Pure metals from hydrogen. Cleaner, even cleaner! Are there absolutely pure metals?

Metals Common iron Iron is one of the most common elements in nature. Its content in the earth's crust is about 4.7% by weight, therefore iron, from the point of view of its occurrence in nature, is usually called a macroelement. In natural water, iron

Pure metals and alloys used in radio electronics

Lecture 8. Conductor materials and wires

Purpose of conductor materials;

Purpose and types of wires.

Lecture objectives:

Study of conductive materials;

Studying wires.

8.1 Meaning spring materials

Most metallic conductor materials have high electrical conductivity ( ρ = 0.015 ÷ 0.028 µOhm m). These are predominantly pure metals that are used for the manufacture of winding and radio installation wires and cables.

Along with this, conductors with high electrical resistance - alloys of various metals - are used in radio electronics. For metal (resistive) ρ = 0.4 ÷ 2.0 µOhm m. These alloys constitute a group of metallic materials with a low temperature coefficient of resistivity (TC ρ ) and are used for the manufacture of wirewound resistors and other radio components.

Copper– the main material with high ductility, sufficient mechanical strength and high electrical conductivity. The melting point of copper is 1083°C, the coefficient of thermal expansion CTE = 17·10 -6 1/°C. For the manufacture of products (winding, radio installation wires and cables) pure copper grade M00k is used; MOKU; Mok; M1k and M00b; Mob; M1b. Copper content 99.99 – 99.90%. Products made of soft copper (at 20°C) have a density of 8900 kg/m3; σ р = 200÷280 MPa; e = 6÷35%; ρ = 0.072÷0.01724 µOhm m. Temperature coefficient of resistivity for all grades of copper TK ρ = 0.0041/°C.

Bronze is an alloy of copper with tin (tin bronze), aluminum (aluminum), beryllium (beryllium) and other alloying elements. In terms of electrical conductivity, bronze is inferior to copper, but superior to it in mechanical strength, elasticity, abrasion resistance and corrosion resistance. Spring contacts, contact parts of connectors and other parts are made from bronze.

Brass– an alloy of copper and zinc, in which the highest zinc content can be 45% (by weight). Various parts are made from sheet brass: clamps, contacts, fasteners. The main characteristics of bronze, brass and copper are given in Table 8.1.

Kovar– an alloy of nickel (about 29% by weight), cobalt (about 18%), iron (the rest). Characteristic feature Kovar is the closeness of its CTE values ​​= (4.3÷5.4) · 10 -6 1/°C to the CTE values ​​of glass and ceramics in the temperature range 20 – 200°C. This allows the production of consistent, hermetically sealed joints between the kovar and glass and ceramics. It is used to make IC packages and semiconductor devices.

Aluminum is the second conductor material after copper due to its relatively high electrical conductivity and resistance to atmospheric corrosion.

Aluminum density 2700 kg/m 3, ᴛ.ᴇ. it is 3.3 times lighter than copper, melting point 658°C. Aluminum is characterized by low hardness and low tensile strength (σ р = 80÷180 MPa) and higher CTE = 24·10 -6 1/°С compared to copper. This is a disadvantage of aluminum.

Platings of electrolytic capacitors, as well as foil, are made from high-purity aluminum grades. Aluminum wire is produced Ø0.08 – 8mm in three varieties: soft (AM), semi-hard (APT), hard (AT).

Table 8.1

Silver belongs to the group of noble metals that do not oxidize in air at room temperature. Oxidation begins at 200°C. Silver is distinguished by its high ductility, which makes it possible to produce foil and wire with a diameter of up to 0.01 mm, and the highest electrical conductivity.

Main characteristics of silver: density 1050 kg/m 3 ; melting point 960.5 °C; σ р = 150÷180 MPa (soft silver); σ р = 200÷300 MPa (solid silver); ρ = 0.0158 µOhm m; TK ρ = 0.003691/°C; KTE= 24·10 -6 1/°С.

Silver is used to make protective layers on copper conductors of radio installation wires used at temperatures up to 250°C. Silver is applied to the inner surface of the waveguides to obtain a layer with high electrical conductivity, and is also introduced into solders (PSr10, PSr50) used for soldering conductive parts in electronic devices.

