1. Pure copper
Pure copper is a rose-red metal, and it turns purple after a copper oxide film is formed on the surface, so industrial pure copper is often called red copper or electrolytic copper. The density is 8-9g/cm3 and the melting point is 1083°C. Pure copper has good electrical conductivity, and is widely used in the manufacture of wires, cables, brushes, etc.; it has good thermal conductivity, and is often used to manufacture magnetic instruments and instruments that must be protected from magnetic interference, such as compasses, aviation instruments, etc.; excellent plasticity, easy to heat Pressed and cold pressed, it can be made into copper materials such as pipes, rods, wires, strips, strips, plates, foils, etc. There are two kinds of pure copper products: smelted products and processed products.
2. Copper alloy
(1) Brass
Brass is an alloy of copper and zinc. The simplest brass is a copper-zinc binary alloy called simple brass or plain brass. Brass with different mechanical properties can be obtained by changing the zinc content in brass. The higher the zinc content in brass, the higher the strength and the lower the plasticity. The zinc content of brass used in the industry does not exceed 45%. No matter how high the zinc content is, it will cause brittleness and deteriorate the alloy properties.
In order to improve certain properties of brass, the brass that adds other alloying elements on the basis of one-dimensional brass is called special brass. Commonly used alloying elements are silicon, aluminum, tin, lead, manganese, iron and nickel. Adding aluminum to brass can improve the yield strength and corrosion resistance of brass, and slightly reduce the plasticity. Brass containing less than 4% aluminum has good comprehensive properties such as processing and casting. Adding 1% tin to brass can significantly improve the resistance of brass to seawater and marine atmospheric corrosion, so it is called "navy brass". Tin also improves the machinability of brass. The main purpose of adding lead to brass is to improve machinability and wear resistance, and lead has little effect on the strength of brass. Manganese brass has good mechanical properties, thermal stability and corrosion resistance; adding aluminum to manganese brass can also improve its performance and obtain castings with a smooth surface. Brass can be divided into two categories: cast and press-worked products. The chemical composition of commonly processed brass.
(2) Bronze
Bronze is one of the earliest alloys used in history. It originally refers to copper-tin alloys. It is called bronze because of its blue-gray color. In order to improve the technological properties and mechanical properties of the alloy, other alloying elements, such as lead, zinc, phosphorus, etc., are also added to most bronzes. Since tin is a scarce element, many tin-free Wuxi bronzes are also used in industry, which are not only cheap, but also have the required special properties. Wuxi bronze mainly includes aluminum bronze, beryllium bronze, manganese bronze, silicon bronze and so on. In addition, there are ternary or quaternary bronzes with more complex compositions. Now all copper alloys except brass and cupronickel (copper-nickel alloy) are called bronze.
Tin bronze has high mechanical properties, good corrosion resistance, anti-friction and good casting properties; small sensitivity to overheating and gas, good welding performance, no ferromagnetism, and small shrinkage coefficient. Tin bronze has higher corrosion resistance than brass in atmosphere, sea water, fresh water and steam. Aluminum bronze has higher mechanical properties than tin bronze, wear resistance, corrosion resistance, cold resistance, heat resistance, no ferromagnetism, good fluidity, no segregation tendency, and dense castings can be obtained. Adding elements such as iron, nickel and manganese to aluminum bronze can further improve various properties of the alloy.