Copper - properties, characteristics properties

Copper is a ductile golden-pink metal with a characteristic metallic luster.
In the periodic system of D.I. Mendeleev, this chemical element is designated as Cu (Cuprum) and is located under serial number 29 in group I (side subgroup), in the 4th period. The Latin name Cuprum comes from the name of the island of Cyprus. There are known facts that in Cyprus back in the 3rd century BC there were copper mines and local craftsmen smelted copper. You can buy copper from the KUPRUM company.

According to historians, society has been familiar with copper for about nine thousand years. The most ancient copper products were found during archaeological excavations in the area of ​​modern Turkey. Archaeologists have discovered small copper beads and plates used to decorate clothing. The finds date back to the turn of the 8th-7th millennium BC. In ancient times, copper was used to make jewelry, expensive dishes, and various tools with thin blades.

A great achievement of ancient metallurgists can be called the production of an alloy with a copper base - bronze.

Basic properties of copper

Physical properties.

In air, copper acquires a bright yellowish-red hue due to the formation of an oxide film. Thin plates have a greenish-blue color when examined through them. In its pure form, copper is quite soft, malleable and easily rolled and drawn. Impurities can increase its hardness.

The high electrical conductivity of copper can be called the main property that determines its predominant use. Copper also has very high thermal conductivity. Impurities such as iron, phosphorus, tin, antimony and arsenic affect the basic properties and reduce electrical and thermal conductivity. According to these indicators, copper is second only to silver.

Copper has high densities, melting points and boiling points. An important property is also good resistance to corrosion. For example, at high humidity, iron oxidizes much faster.

Copper lends itself well to processing: it is rolled into copper sheets and copper rods, and drawn into copper wire with a thickness brought to thousandths of a millimeter. This metal is diamagnetic, that is, it is magnetized against the direction of the external magnetic field.

Chemical properties.

Copper is a relatively low-active metal. Under normal conditions in dry air, its oxidation does not occur. It reacts easily with halogens, selenium and sulfur. Acids without oxidizing properties have no effect on copper. There are no chemical reactions with hydrogen, carbon and nitrogen. In humid air, oxidation occurs to form copper (II) carbonate, the top layer of platinum. Copper is amphoteric, meaning it forms cations and anions in the earth's crust. Depending on the conditions, copper compounds exhibit acidic or basic properties.

Characteristics of copper, reaction of the metal with nitric acid

Copper is the oldest metal used by people since ancient times. Copper has a Latin name - cuprum. Its serial number is 29. In Mendeleev’s periodic table, copper is located in the fourth period, in the first group.

Physical and chemical properties of copper

Copper is a heavy, rose-red colored metal with a malleable and soft structure. The boiling point of copper is more than 1000 °C. Сuprum is a good electrical and thermal conductor, melts at 1084 °C, metal density is 8.9 g/cm³, and is found in nature in its native form.

The copper atom has 4 levels. There is one electron in the valence 4s orbital. During chemical interaction with other substances, 1-3 negatively charged particles are split off from the atom, resulting in the formation of copper compounds with the oxidation state “+3”, “+2”, “+1”. Divalent copper derivatives have the maximum stability.

Copper has low reactivity. There are two main oxidation states of the metal that appear in compounds: “+1” and “+2”. Substances in which these values ​​are replaced by “+3” are rare. Copper reacts with carbon dioxide, air, hydrochloric acid and other compounds at very high temperatures. A protective oxide film is formed on the surface of the metal, which protects copper from further oxidation and makes the metal stable and low-active.

Copper interacts with simple substances: halogens, selenium, sulfur. The metal is capable of forming double salts or complex compounds. Almost all complex compounds of this chemical element (except oxides) are toxic substances. Substances formed by monovalent copper are easily oxidized to divalent analogues.

In chemical reactions, copper acts as a low-active metal. The metal does not dissolve in water under normal conditions. Metal corrosion does not occur in dry air, but when heated, copper becomes covered with a black oxide coating. The chemical stability of the element is manifested by the action of carbon, anhydrous gases, several organic compounds, alcohols and phenolic resins. Copper is characterized by complexation reactions, which result in the release of colored compounds. Copper has similarities with alkaline metals due to the formation of monovalent derivatives.

Interaction with nitric acid

Copper dissolves in nitric acid. This reaction occurs due to the oxidation of the metal by a strong reagent. Nitric acid (diluted and concentrated) exhibits oxidizing properties with the dissolution of copper.

Nitric acid molecule

When the metal reacts with dilute acid, copper nitrate and divalent nitric oxide are formed in a ratio of 75%:25%. Reaction equation:

8HNO₃ + 3Cu → 3Cu(NO₃)₂ + 2NO + 4H₂O

The reaction involves 1 mole of copper and 3 moles of concentrated nitric acid. When copper is dissolved, the solution becomes very hot, resulting in thermal decomposition of the oxidizing agent and the release of an additional volume of nitrogen oxides. Reaction equation:

4HNO₃ + Cu → Cu(NO₃) + 2NO₂ + 2H₂O

This method of dissolving copper has a disadvantage: during the reaction of copper with nitric acid, a large amount of nitric oxides is released. To capture (or neutralize) nitrogen oxides, special equipment is required, which is why this process is too expensive.

The dissolution of copper in nitric acid is considered complete when the production of volatile nitrogen oxides completely ceases. The reaction temperature is 60–70 °C. The next stage is draining the solution from the chemical reactor. After this, pieces of copper that have not reacted remain at the bottom of the reactor. Water is added to the resulting liquid and filtered.

Methods for obtaining copper

In nature, copper exists in compounds and in the form of nuggets. The compounds are represented by oxides, bicarbonates, sulfur and carbon dioxide complexes, as well as sulfide ores. The most common ores are copper pyrite and copper luster. The copper content in them is 1-2%. 90% of primary copper is mined using the pyrometallurgical method and 10% using the hydrometallurgical method.

1. The pyrometallurgical method includes the following processes: enrichment and roasting, smelting for matte, purging in a converter, electrolytic refining. Copper ores are enriched by flotation and oxidative roasting. The essence of the flotation method is as follows: copper particles suspended in an aqueous medium adhere to the surface of air bubbles and rise to the surface. The method allows you to obtain copper powder concentrate, which contains 10-35% copper.

Copper ores and concentrates with a significant sulfur content are subject to oxidative roasting. When heated in the presence of oxygen, sulfides are oxidized, and the amount of sulfur is reduced by almost half. Poor concentrates containing 8-25% copper are roasted. Rich concentrates containing 25-35% copper are melted without resorting to roasting.

The next stage of the pyrometallurgical method for producing copper is smelting for matte. If lump copper ore with a large amount of sulfur is used as a raw material, then smelting is carried out in shaft furnaces. And for powdered flotation concentrate, reverberatory furnaces are used. Melting occurs at a temperature of 1450 °C.

