Copper is used in a wide variety of metals, alloys, and compounds, and has deeply permeated every aspect of production and life, becoming an indispensable metal for humanity's rapid development in the 21st century.
Definition of Copper
Copper is a chemical element with the chemical symbol Cu and atomic number 29. It is a transition metal. Copper's most common use is in electrical wiring. Current electrical wiring is typically made of pure copper because its electrical and thermal conductivity are second only to silver, yet it is much cheaper.
Common Classifications
Many people believe that there is only one type of copper. However, there are actually many different types of copper. For example, copper alloys; brass is an alloy of copper and zinc; white copper is an alloy of copper and nickel; bronze is an alloy of copper with elements other than zinc and nickel, primarily tin bronze and aluminum bronze; and red copper is copper with a very high copper content, with the total impurity content below 1%. Copper materials include copper sulfate, copper chloride, copper rods, copper bars, copper ingots, copper plates, copper wire, copper alloys, crude copper, copper strip, copper oxide, copper foil, copper tubes, copper foil, copper sludge, copper castings, electrolytic copper, and other copper alloys.
Copper materials are any material made from pure copper or copper alloys in various shapes, including rods, wire, plates, strips, bars, tubes, and foil. Copper materials are processed by rolling, extrusion, and drawing. Plates and bars are either hot-rolled or cold-rolled, while strips and foil are cold-rolled. Tubes and bars are either extruded or drawn, and wire is drawn.
1. Pure Copper
Pure copper is a rose-red metal that becomes purple after a copper oxide film forms on its surface. Therefore, industrial pure copper is often called red copper or electrolytic copper. With a density of 8-9 g/cm² and a melting point of 1083°C, pure copper has excellent electrical conductivity and is widely used in the manufacture of wires, cables, brushes, and other materials. It also has excellent thermal conductivity and is often used in the manufacture of magnetic instruments and meters that must be protected against magnetic interference, such as compasses and aviation instruments. Its excellent plasticity makes it easy to hot-press and cold-form, and can be made into tubes, rods, wires, strips, strips, plates, foil, and other materials. Pure copper products come in both smelted and processed forms.
Chinese processed copper materials can be divided into four categories based on their composition: ordinary copper (T1, T2, T3, and T4), oxygen-free copper (TU1, TU2, and high-purity, vacuum-free copper), deoxidized copper (TUP and TUMn), and specialty coppers with small amounts of alloying elements (arsenic copper, tellurium copper, and silver copper).
Pure copper's electrical and thermal conductivity is second only to silver, making it widely used in the manufacture of electrical and thermal conductive materials. Red copper exhibits excellent corrosion resistance in air, seawater, certain non-oxidizing acids (hydrochloric acid, dilute sulfuric acid), alkalis, saline solutions, and various organic acids (acetic acid, citric acid), making it used in the chemical industry. Red copper also exhibits excellent weldability and can be processed through cold and hot plastic processing into a variety of semi-finished and finished products. In the 1970s, the production of red copper exceeded the total output of all other copper alloys.
Trace impurities in pure copper have a significant impact on its electrical and thermal conductivity. Titanium, phosphorus, iron, and silicon significantly reduce electrical conductivity, while cadmium and zinc have minimal impact. Oxygen, sulfur, selenium, and tellurium have low solid solubility in copper and can form brittle compounds with it. This has little impact on electrical conductivity, but can reduce processing plasticity. When ordinary red copper is heated in a reducing atmosphere containing hydrogen or carbon monoxide, the hydrogen or carbon monoxide reacts with cuprous oxide (Cu2O) at grain boundaries, generating high-pressure water vapor or carbon dioxide gas, which can cause the copper to crack. This phenomenon is often referred to as copper's "hydrogen disease." Oxygen is detrimental to copper weldability. Bismuth or lead form a low-melting-point eutectic with copper, causing hot brittleness. When brittle bismuth forms thin films at grain boundaries, it causes cold brittleness. Phosphorus significantly reduces copper conductivity, but it increases the fluidity of molten copper and improves weldability. Appropriate amounts of lead, tellurium, and sulfur can improve machinability.
2. 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. Varying the zinc content in brass can produce brass with varying mechanical properties. A higher zinc content increases its strength and reduces its ductility. Industrially used brass should contain no more than 45% zinc. Higher zinc contents will cause brittleness and deteriorate the alloy's properties. Brass can be categorized as cast or press-worked.
Brass is further categorized as follows:
1) Ordinary brass
It is an alloy of copper and zinc. When the zinc content is less than 39%, zinc dissolves in the copper to form a single phase, called single-phase brass. This has excellent plasticity and is suitable for hot and cold press working. When the zinc content exceeds 39%, the brass contains both single-phase brass (a) and a copper-zinc solid solution (b), known as duplex brass. The phase (b) reduces plasticity but increases tensile strength, making it suitable only for hot press working.
