Iron is an element of a secondary subgroup of the eighth group of the fourth period of the periodic system of chemical elements of D. I. Mendeleev with atomic number 26. It is designated by the symbol Fe (lat. Ferrum). One of the most common metals in the earth's crust (second place after aluminum). Medium activity metal, reducing agent.
Main oxidation states - +2, +3
A simple substance iron is a malleable silver-white metal with a high chemical reactivity: iron quickly corrodes at high temperatures or high humidity in the air. In pure oxygen, iron burns, and in a finely dispersed state, it ignites spontaneously in air.
Chemical properties of a simple substance - iron:
Rusting and burning in oxygen
1) In air, iron is easily oxidized in the presence of moisture (rusting):
4Fe + 3O 2 + 6H 2 O → 4Fe(OH) 3
A heated iron wire burns in oxygen, forming scale - iron oxide (II, III):
3Fe + 2O 2 → Fe 3 O 4
3Fe + 2O 2 → (Fe II Fe 2 III) O 4 (160 ° С)
2) At high temperatures (700–900°C), iron reacts with water vapor:
3Fe + 4H 2 O - t ° → Fe 3 O 4 + 4H 2
3) Iron reacts with non-metals when heated:
2Fe+3Cl 2 →2FeCl 3 (200 °С)
Fe + S – t° → FeS (600 °C)
Fe + 2S → Fe +2 (S 2 -1) (700 ° С)
4) In a series of voltages, it is to the left of hydrogen, reacts with dilute acids Hcl and H 2 SO 4, while iron (II) salts are formed and hydrogen is released:
Fe + 2HCl → FeCl 2 + H 2 (reactions are carried out without air access, otherwise Fe +2 is gradually converted by oxygen into Fe +3)
Fe + H 2 SO 4 (diff.) → FeSO 4 + H 2
In concentrated oxidizing acids, iron dissolves only when heated, it immediately passes into the Fe 3+ cation:
2Fe + 6H 2 SO 4 (conc.) – t° → Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O
Fe + 6HNO 3 (conc.) – t° → Fe(NO 3) 3 + 3NO 2 + 3H 2 O
(in the cold, concentrated nitric and sulfuric acids passivate
An iron nail immersed in a bluish solution of copper sulphate is gradually covered with a coating of red metallic copper.
5) Iron displaces metals to the right of it in solutions of their salts.
Fe + CuSO 4 → FeSO 4 + Cu
Amphotericity of iron is manifested only in concentrated alkalis during boiling:
Fe + 2NaOH (50%) + 2H 2 O \u003d Na 2 ↓ + H 2
and a precipitate of sodium tetrahydroxoferrate(II) is formed.
Technical iron- alloys of iron with carbon: cast iron contains 2.06-6.67% C, steel 0.02-2.06% C, other natural impurities (S, P, Si) and artificially introduced special additives (Mn, Ni, Cr) are often present, which gives iron alloys technically useful properties - hardness, thermal and corrosion resistance, malleability, etc. .
Blast furnace iron production process
The blast-furnace process of iron production consists of the following stages:
a) preparation (roasting) of sulfide and carbonate ores - conversion to oxide ore:
FeS 2 → Fe 2 O 3 (O 2, 800 ° С, -SO 2) FeCO 3 → Fe 2 O 3 (O 2, 500-600 ° С, -CO 2)
b) burning coke with hot blast:
C (coke) + O 2 (air) → CO 2 (600-700 ° C) CO 2 + C (coke) ⇌ 2CO (700-1000 ° C)
c) reduction of oxide ore with carbon monoxide CO in succession:
Fe2O3 →(CO)(Fe II Fe 2 III) O 4 →(CO) FeO →(CO) Fe
d) carburization of iron (up to 6.67% C) and melting of cast iron:
Fe (t ) →(C(coke)900-1200°С) Fe (g) (cast iron, t pl 1145°C)
In cast iron, cementite Fe 2 C and graphite are always present in the form of grains.
Steel production
The redistribution of cast iron into steel is carried out in special furnaces (converter, open-hearth, electric), which differ in the method of heating; process temperature 1700-2000 °C. Blowing oxygen-enriched air burns out excess carbon from cast iron, as well as sulfur, phosphorus and silicon in the form of oxides. In this case, oxides are either captured in the form of exhaust gases (CO 2, SO 2), or are bound into an easily separated slag - a mixture of Ca 3 (PO 4) 2 and CaSiO 3. To obtain special steels, alloying additives of other metals are introduced into the furnace.