Gold– unlike silver, it does not oxidize in the air even at high temperatures. It has very high ductility; foil with a thickness of up to 0.005 mm and wire with a diameter of up to 0.01 mm are produced from it.

Main characteristics of gold: density 1930 kg/m 3; melting point 1063°C; σ р = 150÷180 MPa, ρ = 0.0224 µOhm m; TK ρ = 0.003691/°C;

KTE= 14.2·10 -6 1/°С.

Gold is used for thin-film contact coatings when switching low currents in microcircuits, as well as for coating walls

waveguides and microwave resonators.

Pure metals and alloys used in radio electronics - concept and types. Classification and features of the category "Pure metals and alloys used in radio electronics" 2017, 2018.

If in D.I. Mendeleev’s periodic table of elements we draw a diagonal from beryllium to astatine, then on the lower left along the diagonal there will be metal elements (these also include elements of side subgroups, highlighted in blue), and on the upper right - non-metal elements (highlighted yellow). Elements located near the diagonal - semimetals or metalloids (B, Si, Ge, Sb, etc.) have a dual character (highlighted in pink).

As can be seen from the figure, the vast majority of elements are metals.

By their chemical nature, metals are chemical elements whose atoms give up electrons from external or pre-external energy levels, forming positively charged ions.

Almost all metals have relatively large radii and a small number of electrons (from 1 to 3) at the outer energy level. Metals are characterized by low electronegativity values ​​and reducing properties.

The most typical metals are located at the beginning of the periods (starting from the second), then from left to right the metallic properties weaken. In the group from top to bottom, the metallic properties increase as the radius of the atoms increases (due to an increase in the number of energy levels). This leads to a decrease in electronegativity (the ability to attract electrons) of elements and an increase in reducing properties (the ability to donate electrons to other atoms in chemical reactions).

Typical metals are s-elements (elements of the IA group from Li to Fr. elements of the PA group from Mg to Ra). The general electronic formula of their atoms is ns 1-2. They are characterized by oxidation states + I and + II, respectively.

The small number of electrons (1-2) in the outer energy level of typical metal atoms means that these electrons are easily lost and exhibit strong reducing properties, as reflected by low electronegativity values. This implies the limited chemical properties and methods of obtaining typical metals.

A characteristic feature of typical metals is the tendency of their atoms to form cations and ionic chemical bonds with non-metal atoms. Compounds of typical metals with nonmetals are ionic crystals of “metalanion of nonmetal,” for example K + Br -, Ca 2+ O 2-. Cations of typical metals are also included in compounds with complex anions - hydroxides and salts, for example Mg 2+ (OH -) 2, (Li +)2CO 3 2-.

The A-group metals that form the diagonal of amphotericity in the Periodic Table Be-Al-Ge-Sb-Po, as well as the metals adjacent to them (Ga, In, Tl, Sn, Pb, Bi) do not typically exhibit metallic properties. General electronic formula of their atoms ns 2 n.p. 0-4 involves a greater variety of oxidation states, a greater ability to retain their own electrons, a gradual decrease in their reducing ability and the appearance of oxidizing ability, especially in high oxidation states (typical examples are compounds Tl III, Pb IV, Bi v). Similar chemical behavior is characteristic of most (d-elements, i.e. elements of the B-groups of the Periodic Table (typical examples are the amphoteric elements Cr and Zn).

This manifestation of duality (amphoteric) properties, both metallic (basic) and non-metallic, is due to the nature of the chemical bond. In the solid state, compounds of atypical metals with nonmetals contain predominantly covalent bonds (but less strong than bonds between nonmetals). In solution, these bonds are easily broken, and the compounds dissociate into ions (in whole or in part). For example, the metal gallium consists of Ga 2 molecules; in the solid state, the chlorides of aluminum and mercury (II) AlCl 3 and HgCl 2 contain strongly covalent bonds, but in solution AlCl 3 dissociates almost completely, and HgCl 2 - to a very small extent (and then into HgCl + and Cl - ions).

General physical properties of metals

Due to the presence of free electrons ("electron gas") in the crystal lattice, all metals exhibit the following characteristic general properties:

1) Plastic- the ability to easily change shape, stretch into wire, and roll into thin sheets.

