The most commonly used copper and its alloys are: pure copper, brass, bronze, etc. The appearance of pure copper is red-yellow. In the air, the surface will form a purple-red dense film due to oxidation, so it is also called red copper. The electrical conductivity and thermal conductivity of pure copper are very good, second only to silver. It also has high chemical stability and good corrosion resistance in the atmosphere and fresh water. Usually, in a humid environment, it is easy to generate basic copper carbonate (commonly known as patina). Pure copper has good plasticity but low mechanical strength. Industrial pure copper often contains a certain amount of oxygen, sulfur, lead, bismuth, arsenic and other impurity elements. Small amounts of arsenic can increase copper’s strength, hardness, and reduce electrical and thermal conductivity. The rest of the impurity elements are harmful. Pure copper is mainly used to manufacture wires, electrical components and various copper materials in industry. Among them, oxygen-free pure copper is used as electric vacuum components.
Brass is an alloy of copper and zinc. When the zinc content of brass is below 32, the plasticity is good, suitable for cold and hot processing, and toughness is strong, but the cutting performance is poor. In order to improve some properties of brass, a small amount of other elements are often added, such as aluminum, manganese, tin, silicon, lead, etc. This brass is called special brass. Brass is used in thermal power plants to make heat exchange tubes for steam turbine condensers. For example, the N-11200-1 type condenser copper tube material used in the domestic 200,000-kilowatt steam turbine is: generally 77-2 aluminum brass in the pure seawater area, and 70-1 tin brass in the fresh water area.
Post time: May-17-2022