Receipt pure iron in industry - electrolysis of a solution of iron salts, for example:
FeCl 2 → Fe↓ + Cl 2 (90°C) (electrolysis)
(there are other special methods, including the reduction of iron oxides with hydrogen).
Pure iron is used in the production of special alloys, in the manufacture of cores of electromagnets and transformers, cast iron is used in the production of castings and steel, steel is used as structural and tool materials, including wear-, heat- and corrosion-resistant materials.
Iron(II) oxide F EO . Amphoteric oxide with a large predominance of basic properties. Black, has an ionic structure of Fe 2+ O 2-. When heated, it first decomposes, then re-forms. It is not formed during the combustion of iron in air. Does not react with water. Decomposed by acids, fused with alkalis. Slowly oxidizes in moist air. Recovered by hydrogen, coke. Participates in the blast-furnace process of iron smelting. It is used as a component of ceramics and mineral paints. Equations of the most important reactions:
4FeO ⇌ (Fe II Fe 2 III) + Fe (560-700 ° С, 900-1000 ° С)
FeO + 2HC1 (razb.) \u003d FeC1 2 + H 2 O
FeO + 4HNO 3 (conc.) \u003d Fe (NO 3) 3 + NO 2 + 2H 2 O
FeO + 4NaOH \u003d 2H 2 O + Na 4FeO3(red.) trioxoferrate(II)(400-500 °С)
FeO + H 2 \u003d H 2 O + Fe (high purity) (350 ° C)
FeO + C (coke) \u003d Fe + CO (above 1000 ° C)
FeO + CO \u003d Fe + CO 2 (900 ° C)
4FeO + 2H 2 O (moisture) + O 2 (air) → 4FeO (OH) (t)
6FeO + O 2 \u003d 2 (Fe II Fe 2 III) O 4 (300-500 ° С)
Receipt V laboratories: thermal decomposition of iron (II) compounds without air access:
Fe (OH) 2 \u003d FeO + H 2 O (150-200 ° C)
FeSOz \u003d FeO + CO 2 (490-550 ° С)
Diiron oxide (III) - iron ( II ) ( Fe II Fe 2 III) O 4 . Double oxide. Black, has the ionic structure of Fe 2+ (Fe 3+) 2 (O 2-) 4. Thermally stable up to high temperatures. Does not react with water. Decomposed by acids. It is reduced by hydrogen, red-hot iron. Participates in the blast-furnace process of iron production. It is used as a component of mineral paints ( minium iron), ceramics, colored cement. The product of special oxidation of the surface of steel products ( blackening, bluing). The composition corresponds to brown rust and dark scale on iron. The use of the Fe 3 O 4 formula is not recommended. Equations of the most important reactions:
2 (Fe II Fe 2 III) O 4 \u003d 6FeO + O 2 (above 1538 ° С)
(Fe II Fe 2 III) O 4 + 8HC1 (razb.) \u003d FeC1 2 + 2FeC1 3 + 4H 2 O
(Fe II Fe 2 III) O 4 + 10HNO 3 (conc.) \u003d 3 Fe (NO 3) 3 + NO 2 + 5H 2 O
(Fe II Fe 2 III) O 4 + O 2 (air) \u003d 6Fe 2 O 3 (450-600 ° С)
(Fe II Fe 2 III) O 4 + 4H 2 \u003d 4H 2 O + 3Fe (high purity, 1000 ° C)
(Fe II Fe 2 III) O 4 + CO \u003d 3 FeO + CO 2 (500-800 ° C)
(Fe II Fe 2 III) O4 + Fe ⇌4 FeO (900-1000 ° С, 560-700 ° С)
Receipt: combustion of iron (see) in air.
magnetite.
Iron(III) oxide F e 2 O 3 . Amphoteric oxide with a predominance of basic properties. Red-brown, has an ionic structure (Fe 3+) 2 (O 2-) 3. Thermally stable up to high temperatures. It is not formed during the combustion of iron in air. Does not react with water, a brown amorphous hydrate Fe 2 O 3 nH 2 O precipitates from the solution. Slowly reacts with acids and alkalis. It is reduced by carbon monoxide, molten iron. Alloys with oxides of other metals and forms double oxides - spinels(technical products are called ferrites). It is used as a raw material in iron smelting in the blast furnace process, as a catalyst in the production of ammonia, as a component of ceramics, colored cements and mineral paints, in thermite welding of steel structures, as a sound and image carrier on magnetic tapes, as a polishing agent for steel and glass.
