Classification and application fields of copper

1. Common classification: Brass is an alloy composed of copper and zinc. White copper is an alloy of copper and nickel. Bronze is an alloy formed of copper and elements other than zinc and nickel. There are mainly tin bronze, aluminum bronze and other copper. Copper content Very high copper,
The total content of other impurities is below 1%.
1. Copper:
Red copper is pure copper, also known as red copper. The density of pure copper is 8.96 and the melting point is 1083 ° C. It has good electrical conductivity and thermal conductivity, excellent plasticity, and is easy to be processed by hot and cold pressure. It is widely used in the manufacture of wires, cables, brushes, electric corrosion copper for sparks and other products that require good conductivity.
Named for being purple-red. 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 classified as a copper alloy. Chinese copper processing materials can be divided into ordinary copper (T1, T2, T3, T4), oxygen-free copper (TU1, TU2 and high purity, vacuum oxygen-free copper), deoxidized copper (TUP, TUMn), and a small amount of alloy Elements of special copper (copper arsenic, tellurium copper, silver copper) four categories.
The electrical conductivity and thermal conductivity of copper is second only to silver, and it is widely used to make electrical and thermal equipment. Red copper has good corrosion resistance in the atmosphere, sea water and 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 made into various semi-finished products and finished products by cold and thermoplastic processing. In the 1970s, the output of red copper exceeded the total output of other types of copper alloys.
Trace impurities in red copper have a serious impact on the electrical and thermal conductivity of copper. Among them, titanium, phosphorus, iron, silicon, etc. significantly reduce the 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, 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 the cuprous oxide (Cu2O) at the grain boundary to produce high-pressure water vapor or carbon dioxide gas, which can cause the copper to crack. This phenomenon is often referred to as «hydrogen disease» of copper. Oxygen is harmful to copper’s weldability. Bismuth or lead and copper form a low melting point eutectic, which makes copper hot brittle; and brittle bismuth is distributed in a thin film shape at the grain boundary, which makes copper cold brittle. Phosphorus can significantly reduce the conductivity of copper, but can improve the fluidity of copper liquid and improve the weldability. Appropriate amounts of lead, tellurium, sulfur, etc. can improve machinability.

2. Brass
The copper alloy with zinc as the main added element has a beautiful yellow color and is collectively 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 commonly used to make bullet casings, commonly known as bullet casing brass or seven-three brass. Brass alloys with a zinc content of 36 to 42% are composed of solid solutions, of which the most commonly used is brass with 40% zinc content. 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 sea-wheel condenser and other corrosion-resistant parts.
Tin can improve the strength of brass and the corrosion resistance of seawater, so it is called navy brass and is used as thermal equipment for ships and propellers. Lead can improve the cutting performance of brass; this free-cutting brass is often used as a watch part. Brass castings are commonly used to make valves and pipe fittings.
The simplest brass is a copper-zinc binary alloy, called simple brass or ordinary brass, and brass with different mechanical properties can be obtained by changing the content of zinc in brass. The higher the zinc content in brass, the higher its strength and the slightly lower plasticity. The zinc content of brass used in the industry is not more than 45%, and even higher zinc content will produce brittleness and deteriorate the performance of the alloy.
Adding 1% tin to brass can significantly improve the resistance of brass to seawater and marine atmospheric corrosion, so it is called «Navy Brass». Tin can improve the cutting performance of brass. Lead brass is what we usually call the easily cut national standard copper.
The main purpose of adding lead is to improve the machinability and wear resistance, and lead has little effect on the strength of brass. Carved copper is also a type of lead brass. Most brasses have good color, workability and ductility, and are easy to be electroplated or painted.