In horizontal converters with side blowing, the copper matte is blown with compressed air in order for the oxidation of sulfides and ferrum to occur. Next, the resulting oxides are converted into slag, and sulfur into oxide. The converter produces blister copper, which contains 98.4-99.4% copper, iron, sulfur, as well as small amounts of nickel, tin, silver and gold.

Blister copper is subject to fire and then electrolytic refining. Impurities are removed with gases and converted into slag. As a result of fire refining, copper is formed with a purity of up to 99.5%. And after electrolytic refining, the purity is 99.95%.

2. The hydrometallurgical method involves leaching copper with a weak solution of sulfuric acid, and then separating copper metal directly from the solution. This method is used for processing low-grade ores and does not allow for the associated extraction of precious metals along with copper.

Solubility of copper in water and acids

The chemical properties of most elements are based on their ability to dissolve in aqueous media and acids. The study of the characteristics of copper is associated with a low-active effect under normal conditions.

A feature of its chemical processes is the formation of compounds with ammonia, mercury, nitric and sulfuric acids. The low solubility of copper in water is not capable of causing corrosion processes.

It has special chemical properties that allow the compound to be used in various industries.

Item Description

Copper is considered the oldest metal, which people learned to mine even before our era. This substance is obtained from natural sources in the form of ore. Copper is an element of the chemical table with the Latin name cuprum, the serial number of which is 29. In the periodic table it is located in the fourth period and belongs to the first group.

The naturally occurring substance is a pink-red heavy metal with a soft and malleable structure. Its boiling and melting point is more than 1000 °C. Considered a good guide.

Chemical structure and properties

If you study the electronic formula of a copper atom, you will find that it has 4 levels. There is only one electron in the 4s valence orbital. During chemical reactions, from 1 to 3 negatively charged particles can be split off from an atom, then copper compounds with an oxidation state of +3, +2, +1 are obtained. Its divalent derivatives are most stable.

In chemical reactions it acts as a low-reactive metal. Under normal conditions, copper has no solubility in water. Corrosion is not observed in dry air, but when heated, the metal surface becomes covered with a black coating of divalent oxide.

The chemical stability of copper is manifested under the action of anhydrous gases, carbon, a number of organic compounds, phenolic resins and alcohols. It is characterized by complex formation reactions with the release of colored compounds.

Copper has slight similarities with alkali group metals due to the formation of monovalent derivatives.

What is solubility?

This is the process of formation of homogeneous systems in the form of solutions when one compound interacts with other substances. Their components are individual molecules, atoms, ions and other particles. The degree of solubility is determined by the concentration of the substance that was dissolved when obtaining a saturated solution.

The unit of measurement is most often percentages, volume fractions or weight fractions. The solubility of copper in water, like other solid compounds, is subject only to changes in temperature conditions. This dependence is expressed using curves. If the indicator is very small, then the substance is considered insoluble.

The metal exhibits corrosion resistance when exposed to sea water. This proves its inertness under normal conditions. The solubility of copper in water (fresh) is practically not observed. But in a humid environment and under the influence of carbon dioxide, a green film forms on the metal surface, which is the main carbonate:

Cu + Cu + O2 + H2O + CO2 → Cu(OH)2 · CuCO2.

If we consider its monovalent compounds in the form of salts, then their insignificant dissolution is observed. Such substances are subject to rapid oxidation. The result is divalent copper compounds. These salts have good solubility in aqueous media. Their complete dissociation into ions occurs.

Solubility in acids

The usual conditions for reactions of copper with weak or dilute acids do not favor their interaction. The chemical process of the metal with alkalis is not observed. Copper solubility in acids is possible if they are strong oxidizing agents. Only in this case does interaction take place.

Solubility of copper in nitric acid

This reaction is possible due to the fact that the process of oxidation of the metal with a strong reagent occurs. Nitric acid in diluted and concentrated form exhibits oxidizing properties with the dissolution of copper.

In the first option, the reaction produces copper nitrate and nitrogen divalent oxide in a ratio of 75% to 25%. The process with dilute nitric acid can be described by the following equation:

8HNO3 + 3Cu → 3Cu(NO3)2 + NO + NO + 4H2O.

In the second case, copper nitrate and nitrogen oxides are obtained, divalent and tetravalent, the ratio of which is 1 to 1. This process involves 1 mole of metal and 3 moles of concentrated nitric acid. When copper dissolves, the solution heats up strongly, resulting in thermal decomposition of the oxidizing agent and the release of an additional volume of nitrogen oxides:

4HNO3 + Cu → Cu(NO3)2 + NO2 + NO2 + 2H2O.

The reaction is used in small-scale production associated with recycling scrap or removing coatings from waste. However, this method of dissolving copper has a number of disadvantages associated with the release of large amounts of nitrogen oxides. To capture or neutralize them, special equipment is required. These processes are very expensive.

The dissolution of copper is considered complete when the production of volatile nitrogen oxides completely ceases. The reaction temperature ranges from 60 to 70 °C. The next step is to drain the solution from the chemical reactor. At its bottom there are small pieces of metal that have not reacted. Water is added to the resulting liquid and filtered.

Solubility in sulfuric acid

Under normal conditions, this reaction does not occur. The factor determining the dissolution of copper in sulfuric acid is its strong concentration. A dilute medium cannot oxidize the metal. The dissolution of copper in concentrated sulfuric acid proceeds with the release of sulfate.

The process is expressed by the following equation:

Cu + H2SO4 + H2SO4 → CuSO4 + 2H2O + SO2.

Properties of copper sulfate

Dibasic salt is also called sulfuric acid and is designated as CuSO4. It is a substance without a characteristic odor and does not exhibit volatility.

In its anhydrous form, salt is colorless, opaque, and highly hygroscopic. Copper (sulfate) has good solubility. Water molecules, when added to salt, can form crystalline hydrate compounds.

An example is copper sulfate, which is a blue pentahydrate. Its formula: CuSO4·5H2O.

Crystalline hydrates have a transparent structure with a bluish tint and exhibit a bitter, metallic taste. Their molecules are capable of losing bound water over time. They are found in nature in the form of minerals, which include chalcanthite and butite.

Susceptible to copper sulfate. Solubility is an exothermic reaction. The process of salt hydration generates a significant amount of heat.

Solubility of copper in iron

As a result of this process, pseudo-alloys of Fe and Cu are formed. For metallic iron and copper, limited mutual solubility is possible.

Its maximum values ​​are observed at a temperature of 1099.85 °C. The degree of solubility of copper in the solid form of iron is 8.5%. These are small numbers.

The dissolution of metallic iron in the solid form of copper is about 4.2%.

Reducing the temperature to room values ​​makes the mutual processes insignificant. When metallic copper is melted, it is able to well wet iron in solid form.

When producing Fe and Cu pseudo-alloys, special blanks are used. They are created by pressing or baking iron powder in pure or alloyed form.

Such workpieces are impregnated with liquid copper, forming pseudo-alloys.