Equations of the most important reactions:
6Fe 2 O 3 \u003d 4 (Fe II Fe 2 III) O 4 + O 2 (1200-1300 ° С)
Fe 2 O 3 + 6HC1 (razb.) → 2FeC1 3 + ZH 2 O (t) (600 ° C, p)
Fe 2 O 3 + 2NaOH (conc.) → H 2 O+ 2 NAFeO 2 (red)dioxoferrate(III)
Fe 2 O 3 + MO \u003d (M II Fe 2 II I) O 4 (M \u003d Cu, Mn, Fe, Ni, Zn)
Fe 2 O 3 + ZN 2 \u003d ZN 2 O + 2Fe (highly pure, 1050-1100 ° С)
Fe 2 O 3 + Fe \u003d ZFeO (900 ° C)
3Fe 2 O 3 + CO \u003d 2 (Fe II Fe 2 III) O 4 + CO 2 (400-600 ° С)
Receipt in the laboratory - thermal decomposition of iron (III) salts in air:
Fe 2 (SO 4) 3 \u003d Fe 2 O 3 + 3SO 3 (500-700 ° С)
4 (Fe (NO 3) 3 9 H 2 O) \u003d 2 Fe a O 3 + 12NO 2 + 3O 2 + 36H 2 O (600-700 ° С)
In nature - iron oxide ores hematite Fe 2 O 3 and limonite Fe 2 O 3 nH 2 O
Iron(II) hydroxide F e(OH) 2 . Amphoteric hydroxide with a predominance of basic properties. White (sometimes with a greenish tinge), Fe-OH bonds are predominantly covalent. Thermally unstable. Easily oxidizes in air, especially when wet (darkens). Insoluble in water. Reacts with dilute acids, concentrated alkalis. Typical restorer. An intermediate product in the rusting of iron. It is used in the manufacture of the active mass of iron-nickel batteries.
Equations of the most important reactions:
Fe (OH) 2 \u003d FeO + H 2 O (150-200 ° C, in atm.N 2)
Fe (OH) 2 + 2HC1 (razb.) \u003d FeC1 2 + 2H 2 O
Fe (OH) 2 + 2NaOH (> 50%) \u003d Na 2 ↓ (blue-green) (boiling)
4Fe(OH) 2 (suspension) + O 2 (air) → 4FeO(OH)↓ + 2H 2 O (t)
2Fe (OH) 2 (suspension) + H 2 O 2 (razb.) \u003d 2FeO (OH) ↓ + 2H 2 O
Fe (OH) 2 + KNO 3 (conc.) \u003d FeO (OH) ↓ + NO + KOH (60 ° С)
Receipt: precipitation from solution with alkalis or ammonia hydrate in an inert atmosphere:
Fe 2+ + 2OH (razb.) = Fe(OH) 2 ↓
Fe 2+ + 2 (NH 3 H 2 O) = Fe(OH) 2 ↓+ 2NH4
Iron metahydroxide F eO(OH). Amphoteric hydroxide with a predominance of basic properties. Light brown, Fe-O and Fe-OH bonds are predominantly covalent. When heated, it decomposes without melting. Insoluble in water. It precipitates from solution in the form of a brown amorphous polyhydrate Fe 2 O 3 nH 2 O, which, when kept under a dilute alkaline solution or when dried, turns into FeO (OH). Reacts with acids, solid alkalis. Weak oxidizing and reducing agent. Sintered with Fe(OH) 2 . An intermediate product in the rusting of iron. It is used as a base for yellow mineral paints and enamels, as an exhaust gas absorber, as a catalyst in organic synthesis.
Connection composition Fe(OH) 3 is not known (not received).
Equations of the most important reactions:
Fe 2 O 3 . nH 2 O→( 200-250 °С, —H 2 O) FeO(OH)→( 560-700°C in air, -H2O)→Fe 2 O 3
FeO (OH) + ZNS1 (razb.) \u003d FeC1 3 + 2H 2 O
FeO(OH)→ Fe 2 O 3 . nH 2 O-colloid(NaOH (conc.))
FeO(OH)→ Na 3 [Fe(OH) 6 ]white, Na 5 and K 4, respectively; in both cases, a blue product of the same composition and structure, KFe III, precipitates. In the laboratory, this precipitate is called Prussian blue, or turnbull blue:
Fe 2+ + K + + 3- = KFe III ↓
Fe 3+ + K + + 4- = KFe III ↓
Chemical names of initial reagents and reaction product:
K 3 Fe III - potassium hexacyanoferrate (III)
K 4 Fe III - potassium hexacyanoferrate (II)
KFe III - hexacyanoferrate (II) iron (III) potassium
In addition, the thiocyanate ion NCS - is a good reagent for Fe 3+ ions, iron (III) combines with it, and a bright red (“bloody”) color appears:
Fe 3+ + 6NCS - = 3-
With this reagent (for example, in the form of KNCS salt), even traces of iron (III) can be detected in tap water if it passes through iron pipes covered with rust from the inside.