Brass is divided into:
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, good plasticity, suitable for cold and hot press processing. When the zinc content is greater than 39%, there is a single-phase and copper-zinc-based b solid solution, called dual-phase brass, b makes the plasticity small and the tensile strength increase, and is only suitable for hot-press processing. The code is represented by «H + number», H represents brass, and the number represents the mass fraction of copper. For example, H68 indicates that the copper content is 68% and the zinc content is 32%. For the cast brass, the word «Z» before the code name, such as ZH62. H90 and H80 are single-phase, golden yellow, so they are collectively called gold, called plating, decorations, medals, etc. H68 and H59 belong to duplex brass and are widely used in structural parts of electrical appliances, such as bolts, nuts, washers, springs, etc. In general, single-phase brass for cold deformation processing and dual-phase brass for hot deformation processing.
2) Special brass A multi-component alloy composed of other alloy elements added to ordinary brass is called brass. Commonly added elements are lead, tin, aluminum, etc., which can be referred to as lead brass, tin brass, aluminum brass. The purpose of adding alloying elements. Mainly to improve the tensile strength and improve the manufacturability. Code: «H + main plus element symbol (except zinc) + copper mass fraction + main plus element mass score + other element mass score». For example: HPb59-1 means that the mass fraction of copper is 59%, the mass fraction of the main element containing lead is 1%, and the balance is zinc lead brass.
3. Cupronickel
Copper alloy with nickel as the main added element. The copper-nickel binary alloy is called ordinary white copper; the white copper alloy added with manganese, iron, zinc, aluminum and other elements is called complex white copper. Cupronickel for industrial use is divided into two major categories: structural coppernickel and electrical coppernickel. The structure of copper-nickel alloy is characterized by good mechanical properties and corrosion resistance, and beautiful color. This white copper is widely used in manufacturing precision machinery, chemical machinery and ship components. Electrotechnical white copper generally has good thermoelectric properties. Manganese copper, constantan, and copper are manganese white copper with different manganese content. They are materials used to manufacture precision electrical instruments, varistor, precision resistance, strain gauges, thermocouples and so on.
4. Bronze Originally referred to as copper-tin alloy, copper alloys other than brass and cupronickel are also called bronze, and are often given the name of the first major added element before the bronze name. Tin bronze has good casting performance, anti-friction performance and good mechanical performance, and is suitable for manufacturing bearings, worm gears and gears. Lead bronze is a widely used bearing material for modern engines and grinding machines. Aluminum bronze has high strength, good wear resistance and corrosion resistance, and is used for casting high-load gears, bushings, marine propellers, etc. Beryllium bronze and phosphor bronze have high elastic limit and good conductivity, and are suitable for manufacturing precision springs and electrical contact elements. Beryllium bronze is also used to manufacture non-sparking tools used in coal mines and oil depots.
Because tin bronze has a wide crystallization temperature range and poor fluidity, it is not easy to form concentrated shrinkage pores, but it is easy to form dendrite segregation and dispersed shrinkage pores. The casting shrinkage rate is small, which is beneficial to castings with dimensions very close to the mold, so it is suitable for casting The shape is complex. The condition of larger wall thickness is not suitable for castings that require high density and good sealing. Tin bronze has good friction reduction, diamagnetism and low temperature toughness. According to the production method, tin bronze can be divided into two categories: pressure processed tin bronze and cast tin bronze.
A. Pressure processed tin bronze
The tin content is generally less than 8%. It should be processed into plates by cold and hot pressure, and supplied with profiles such as strips, rods, and pipes. After processing and hardening, the tensile strength and hardness increase, and the plasticity decreases. After re-annealing, it can maintain higher tensile strength to improve plasticity, especially to obtain high elastic limit. Corrosion-resistant and wear-resistant parts, elastic parts, anti-magnetic parts, sliding bearings, bushings, etc. are commonly required on suitable instruments. Qsn4-3 Qsn6.5 ~ 0.1 are commonly used. B. Cast tin bronze is supplied as an ingot and cast into castings in a casting workshop. It is suitable for castings with complex shapes but low density requirements, such as sliding bearings and gears. Commonly used are ZQsn10-1 ZQsn6-6-3.