Dissolution in ammonia

The process often occurs by passing NH3 in gaseous form over hot metal. The result is the dissolution of copper in ammonia, the release of Cu3N. This compound is called monovalent nitride.

Its salts are exposed to ammonia solution. The addition of such a reagent to copper chloride leads to the formation of a precipitate in the form of hydroxide:

CuCl2 + NH3 + NH3 + 2H2O → 2NH4Cl + Cu(OH)2↓.

Excess ammonia promotes the formation of a complex type compound that is dark blue in color:

Cu(OH)2↓+ 4NH3 → [Cu(NH3)4] (OH)2.

This process is used to determine cupric ions.

Solubility in cast iron

In the structure of malleable pearlitic cast iron, in addition to the main components, there is an additional element in the form of ordinary copper. It is this that increases the graphitization of carbon atoms and helps to increase the fluidity, strength and hardness of alloys.

The metal has a positive effect on the level of perlite in the final product. The solubility of copper in cast iron is used to alloy the original composition. The main purpose of this process is to obtain a malleable alloy.

It will have increased mechanical and corrosion properties, but reduced embrittlement.

If the copper content in cast iron is about 1%, then the tensile strength is equal to 40%, and the yield strength increases to 50%. This significantly changes the characteristics of the alloy.

Increasing the amount of metal alloying to 2% leads to a change in strength to 65%, and the fluidity rate becomes 70%. With a higher copper content in cast iron, spheroidal graphite is more difficult to form. The introduction of an alloying element into the structure does not change the technology for forming a viscous and soft alloy.

The time allotted for annealing coincides with the duration of such a reaction in the production of cast iron without copper admixture. It is about 10 hours.

The use of copper for the production of cast iron with a high silicon concentration is not able to completely eliminate the so-called ferruginization of the mixture during annealing. The result is a product with low elasticity.

Solubility in mercury

When mercury is mixed with metals of other elements, amalgams are obtained. This process can take place at room temperature, because under such conditions Pb is a liquid. The solubility of copper in mercury disappears only during heating. The metal must first be crushed.

When solid copper is wetted with liquid mercury, mutual penetration of one substance into another or a process of diffusion occurs. The solubility value is expressed as a percentage and is 7.4*10-3. The reaction produces a hard, simple amalgam similar to cement. If you heat it up a little, it softens.

As a result, this mixture is used to repair porcelain products. There are also complex amalgams with an optimal content of metals. For example, dental alloy contains the elements silver, tin, copper and zinc. Their percentage ratio is 65: 27: 6:2. Amalgam with this composition is called silver.

Each component of the alloy performs a specific function, which allows you to obtain a high-quality filling.

Another example is an amalgam alloy, which has a high copper content. It is also called copper alloy. The amalgam contains from 10 to 30% Cu.

The high copper content prevents the interaction of tin with mercury, which prevents the formation of a very weak and corrosive phase of the alloy. In addition, reducing the amount of silver in a filling leads to cheaper prices.

To prepare amalgam, it is advisable to use an inert atmosphere or a protective liquid that forms a film. The metals that make up the alloy can be quickly oxidized by air.

The process of heating cuprum amalgam in the presence of hydrogen causes the mercury to be distilled off, allowing the elemental copper to be separated. As you can see, this topic is not difficult to learn. Now you know how copper interacts not only with water, but also with acids and other elements.

Copper Applications

Due to their valuable qualities, copper and copper alloys are used in the electrical and electrical engineering industries, in radio electronics and instrument making. There are alloys of copper with metals such as zinc, tin, aluminum, nickel, titanium, silver, and gold. Less commonly used are alloys with non-metals: phosphorus, sulfur, oxygen. There are two groups of copper alloys: brass (alloys with zinc) and bronze (alloys with other elements).

Copper is highly environmentally friendly, which allows its use in the construction of residential buildings. For example, a copper roof, due to its anti-corrosion properties, can last more than a hundred years without special care or painting.

Copper in alloys with gold is used in jewelry. This alloy increases the strength of the product, increases resistance to deformation and abrasion.

Copper compounds are characterized by high biological activity. In plants, copper takes part in the synthesis of chlorophyll. Therefore, it can be seen in the composition of mineral fertilizers. A lack of copper in the human body can cause deterioration in blood composition. It is found in many food products. For example, this metal is found in milk. However, it is important to remember that excess copper compounds can cause poisoning. This is why you should not cook food in copper cookware. During boiling, large amounts of copper can leach into food. If the dishes inside are covered with a layer of tin, then there is no danger of poisoning.

In medicine, copper is used as an antiseptic and astringent. It is a component of eye drops for conjunctivitis and solutions for burns.

Copper crystal lattice:

salita-mart.ru

Full text search:

Home > Coursework >Chemistry

Copper does not react with hydrogen, nitrogen, graphite, or silicon. When exposed to hydrogen, copper becomes brittle (so-called copper “hydrogen disease”) due to the dissolution of hydrogen in the metal.

In the presence of oxidizing agents, primarily oxygen, copper can react with hydrochloric acid and dilute sulfuric acid, but hydrogen is not released:

2Cu + 4HCl + O2 = 2CuCl2 + 2H2O

Copper reacts quite actively with nitric acid of various concentrations, resulting in the formation of copper (II) nitrate and the release of various nitrogen oxides. For example, with 30% nitric acid the reaction of copper proceeds as follows:

3Cu + 8HNO 3 = 3Cu(NO 3) 2 + 2NO + 4H 2 O

Copper reacts with concentrated sulfuric acid under strong heating:

Cu + 2H 2 SO 4 = CuSO 4 + SO 2 + 2H 2 O

Of practical importance is the ability of copper to react with solutions of iron (III) salts, with copper going into solution and iron (III) being reduced to iron (II):

2FeCl 3 + Cu = CuCl 2 + 2FeCl 2

This process of etching copper with iron (III) chloride is used, in particular, if it is necessary to remove a layer of copper deposited on plastic in certain places.

Copper ions Cu 2+ easily form complexes with ammonia, for example, composition 2+. When acetylene C 2 H 2 is passed through ammonia solutions of copper salts, copper carbide (more precisely, acetylenide) CuC 2 precipitates.

Copper hydroxide Cu(OH) 2 is characterized by a predominance of basic properties. It reacts with acids to form salt and water, for example:

Сu(OH) 2 + 2HNO 3 = Cu(NO 3) 2 + 2H 2 O

But Cu(OH) 2 also reacts with concentrated solutions of alkalis, and the corresponding cuprates are formed, for example:

Сu(OH) 2 + 2NaOH = Na 2

If cellulose is placed in a copper-ammonia solution obtained by dissolving Cu(OH) 2 or basic copper sulfate in ammonia, then cellulose dissolves and a solution of copper-ammonium cellulose complex is formed.