2) Metallic shine and opacity. This is due to the interaction of free electrons with light incident on the metal.

3) Electrical conductivity. It is explained by the directional movement of free electrons from the negative pole to the positive one under the influence of a small potential difference. When heated, electrical conductivity decreases, because As the temperature increases, vibrations of atoms and ions in the nodes of the crystal lattice intensify, which complicates the directional movement of the “electron gas”.

4) Thermal conductivity. It is caused by the high mobility of free electrons, due to which the temperature quickly equalizes over the mass of the metal. The highest thermal conductivity is found in bismuth and mercury.

5) Hardness. The hardest is chrome (cuts glass); the softest alkali metals - potassium, sodium, rubidium and cesium - are cut with a knife.

6) Density. The smaller it is, the smaller it is atomic mass metal and larger atomic radius. The lightest is lithium (ρ=0.53 g/cm3); the heaviest is osmium (ρ=22.6 g/cm3). Metals with a density of less than 5 g/cm3 are considered “light metals”.

7) Melting and boiling points. The most fusible metal is mercury (mp = -39°C), the most refractory metal is tungsten (mp = 3390°C). Metals with melting temperature above 1000°C are considered refractory, below – low-melting.

General chemical properties of metals

Strong reducing agents: Me 0 – nē → Me n +

A number of voltages characterize the comparative activity of metals in redox reactions in aqueous solutions.

I. Reactions of metals with non-metals

1) With oxygen:
2Mg + O 2 → 2MgO

2) With sulfur:
Hg + S → HgS

3) With halogens:
Ni + Cl 2 – t° → NiCl 2

4) With nitrogen:
3Ca + N 2 – t° → Ca 3 N 2

5) With phosphorus:
3Ca + 2P – t° → Ca 3 P 2

6) With hydrogen (only alkaline and alkaline earth metals):
2Li + H 2 → 2LiH

Ca + H 2 → CaH 2

II. Reactions of metals with acids

1) Metals in the electrochemical voltage series up to H reduce non-oxidizing acids to hydrogen:

Mg + 2HCl → MgCl 2 + H 2

2Al+ 6HCl → 2AlCl 3 + 3H 2

6Na + 2H 3 PO 4 → 2Na 3 PO 4 + 3H 2

2) With oxidizing acids:

When nitric acid of any concentration and concentrated sulfuric acid interact with metals Hydrogen is never released!

Zn + 2H 2 SO 4(K) → ZnSO 4 + SO 2 + 2H 2 O

4Zn + 5H 2 SO 4(K) → 4ZnSO 4 + H 2 S + 4H 2 O

3Zn + 4H 2 SO 4(K) → 3ZnSO 4 + S + 4H 2 O

2H 2 SO 4 (k) + Cu → Cu SO 4 + SO 2 + 2H 2 O

10HNO 3 + 4Mg → 4Mg(NO 3) 2 + NH 4 NO 3 + 3H 2 O

4HNO 3 (k) + Cu → Cu (NO 3) 2 + 2NO 2 + 2H 2 O

III. Interaction of metals with water

1) Active (alkali and alkaline earth metals) form a soluble base (alkali) and hydrogen:

2Na + 2H 2 O → 2NaOH + H 2

Ca+ 2H 2 O → Ca(OH) 2 + H 2

2) Metals of medium activity are oxidized by water when heated to an oxide:

Zn + H 2 O – t° → ZnO + H 2

3) Inactive (Au, Ag, Pt) - do not react.

IV. Displacement of less active metals by more active metals from solutions of their salts:

Cu + HgCl 2 → Hg+ CuCl 2

Fe+ CuSO 4 → Cu+ FeSO 4

In industry, they often use not pure metals, but mixtures of them - alloys, in which the beneficial properties of one metal are complemented by the beneficial properties of another. Thus, copper has low hardness and is unsuitable for the manufacture of machine parts, while alloys of copper and zinc ( brass) are already quite hard and are widely used in mechanical engineering. Aluminum has high ductility and sufficient lightness (low density), but is too soft. Based on it, an alloy with magnesium, copper and manganese is prepared - duralumin (duralumin), which, without losing beneficial properties aluminum, acquires high hardness and becomes suitable for aircraft construction. Alloys of iron with carbon (and additives of other metals) are widely known cast iron And steel.

