Copper is a chemical element, its chemical symbol is Cu, its atomic number is 29, is a kind of transition metal. The most common use of copper lies in the manufacture of wires. Usually the wires used are made of pure copper, because their conductivity and thermal conductivity are only inferior to silver, but much cheaper than silver. Copper can be used to make a variety of alloys. The important alloys of copper are as follows:

Brass: brass is an alloy of copper and zinc. It is famous for its yellow color. Brass has excellent mechanical and wear resistance, and can be used in the manufacture of fine instruments, parts of ships, cartridges of guns, etc. Brass ringing sounds sound, so gongs, cymbals, bells, and other instruments are made of brass.

The alloy of copper and zinc and tin, resistant to seawater corrosion, can be used to make parts and balancers for ships.

Bronze: the alloy of copper and tin is called bronze, and it is named because of the color green. Bronze has good corrosion resistance, wear resistance, casting and excellent mechanical properties. It is used for the manufacture of fine bearings, high pressure bearings, and marine corrosion resistant mechanical parts on ships, as well as all kinds of plates, pipes, bars and so on. Bronze also has a abnormal characteristic, "heat shrinkable and cold expansion", used to cast the statue, and the cooling after the expansion, can make the clue more clear.

P: copper and tin bronze, phosphorus alloy, solid, can spring.

Paktong: copper nickel alloy is an alloy of copper and nickel, and the color of silver, silver, not easy to rust. It is often used to make electrical appliances, appearances and ornaments. Eighteen karat gold (18 K). 6/24's alloy of copper and gold of 18/24. Red and yellow, large hardness, can be used to make jewelry, ornaments.