2.2 Basic copper carbonate and its physicochemical properties

СuCO(OH) - dihydroxide carbonate of dicopper

Sometimes found as green, monoclinic, needle-shaped, mostly fused crystals, but most often as a dense or fibrous green mass. When heated slightly, it decomposes without melting. When heated above 200˚C, it turns black and turns into black copper oxide powder, while water vapor and carbon dioxide are released. When precipitated from solution, it has a variable composition (1-2)CuCO∙Cu(OH) (mineral malachite). Insoluble in cold water, decomposed by boiling water and acids; reacts with potassium cyanide, ammonium salts. Converted to medium salt by the action of CO under excess pressure.

Chemical properties:

2.3 Synthesis of malachite

1) Calculation of initial masses of substances

CuSO∙5H 2 O+ 4NaHCO= CuCO∙Cu(OH)↓+ NaSO+ 3CO+ 11HO m(CuSO∙5H 2 O) = 5.5 g

2) Description of work

Porcelain mortar and pestle – 1,

thermal glass – 250 ml,

• glass rod – 2,

  Buchner funnel – 1,

  Bunzan flask – 1,

  filter paper,

  test tube,

Progress.

In a porcelain mortar, 5.5 g of finely ground dry salt CuSO 4 5H 2 O was mixed with 3.696 g of sodium bicarbonate.

In a glass, 100 ml was heated to boiling. water. The mixture was poured in small portions into boiling water, stirring quickly. In this case, foaming is observed. The next portion of the mixture was added after the foaming stopped. The contents of the glass were boiled for 10-15 minutes to remove CO 2 from the solution. As a result of the reaction, copper hydroxycarbonate is formed:

2CuSO∙5H 2 O+ 4NaHCO= CuCO∙Cu(OH)↓+ NaSO+ 3CO+ 11HO

The precipitate was allowed to settle, then washed by decantation with hot water, washing away the SO ion

; After each wash, a sample was taken to determine the completeness of the wash: for this, a small amount of this solution was poured into a test tube and a few drops of barium chloride were added. Initially, the formation of a white precipitate (BaSO) was observed in the test tube, but after seven consecutive decantations the precipitate ceased to form.

We placed the remaining solution in a drying cabinet and dried for five days at a temperature of 60˚C.

Chapter 3. Experimental results and discussion

3.1 Chemical evidence for the formation of malachite

To prove that we obtained exactly basic copper carbonate, we carried out a decomposition reaction and a reaction with HCl.

3.2 Practical yield

Based on the amount of starting substances, from this reaction we should have obtained a base of copper carbonate weighing 2.442 g. But during this experiment we obtained a salt weighing 2.11 g. The yield of the product was 84.405%.

3.3 Interesting facts

Myths, legends, beliefs, folklore

Since ancient times, some have used malachite as a stone capable of protecting small children from all sorts of misfortunes. But according to strange Ural beliefs, malachite is a “joyful stone”; it brings good luck and happiness, especially to kind people.

The most famous tales about Ural malachite, united by the theme “Malachite Box,” were written in 1939 by Pavel Bazhov. However, tales and legends about malachite existed long before this.

There is an old legend about the miraculous properties of malachite. It says that there lived a mother and son. One day, the mother fell ill, and the doctor said that she could be saved only by placing an opaque green stone with beautiful patterns on her chest. This stone was mined in the mountains far to the north, and the son did not have time to go get it, since the mother was quickly getting worse. The visiting man said that two days' journey from here the khan was building a new palace and there was a lot of beautiful green stone that was used to decorate the main entrance.

The son jumped after the stone. Having galloped to the place, he waited until the craftsmen had left, and took a tile the size of two palms, put it in his bosom and headed back to his horse. It was a terrible thing to steal from the khan. He knew that if he asked for a stone for his sick mother, he would be thrown into prison, since the khan did not share his property with anyone.

Suddenly the guard noticed the thief, who bent into the saddle and galloped into the mountains. They organized a chase after him. The fugitive did not have time to get to the caves and said out loud: “What should we do?” Suddenly he heard someone answering him. His horse spoke to him. “Put the stone on my back and rest your hands on it, then it will make us invisible,” the horse answered. So they did. The guards galloped past without noticing them. The son brought the stone to his mother. A green stone was tied to the patient’s chest, and the illness began to quickly go away.

Legends and traditions attributed two properties to malachite that other minerals did not possess. “First: malachite could make a person invisible. Second: the stone helped to understand the language of animals. To do this, one had to drink from a malachite cup or press the stone to the body so that sweat washed over it.

Malachite is associated with the constellation Capricorn, and is considered to be a good talisman, especially for those born under this sign. Malachite will strengthen the spirit of Capricorn, cheer up and bring health and success to business.

But he is kind not only to them. Myths, legends, tales and tales claim that malachite is able to help all people, however, in certain situations. It awakens a person’s spiritual and creative powers, and wearing it is useful for those who are involved in creativity, or more precisely, in creative work.

Bibliography

Gorelov A.A. Ecology. – M.: Yurayt Publishing House, 2001. – 128 p.

Zdorik T.B. Stone giving birth to metal. M.: Publishing house Enlightenment, 1984. – 21, 136 p.

Lebedinsky V.I. In the wonderful world of stone. – M.: Krugosvet, 1985. – 198 p.

Putolova L.S. Gems and colored stones. – M.: Nedra Publishing House, 1991. – 113, 115 – 116 p.

Fersman A.E. Stories about gems. – M.: publishing house Detgiz, 1952. – 74-76 p.

Kornilov N.I., Solodova Yu.P. Jewelry stones. – M.: Mir Publishing House, 1982.- 84,181 p.

Podchainova V.N., Simonova L.N. Analytical chemistry of copper. – M.: Publishing house Nauka, 1990. – 7.8-12 p.

Aksenova M., Khramov G., Volodin V. Stones of the world. – M.: Avanta +, 2001 – 76,159 p.

Zdorik T.B., Matias V.V., Timofeev I.N. Minerals and rocks of the USSR. – M.: Publishing house Mysl, 1970. – 136 p.

Lidin R.A., Molochko V.A., Andreeva. Chemical properties of inorganic substances. – M.: Publishing House Chemistry, 1997. – 289 p.

Viktorov S. Affectionate silk of stone // Nature. – 1990. – No. 4. – 136 p.

Gems // Kulikov B.F., Bukanov V.V. Dictionary of gemstones. – Leningrad: Nedra, 1989. – 62 p.

Ed. Tretyakova Yu.D. Inorganic chemistry: in 3 volumes - M.: Academy Publishing Center, 2007. - T.3.

Remi G. Course of inorganic chemistry: in 2 volumes - M.: Foreign Literature Publishing House, 1963. - T. 2.

(polymerization and polycondensation); in relation to heat (thermoplastic and thermosetting); according to the physical and mechanical properties
... are: coloring in the mass -
obtaining
a uniform color (uniform), surface (dye ...