Free metals are restorers. However, some metals have low reactivity due to the fact that they are coated surface oxide film, to varying degrees resistant to the effects of such chemical reagents, like water, solutions of acids and alkalis.

For example, lead is always covered with an oxide film; its transition into solution requires not only exposure to a reagent (for example, dilute nitric acid), but also heating. The oxide film on aluminum prevents its reaction with water, but is destroyed by acids and alkalis. Loose oxide film (rust), formed on the surface of iron in moist air, does not interfere with further oxidation of iron.

Under the influence concentrated acids form on metals sustainable oxide film. This phenomenon is called passivation. So, in concentrated sulfuric acid metals such as Be, Bi, Co, Fe, Mg and Nb are passivated (and then do not react with acid), and in concentrated nitric acid - metals A1, Be, Bi, Co, Cr, Fe, Nb, Ni, Pb , Th and U.

When interacting with oxidizing agents in acidic solutions, most metals transform into cations, the charge of which is determined by the stable oxidation state of a given element in compounds (Na +, Ca 2+, A1 3+, Fe 2+ and Fe 3+)

The reducing activity of metals in an acidic solution is transmitted by a series of stresses. Most metals are transferred into solution with hydrochloric and dilute sulfuric acids, but Cu, Ag and Hg - only with sulfuric (concentrated) and nitric acids, and Pt and Au - with “regia vodka”.

Metal corrosion

Undesirable chemical property metals is their, i.e. active destruction (oxidation) upon contact with water and under the influence of oxygen dissolved in it (oxygen corrosion). For example, the corrosion of iron products in water is widely known, as a result of which rust forms and the products crumble into powder.

Corrosion of metals also occurs in water due to the presence of dissolved gases CO 2 and SO 2; an acidic environment is created, and H + cations are displaced by active metals in the form of hydrogen H 2 ( hydrogen corrosion).

The area of ​​contact between two dissimilar metals can be especially corrosive ( contact corrosion). A galvanic couple occurs between one metal, for example Fe, and another metal, for example Sn or Cu, placed in water. The flow of electrons goes from the more active metal, which is to the left in the voltage series (Re), to the less active metal (Sn, Cu), and the more active metal is destroyed (corroded).

It is because of this that the tinned surface of cans (iron coated with tin) rusts when stored in a humid atmosphere and handled carelessly (iron quickly collapses after even a small scratch appears, allowing the iron to come into contact with moisture). On the contrary, the galvanized surface of an iron bucket does not rust for a long time, since even if there are scratches, it is not the iron that corrodes, but the zinc (a more active metal than iron).

Corrosion resistance for a given metal increases when it is coated with a more active metal or when they are fused; Thus, coating iron with chromium or making an alloy of iron and chromium eliminates corrosion of iron. Chromed iron and steel containing chromium ( stainless steel), have high corrosion resistance.

electrometallurgy, i.e., obtaining metals by electrolysis of melts (for the most active metals) or salt solutions;

pyrometallurgy, i.e., the recovery of metals from ores at high temperatures (for example, the production of iron in the blast furnace process);

hydrometallurgy, i.e., the separation of metals from solutions of their salts by more active metals (for example, the production of copper from a solution of CuSO 4 by the action of zinc, iron or aluminum).

Native metals are sometimes found in nature (typical examples are Ag, Au, Pt, Hg), but more often metals are found in the form of compounds ( metal ores). Metals vary in abundance in the earth's crust: from the most common - Al, Na, Ca, Fe, Mg, K, Ti) to the rarest - Bi, In, Ag, Au, Pt, Re.

PURE METALS

metals, metals with low impurity content. Depending on the degree of purity, there are metals of high purity (99.90-99.99%), metals of high purity, or chemically pure (99.99-99.999%), metals of special purity, or spectral pure, ultra-pure metals (over 99.999 %).

