Copper is utilized by people in the form of a wide variety of metals, alloys, and compounds, and has deeply penetrated into various aspects of production and life, becoming an indispensable and important metal for humanity to achieve rapid development in the 21st century.

Definition of Copper

Copper is a chemical element with the chemical symbol Cu and an atomic number of 29. It is a transition metal. The most common use of copper is in the manufacture of wires, and currently used wires are usually made of pure copper because its conductivity and thermal conductivity are second only to silver, but much cheaper than silver.

Common Categories

Many people believe that there is only one type of copper. It's the only one. But there are actually other types of copper. For example, alloy copper; Brass is an alloy composed 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; Purple copper is copper with a high copper content, with a total impurity content of less than 1%.

Classification of copper processing materials: copper sulfate, copper chloride, copper rod, copper bar, copper ingot, copper plate, copper wire, copper alloy, rough copper, copper strip, copper oxide, copper foil, copper tube, copper foil, copper paste, copper casting, electrolytic copper, other copper alloy copper materials.

Various shapes including rods, wires, plates, strips, bars, tubes, foils, etc. made of pure copper or copper alloys are collectively referred to as copper materials. The processing of copper materials includes rolling, extrusion, and drawing methods, and the plates and strips in copper materials can be hot-rolled or cold-rolled; And both strip and foil are cold-rolled; Pipes and bars are divided into extruded and drawn products; The wires are all pulled products.

Pure copper

Pure copper is a rose red metal with a purple color after forming a copper oxide film on its surface, so industrial pure copper is often called purple copper or electrolytic copper. Density of 8-9g/cm?, Melting point of 1083 ℃. Pure copper has good conductivity and is widely used in the manufacture of wires, cables, electric brushes, etc; Good thermal conductivity, commonly used to manufacture magnetic instruments and meters that require anti magnetic interference, such as compasses, aviation instruments, etc; Excellent plasticity, easy to process by hot and cold pressing, can be made into copper materials such as pipes, rods, wires, strips, strips, plates, foils, etc. There are two types of pure copper products: smelting products and processed products.

Chinese purple copper processing materials can be divided into four categories according to their composition: ordinary purple copper (T1, T2, T3, T4), oxygen free copper (TU1, TU2 and high-purity, vacuum oxygen free copper), deoxidized copper (TUP, TUMn), and special copper with a small amount of alloying elements added (arsenic copper, tellurium copper, silver copper).

The conductivity and thermal conductivity of pure copper are second only to silver, and it is widely used in the production of conductive and heat-conducting equipment. Copper has good corrosion resistance in the atmosphere, seawater, certain non oxidizing acids (hydrochloric acid, dilute sulfuric acid), alkalis, salt solutions, and various organic acids (acetic acid, citric acid), and is used in the chemical industry. In addition, copper has good weldability and can be processed into various semi-finished and finished products through cold and hot plastic processing. In the 1970s, the production of purple copper exceeded the total production of other types of copper alloys.

Trace impurities in pure copper have a serious impact on the conductivity and thermal conductivity of copper. Among them, titanium, phosphorus, iron, silicon, etc. significantly reduce conductivity, while cadmium, zinc, etc. have little effect. The solid solubility of oxygen, sulfur, selenium, tellurium, etc. in copper is very low, and they can form brittle compounds with copper, which has little effect on conductivity but can reduce processing plasticity. When ordinary copper is heated in a reducing atmosphere containing hydrogen or carbon monoxide, hydrogen or carbon monoxide easily reacts with cuprous oxide (Cu2O) at grain boundaries, producing high-pressure water vapor or carbon dioxide gas, which can cause copper to fracture. This phenomenon is often referred to as the "hydrogen disease" of copper. Oxygen is harmful to the weldability of copper. Bismuth or lead forms low melting point eutectic with copper, causing copper to become thermally brittle; When brittle bismuth is distributed in a thin film at grain boundaries, it causes copper to become cold brittle. Phosphorus can significantly reduce the conductivity of copper, but it can improve the fluidity of copper liquid and enhance weldability. Moderate amounts of lead, tellurium, sulfur, etc. can improve machinability.

brass

Brass is an alloy of copper and zinc. The simplest brass is a binary alloy of copper and zinc, known as simple brass or ordinary brass. Changing the zinc content in brass can result in brass with different mechanical properties. The higher the content of zinc in brass, the higher its strength and lower its plasticity. Brass used in industry has a zinc content of no more than 45%. Any higher zinc content will result in brittleness and deteriorate the alloy's properties. Brass can be divided into two types of products: casting and pressure processing.

Ordinary brass

It is an alloy composed of copper and zinc. When the zinc content is less than 39%, zinc can dissolve in copper to form single-phase a, which is called single-phase brass. It has good plasticity and is suitable for cold and hot pressure processing. When the zinc content is greater than 39%, there are a single-phase and a copper zinc based b solid solution, called biphasic brass. b reduces plasticity and increases tensile strength, making it only suitable for hot pressure processing.

The code is represented by "H+number", where H represents brass and the number represents the mass fraction of copper. H68 represents brass with a copper content of 68% and a zinc content of 32%; When casting brass, the letter "Z" should be placed before the code, such as ZH62.

H90 and H80 are single-phase and golden in color, hence they are collectively referred to as gold and are called coatings, decorations, medals, etc. H68 and H59 belong to duplex brass and are widely used in structural components of electrical appliances, such as bolts, nuts, washers, springs, etc.