2) Special bronze is added with other elements 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 aluminum bronze (QAL7 QAL5) lead bronze ( ZQPB30) etc. The copper-based alloy with nickel as the main added element is silver-white and is called white copper. Nickel content is usually 10%, 15%, 20%, the higher the content, the whiter the color. The copper-nickel binary alloy is called ordinary white copper, and the copper-nickel alloy added with manganese, iron, zinc, and aluminum is called complex white copper. Pure copper plus nickel can significantly improve strength, corrosion resistance, resistance, and thermoelectricity. According to different performance characteristics and uses, industrial copper-nickel alloy is divided into structural copper-nickel alloy and electrical copper-nickel alloy, which meet various corrosion resistance and special electrical and thermal properties. Second, distinguish: white copper, brass, red copper (also known as «purple copper»), bronze (blue gray or grayish yellow) are distinguished from the color.
Among them, white copper and brass are very easy to distinguish; red copper is pure copper (impurity <1%), bronze (about 5% of other alloy components) is slightly difficult to distinguish. When not oxidized, the red copper is brighter than bronze, and the bronze is slightly bluish or yellowish. After oxidation, the red copper becomes black, and the bronze is greenish (harmful oxidation of water) or chocolate.
Classification and welding characteristics of copper and copper alloys
(1) Pure copper: Pure copper is often called red copper. It has good electrical conductivity, thermal conductivity and corrosion resistance. Pure copper is represented by the letters + T}} (copper), such as Tl, T2, T3, etc. The content of oxygen is extremely low, and pure copper no more than 0.01% is called oxygen-free copper, which is represented by TU (copper-free), such as TU1, TU2, etc.
(2) Brass: Copper alloy with zinc as the main alloying element is called brass. Brass with + H; (yellow) means H80, H70, H68, etc. (3) Bronze: In the past, the alloy of copper and tin was called bronze, but now the alloy of copper other than brass is called bronze. Commonly used are tin bronze, aluminum bronze and sensitive bronze. Bronze is represented by «Q, ‘(green).
The welding characteristics of copper and copper alloys are:
(1) Difficult to fuse and deform
(2) Hot cracks are prone to occur
(3) Porosity easily occurs Copper and copper alloy welding mainly adopts gas welding, inert gas shielded welding, submerged arc welding, brazing and other methods. Copper and copper alloys have good thermal conductivity, so they should generally be preheated before welding and welded with large line energy. Tungsten hydrogen arc welding adopts DC direct connection. For gas welding, neutral flame or weak carbonized flame is used for copper, and weak oxidation flame is used for brass to prevent the evaporation of zinc.
supplement:
1. Natural properties of copper Copper is one of the earliest ancient metals discovered by mankind. Humans began to use copper as early as three thousand years ago. Copper in nature is divided into natural copper, copper oxide ore and copper sulfide ore. The reserves of natural copper and copper oxide are small. Now more than 80% of the world’s copper is refined from copper sulfide ore. This kind of ore has a very low copper content, generally about 2-3%. Copper metal, element symbol CU, atomic weight 63.54, specific gravity 8.92, melting point 1083Co. Pure copper is light rose or light red. Copper has many valuable physical and chemical properties, such as high thermal conductivity, strong chemical stability, high tensile strength, easy welding, and corrosion resistance, plasticity, and ductility. Pure copper can be drawn into very thin copper wire to make very thin copper foil. It can form alloys with zinc, tin, lead, manganese, cobalt, nickel, aluminum, iron and other metals. The alloys formed are mainly divided into three categories: brass is a copper-zinc alloy, bronze is a copper-tin alloy, and white copper is a copper-cobalt-nickel alloy.
2. Copper smelting Copper ore mined from copper mines becomes a copper concentrate or copper ore with higher copper content after beneficiation. Copper concentrates need to be refined and refined to become refined copper and copper products.
