Copper is easily alloyed with other metals. It is generally divided into red copper, bronze, brass and cupronickel.
Pure copper is in red color, but not all red copper is pure copper, because sometimes people will add some deoxygenation elements.or other elements to improve its quality and function. Its copper content is over 99%, melting point is 1083 ℃ and density is 8.9 g/cm³.
It is of high ductility, malleability, thermal and electrical conductivity. However, the light impurities has great effect on thermal and electrical conductivity. Therefore, every year, half amount of red copper will be refined to be pure copper, then used in electrical industry. After these copper wire can’t be used anymore, they are still of high recycling value. Copper cable granulator and wire stripping machines are two popular choices in copper recycling. Red copper is also of good resistance to corrosion in air, sea water, non-oxidative acid, soda, saline solution and multiple organic acid, therefore it is widely used in chemical industry.
Generally speaking, bronze is an alloy of copper and tin. The content of tin is usually above 3%. Compared with red copper, bronze is of high intensity, low melting point, good castability, anti-friction and bright color . It is also harder than iron and pure copper, therefore it is very suitable for casting various utensils, machinery parts, bearing, gear, etc.
Bronze is the earliest copper alloy used in history. And from early days, people have known different percentage of copper, tin or other elements like zinc and manganese will meet different purpose. For example, bronze chime has relatively high tin content, thus making a sonorous sound when it is struck. Zinc can improve hardness, so bearing usually contain a spot of zinc.
Brass consist of copper and zinc. It is usually used in manufacturing valve, water pipe, internal and external connecting pipe of air conditioner, radiator, etc. Brass can be generally divided into common brass and special brass. Common brass is the alloy of copper and zinc, which has been mentioned above. The content of zinc in brass changes greatly, which lead to the diversification of its tissue at room temperature.,thus causing different function. Special brass is adding some other elements into the common brass. The often-added elements are lead, tin, aluminum,manganese, etc. The purpose of this way is for improving tensile strength and weldability.
Cupronickel (also known as copper-nickel) is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Despite its high copper content, cupronickel is silver in color.
Cupronickel is highly resistant to corrosion in seawater because its electrode potential is adjusted to be neutral with regard to seawater. For this reason, it is used for piping, heat exchangers and condensers in seawater systems, marine hardware, and sometimes for the propellers,crankshafts and hulls of premium tugboats, fishing boats and other working boats.
Another common use of cupronickel is in silver-coloured modern-circulated coins. A typical mix is 75% copper, 25% nickel, and a trace amount of manganese. In the past, true silver coins were debased with cupronickel.