Copper characteristics
Brass is an alloy of copper and zinc
White copper is an alloy of copper and nickel
Bronze is an alloy of copper and elements other than zinc and nickel, mainly tin bronze, aluminum bronze, etc.
Red copper is copper with a high copper content, and the total content of other impurities is less than 1%.
Red copper is pure copper, also known as red copper. The density of pure copper is 8.96 and the melting point is 1083℃. It has good electrical and thermal conductivity, excellent plasticity, and is easy to process by hot pressing and cold pressing. It is widely used in the manufacture of wires, cables, brushes, special electro-etching copper for electric sparks, and other products that require good conductivity.
It is named because of its purple-red color. It is not necessarily pure copper. Sometimes a small amount of deoxidizing elements or other elements are added to improve the material and performance, so it is also classified as a copper alloy. According to the composition, Chinese copper processing materials can be divided into four categories: ordinary 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 alloy elements (arsenic copper, tellurium copper, silver copper).
The electrical conductivity and thermal conductivity of copper are second only to silver, and it is widely used to make conductive and thermal conductive 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 output of copper exceeded the total output of other types of copper alloys.
Trace impurities in copper have a serious impact on the electrical and thermal conductivity of copper. Among them, titanium, phosphorus, iron, silicon, etc. significantly reduce the electrical conductivity, while cadmium, zinc, etc. have little effect. Oxygen, sulfur, selenium, tellurium, etc. have very low solid solubility in copper and can form brittle compounds with copper. They have 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 the grain boundary to produce high-pressure water vapor or carbon dioxide gas, which can cause copper to crack. This phenomenon is often called the "hydrogen disease" of copper. Oxygen is harmful to the weldability of copper. Bismuth or lead forms a low-melting point eutectic with copper, making copper hot and brittle; and when brittle bismuth is distributed in the form of a thin film at the grain boundary, it makes copper cold and brittle. Phosphorus can significantly reduce the conductivity of copper, but can increase the fluidity of copper liquid and improve weldability. Appropriate amounts of lead, tellurium, sulfur, etc. can improve machinability.
Brass: Copper alloys with zinc as the main additive element have a beautiful yellow color and are collectively called brass. Copper-zinc binary alloys are called ordinary brass or simple brass. Brasses with more than three elements are called special brass or complex brass. Brass alloys with a zinc content of less than 36% are composed of solid solutions and have good cold working properties. For example, brass with a zinc content of 30% is often used to make cartridge cases, commonly known as cartridge brass or 73 brass. Brass alloys with a zinc content between 36% and 42% are composed of solid solutions, of which 64 brass with a zinc content of 40% is the most commonly used. In order to improve the performance of ordinary brass, other elements such as aluminum, nickel, manganese, tin, silicon, and lead are often added. Aluminum can improve the strength, hardness, and corrosion resistance of brass, but reduce its plasticity, making it suitable for sea-going condensers and other corrosion-resistant parts. Tin can improve the strength and corrosion resistance of brass to seawater, so it is called naval brass, which is used for ship thermal equipment and propellers. Lead can improve the cutting performance of brass; this easy-to-cut brass is often used as watch parts. Brass castings are often used to make valves and pipe fittings.
Bronze: Originally refers to copper-tin alloys. Later, copper alloys other than brass and nickel silver were called bronze, and the name of the first main added element was often added before the name of bronze. Tin bronze has good casting performance, anti-friction performance and mechanical properties, and is suitable for manufacturing bearings, worm gears, gears, etc. Lead bronze is a widely used bearing material for modern engines and grinders. Aluminum bronze has high strength, good wear resistance and corrosion resistance, and is used to cast high-load gears, bushings, marine propellers, etc. Beryllium bronze and phosphor bronze have high elastic limits and good conductivity, and are suitable for manufacturing precision springs and electrical contact elements. Beryllium bronze is also used to manufacture spark-free tools used in coal mines, oil depots, etc.
Nickel silver: a copper alloy with nickel as the main added element. Copper-nickel binary alloy is called ordinary nickel silver; nickel silver alloys with manganese, iron, zinc, aluminum and other elements are called complex nickel silver. Industrial nickel silver is divided into two categories: structural nickel silver and electrical nickel silver. Structural nickel silver is characterized by good mechanical properties and corrosion resistance, and beautiful color. This type of nickel silver is widely used in the manufacture of precision machinery, chemical machinery and ship components. Electrical nickel silver generally has good thermoelectric properties.
Manganese copper, constantan and corundum are manganese copper with different manganese contents. They are materials used to manufacture precision electrical instruments, rheostats, precision resistors, strain gauges, thermocouples, etc.
