Pure copper

Pure copper is a rose red metal, the surface of the formation of copper oxide film is purple, so industrial pure copper is often called copper or electrolytic copper. It has a density of 8-9g/cm3 and a melting point of 1083°C. Pure copper conductivity is very good, a large number of used in the manufacture of wire, cable, brush and so on; Good thermal conductivity, commonly used to manufacture magnetic instruments, instruments, such as compasses, Aeronautical instrument Etc.; Excellent plasticity, easy to hot press and cold pressure processing, can be made into tubes, rods, wires, strips, belts, plates, foils and other copper materials ^[1] .

(T1, T2, T3), Oxygen-free copper (oxygen free copper, silver oxygen free copper, zirconium oxygen free copper and dispersion oxygen free copper), Phosphorus deoxidized copper Special copper with a small amount of alloying elements (arsenic copper, Tellurium copper Silver copper, sulfur copper and zirconium copper) four categories. coppery Electric conductivity and Thermal conductivity Second only to silver, widely used in the production of electrical and thermal conductivity equipment. Copper in the atmosphere, seawater and certain Non-oxidizing acid (Hydrochloric acid, Dilute sulfuric acid ), alkali, salt solution and various organic acids ( Acetic acid Citric acid), has good corrosion resistance, used in the chemical industry. In addition, copper has good weldability, can be cooled, thermoplasticity Processed into a variety of semi-finished products and finished products. In the 1970s, the production of red copper exceeded that of other types Copper alloy Total output.

Pure copper Electrical resistivity Theoretical value if the length of various materials is 1 meter, the cross-sectional area is 1 Square millimeter To measure their resistance (called the resistivity of this material) at 20 ° C and compare, the resistivity of silver is the smallest, followed by copper, aluminum, tungsten, iron, copper, iron, and copper. manganin , nichrome In the sequence, the resistivity increases in turn.

The resistivity of aluminum wire is more than 1.5 times that of copper wire, and its resistivity p=0.0294Ωmm 2 /m, the resistivity of copper p= 0.01851Ω ·mm2/m, resistivity changes with temperature will have some differences ^[1] .

Many black merchants in order to deceive consumers, through the process of plating copper color, or other processes to make copper color, the cheap iron as the so-called pure copper to sell. In fact, it is very simple, we can identify by its density, magnetic field and so on. The specific gravity of iron and copper is similar, but copper is not attracted to magnets. Many people who buy scrap products use special strong magnetism to determine whether it is pure copper. Of course, we can also use the speaker at home or other objects containing magnets to test whether the items we buy are really pure copper. The greater the suction, the greater the iron content. Other metal raw materials that can be attracted by magnets are more expensive, such as nickel, cobalt and other metals they will not add.

This method can only be sure that it is not pure copper that can be attracted by the magnet. However, what is not attracted by the magnet is not necessarily pure copper, and it may also be an alloy with other raw materials. For example, most of the utensils in our daily life use copper and zinc alloys, that is," Orichalcum ". Pure copper is purplish red from the inside out, so it is called Red copper . For some wires, the color can be viewed on the appearance of the vessel, generally scraping off the outer layer, or observing the section, the pure copper that is purple and red inside and outside is likely to be large ^[2] .

Pure copper has a much wider range of uses than iron, and a large amount of copper is used in the electrical industry every year. Pure copper is mainly used in the production of electrical equipment such as generators, busbars, cables, switching devices, transformers and heat exchangers, pipelines, solar heating devices Plate collector Such as thermal conductivity equipment. The oxygen content of copper (it is easy to mix a small amount of oxygen in copper smelting) has a great impact on the conductivity, and the copper used in the electrical industry must generally be oxygen-free copper. Pure copper is also mainly used in the production of motor short-circuit rings, electromagnetic heating sensors, and high-power electronic components, wiring bar terminals and the like. Pure copper is also used in doors, Windows, handrails and other furniture and decoration ^[3] .