In general, single-phase brass is used for cold deformation processing, and two-phase brass is used for hot deformation processing.

special brass 

The multi-element alloy composed of adding other alloying elements to ordinary brass is called brass. The commonly added elements include lead, tin, aluminum, etc., which can be referred to as lead brass, tin brass, aluminum brass, etc. The purpose of adding alloying elements. Mainly to improve tensile strength and processability.

Code: It is represented by "H+main additive element symbol (excluding zinc)+mass fraction of copper+mass fraction of main additive element+mass fraction of other elements". For example, HPb59-1 represents lead brass with a mass fraction of 59% copper, 1% lead as the main additive element, and the remaining zinc.

bronze

Bronze is one of the earliest alloys used in history, originally referring to copper tin alloy. Due to its bluish gray color, it is called bronze. In order to improve the process and mechanical properties of alloys, most bronze is also added with other alloying elements such as lead, zinc, phosphorus, etc. Due to tin being a scarce element, many tin free Wuxi bronzes are still used in industry. They are not only cheap, but also have the required special properties. Bronze is also divided into two categories: pressure processing and casting products.

Code: The representation method consists of "Q+main element symbol and mass fraction+mass fraction of other elements". For cast products, the letter "Z" should be added before the code. For example, Qal7 represents aluminum bronze with 5% aluminum content, while ZQsn10-1 represents cast tin bronze with 10% tin content, 1% other alloy element content, and the remaining copper content.

Bronze can be divided into two types: tin bronze and special bronze (i.e. Wuxi bronze).

(1) It is a copper tin alloy with tin as the main additive element, also known as tin bronze. When the tin content is less than 5-6%, tin dissolves in copper to form a solid solution, and the plasticity increases. When the tin content is greater than 5-6%, due to the appearance of Cu31Sb8 based solid solution, the tensile strength decreases. Therefore, the tin content of tin bronze is mostly between 3-14%. When the tin content is less than 5%, it is suitable for cold deformation processing, and when the tin content is 5-7%, it is suitable for hot deformation processing. When the tin content is greater than 10%, it is suitable for casting.

Due to the similar potential between a and the electrode, and the formation of a dense tin dioxide film after tin nitridation in the composition, the corrosion resistance to atmospheric and seawater increases, but the acid resistance is poor.

Due to the wide range of crystallization temperature and poor fluidity of tin bronze, it is not easy to form concentrated shrinkage pores, but prone to dendritic segregation and dispersed shrinkage pores. The casting shrinkage rate is small, which is conducive to obtaining castings with sizes very close to the mold. Therefore, it is suitable for casting complex shapes and large wall thicknesses, but not suitable for casting castings with high density and good sealing requirements. Tin bronze has good anti friction, anti magnetism, and low-temperature toughness.

Tin bronze can be divided into two categories based on production methods: pressure processed tin bronze and cast tin bronze.

A、 The tin content of pressure processed tin bronze is generally less than 8%, and it is suitable for cold and hot pressure processing into profiles such as plates, strips, rods, and tubes for supply. After work hardening, its tensile strength and hardness increase, while its plasticity decreases. After annealing, it can improve plasticity while maintaining high tensile strength, especially achieving high elastic limit. The commonly used components for instruments that require corrosion resistance and wear resistance, elastic components, anti magnetic components, as well as sliding bearings and shaft sleeves in machines include Qsn4-3Qsn6.5~0.1.

B、 Cast tin bronze is supplied as ingots and used in casting workshops for casting castings. It is suitable for casting castings with complex shapes but low density requirements, such as sliding bearings, gears, etc. The commonly used ones are ZQsn10-1ZQsn6-6-3.

Special bronze is added with other elements to replace tin, or Wuxi bronze. Most special bronzes have higher mechanical properties, wear resistance, and corrosion resistance than tin bronze. Commonly used ones include aluminum bronze (QAL7QAL5) and lead bronze (ZQPB30). Copper based alloys with nickel as the main additive element appear silver white and are called white copper. The nickel content is usually 10%, 15%, and 20%, and the higher the content, the whiter the color. Copper nickel binary alloys are called ordinary white copper, while copper nickel alloys with added elements such as manganese, iron, zinc, and aluminum are called complex white copper. Adding nickel to pure copper can significantly improve strength, corrosion resistance, resistance, and thermoelectric properties. Industrial white copper is divided into two types based on its performance characteristics and applications: structural white copper and electrical white copper, which respectively meet various corrosion resistance and special electrical and thermal properties.

White copper

White copper is a copper based alloy with nickel as the main additive element, which appears silver white and is called white copper. Copper nickel binary alloys are called ordinary white copper, while copper nickel alloys with added elements such as manganese, iron, zinc, and aluminum are called complex white copper. Adding nickel to pure copper can significantly improve strength, corrosion resistance, resistance, and thermoelectric properties. Industrial white copper is divided into two types based on its performance characteristics and applications: structural white copper and electrical white copper, which respectively meet various corrosion resistance and special electrical and thermal properties.

Identification method

White copper, brass, red copper (also known as "purple copper"), and bronze (bluish gray or grayish yellow) are distinguished by color. Among them, white copper and brass are easily distinguishable; Red copper is slightly difficult to distinguish between pure copper (impurities<1%) and bronze (other alloy components around 5%). When unoxidized, the color of red copper is brighter than that of bronze, and bronze has a slight bluish or yellowish tint that is darker; After oxidation, red copper turns black, while bronze appears blue-green (harmful oxidation caused by excessive water) or chocolate colored.

Article source: Internet

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