Iron is the eighth element of the fourth period in the periodic table. Its number in the table (also called atomic) is 26, which corresponds to the number of protons in the nucleus and electrons in the electron shell. It is designated by the first two letters of its Latin equivalent - Fe (lat. Ferrum - reads like "ferrum"). Iron is the second most common element in the earth's crust, the percentage is 4.65% (the most common is aluminum, Al). In its native form, this metal is quite rare, more often it is mined from mixed ore with nickel.
In contact with
What is the nature of this compound? Iron as an atom consists of a metal crystal lattice, which ensures the hardness of compounds containing this element and molecular stability. It is in connection with this that this metal is a typical solid body, unlike, for example, mercury.
Iron as a simple substance- silver-colored metal with properties typical for this group of elements: malleability, metallic luster and ductility. In addition, iron has a high reactivity. The latter property is evidenced by the fact that iron corrodes very quickly in the presence of high temperature and appropriate humidity. In pure oxygen, this metal burns well, and if it is crushed into very small particles, they will not only burn, but ignite spontaneously.
Often we call iron not a pure metal, but its alloys containing carbon ©, for example, steel (<2,14% C) и чугун (>2.14% C). Also of great industrial importance are alloys, to which alloying metals (nickel, manganese, chromium, and others) are added, due to which the steel becomes stainless, i.e., alloyed. Thus, based on this, it becomes clear what an extensive industrial application this metal has.
Characteristic Fe
Chemical properties of iron
Let's take a closer look at the features of this element.
Properties of a simple substance
- Oxidation in air at high humidity (corrosive process):
4Fe + 3O2 + 6H2O \u003d 4Fe (OH) 3 - iron (III) hydroxide (hydroxide)
- Combustion of an iron wire in oxygen with the formation of a mixed oxide (it contains an element with both an oxidation state of +2 and an oxidation state of +3):
3Fe+2O2 = Fe3O4 (iron scale). The reaction is possible when heated to 160 ⁰C.
- Interaction with water at high temperature (600−700 ⁰C):
3Fe+4H2O = Fe3O4+4H2
- Reactions with non-metals:
a) Reaction with halogens (Important! With this interaction, it acquires the oxidation state of the element +3)
2Fe + 3Cl2 \u003d 2FeCl3 - ferric chloride
b) Reaction with sulfur (Important! In this interaction, the element has an oxidation state of +2)
Iron (III) sulfide - Fe2S3 can be obtained during another reaction:
Fe2O3+ 3H2S=Fe2S3+3H2O
c) Formation of pyrite
Fe + 2S \u003d FeS2 - pyrite. Pay attention to the degree of oxidation of the elements that make up this compound: Fe (+2), S (-1).
- Interaction with metal salts in the electrochemical series of metal activity to the right of Fe:
Fe + CuCl2 \u003d FeCl2 + Cu - iron (II) chloride
- Interaction with dilute acids (for example, hydrochloric and sulfuric):
Fe+HBr = FeBr2+H2
Fe+HCl = FeCl2+ H2
Note that these reactions produce iron with an oxidation state of +2.
- In undiluted acids, which are the strongest oxidizing agents, the reaction is possible only when heated; in cold acids, the metal is passivated:
Fe + H2SO4 (concentrated) = Fe2 (SO4) 3 + 3SO2 + 6H2O
Fe+6HNO3 = Fe(NO3)3+3NO2+3H2O
- The amphoteric properties of iron are manifested only when interacting with concentrated alkalis:
Fe + 2KOH + 2H2O \u003d K2 + H2 - potassium tetrahydroxyferrate (II) precipitates.
Iron making process in a blast furnace
- Roasting and subsequent decomposition of sulfide and carbonate ores (isolation of metal oxides):
FeS2 -> Fe2O3 (O2, 850 ⁰C, -SO2). This reaction is also the first step in the industrial synthesis of sulfuric acid.
FeCO3 -> Fe2O3 (O2, 550−600 ⁰C, -CO2).