• Childhood years of Bagrov-grandson

  Story >> Literature and the Russian language
  And in childhood I passionately indulged. This property

  they called me unsociable, savage... for moving to the village: a letter
  received
  from Praskovya Ivanovna Kurolesova.
  Having recognized... the staircase made of green marble, malachite
  , with gilded railings, he descends...

• Improving the system of adaptation by personnel in the organization

  Abstract >> State and law
  Enterprise development strategy before receiving

  required management skills;
  Mentoring… optimizing the mentoring procedure; obtaining
  useful information aimed at... the same
  malachite
  , marble, similar in both qualities and
  properties
  . Let's consider...

Experiment 1. Interaction of copper with acids

a) Place some copper shavings in a test tube and add 1-2 ml of H 2 SO 4 (2N). Note no changes. Pour a few drops of hydrogen peroxide (H 2 O 2) into the test tube and lightly shake the contents of the test tube. Note the change in color of the solution and explain the phenomenon occurring. Write the reaction equation.

Cu + H 2 SO 4 dil. ¹

Cu + H 2 SO 4 dil. + H 2 O 2 ® CuSO 4 + H 2 O

b) Place some copper shavings in two test tubes (conduct the experiment under traction). Pour some concentrated sulfuric acid into the first test tube and heat it. What are you observing? Write the reaction equation. Pour a little concentrated nitric acid HNO 3 into the second test tube. What are you observing? Write the reaction equation.

Cu + H 2 SO 4 conc. ® CuSO 4 + SO 2 + H 2 O

Cu + HNO 3 conc. ® Cu(NO 3) 2 + NO 2 + H 2 O

Cu + HNO 3 dil. ® Cu(NO 3) 2 + NO + H 2 O

Experiment 2. Preparation and properties of copper(II) hydroxide

Pour 5-6 drops of copper(II) salt solution into a test tube and add the same volume of NaOH alkali (2N). Write the equation for the reaction, noting the color of the precipitate. Divide the sediment into three test tubes. Pour 1-2 ml of H 2 SO 4 solution (2N) into the first test tube, and 1-2 ml of NaOH solution (2N) into the second test tube. What are you observing? Does copper hydroxide exhibit acidic properties under these conditions? Write the reaction equations. Heat the third test tube with copper(II) hydroxide in a water bath. What are you observing? Draw a conclusion about the thermal stability of copper(II) hydroxide. Write the reaction equation.

CuSO 4 + NaOH ® Cu(OH) 2 + Na 2 SO 4

Cu(OH) 2 + H 2 SO 4 ® CuSO 4 + H 2 O

Cu(OH) 2 + NaOH ¹

Cu(OH) 2 CuO + H 2 O

Experiment 3. Oxidizing properties of copper(II) ion

Pour about 1 ml of copper(II) sulfate solution into the test tube and add some KI solution. Observe a change in the color of the solution and the formation of a white CuI precipitate. Add a few drops of starch. Why did the starch turn blue? Write the reaction equation.

CuSO 4 + KI ® CuI + + I 2 K 2 SO 4

Experiment 4. Preparation of copper ammonia. Qualitative reaction to Cu 2+ ion

Pour 2-3 drops of copper(II) sulfate solution into a test tube and add the same amount of NH 4 OH solution (2N). Write an equation for the reaction and note the color of the hydroxycopper(II) sulfate precipitate. Add a concentrated solution of NH 4 OH (25%) drop by drop to the test tube. Observe the dissolution of the precipitate and the change in color of the solution due to the formation of 2+ ions. Write an equation for the reaction.

CuSO 4 + NH 4 OH ® (CuOH) 2 SO 4 + (NH 4) 2 SO 4

(CuOH) 2 SO 4 + (NH 4) 2 SO 4 + NH 4 OH ® SO 4 + H 2 O

Experiment 1. Interaction of copper with acids - concept and types. Classification and features of the category “Experiment 1. Interaction of copper with acids” 2014, 2015-2016.

And concentrated acids

Place 2-3 microspatulas of copper powder into three test tubes and add 5-6 drops of 2 N acid solution: hydrochloric acid in the first, sulfuric in the second, nitric in the third.

Do a similar experiment with concentrated acids. What acids does copper react with? Write an equation for the reaction between copper and dilute nitric acid, assuming that nitric oxide (II) is formed. How does the color of the solution change? Why does copper not react with hydrochloric acid and dilute sulfuric acid? Write an equation for the reaction of copper with concentrated acids, assuming that concentrated nitric acid is reduced by copper to nitrogen oxide (IV), and sulfuric acid to sulfur oxide (IV).

Experiment 2. The ratio of copper (II) hydroxide to acids and alkalis

In two test tubes, obtain copper(II) hydroxide. To the resulting precipitates, add 5-6 drops of 2 N sulfuric acid solution to one test tube, and the same amount of 2 N alkali solution to another.

Describe the work done. In what case does copper(II) hydroxide dissolve? What conclusion can be drawn from this experiment about the properties of copper (II) hydroxide?

Experiment 3. Preparation of slightly soluble hydroxycopper carbonate (II)

Add the same amount of soda solution to a test tube with a solution of copper (II) sulfate (2-3 drops). Observe the precipitation of a green precipitate of hydroxycopper (II) carbonate (CuOH) 2 CO 3. Why doesn’t medium copper carbonate precipitate when interacting with a soda solution? Write an equation for the interaction of copper sulfate with soda with the participation of water.

Experiment 4. Preparation of ammonia complex of copper (II)

Add 2 N ammonia solution drop by drop to a test tube with a solution of copper (II) sulfate (2-3 drops) until the precipitate of basic salt (CuOH) 2 SO 4 that precipitated when adding the first drops of ammonium hydroxide is completely dissolved. Note the color of the initial solution of copper (II) sulfate and the solution of the resulting copper-ammonium complex. What ions cause the color of the solution in the first and second cases? Write the reaction equations:

a) interaction of copper (II) sulfate with ammonium hydroxide to form a precipitate of hydroxycopper (II) sulfate.

b) dissolving hydroxycopper (II) sulfate in excess ammonium hydroxide to form complex compounds.

c) dissociation equations for the resulting copper complex compounds.

Experiment 5. Copper production by chemical reduction

From solutions

Immerse an iron plate, previously cleaned with sandpaper and washed with water, into a solution of copper (II) nitrate. After 1-2 minutes. take out the record. Write the equation for the reaction that occurs.

Control questions

1 What are the similarities and differences in the atomic structure of elements of the copper subgroup from alkali metals?

2 How can we explain the appearance of a greenish coating on copper products during prolonged contact with atmospheric air?

3 Write down the reaction equations for the dissolution of copper and silver in concentrated sulfuric acid when heated?

4 What substance precipitates when hot solutions of copper (II) nitrate and potassium hydroxide are combined? Draw up reaction equations in molecular and molecular-ionic forms.

5 Silver chloride is soluble in solutions of ammonia and sodium thiosulfate. Draw up equations for the formation of silver complex compounds, taking into account that the coordination number of the Ag + ion is two.

