1、 Common classification
Brass is an alloy of copper and zinc
White copper is an alloy of copper and nickel
Bronze is an alloy formed by copper and elements other than zinc and nickel, mainly including tin bronze, aluminum bronze, etc
Red copper is copper with high copper content, and the total content of other impurities is less than 1%.
1. Red copper
Red copper is pure copper, also known as red copper. The density of pure copper is 8.90, and the point is 1083 ° C. It has good conductivity and thermal conductivity, excellent plasticity, and is easy to be hot pressed and cold pressed. It is widely used in the manufacture of wire, cable, brush, electric spark and other products requiring good conductivity.
It gets its name from its purplish red color. It is not necessarily pure copper, and sometimes a small amount of deoxidizing elements or other elements are added to improve the material and performance, so it is also included in the copper alloy. Chinese red copper processing materials can be divided into four categories according to composition: ordinary red copper (T1, T2, T3, T4), oxygen free copper (TU1, TU2 and high-purity, vacuum oxygen free copper), deoxidized copper (TUP, Tumn), and special copper (arsenic copper, tellurium copper, silver copper) added with a small amount of alloy elements.
The conductivity and thermal conductivity of red copper are second only to silver, and it is widely used to make conductive and thermal conductive materials. Red copper has good corrosion resistance in sea water, some non oxidizing acids (hydrochloric acid, dilute sulfuric acid), alkali, salt solutions and a variety of organic acids (acetic acid and citric acid), and is used in the chemical industry. In addition, red copper has good weldability and can be made into various semi-finished products and finished products through cold and thermoplastic processing. In the 1970s, the output of red copper exceeded the total output of other copper alloys.
The trace impurities in red copper have a serious impact on the conductivity and thermal conductivity of copper. Among them, titanium, phosphorus, iron and silicon significantly reduce the conductivity, while cadmium and zinc have little effect. The solid solubility of oxygen, sulfur, selenium, tellurium, etc. in copper is very small, and they can form brittle compounds with copper, which has little effect on conductivity, but can reduce processing plasticity. When ordinary red copper is heated in a reducing atmosphere containing hydrogen or carbon monoxide, hydrogen or carbon monoxide is easy to react with cuprous oxide (Cu20) at the grain boundary, generating high-pressure water vapor or carbon dioxide gas, which can crack copper. This phenomenon is often called the "hydrogen disease" of copper. Oxygen is harmful to the solderability of copper. Bismuth or lead and copper form low melting point eutectic, which makes copper produce hot brittleness and brittle bismuth distributed at the grain boundary in the form of film, and makes copper produce cold brittleness. Phosphorus can significantly reduce the conductivity of copper, but it can improve the fluidity of copper liquid and improve the solderability. An appropriate amount of lead, tellurium, sulfur, etc. can improve the machinability.
2. Brass
Copper alloy with zinc as the main addition element has beautiful yellow color, which is generally called brass. The copper zinc binary alloy is called ordinary brass or simple brass. Brass with more than three yuan is called special brass or complex brass. Brass alloys containing less than 36% zinc are composed of solid solutions and have good cold workability. For example, brass containing 30% zinc is often used to make cartridge cases, commonly known as cartridge case brass or 73 brass. Brass alloys containing zinc between 36% and 42% are composed of and solid solutions, of which the most commonly used is 64% brass containing 40% zinc. In order to improve the performance of ordinary brass, other elements are often added, such as aluminum, nickel, manganese, tin, silicon, lead, etc. Aluminum can improve the strength, hardness and corrosion resistance of brass, but reduce the plasticity. It is suitable for use as condensing tubes and other corrosion resistant parts of seagoing ships. Tin can improve brass