- Burning coke (in excess):
С (coke) + O2 (air) —> CO2 (600−700 ⁰C)
CO2+С (coke) —> 2CO (750−1000 ⁰C)
- Recovery of ore containing oxide with carbon monoxide:
Fe2O3 —> Fe3O4 (CO, -CO2)
Fe3O4 —> FeO (CO, -CO2)
FeO —> Fe(CO, -CO2)
- Carburization of iron (up to 6.7%) and melting of cast iron (t⁰melting - 1145 ⁰C)
Fe (solid) + C (coke) -> cast iron. The reaction temperature is 900−1200 ⁰C.
In cast iron, cementite (Fe2C) and graphite are always present in the form of grains.
Characterization of compounds containing Fe
We will study the features of each connection separately.
Fe3O4
Mixed or double iron oxide, containing an element with an oxidation state of both +2 and +3. Also Fe3O4 is called iron oxide. This compound is resistant to high temperatures. Does not react with water, water vapor. Decomposed by mineral acids. Can be reduced with hydrogen or iron at high temperature. As you can understand from the above information, it is an intermediate product in the reaction chain of the industrial production of iron.
Directly iron oxide is used in the production of mineral-based paints, colored cement and ceramic products. Fe3O4 is what is obtained by blackening and bluing steel. A mixed oxide is obtained by burning iron in air (the reaction is given above). An ore containing oxides is magnetite.
Fe2O3
Iron(III) oxide, trivial name - hematite, red-brown compound. Resistant to high temperatures. In its pure form, it is not formed during the oxidation of iron with atmospheric oxygen. Does not react with water, forms hydrates that precipitate. Reacts poorly with dilute alkalis and acids. It can be alloyed with oxides of other metals, forming spinels - double oxides.
Red iron ore is used as a raw material in the industrial production of pig iron by the blast-furnace method. It also accelerates the reaction, that is, it is a catalyst in the ammonia industry. It is used in the same areas as iron oxide. Plus, it was used as a carrier of sound and pictures on magnetic tapes.
FeOH2
Iron(II) hydroxide, a compound that has both acidic and basic properties, the latter predominate, that is, it is amphoteric. A white substance that quickly oxidizes in air, "turns brown" to iron (III) hydroxide. Decomposes when exposed to temperature. It reacts with both weak solutions of acids and alkalis. We will not dissolve in water. Acts as a reducing agent in the reaction. It is an intermediate product in the corrosion reaction.
Detection of Fe2+ and Fe3+ ions (“qualitative” reactions)
Recognition of Fe2+ and Fe3+ ions in aqueous solutions is carried out using complex complex compounds - K3, red blood salt, and K4, yellow blood salt, respectively. In both reactions, a precipitate of saturated blue color with the same quantitative composition, but a different position of iron with a valence of +2 and +3, is formed. This precipitate is also often referred to as Prussian blue or Turnbull blue.
Reaction written in ionic form
Fe2++K++3- K+1Fe+2
Fe3++K++4- K+1Fe+3
A good reagent for detecting Fe3+ is thiocyanate ion (NCS-)
Fe3++ NCS- 3- - these compounds have a bright red ("bloody") color.
This reagent, for example, potassium thiocyanate (formula - KNCS), allows you to determine even a negligible concentration of iron in solutions. So, he is able to determine if the pipes are rusty when examining tap water.
Iron is the main structural material. Metal is used literally everywhere - from rockets and submarines to cutlery and forged ornaments on the grill. To a large extent, this is facilitated by an element in nature. However, the real reason is, nevertheless, its strength and durability.
In this article, we will characterize iron as a metal, indicate its useful physical and chemical properties. Separately, we tell why iron is called ferrous metal, how it differs from other metals.
Strange as it may seem, the question still sometimes arises as to whether iron is a metal or a non-metal. Iron is an element of the 8th group, 4 periods of the table of D. I. Mendeleev. The molecular weight is 55.8, which is quite a lot.
This is a silver-gray metal, rather soft, ductile, with magnetic properties. In fact, pure iron is found and used extremely rarely, since the metal is chemically active and enters into a variety of reactions.
About what iron is, this video will tell:
Concept and features
Iron is usually called an alloy with a small proportion of impurities - up to 0.8%, which retains almost all the properties of the metal. It is not even this option that finds widespread use, but steel and cast iron. Its name - ferrous metal, iron, or rather, all the same cast iron and steel, received due to the color of the ore - black.
Today, iron alloys are called ferrous metals: steel, cast iron, ferrite, as well as manganese, and sometimes chromium.
Iron is a very common element. In terms of content in the earth's crust, it ranks 4th, behind oxygen, and. The core of the Earth contains 86% of iron, and only 14% - in the mantle. In sea water, the substance contains very little - up to 0.02 mg / l, in river water a little more - up to 2 mg / l.