A. Copper ore processing There are two types of copper used in the industry, electrolytic copper (containing 99.9% -99.95% of copper) and refined copper (containing 99.0% -99.9% of copper). The former is used in the electrical industry to manufacture special alloys, wires and wires. The latter is used to manufacture other alloys, copper tubes, copper plates, shafts, etc. a. Classification and properties of copper ore: The raw material for copper smelting is copper ore. Copper ore can be divided into three categories:
(1) Sulfide ores, such as chalcopyrite (CuFeS2), porphyrite (Cu5FeS4) and chalcopyrite (Cu2S), etc.
(2) Oxide ores, such as cuprite (Cu2O), malachite [Cu2 (OH) 2CO3], azurite [2CuCO3 · Cu (OH) 2], silicon malachite (CuSiO3 · 2H2O), etc.
(3) Natural copper. Copper content in copper ore is about 1% (0.5% to 3%), which has mining value, because the flotation method can remove some of the impurities such as gangue in the ore, and the copper content is higher (8% ~ 35%) of concentrate sand. b. Copper smelting process: The process of smelting copper from copper ore is relatively complicated. Taking chalcopyrite as an example, first, concentrate sand, flux (limestone, sand, etc.) and fuel (coke, charcoal, or anthracite) are mixed, put into a «closed» blast furnace, and smelted at about 1000 ° C. So part of the sulfur in the ore becomes SO2 (for sulfuric acid), and most of the impurities such as arsenic and antimony become volatile substances such as AS2O3 and Sb2O3 and are removed: 2CuFeS2 + O2 = Cu2S + 2FeS + SO2 ↑ A part of iron sulfide is converted into oxide: 2FeS + 3O2 = 2FeO + 2SO2 ↑. Cu2S and remaining FeS will melt together to form «copper matte» (mainly formed by the mutual dissolution of Cu2S and FeS, its copper content is between 20% -50%, sulfur content is 23% -27% Between), FeO and SiO2 form slag: FeO + SiO2 = FeSiO3.

The slag floats on top of the molten matte copper, which can be easily separated to remove some impurities. Then move the matte copper into the converter, add the flux (quartz sand) and blow into the air for blowing (1100 ～ 1300 ℃). Since iron has a greater affinity for oxygen than copper, and copper has a greater affinity for sulfur than iron, FeS in matte is first converted to FeO and combined with flux to form slag, and then Cu2S is converted to Cu2O, Cu2O and Cu2S reaction produces blister copper (copper content is about 98.5%). 2Cu2S + 3O2 = 2Cu2O + 2SO2 ↑, 2Cu2O + Cu2S = 6Cu + SO2 ↑, then move the blister copper into the reverberatory furnace, add the flux (quartz sand), pass the air, oxidize the impurities in the blister copper, and form slag with the flux to remove. After the impurities are removed to a certain degree, heavy oil is injected again, and the reducing gas such as carbon monoxide produced by the combustion of the heavy oil reduces the cuprous oxide to copper at high temperature. The refined copper obtained contained approximately 99.7% copper. B. Copper smelting process The development of copper metallurgy technology has gone through a long process, but so far copper smelting is still dominated by fire law, its output accounts for about 85% of the world’s total copper output, modern wet smelting technology is gradually Promotion, the introduction of wet smelting has greatly reduced the cost of copper smelting. Fire smelting and wet smelting (SX-EX).
