Uses of Copper
Classification based on various properties of copper
Conductivity of copper
One of the most important properties of copper is its excellent conductivity, with a conductivity of 58m/(Ω.mm squared). This property makes copper widely used in the electronics, electrical, telecommunications and electronics industries. This high conductivity of copper is related to its atomic structure: when multiple individual copper atoms are combined into a copper block, their valence electrons are no longer confined to the copper atoms, so they can move freely in all solid copper, and their conductivity is second only to silver. The international standard for the conductivity of copper is: the conductivity of a copper with a length of 1m and a weight of 1g at 20℃ is generally recognized as 100%. Current copper smelting technology can produce copper of the same grade with a conductivity that is 4%~5% higher than this international standard.
Thermal conductivity of copper
Another important effect of the presence of free electrons in solid copper is that it has extremely high thermal conductivity, which is 386W/(m.k), second only to silver. In addition, copper is more abundant than gold and silver and cheaper, so it is made into various products such as wires and cables, connector terminals, busbars, lead frames, etc., and is widely used in electronic, electrical, telecommunications and electronic industries. Copper is also a key material for various heat exchange equipment such as heat exchangers, condensers, and radiators. It is widely used in various heat exchange occasions such as power station auxiliary equipment, air conditioning, refrigeration, automobile water tanks, solar collector grids, seawater desalination, and medicine, chemical industry, metallurgy, etc.
Corrosion resistance of copper
Copper has good corrosion resistance, better than ordinary steel, and better than aluminum in alkaline atmosphere. The potential series of copper is +0.34V, which is higher than hydrogen and is a metal with a positive potential. The corrosion rate of copper in fresh water is also very low (about 0.05mm/a). And when copper pipes are used to transport tap water, minerals are not deposited on the pipe wall, which is far beyond the reach of iron water pipes. Because of this characteristic, copper water pipes, faucets and related equipment are widely used in high-end bathroom water supply devices. Copper is extremely resistant to atmospheric corrosion. It can form a protective film mainly composed of basic copper sulfate on its surface, namely patina, whose chemical composition is CuS04*Cu(OH)2 and CuSO4*3Cu(OH)2. Therefore, copper is used in building roof panels, rainwater pipes, upper and lower pipes, pipe fittings; chemical and pharmaceutical containers, reactors, pulp filters; ship equipment, propellers, life and fire protection pipe networks; punching coins (corrosion resistance), decorations, medals, trophies, sculptures and crafts (corrosion resistance and elegant color), etc.