Iron is a typical metal, and also quite active. It reacts with dilute and concentrated acids, but under the action of very strong oxidizing agents, it can form iron salts. In air, iron quickly becomes covered with an oxide film that prevents further reaction.
However, in the presence of moisture, instead of an oxide film, rust appears, which, due to its loose structure, does not prevent further oxidation. This feature - corrosion in the presence of moisture - is the main disadvantage of iron alloys. It is worth noting that impurities provoke corrosion, while chemically pure metal is resistant to water.
Important parameters
Pure metal iron is quite ductile, lends itself well to forging and poorly cast. However, small impurities of carbon significantly increase its hardness and brittleness. This quality became one of the reasons for the displacement of bronze tools by iron ones.
- If we compare iron alloys and, from those that were known in the ancient world, it is obvious that, and in terms of corrosion resistance, and, therefore, in terms of durability. However, the mass led to the depletion of tin mines. And, since it is much less than, the metallurgists of the past had the question of replacing. And iron replaced bronze. The latter was completely supplanted when steel appeared: bronze does not give such a combination of hardness and elasticity.
- Iron forms an iron triad with cobalt. The properties of the elements are very close, closer than their counterparts with the same structure of the outer layer. All metals have excellent mechanical properties: they are easily processed, rolled, stretched, they can be forged and stamped. Cobalt is both not as reactive and more resistant to corrosion than iron. However, the lower prevalence of these elements does not allow their use as widely as iron.
- The main "competitor" of iron in terms of use is. But in fact, both materials have completely different qualities. far from being as strong as iron, it stretches worse, cannot be forged. On the other hand, the metal differs, much less weight, which significantly facilitates the design.
The electrical conductivity of iron is very average, while aluminum in this indicator is second only to silver and gold. Iron is a ferromagnet, that is, it remains magnetized in the absence of a magnetic field, and is drawn into a magnetic field.
Such different properties lead to completely different areas of application, so that structural materials "fight" very rarely, for example, in the manufacture of furniture, where the lightness of an aluminum profile is opposed to the strength of a steel one.
The advantages and disadvantages of iron are discussed below.
Advantages and disadvantages
The main advantage of iron in comparison with other structural metals is the prevalence and relative ease of smelting. But, considering how much iron is used, this is a very important factor.
Advantages
The advantages of metal include other qualities.
- Strength and hardness while maintaining elasticity - we are not talking about chemically pure iron, but about alloys. Moreover, these qualities vary over a fairly wide range depending on the steel grade, heat treatment method, production method, and so on.
- A variety of steels and ferrites allows you to create and select a material for literally any task - from the bridge frame to the cutting tool. The ability to obtain desired properties by adding very small impurities is an unusually great advantage.
- The ease of machining makes it possible to obtain products of various types: rods, pipes, shaped products, beams, sheet iron, and so on.
- The magnetic properties of iron are such that the metal is the main material in the production of magnetic drives.
- The cost of alloys, of course, depends on the composition, but it is still significantly lower than that of most non-ferrous alloys, albeit with higher strength characteristics.
- The ductility of iron provides the material with very high decorative possibilities.
Flaws
The disadvantages of iron alloys are significant.
- First of all, this is insufficient corrosion resistance. Special types of steels - stainless, have this useful quality, but they are much more expensive. Much more often, the metal is protected by a coating - metal or polymer.
- Iron is able to accumulate electricity, so products made from its alloys are subject to electrochemical corrosion. Cases of devices and machines, pipelines must be protected in some way - cathodic protection, tread protection, and so on.
- The metal is heavy, so iron structures significantly increase the weight of the construction object - a building, a railway car, a sea vessel.
Composition and structure
Iron exists in 4 different modifications, differing from each other in lattice parameters and structure. The presence of phases is really of decisive importance for smelting, since it is precisely phase transitions and their dependence on alloying elements that ensure the very course of metallurgical processes in this world. So, we are talking about the following phases:
- The α-phase is stable up to +769 C, has a body-centered cubic lattice. The α-phase is ferromagnetic, that is, it retains its magnetization in the absence of a magnetic field. A temperature of 769 C is the Curie point for the metal.
- The β-phase exists from +769 C to +917 C. The structure of the modification is the same, but the lattice parameters are somewhat different. At the same time, almost all physical properties are preserved, with the exception of magnetic ones: iron becomes a paramagnet.
- γ - phase appears in the range from +917 to +1394 C. It has a face-centered cubic lattice.