a. Copper smelting by fire: cathode copper is produced by melting smelting and electrolytic refining, that is, electrolytic copper, which is generally suitable for high-grade copper sulfide ores. Pyrometallurgical smelting generally first raises the ore containing a few percent or a few thousandths of copper to 20-30% through beneficiation. As a copper concentrate, it is manufactured in a closed blast furnace, reverberatory furnace, electric furnace or flash furnace The matte smelting, the produced matte (copper matte) is then sent to the converter to be blown into blister copper, and then deoxidized by oxidation refining in another reverberatory furnace, or cast into an anode plate for electrolysis, with a grade of up to 99.9% Electrolytic copper. The process is short and adaptable, and the recovery rate of copper can reach 95%, but because the sulfur in the ore is discharged as sulfur dioxide exhaust gas in the two stages of matte and blowing, it is not easy to recover and easy to cause pollution. In recent years, there have been molten pool smelting such as the silver method and the Nolanda method, as well as the pyrometallurgical smelting of the Mitsubishi method in Japan. The production process is roughly as follows: In addition to copper concentrate, copper scrap is used as one of the main raw materials for copper refining, including old copper scrap and new copper scrap. ; The new scrap copper comes from the copper scrap discarded by the processing plant (the output ratio of copper materials is about 50%), the general scrap copper supply is relatively stable, and the scrap copper can be divided into: bare mixed copper:
The grade is above 90%; yellow copper (wire): copper-containing materials (old motors, circuit boards); copper produced from scrap copper and other similar materials, also known as recycled copper.
b. Wet copper smelting: A ship is suitable for low-grade copper oxide. The refined copper produced is called electrowinning copper. Modern wet smelting includes sulfated roasting-leaching-electrowinning, leaching-extracting-electrowinning, bacterial leaching, etc. It is suitable for heap leaching of low-grade complex ores, copper oxide ores, copper-containing waste ores, or tank leaching. Leaching. Wet smelting technology is gradually being promoted and is expected to reach 20% of the total output by the end of this century. The introduction of wet smelting has greatly reduced the cost of copper smelting. The wet smelting process is:
c. Comparing the characteristics of the two methods of fire and wet method The production methods of fire and wet method are as follows: (1) The latter’s smelting equipment is simpler, but the impurity content is higher, which is beneficial to the former supplement. (2) The latter has limitations and is subject to the grade and type of ore. (3) The cost of the former is higher than that of the latter. It can be seen that the wet smelting technology has considerable advantages, but its scope of application has limitations, and not all copper smelting can adopt this process. However, through technological improvements, more and more countries, including the United States, Chile, Canada, Australia, Mexico and Peru, have applied the process to more copper smelting in recent years. The improvement of wet smelting technology and the promotion of its application have reduced the production cost of copper, increased the production capacity of copper mines, and increased the supply of social resources in the short term, resulting in a relative surplus of total social supply, which has a pulling effect on prices.
3. Copper production and consumption a. Distribution of copper resources: The world ’s copper resources are mainly distributed in North America, Latin America and Central Africa. At present, the world ’s proven reserves total 350 million tons, of which Chile accounts for 24%. The United States accounts for 16.9%, the CIS 10.15%, Zaire 7.39%, Zambia 4.55%, Peru 3.41%, and the Americas 60% of the world ’s reserves. China’s copper production areas are concentrated in East China, where copper production accounts for 51.84% of the country’s total output, of which Anhui and Jiangxi provinces account for about 30%. Copper is mainly consumed in East and South China, and their consumption accounts for about 70% of the national total. b. The main purpose of copper: Copper is a red metal, but also a green metal. Said it is a green metal, mainly because it is durable, easy to re-melt, re-smelt, so recycling is quite cheap.
In the 1960s, the largest market for copper was the electrical and electronic markets, which accounted for about 28% of the total. In 1997, these two markets became the second largest end user of copper consumption, with a 25% stake. In many electrical products, (such as wires, busbars, transformer windings, heavy motors, telephone wires and telephone cables) the service life of copper is quite long. Only after 20 to 50 years can the copper in it be recycled . The service life of other copper-containing electrical appliances and electronic products (such as small electrical appliances and consumer electronics) is relatively short, generally 5-10 years. Commercial electronic products and large electrical products are usually recycled because they contain other precious metals in addition to copper. Nevertheless, the recovery rate of small consumer electronics products is still quite low, because they have almost no copper in them.