The designation is "H + a number," where H represents brass and the number represents the mass fraction of copper. For example, H68 represents brass with a copper content of 68% and a zinc content of 32%. Cast brass has a "Z" before the designation, such as ZH62.
H90 and H80 are single-phase brass with a golden color, hence the common name "gold." They are used for plating, decorations, medals, and the like. H68 and H59 are duplex brass, widely used in electrical components such as bolts, nuts, washers, and springs. Generally, single-phase brass is used for cold deformation, while duplex brass is used for hot deformation.
2) Special Brasses
Alloys formed by adding other alloying elements to ordinary brass are called brasses. Commonly added elements include lead, tin, and aluminum, resulting in corresponding names such as lead brass, tin brass, and aluminum brass. The purpose of adding alloying elements is primarily to increase tensile strength and improve processability.
The designation is "H + symbol of the main added element (excluding zinc) + mass fraction of copper + mass fraction of the main added 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 added element, and the balance being zinc.
3. Bronze
Bronze is one of the earliest alloys used in history. Originally referring to a copper-tin alloy, it was called bronze because of its bluish-gray color. To improve the alloy's processability and mechanical properties, most bronzes also contain other alloying elements such as lead, zinc, and phosphorus. Because tin is a scarce element, many tin-free, tin-free bronzes are used in industry. These are not only inexpensive but also possess the desired special properties. Bronze is also divided into two categories: press-worked and cast products.
Codes: The designation consists of "Q + the symbol and mass fraction of the primary element + the mass fractions of other elements." Cast products are prefixed with a "Z." For example, Qal7 represents aluminum bronze with 5% aluminum and the balance copper. ZQsn10-1 represents cast tin bronze with 10% tin, 1% other alloying elements, and the balance copper. Bronze is further divided into tin bronze and special bronze (also known as tin-free bronze). (1) A copper-tin alloy with tin as the main 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 a solid solution based on Cu31Sb8, 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. 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. Because a is close to the electrode potential, and the tin in the composition forms a dense tin dioxide film after nitriding, the corrosion resistance to the atmosphere and seawater is increased, but the acid resistance is poor. Because tin bronze has a wide crystallization temperature range and poor fluidity, it is less likely to form concentrated shrinkage cavities, but more likely to form dendritic segregation and dispersed shrinkage cavities. Its low casting shrinkage allows for castings with dimensions very close to the mold. Therefore, it is suitable for casting complex shapes and thicker walls, but not for castings requiring high density and tightness. Tin bronze exhibits excellent anti-friction properties, anti-magnetic properties, and low-temperature toughness. Based on its production method, tin bronze can be divided into two categories: press-formed tin bronze and cast tin bronze.
A. Press-Formed Tin Bronze
Tin content is generally less than 8%. It is suitable for hot or cold press forming into profiles such as plates, strips, rods, and tubes. After work hardening, its tensile strength and hardness increase, while its ductility decreases. Annealing can improve ductility while maintaining high tensile strength, particularly achieving a high elastic limit. Commonly used grades include Qsn4-3 and Qsn6.5-0.1 for corrosion- and wear-resistant instrumentation, elastic components, anti-magnetic components, and sliding bearings and bushings in machinery. B. Cast Tin Bronze
Supplied as ingots, it is cast into castings in the foundry. It is suitable for castings with complex shapes but low density requirements, such as sliding bearings and gears. Commonly used grades include ZQSN10-1 and ZQSN6-6-3.
2) Special Bronze
Other elements are added to replace tin, or tin-free bronzes are used. Most special bronzes offer higher mechanical properties, wear resistance, and corrosion resistance than tin bronzes. Commonly used grades include aluminum bronze (QAL7 and QAL5) and lead bronze (ZQPB30).
Copper-based alloys with nickel as the primary additive are silvery white and are called white copper. Nickel content is typically 10%, 15%, or 20%, with 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 significantly improves strength, corrosion resistance, electrical resistance, and thermoelectric properties. Industrial cupronickel is divided into structural cupronickel and electrical cupronickel according to its performance characteristics and uses, which respectively meet various corrosion resistance and special electrical and thermal properties.
4. Copper-based alloys with nickel as the primary additive are silvery white and are 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 significantly improves its strength, corrosion resistance, electrical resistance, and thermoelectric properties. Industrial white copper is divided into structural white copper and electrical white copper, depending on its performance characteristics and application, meeting various corrosion resistance requirements and specific electrical and thermal properties.
The company has a cluster of leading copper processing production lines in China, including:
German imported precision copper tube production line (annual output of 30,000 tons)
Japanese technology copper foil rolling line (thinnest up to 6μm)
Fully automatic copper bar continuous extrusion line
Intelligent copper sheet and strip finishing mill unit
Digitalized control and management of the whole production process is realized through MES system, and the dimensional accuracy of the products can reach ±0.01mm.