1. Brass
(1) 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 a single phase a, called single-phase brass, which has good plasticity and is suitable for hot and cold pressure processing. When the zinc content is greater than 39%, there is a single phase a and a copper-zinc-based solid solution b, called dual-phase brass. b makes the plasticity small and the tensile strength increases, which is only suitable for hot pressure processing. If the mass fraction of zinc continues to increase, the tensile strength decreases and it has no use value. The code is represented by "H + number", H represents brass, and the number represents the mass fraction of copper. For example, H68 indicates brass with a copper content of 68% and a zinc content of 32%. For cast brass, the letter "Z" is placed before the code, such as ZH62. For example, Zcuzn38 indicates cast brass with a zinc content of 38% and the remainder being copper. H90 and H80 are single-phase and golden yellow, so they are collectively referred to as gold, and are called plating, decorations, medals, etc. H68 and H59 are duplex brass, which are widely used in electrical structural parts, such as bolts, nuts, washers, springs, etc. In general, single-phase brass is used for cold deformation processing and duplex brass is used for hot deformation processing.
(2) Special brass: A multi-element alloy composed of other alloying elements added to ordinary brass is called brass. Commonly added elements include lead, tin, aluminum, etc., which can be called lead brass, tin brass, and aluminum brass accordingly. The purpose of adding alloying elements. Mainly to improve tensile strength and processability. Code: "H + symbol of main added element (except zinc) + mass fraction of copper + mass fraction of main added element + mass fraction of other elements". For example, HPb59-1 means lead brass with a mass fraction of 59% copper, a mass fraction of 1% lead as main added element, and the remainder is zinc.
2. Bronze: Except brass and nickel silver, other copper alloys are collectively called bronze. Bronze can be divided into tin bronze and special bronze (i.e. tin-free bronze). Code: The representation method is composed of "Q + symbol and mass fraction of main added element + mass fraction of other elements". Casting products are preceded by "Z", such as: Qal7 means aluminum bronze with 7% aluminum and the rest copper. ZQsn10-1 means cast tin bronze with a tin content of 10%, other alloying elements of 1%, and the remainder copper.
(1) Tin bronze: a copper-tin alloy with tin as the main added 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, so the tin content of the 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. Since the a and & electrode potentials are similar, and the tin in the composition forms a dense tin dioxide film after nitridation, the corrosion resistance to the atmosphere and seawater increases, but the acid resistance is poor. Because the crystallization temperature range of tin bronze is wide, the fluidity is poor, it is not easy to form concentrated shrinkage cavities, but it is easy to form dendrite segregation and dispersed shrinkage cavities, and the casting shrinkage rate is small, which is conducive to obtaining castings with sizes very close to the casting mold, so it is suitable for casting complex shapes. The condition of thick wall is not suitable for casting castings requiring high density and good sealing. Tin bronze has good anti-friction, anti-magnetic and low-temperature toughness. Tin bronze can be divided into two categories according to the production method: pressure-processed tin bronze and cast tin bronze.
A. Pressure-processed tin bronze: The tin content is generally less than 8%, and it is suitable for cold and hot pressure processing into plates, strips, rods, tubes and other profiles. After hardening, its tensile strength and hardness increase, while its plasticity decreases. After annealing, it can maintain high tensile strength while improving plasticity, especially obtaining a high elastic limit. It is suitable for instruments that require corrosion-resistant and wear-resistant parts, elastic parts, anti-magnetic parts, and sliding bearings and sleeves in machines. Commonly used ones are Qsn4-3 Qsn6.5~0.1.
B. Cast tin bronze: It is supplied as ingots and cast into castings by the foundry. It is suitable for casting castings with complex shapes but low density requirements, such as sliding bearings, gears, etc. Commonly used ones are ZQsn10-1 ZQsn6-6-3.
(2) Special bronze: other elements are added to replace tin, or it is tin-free bronze. Most special bronzes have higher mechanical properties, wear resistance and corrosion resistance than tin bronze. Commonly used ones include aluminum bronze (QAL7 QAL5) and lead bronze (ZQPB30). Copper-based alloys with nickel as the main added element are silvery white and are called white copper. The nickel content is usually 10%, 15%, and 20%. The higher the content, the whiter the color. Copper-nickel binary alloys are called ordinary white copper. Copper-nickel alloys with manganese, iron, zinc, and aluminum are called complex white copper. Pure copper plus nickel can significantly improve strength, corrosion resistance, electrical resistance, and thermoelectric properties. Industrial white copper is divided into structural white copper and electrical white copper according to different performance characteristics and uses, which meet various corrosion resistance and special electrical and thermal properties respectively.
Typical grades, chemical composition (%) (mass fraction): Sn (tin), Al (aluminum), Fe (iron), Pb (lead), Sb (antimony), Bi (bismuth), Si (silicon), P (phosphorus), Cu, total impurities.