ALUMINUM

Aluminum

- element of the main subgroup of group III. At the outer energy level, the aluminum atom has three electrons (s 2 p 1), therefore in most compounds it exhibits an oxidation state (+3)

Aluminum is an active metal. But at ordinary temperatures in air it does not change, since it is quickly covered with a thin dense layer of oxide, protecting it from further oxidation. Destruction of this layer, for example by amalgamation, causes rapid oxidation of the metal. Due to the presence of a protective layer, aluminum does not displace hydrogen from water; but lacking this layer, aluminum reacts well with water to form hydroxide A1(OH) 3 and hydrogen.

Aluminum dissolves well in dilute acids - hydrochloric and sulfuric, especially when heated. Being an amphoteric metal, it dissolves well in alkalis with the formation of hydroxo-alumanates

and hydrogen:

2Al + 6KOH + 6H 2 O = 2K 3 [Al (OH) 6 ] + ZH 2.

Highly diluted and cold concentrated nitric acid and concentrated sulfuric acid do not dissolve aluminum, as they passivate it. Aluminum reacts well with many non-metals: nitrogen, sulfur, halogens.

Aluminum forms oxide

Al 2 O 3 and
hydroxide
are white, water-insoluble substances with amphoteric properties.

Aluminum salts formed by strong acids have an acidic environment in solutions due to hydrolysis. Some salts—sulfides and carbonates—in aqueous solutions undergo complete hydrolysis.

LABORATORY WORK

Physical properties

Copper in its pure form is a metal whose color can vary from pink to red.

The radius of copper ions having a positive charge can take the following values:

• if the coordination index corresponds to 6 - up to 0.091 nm;
• if this indicator corresponds to 2 - up to 0.06 nm.

The radius of the copper atom is 0.128 nm, and it is also characterized by an electron affinity of 1.8 eV. When an atom is ionized, this value can take a value from 7.726 to 82.7 eV.

Copper is a transition metal with an electronegativity value of 1.9 on the Pauling scale. In addition, its oxidation state can take on different values. At temperatures ranging from 20 to 100 degrees, its thermal conductivity is 394 W/m*K. The electrical conductivity of copper, which is surpassed only by silver, is in the range of 55.5–58 MS/m.

Since copper in the potential series is to the right of hydrogen, it cannot displace this element from water and various acids. Its crystal lattice has a cubic face-centered type, its value is 0.36150 nm. Copper melts at a temperature of 1083 degrees, and its boiling point is 26570. The physical properties of copper are also determined by its density, which is 8.92 g/cm3.

History of copper

Humanity began mining copper several thousand years ago. The most ancient products found from this metal date back to the 7-6 centuries BC. Among them are jewelry, tools, dishes and tools.

A big step forward in the development of metallurgy was the discovery of an alloy of copper and tin - bronze. This material was distinguished by its increased strength and ability to forge, due to which all products made from this copper alloy were of higher quality.

In our country, copper has long been mined in the Urals, Altai and Siberia. The most famous cultural monuments were cast from it: the Tsar Cannon, the Tsar Bell, the Bronze Horseman.

Copper hardness

Native copper measuring about 4 cm

Copper

- a mineral from the class of native elements. Fe, Ag, Au, As and other elements are found in natural minerals as impurities or forming solid solutions with Cu. The simple substance copper is a ductile transition metal of golden-pink color (pink in the absence of an oxide film). One of the first metals widely mastered by man due to its relative availability for extraction from ore and low melting point. It is one of the seven metals known to man since very ancient times. Copper is an essential element for all higher plants and animals.

1. Structure
2. Properties
3. Reserves and production
4. Origin
5. Application
6. Classification
7. Physical properties
8. Optical properties
9. Crystallographic properties

See also:

Copper and its alloys

Copper belongs to the group of non-ferrous metals most widely used in industry. The serial number of copper in the periodic system of D.I. Mendeleev is 29, atomic weight A = 63.57. Copper has a face-centered cubic lattice (fcc) with a period a = 3.607 Å.

Specific gravity of copper g = 8.94 g/cm3, melting point - 1083 0C. Pure copper has high thermal and electrical conductivity. The electrical resistivity of copper is 0.0175 μΩ×m, thermal conductivity l = 395 W/(m×deg).

Ultimate strength sв = 200…250 MPa, hardness 85…115 НВ, relative elongation d = 50%, relative contraction y = 75%.

Copper is a non-magnetic metal. It has good manufacturability: it can be processed by pressure, cutting, is easy to polish, is well soldered and welded, and has high corrosion resistance. The main area of ​​application is the electrical industry.

The electrical conductivity of copper is significantly reduced in the presence of even very small amounts of impurities. Therefore, especially pure copper M00 (99.99%), electrolytic copper M0 (99.95%), and M1 (99.9%) are used as conductor materials. Technical copper grades M2 (99.7%), M3 (99.5%), M4 (99.0%).

Depending on the mechanical properties, a distinction is made between hard, cold-worked copper (MT) and soft, annealed copper (MM).

Harmful impurities in copper are bismuth, lead, sulfur and oxygen. The action of bismuth and lead is similar to the action of sulfur in steel; They form low-melting eutectics with copper, located along the grain boundaries, which leads to the destruction of copper when it is processed under pressure in a hot state (the melting point of the eutectic is 270 0C and 326 0C, respectively).

Sulfur and oxygen reduce the ductility of copper due to the formation of brittle chemical compounds Cu2O and Cu2S.

Technically pure copper is rarely used as a structural material, since it has low strength properties and hardness. The main copper-based structural materials are alloys of brass and bronze. To mark copper alloys, use the following letter designation of alloying elements:

• O - tin; C - zinc; X - chromium;
• F - iron; N - nickel; C - lead;
• K - silicon; A - aluminum; F - phosphorus;
• Mts - manganese; Mg – magnesium; B – beryllium.

Bronze

Bronzes are alloys of copper with tin, aluminum, silicon and other elements.

Based on technological characteristics, bronzes are divided into wrought and cast bronzes. The deformable ones are marked with the letters Br, after which the alloying elements are listed, and then, accordingly, the content of these elements in percentage. copper is determined by the difference from 100%. For example, BrOTsS 8-4-3 contains 8% Sn, 4% Zn, 3% Pb, 85% Cu.

Cast bronzes are marked similarly to cast brass. For example, bronze Br06Ts3N6 contains 6% Sn, 3% Zn, 6% Pb, 85% Cu.

Compared to brass, bronze has better mechanical, antifriction properties and corrosion resistance.

Tin bronzes.

Alloys containing up to 10...12% Sn are of greatest practical importance. The limiting solubility of tin in copper is 15.8%, however, under real conditions of crystallization and cooling, the limiting solubility decreases to approximately 6%.

Single-phase alloys include bronzes with a tin content of up to 5...6% and a - phase, which is a solid solution of tin in copper with an fcc lattice. At a higher tin content, along with the a - solution, a eutectoid (a + Cu31Sn8) is present.