- The δ-phase exists above a temperature of +1394 C and has a body-centered cubic lattice.
There is also an ε-modification, which appears at high pressure, as well as as a result of doping with some elements. The ε phase has a close-packed hexagonal lattice.
This video will tell about the physical and chemical properties of iron:
Properties and characteristics
Very much depends on its purity. The difference between the properties of chemically pure iron and ordinary technical, and even more alloyed steel, is very significant. As a rule, physical characteristics are given for technical iron with an impurity content of 0.8%.
It is necessary to distinguish harmful impurities from alloying additives. The former, sulfur and phosphorus, for example, impart brittleness to the alloy without increasing hardness or mechanical strength. Carbon in steel increases these parameters, that is, it is a useful component.
- The density of iron (g/cm3) depends to some extent on the phase. So, α-Fe has a density of 7.87 g / cu. cm at normal temperature and 7.67 g / cu. cm at +600 C. The density of the γ-phase is lower - 7.59 g / cu. cm. and the δ-phase is even less - 7.409 g / cc.
- The melting point of the substance is +1539 C. Iron belongs to moderately refractory metals.
- Boiling point - +2862 C.
- Strength, that is, resistance to loads of various kinds - pressure, tension, bending, is regulated for each grade of steel, cast iron and ferrite, so it is difficult to talk about these indicators in general. Thus, high-speed steels have a bending strength equal to 2.5–2.8 GPa. And the same parameter of conventional technical iron is 300 MPa.
- Hardness on the Mohs scale - 4–5. Special steels and chemically pure iron achieve much higher rates.
- Specific electrical resistance 9.7·10-8 ohm·m. Iron conducts current much worse than copper or aluminum.
- The thermal conductivity is also lower than that of these metals and depends on the phase composition. At 25 C it is 74.04 W/(m K), at 1500 C it is 31.8 [W/(m.K)].
- Iron is perfectly forged, both at normal and elevated temperatures. Cast iron and steel can be cast.
- A substance cannot be called biologically inert. However, its toxicity is very low. This is connected, however, not so much with the activity of the element, but with the inability of the human body to absorb it well: the maximum is 20% of the dose received.
Iron cannot be attributed to environmental substances. However, the main harm to the environment is not caused by its waste, since iron rusts quite quickly, but by production waste - slag, gases released.
Production
Iron is one of the most common elements, so it does not require large expenditures. Deposits are being developed both by open and mine methods. In fact, all mining ores include iron, but only those where the proportion of metal is large enough are being developed. These are rich ores - red, magnetic and brown iron ore with an iron content of up to 74%, ores with an average content - marcasite, for example, and poor ores with an iron content of at least 26% - siderite.
Rich ore is immediately sent to the plant. Breeds with medium and low content are enriched.
There are several methods for producing iron alloys. As a rule, the smelting of any steel includes the production of pig iron. It is smelted in a blast furnace at a temperature of 1600 C. The charge - sinter, pellets, is loaded into the furnace together with the flux and blown with hot air. In this case, the metal melts and the coke burns, which allows you to burn out unwanted impurities and separate the slag.
To obtain steel, white cast iron is usually used - in it carbon is bound into a chemical compound with iron. The most common 3 ways are:
- open-hearth - molten iron with the addition of ore and scrap is melted at 2000 C in order to reduce the carbon content. Additional ingredients, if any, are added at the end of the melt. In this way, the highest quality steel is obtained.
- oxygen-converter - a more productive way. In the furnace, the thickness of the cast iron is blown with air at a pressure of 26 kg / sq. see. A mixture of oxygen with air or pure oxygen can be used to improve the properties of steel;
- electrosmelting - more often used to produce special alloy steels. Cast iron is fired in an electric furnace at a temperature of 2200 C.
Steel can also be obtained by the direct method. To do this, pellets with a high iron content are loaded into a shaft furnace and blown with hydrogen at a temperature of 1000 C. The latter restores iron from oxide without intermediate steps.
In connection with the specifics of ferrous metallurgy, either ore with a certain iron content or finished products - cast iron, steel, ferrite - are sold. Their price is very different. The average cost of iron ore in 2016 - rich, with an element content of more than 60%, is $ 50 per ton.
The cost of steel depends on many factors, which sometimes makes the ups and downs of prices completely unpredictable. In the autumn of 2016, the cost of rebar, hot and cold rolled steel increased sharply due to an equally sharp rise in prices for coking coal, an indispensable participant in smelting. In November, European companies offer a coil of hot-rolled steel at 500 Euro per ton.
