Copper is one of the earliest metals discovered by man. The boilers on early steamboats were made from copper. The copper tubing used in water plumbing in Pyramids was found in serviceable condition after more than 5,000 years. Cu is a ductile metal. Pure Cu is soft and malleable, difficult to machine.
Atomic number of copper is 29. Atomic weight is
63.54. Copper has a density of 8.94 g/cm3 and melting temperature 1083°C.
Copper is found as native metal and in 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.
Copper alloys
Brasses and Bronzes are most commonly used alloys of Cu. Brass is an alloy with Zn. Brasses are copper zinc alloys containing up to about 45% zinc, with possibly small additions of lead for machinability, and tin for strength. Copper zinc alloys are single phase up to about 37% zinc in the wrought condition. Bronzes contain tin, aluminum, silicon or beryllium. Other copper alloy families include copper-nickels and nickel silvers. More than 400 copper-base alloys are recognized.
Brass is the most common alloy of Cu – It’s an alloy with Zn Brass has higher ductility than copper or zinc. Easy to cast - Relatively low melting point and high fluidity Properties can be tailored by varying Zn content. Some of the common brasses are yellow, naval and cartridge. Brass is frequently used to make musical instruments (good ductility and acoustic properties).
Bronzes are alloys of copper with tin, plus at least one of phosphorus, aluminum, silicon, manganese and nickel. Copper alloys containing tin, lead, aluminum, silicon and nickel are classified as bronzes. Cu-Sn Bronze is one of the earliest alloy to be discovered as Cu ores invariably contain Sn. Stronger than brasses with good corrosion and tensile properties; can be cast, hot worked and cold worked.
Properties of Copper and its alloys
The valuable properties of copper which were evident at the dawn of civilisation were an attractive colour, excellent ductility and malleability, and a capability of being hardened by working. In modern times, further properties have been appreciated and exploited across a wide range of applications: high thermal and electrical conductivities, excellent corrosion and biofouling resistance and antimicrobial properties. All copper alloys resist corrosion by fresh water and steam. In most rural, marine and industrial atmospheres copper alloys are also resistant to corrosion.
Strain hardening is the only strengthening mechanism that can be used with pure copper. The application of cold work, usually by rolling or drawing, hardens copper and copper alloys. Strength, hardness and springiness increase, while ductility decreases.
Very high electrical conductivity – second only to silver. Copper is refined to high purity for many electrical applications. Excellent thermal conductivity – Copper cookware most Highly regarded – fast and uniform heating.
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.
Use of Copper
Electrical and construction industries are the largest users of Cu. The second largest use of Cu is probably in coins. The U.S. nickel is actually 75% copper. The dime, quarter, and half dollar coins contain 91.67% copper and the Susan B Anthony dollar is 87.5% copper. The various Euro coins are made of Cu-Ni, Cu-Zn-Ni or Cu-Al-Zn-Sn alloys.
Application of copper and its alloys
Copper and its alloys are widely used in deep draw and flat stamped products because they have excellent electrical and thermal performance, good resistance to corrosion, high ductility and relatively low cost.
Wide range of applications: Heat exchangers and refrigeration tubing, ancient Chinese cast artifacts, Electrical wiring, cables and bus bars, Architectural applications, Plumbing, skateboard ball bearings, Cooking utensils , surgical and dental instruments, Spark plugs, Power transmission line, High conductivity wires, Electrodes.