Classification and welding characteristics of copper and copper alloys
(1) Pure copper: Pure copper is often called red copper. It has good electrical conductivity, thermal conductivity and corrosion resistance. Pure copper is represented by the letters + T}} (copper), such as Tl, T2, T3, etc. The content of oxygen is extremely low, and pure copper no more than 0.01% is called oxygen-free copper, which is represented by TU (copper-free), such as TU1, TU2, etc.
(2) Brass: Copper alloy with zinc as the main alloying element is called brass. Brass with + H; (yellow) means H80, H70, H68, etc. (3) Bronze: In the past, the alloy of copper and tin was called bronze, but now the alloy of copper other than brass is called bronze. Commonly used are tin bronze, aluminum bronze and sensitive bronze. Bronze is represented by «Q, ‘(green).
The welding characteristics of copper and copper alloys are:
(1) Difficult to fuse and deform
(2) Hot cracks are prone to occur
(3) It is easy to produce stomata
Copper and copper alloy welding mainly adopts gas welding, inert gas shielded welding, submerged arc welding, brazing and other methods. Copper and copper alloys have good thermal conductivity, so they should generally be preheated before welding and welded with large line energy. Tungsten hydrogen arc welding adopts DC direct connection. For gas welding, neutral flame or weak carbonized flame is used for copper, and weak oxidation flame is used for brass to prevent the evaporation of zinc. Welding of copper and aluminum Seamless flux-cored wire is the latest technological achievement of aluminum-copper brazing connection, and it is an upgraded product of aluminum-copper brazing materials. Its main components are composed of zinc aluminum copper and non-corrosive fluorine aluminum cesium salt. Its brazing processability, joint mechanical properties and joint conductivity are better than zinc cadmium, zinc tin copper brazing material. Widely used in electric appliances, information electronics, stainless steel products, refrigeration industry, electric appliances, hardware products and other industries. The environment-friendly, convenient and safe aluminum-copper connection can be realized without special welding equipment and special production sites. Among them, copper contains common copper alloys, and aluminum mainly refers to 1 series, 3 series and 6 series and some 4 series
Zhengzhou Machinery Research Institute is currently the main domestic manufacturer of seamless flux-cored aluminum welding wire. It has a history of more than 50 years of research on brazing materials and brazing processes. This copper-aluminum solder has been used in refrigeration, transformers, motors and other copper-to-aluminum industries. Distribution of world copper resources World copper resources are mainly concentrated in Chile, the United States, Zambia, Africa, Congo, central and eastern Canada, Russia and Peru. Among them, Chile is the country with the richest copper resources in the world, and its copper metal reserves account for about 1/4 of the world’s total reserves. In terms of output, Chile is the world’s largest copper producer, and its output accounted for about 37% of global output in 2006. In terms of consumption, Western Europe and the United States played the leading role in the copper consumption market before 2000, but after 2000, the protagonists of the copper consumption market were replaced by China, Russia, India and Brazil.
Types of copper Brass Brass is an alloy of copper and zinc, named for its yellow color. Brass has good mechanical properties and wear resistance, and can be used to manufacture precision instruments, parts of ships, shells of guns, etc. Brass sounds nice, so musical instruments such as gongs, cymbals, bells, and trumpets are all made of brass. Nautical brass An alloy of copper, zinc, and tin that resists seawater corrosion and can be used to make ship parts and balancers. Bronze The alloy of copper and tin is called bronze and is named after its blue color. Bronze generally has good corrosion resistance, wear resistance, castability and excellent mechanical properties. It is used to manufacture precision bearings, high-pressure bearings, mechanical parts resistant to seawater corrosion on ships, and various plates, pipes, rods, etc. Bronze also has an abnormal feature-«heat shrinkage and cold expansion», which is used to cast statues. After cooling, it expands to make the eyebrows clearer. Phosphor Bronze The alloy of copper, tin and phosphorus is hard and can be made into springs.
White copper White copper is an alloy of copper and nickel. Its color is the same as silver. The silver is shiny and not easy to rust. Commonly used in the manufacture of electrical appliances, meters and decorations.