The tensile strength of bronze increases with increasing tin, but at high concentrations it decreases sharply due to the larger amount of brittle intermetallic Cu31Sn8.

Tin bronzes are usually alloyed with Zn, Pb, Ni, P. Zinc improves the technological properties of bronze and reduces its cost. Phosphorus improves casting properties. For the production of artistic castings, the phosphorus content can reach 1%.

Lead (up to 3...5%) is introduced into bronze to improve its machinability by cutting. Nickel increases the mechanical properties, corrosion resistance and density of castings, and reduces segregation.

Among copper alloys, tin bronzes have the lowest linear shrinkage (0.8% when cast in earth and 1.4% when cast in a metal mold).

To achieve plasticity, the alloys are homogenized at temperatures of 700...750 0C with rapid cooling. Residual stresses are removed by annealing at 550 0C.

Tin deformable bronzes Br0F7-0.2, BrOTsS4-4-4, BrOTs4-3 and others have higher strength, elasticity, and fatigue resistance than cast bronzes. They are used for the manufacture of sliding bearings, gears, tubes for control and measuring and other instruments, pressure springs, etc.

Foundry tin bronzes.

Compared to deformable ones, they contain a larger amount of alloying elements, have lower fluidity, low linear shrinkage, and are prone to the formation of shrinkage porosity. Bronzes BrOZTS7S5N, BrO10F1, BrO6Ts6S3, BrO5S25 and others are used for the manufacture of fittings operating in water and steam, bearings, gears, bushings.

Aluminum bronzes

They are characterized by high mechanical anti-corrosion properties, fluidity, and low tendency to dendritic segregation. Due to the large shrinkage, it is difficult to obtain complex shaped castings. They are frost-resistant, non-magnetic, and do not spark when struck. They are superior to brass and tin bronze in corrosion resistance.

Aluminum dissolves in copper, forming a - substitutional solid solution with a solubility limit of 9.4%. At higher contents, a eutectoid (a + g|) appears in the structure; g| — Cu32Al9 intermetallic compound.

Single-phase bronzes BrA5, BrA7 have good ductility and are classified as deformable. They have the best combination of strength and ductility: sв = 400...450 MPa, d = 60%.

Two-phase bronzes (a + g|) have increased strength up to 600 MPa, but ductility is noticeably lower d = (35...45)%. These alloys are strengthened by heat treatment and additionally alloyed with Fe, Ni, and Mn.

Iron refines the grain and increases the mechanical and antifriction properties of aluminum bronzes. Nickel improves mechanical properties and wear resistance, recrystallization temperature and corrosion resistance. Manganese increases technological and corrosion properties.

Bronzes BrAZHN10-4-4, BrAZhMts10-3-1-5 and others are used for the manufacture of gears, turbine parts, valve seats and other parts operating under severe wear conditions at elevated temperatures up to 400 0C, pump casings, valve boxes and etc.

Hardening is carried out at a temperature of 950 0C, after which the bronze is subjected to aging at 250...300 0C for 2...3 hours.

Silicon bronzes

used as substitutes for tin bronzes. Up to 3% silicon dissolves in copper, and a single-phase a-solid solution is formed. With a higher silicon content, a hard and brittle g-phase appears.

Nickel and manganese improves mechanical and corrosion properties. They do not lose their ductility at low temperatures, are easily soldered, can be processed under pressure, are non-magnetic and do not produce sparks upon impact.

They are used for parts operating up to 500 0C, as well as in aggressive environments (fresh, sea water).

Bronzes BrKN1-3, BrKMts3-1 are used for the manufacture of springs, anti-friction parts, evaporators, etc.

Beryllium bronzes.

Contains 2…2.5% Be. These alloys are strengthened by heat treatment. The limiting solubility of beryllium in copper at 866 0C is 2.7%, at 600 0C - 1.5%, and at 300 0C only 0.2%. Quenching is carried out at 760...800 0C in water and aging at 300 0C for 3 hours.

The alloy is strengthened due to the release of dispersed particles of the g-phase CuBe, which leads to a sharp increase in strength to 1250 MPa at d = 3...5%. Bronzes BrB2, BrBNT1.9 and BrBNT1.7 have high strength, elasticity, corrosion resistance, heat resistance, are non-magnetic, and are intrinsically safe (a spark is not formed when electrical contacts are opened).

Used for the manufacture of membranes, springs, electrical contacts.

Lead bronzes.

Lead is practically insoluble in liquid copper. Therefore, after solidification, alloys consist of copper crystals and lead inclusions. This structure provides high anti-friction properties.

BrS30 bronze is used for the manufacture of sleeve bearings operating at high pressures and high speeds. Compared to tin bronzes, its thermal conductivity is 4 times greater, so it removes heat generated by friction well.

The strength of these bronzes is low sв = 60 MPa, d = 4%.

Aluminum and its alloys > Continue >

What material is called solid copper - Metals, equipment, instructions

Copper is a highly conductive material. These are materials whose resistivity value is less than one tenth of a microohm per meter. For copper, this value is 0.017-0.018 μOhm*m. Copper is also a conductor in terms of electrical properties and a diamagnetic in terms of magnetic properties.

How is copper obtained?

Copper used in wires and cables is of fairly high purity. To obtain it, copper ores (sulfide, oxide and mixed) are used. Let me remind you what sulfide ores are - they are fossil raw materials that are mined in nature and consist of heavy metal (ore), sulfur (sulfide) and various impurities.

Sulfide ores account for almost all copper production and reserves (among ore production). The most common minerals in terms of deposits and feasibility of extraction among sulfide ores are chalcopyrite (CuFeS2), chalcocite (Cu2S), bornite (Cu5FeS4).

name of the mineral chemical formula % copper color

In general, in the first stage, copper-containing ores are mined.

The mined ores must then be purified of all impurities and foreign metals to produce copper. For these purposes, the following methods are used: pyrometallurgical, hydrometallurgical and electrolysis. For example, after the pyrometallurgical method we will receive copper ingots in which the copper itself will be 90 percent. Not bad, but it could be better.

Then this blister copper is brought to 99.99% purity using electrolytic purification and we get what is used in the energy industry.

The influence of impurities on the properties of copper

The issue of copper purity is quite important:

• in the presence of 0.02% aluminum impurity, electrical conductivity decreases by approximately 10%. But aluminum is a fairly good conductor.
• in the presence of 0.1% phosphorus, the resistance increases by 55%, therefore the conductivity decreases as the reciprocal of the resistance
• if there is bismuth or lead in copper in an amount of more than 0.001%, then this causes red brittleness (cracking during hot pressure treatment)
• Oxygen in copper makes soldering difficult and increases resistivity. To avoid this, a phosphorus additive is introduced
• hydrogen - forms microcracks and increases brittleness

If several impurities are present, then there are situations where they interact and their influence increases significantly.

For the use of copper to transmit electricity, the presence of impurities has only a negative effect.