Great Soviet Encyclopedia, TSB. 2012

See also interpretations, synonyms, meanings of the word and what PURE METALS are in Russian in dictionaries, encyclopedias and reference books:

• CLEAN
  PRIVATE DOMESTIC INVESTMENT - the gross volume of private domestic investment minus depreciation ...
• CLEAN in the Dictionary of Economic Terms:
  LOSSES - losses of economic entities associated with the creation of an artificial shortage by the monopolist, leading to the establishment of prices that do not coincide with the marginal...
• CLEAN in the Dictionary of Economic Terms:
  TRANSFER PAYMENTS - personal and government transfer payments to residents of other countries minus personal and government transfer payments received from residents of other...
• CLEAN in the Dictionary of Economic Terms:
  CURRENT ASSETS - current, easily realizable assets minus the costs associated with them...
• CLEAN in the Dictionary of Economic Terms:
  PURCHASES - the total amount of purchases for a certain period minus discounts, returns of originally purchased products and reductions in the normal price and ...
• CLEAN in the Dictionary of Economic Terms:
  PRODUCT TAXES - the difference between taxes on products and subsidies allocated for their ...
• CLEAN in the Dictionary of Economic Terms:
  IMPORT TAXES - the difference between import taxes and subsidies on ...
• CLEAN in the Dictionary of Economic Terms:
  TAXES - taxes that are paid by the population to the state, minus transfer payments that the population receives from ...
• CLEAN in the Dictionary of Economic Terms:
  LIQUID ASSETS - amount of cash Money, easily marketable securities, etc. accounts receivable By …
• CLEAN in the Dictionary of Economic Terms:
  CAPITAL INVESTMENT - gross capital investment minus...
• CLEAN in the Dictionary of Economic Terms:
  DISCLOSURE COSTS - costs directly related to the process of buying and selling goods; include transportation costs, costs of cargo transshipment, its processing, ...
• CLEAN in the Dictionary of Economic Terms:
  ASSETS - a calculated value determined by subtracting from the amount of assets, which includes monetary and non-monetary property at book value, ...
• METALS in the Dictionary of Economic Terms:
  PRECIOUS - see PRECIOUS METALS...
• METALS in the Bible Encyclopedia of Nikephoros:
  In St. The scriptures often mention metals: iron, copper, tin, lead, zinc, silver, gold. see about each in its own...
• METALS in the Big Encyclopedic Dictionary:
  (Greek) substances that under normal conditions have high electrical conductivity (106-107 Ohm-1 cm-1, decreases with increasing temperature) and thermal conductivity, malleability, “metallic” luster...
• METALS
  simple substances that, under normal conditions, have characteristic properties: high electrical and thermal conductivity, negative temperature coefficient of electrical conductivity, ability to well reflect electromagnetic...
• METALS
  I (and metalloids) (chemical) - M. is a group of simple bodies (see) that have known characteristic properties, which in typical representatives are sharply ...
• METALS in the Modern Encyclopedic Dictionary:
  
• METALS in the Encyclopedic Dictionary:
  simple substances that, under normal conditions, have characteristic properties - high electrical conductivity (106-104 Ohm-1?cm-1), decreasing with increasing temperature, high thermal conductivity, brilliance, ...
• CLEAN
  "PURE BROTHERS" ("Brothers of Purity", Arabic. Ikhwan al-Safa), a group of philosophers of the 10th century, which included thinkers of Iraq (chief sample from the city ...
• METALS in the Big Russian Encyclopedic Dictionary:
  "METALS", scientific. Journal of the Russian Academy of Sciences, since 1959, Moscow. Founder (1998) - Institute of Metallurgy named after. A.A. Baykova. 6 rooms in…
• METALS in the Big Russian Encyclopedic Dictionary:
  METALS, substances that under normal conditions have high electrical conductivity (10 6 - 10 4 Ohm -1 cm -1, decreases with ...
• CLEAN in the New Explanatory Dictionary of the Russian Language by Efremova:
  
