heat treatments or stress relieving.

Copper Alloy Families

Within the wrought and cast categories for copper alloys, the compositions can be divided into the following main families:

·         Pure Coppers

·         High Copper Alloys

·         Brasses

·         Bronzes

Coppers

The Pure Coppers have a Copper content of 99.3% or higher.

High Copper Alloys

Wrought high Copper alloys have Copper contents of less than 99.3% but more than 96% but don’t fall into another Copper alloy group. Cast high Copper alloys have Copper contents in excess of 94%. Silver may be added to impart special properties.

Brasses

Brasses contain Zinc as the principal alloying element.

Other alloying elements may also be present to impart advantageous properties. These elements include Iron, Aluminium, Nickel and Silicon.

Brasses are most commonly characterised by their free machining grades by which machining standards are set for all other metals.

Brasses can also have high corrosion resistance and high tensile strength. Some ses are also suited to hot forging.

Brass Additives

Adding Lead to a brass composition can result in a

Brasses are divided into two classes. These are:

·         The alpha alloys, with less than 37% Zinc. These alloys are ductile and can be cold worked.

·         The alpha/beta or duplex alloys with 37-45% Zinc. These alloys have limited cold ductility and are typically harder and stronger.

Brass Families

There are three main families of wrought alloy brasses:

·         Copper-Zinc alloys

·         Copper-Zinc-Lead alloys (Leaded brasses)

·         Copper-Zinc-Tin alloys (Tin brasses)

Cast brass alloys can be broken into four main families:

·         Copper-Tin-Zinc alloys (red, semi-red and yellow brasses)

·         Manganese Bronze alloys (high strength yellow brasses) and Leaded Manganese Bronze alloys (leaded high strength yellow brasses)

·         Copper-Zinc-Silicon alloys (Silicon brasses and bronzes)

·         Cast Copper-Bismuth and Copper-Bismuth-Selenium alloys.

Bronzes

The term bronze originally described alloys with Tin as the only or principal alloying element.

Modern day bronze tend to be copper alloys in which the major alloying element is not Nickel or Zinc.

Bronzes can be further broken down into four families for both wrought and cast alloys.

Bronze Families

The wrought bronze alloy families are:

·         Copper-Tin-Phosphorus alloys (Phosphor Bronzes)

·         Copper-Tin-Lead-Phosphorus alloys (Leaded Phosphor Bronzes)

·         Copper-aluminum alloys (aluminum Bronzes)

·         Copper-Silicon alloys (Silicon Bronzes)

The cast bronze alloy families are:

·         Copper-Tin alloys (Tin Bronzes)

·         Copper-Tin-Lead alloys (Leaded and high leaded Tin Bronzes)

·         Copper-Tin-Nickel alloys (nickel-tin bronzes)

·         Copper-aluminum alloys (aluminum Bronzes)

Other Alloy Groups

Copper-Nickel Alloys

As the name suggests, the principal alloying element is Nickel. They can contain other alloying elements or simply have Nickel alone.

Copper-Nickel-Zinc Alloys

They contain Zinc and Nickel as the principal alloying elements and may also contain other alloying elements.

Leaded Coppers

Leaded Copper are cast copper alloys with 20% or more Lead added. They may also contain a small amount of Silver but have no Tin or Zinc.

Special Alloys

When alloys have chemical compositions that do not fall into any of the other categories mentioned, they are grouped together as “special alloys”.

Free Machining Coppers

Free machining properties are imparted upon copper alloys by the addition of Sulphur and Tellurium.

Recycling of Copper

Copper alloys are highly suited to recycling. Around 40% of the annual consumption of Copper alloys is derived from recycled Copper materials.




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Updated November 2013