Copper grades for electrical engineering and in general

Copper grades consist of the letter “M”, which means copper. This is followed by a number from 0 to 4.

Sometimes one of the letters is then found that characterize the method of producing the metal: k - cathode, p - deoxidized with low residual phosphorus, f - deoxidized with high residual phosphorus, b - oxygen-free. Oxygen-free is M0, and deoxidized is M1. There are many grades of copper, let's look at some:

A special grade of copper is M1E. This is electrical copper, which is produced in the form of tires, rods of various diameters and sections. It can be extra hard, hard, semi-hard and soft. The conductivity of soft copper is a couple of percent higher.

Available in the form of tires, rods, circles. The rods, in turn, have a diameter from 5 to 40 mm and a cross-sectional shape - circle, square, hexagon. This type of copper has a limited shelf life - up to a year for soft copper and six months for hard copper.

Copper alloys in electrical engineering

There are various copper alloys, including bronze, brass and others. Some of them have found application in energy. Let's look at these alloys.

Bronzes are alloys of copper with tin, aluminum, silicon, and lead.

Among other impurities, the highest electrical conductivities are (in order of decreasing electrical conductivity): cadmium, chromium and beryllium bronze.

The most common tin bronze has a low electrical conductivity. Bronze is used for the manufacture of contacts, spring contacts, plates in parts of electrical machines, and high-strength wires.

Brass is an alloy of copper with zinc (these two substances make up the majority of the alloy) and other impurities. The percentage of zinc reaches 43%. Used for spring contacts, plug connectors.

Manganin is an alloy of copper with the addition of manganese and nickel. Used for the manufacture of additional resistors and shunts in measuring technology. If silver is used instead of copper, the electrical properties are improved.

This article provides basic concepts about the use of copper in the energy sector; a more in-depth study is possible by mastering special technical literature on this topic.

Liquid and gaseous dielectrics

SF6 gas

Copper and its alloys

Copper belongs to the group of non-ferrous metals most widely used in industry. The serial number of copper in the periodic system of D.I. Mendeleev is 29, atomic weight A = 63.57. Copper has a face-centered cubic lattice (fcc) with a period a = 3.607 Å.

Specific gravity of copper g = 8.94 g/cm3, melting point - 1083 0C. Pure copper has high thermal and electrical conductivity. The electrical resistivity of copper is 0.0175 μΩ×m, thermal conductivity l = 395 W/(m×deg).

Ultimate strength sв = 200…250 MPa, hardness 85…115 НВ, relative elongation d = 50%, relative contraction y = 75%.

Copper is a non-magnetic metal. It has good manufacturability: it can be processed by pressure, cutting, is easy to polish, is well soldered and welded, and has high corrosion resistance. The main area of ​​application is the electrical industry.

The electrical conductivity of copper is significantly reduced in the presence of even very small amounts of impurities. Therefore, especially pure copper M00 (99.99%), electrolytic copper M0 (99.95%), and M1 (99.9%) are used as conductor materials. Technical copper grades M2 (99.7%), M3 (99.5%), M4 (99.0%).

Depending on the mechanical properties, a distinction is made between hard, cold-worked copper (MT) and soft, annealed copper (MM).

Harmful impurities in copper are bismuth, lead, sulfur and oxygen. The action of bismuth and lead is similar to the action of sulfur in steel; They form low-melting eutectics with copper, located along the grain boundaries, which leads to the destruction of copper when it is processed under pressure in a hot state (the melting point of the eutectic is 270 0C and 326 0C, respectively).

Sulfur and oxygen reduce the ductility of copper due to the formation of brittle chemical compounds Cu2O and Cu2S.

Technically pure copper is rarely used as a structural material, since it has low strength properties and hardness. The main copper-based structural materials are alloys of brass and bronze. To mark copper alloys, use the following letter designation of alloying elements:

• O - tin; C - zinc; X - chromium;
• F - iron; N - nickel; C - lead;
• K - silicon; A - aluminum; F - phosphorus;
• Mts - manganese; Mg – magnesium; B – beryllium.

Brass

Brasses are copper alloys in which the main alloying element is zinc.

Depending on the zinc content, brasses for industrial use are:

1. single-phase a - brass containing up to 39% zinc (this is the maximum solubility of zinc in copper);
2. two-phase (a+b|)- brass containing up to 46% zinc;
3. single-phase b|- brass containing up to 50% zinc.

Single-phase a-brasses are ductile, can be easily processed by cutting and pressure at temperatures below 300 0C and above 700 0C (in the range from 300 0C to 700 0C - the brittle zone). With increasing zinc content, the strength of brass increases.

In brasses, the b|-phase is an ordered solid solution based on the electronic connection of CuZn with a bcc lattice; it is brittle and strong. Therefore, the more b|-phase in brass, the stronger and less ductile they are.

Brass with a zinc content of up to 42...43% has practical application.

Brasses processed by pressure are marked with the letter L (brass), followed by the letter designations of alloying elements; The numbers following the letters indicate the copper content and the percentage of the corresponding alloying element. zinc is determined by the difference from 100%.

For example, L62 brass contains 62% Cu and 38% Zn. Casting brass is marked with the letter L, after which the content of zinc and other alloying elements is indicated as a percentage. The amount of copper is determined by the difference from 100%. For example, brass LTs36Mts20S2 contains 36% Zn, 20% Mn, 2% Pb and 42% Cu.

Single-phase a-brasses include L96 (tompak), L80 (semi-tompak), L68, which has the greatest ductility (d = 56%). Two-phase (a+b|) - brasses of grades L59 and L60 have less ductility in the cold state, but greater strength and wear resistance. Single-phase ones have after annealing sв = 250...350 MPa and d = (50...56)%, two-phase ones have sв = 400...450 MPa and d = (35...40%).

To increase the mechanical properties and corrosion resistance of brass, they can be alloyed with tin, aluminum, manganese, silicon, nickel, iron, etc.

The introduction of alloying elements (except nickel) reduces the solubility of zinc in copper and promotes the formation of the b|- phase, therefore such brasses are often two-phase (a+b|).

Nickel increases the solubility of zinc in copper, and with sufficient zinc content, brass changes from two-phase to single-phase. Lead facilitates machinability and improves anti-friction properties.

Corrosion resistance is increased by Al, Zn, Si, Mn, Ni, Sn.

In marine shipbuilding, tin-bearing “marine” brasses are used, for example, LO70-1 (70% Cu, 1% Sn, 29% Zn). It is used for the manufacture of condenser tubes and parts of heating equipment.

Aluminum brass

used for the manufacture of condenser tubes, tanks, bushings, as well as for the manufacture of corrosion-resistant parts operating in sea water.

Solid-drawn round pipes are made from brass LANKMts75-2-2.5-0.5-0.5 for the production of pressure tubes and springs in instruments of a high accuracy class. With the help of hardening and aging, sв reaches 700 MPa.