• METALS in Modern explanatory dictionary, TSB:
  (Greek), substances that under normal conditions have high electrical conductivity (106-107 Ohm-1 cm-1, decreases with increasing temperature) and thermal conductivity, malleability, “metallic” luster...
• CLEAN in Ephraim's Explanatory Dictionary:
  pure plural decomposition The money remaining after deductions...
• CLEAN in the New Dictionary of the Russian Language by Efremova:
  pl. decomposition The money remaining after deductions...
• CLEAN in the Large Modern Explanatory Dictionary of the Russian Language:
  pl. decomposition The money remaining after deductions...
• NON-FERROUS METALS in the Great Soviet Encyclopedia, TSB:
  metals, the technical name for all metals and their alloys (except iron and its alloys, called ferrous metals). The term "C. m." V …
• REFRACTORY METALS in the Great Soviet Encyclopedia, TSB:
  metals, according to technical classification- metals that melt at temperatures above 1650-1700 |C; T. m. (table) includes titanium...
• RARE METALS in the Great Soviet Encyclopedia, TSB:
  metals, the conventional name of a group of metals (over 50), the list of which is given in the table. These are metals that are relatively new in technology or else...
• NOBLE METALS in the Great Soviet Encyclopedia, TSB:
  metals, gold, silver, platinum and platinum group metals (iridium, osmium, palladium, rhodium, ruthenium), which received their name mainly due to their high ...
• METAL CASTING: METALS FOR CASTING in Collier's Dictionary:
  To the article CASTING OF METALS All metals can be cast. But not all metals have the same casting properties, in particular fluidity -...
• IMPRESSIONISM in the Lexicon of non-classics, artistic and aesthetic culture of the 20th century, Bychkova:
  (from French impression - impression) A movement in art that arose in France in the last third of the 19th century. Main representatives of I.: Claude...
• SOLID in the Great Soviet Encyclopedia, TSB.
• CHEMICAL REAGENTS in the Great Soviet Encyclopedia, TSB:
  chemicals, chemical reagents, chemical preparations (substances) used in laboratories for analysis, scientific research (when studying methods of production, properties and transformations...
• METALLURGY in the Great Soviet Encyclopedia, TSB:
  (from the Greek metallurgeo - I mine ore, I process metals, from metallon - mine, metal and ergon - work), in the original, narrow ...
• ADHESIVES in the Great Soviet Encyclopedia, TSB:
  natural or synthetic substances used to connect various materials due to the formation of an adhesive bond between the adhesive film and the surfaces of the materials being bonded. ...
• DISCLOSURE COSTS in the Great Soviet Encyclopedia, TSB:
  circulation, the totality of costs associated with the process of circulation of goods. By its economic nature, I. o. are divided into pure and additional. Clean...
• FLUORINE
• TURKS in the Encyclopedic Dictionary of Brockhaus and Euphron:
  (the exact meaning of the word is unknown) - a group of peoples speaking various dialects of the Turkic language (see Turkish languages) and according to physical characteristics ...
• ALLOYS in the Encyclopedic Dictionary of Brockhaus and Euphron.
• PLANTINGS in the Encyclopedic Dictionary of Brockhaus and Euphron:
  areas of forest that naturally differ from neighboring ones in the nature of woody vegetation. The difference between N. may be determined by their origin, composition, age, degree...
• ORGANIC ARTIFICIAL PAINTS in the Encyclopedic Dictionary of Brockhaus and Euphron:
  The development of the production and use of artificial organic compounds is closely related to the history of scientific research on coal tar. Studying the composition of the latter, Runge in ...
• FACTORIES in the Encyclopedic Dictionary of Brockhaus and Euphron:
  In colloquial language, the concepts of Z. and factory are not distinguished, and, perhaps, there is still no particular need for that...
• GERMAN PHYSICAL TYPE in the Encyclopedic Dictionary of Brockhaus and Euphron:
  Rome. writers (Tacitus and others) described G. as a people of tall stature, strong build, blond or red-haired and with light, blue...
• RECOVERY in the Encyclopedic Dictionary of Brockhaus and Euphron:
  Alchemists accepted that metals are complex bodies, consisting of spirit, soul and body, or mercury, sulfur and salt; in spirit...

Pure metals

metals with low impurity content. Depending on the degree of purity, there are metals of high purity (99.90-99.99%), metals of high purity, or chemically pure (99.99-99.999%), metals of special purity, or spectral pure, Ultrapure metals (over 99.999 %).