Application area
The scope of use of iron and iron alloys is huge. It is easier to indicate where the metal is not used.
- Construction - the construction of all types of frames, from the supporting frame of the bridge to the decorative fireplace box in the apartment, cannot do without steel of different grades. Fittings, rods, I-beams, channels, angles, pipes: absolutely all shaped and sectional products are used in construction. The same applies to sheet metal: roofing is made from it, and so on.
- Mechanical engineering - there is very little that can be compared with steel in terms of strength and wear resistance, so the body parts of the vast majority of machines are made of steel. Especially in cases where the equipment must operate at high temperatures and pressures.
- Tools - with the help of alloying elements and hardening, the metal can be given hardness and strength close to diamonds. High-speed steels are the basis of any machining tools.
- In electrical engineering, the use of iron is more limited, precisely because impurities significantly worsen its electrical properties, and they are already small. But the metal is indispensable in the production of magnetic parts of electrical equipment.
- Pipeline - communications of any kind and type are made of steel and cast iron: heating, water pipelines, gas pipelines, including trunk lines, sheaths for power cables, oil pipelines, and so on. Only steel is able to withstand such enormous loads and internal pressure.
- Domestic use - steel is used everywhere: from accessories and cutlery to iron doors and locks. The strength of the metal and wear resistance make it indispensable.
Iron and its alloys combine strength, durability and wear resistance. In addition, the metal is relatively cheap to produce, which makes it an indispensable material for the modern national economy.
This video will tell about iron alloys with non-ferrous metals and heavy black ones:
Iron is a well-known chemical element. It belongs to the metals with average reactivity. We will consider the properties and use of iron in this article.
Prevalence in nature
There is a fairly large number of minerals that include ferrum. First of all, it is magnetite. It is seventy-two percent iron. Its chemical formula is Fe 3 O 4 . This mineral is also called magnetic iron ore. It has a light gray color, sometimes with dark gray, up to black, with a metallic sheen. Its largest deposit among the CIS countries is located in the Urals.
The next mineral with a high iron content is hematite - it consists of seventy percent of this element. Its chemical formula is Fe 2 O 3 . It is also called red iron ore. It has a color from red-brown to red-gray. The largest deposit in the territory of the CIS countries is located in Krivoy Rog.
The third mineral in terms of ferrum content is limonite. Here, iron is sixty percent of the total mass. It is a crystalline hydrate, that is, water molecules are woven into its crystal lattice, its chemical formula is Fe 2 O 3 .H 2 O. As the name implies, this mineral has a yellow-brownish color, occasionally brown. It is one of the main components of natural ocher and is used as a pigment. It is also called brown ironstone. The largest occurrences are the Crimea, the Urals.
In siderite, the so-called spar iron ore, forty-eight percent of ferrum. Its chemical formula is FeCO 3 . Its structure is heterogeneous and consists of crystals of different colors connected together: gray, pale green, gray-yellow, brown-yellow, etc.
The last naturally occurring mineral with a high ferrum content is pyrite. It has the following chemical formula FeS 2 . Iron in it is forty-six percent of the total mass. Due to the sulfur atoms, this mineral has a golden yellow color.
Many of the minerals considered are used to obtain pure iron. In addition, hematite is used in the manufacture of jewelry from natural stones. Pyrite inclusions can be found in lapis lazuli jewelry. In addition, iron is found in nature in the composition of living organisms - it is one of the most important components of the cell. This trace element must be supplied to the human body in sufficient quantities. The healing properties of iron are largely due to the fact that this chemical element is the basis of hemoglobin. Therefore, the use of ferrum has a good effect on the state of the blood, and therefore the whole organism as a whole.
Iron: physical and chemical properties
Let's take a look at these two major sections in order. iron is its appearance, density, melting point, etc. That is, all the distinctive features of a substance that are associated with physics. The chemical properties of iron are its ability to react with other compounds. Let's start with the first.
Physical properties of iron
In its pure form under normal conditions, it is a solid. It has a silvery-gray color and a pronounced metallic sheen. The mechanical properties of iron include a hardness level of She equals four (medium). Iron has good electrical and thermal conductivity. The last feature can be felt by touching an iron object in a cold room. Because this material conducts heat quickly, it takes a lot of it out of your skin in a short amount of time, which is why you feel cold.
Touching, for example, a tree, it can be noted that its thermal conductivity is much lower. The physical properties of iron are its melting and boiling points. The first is 1539 degrees Celsius, the second is 2860 degrees Celsius. It can be concluded that the characteristic properties of iron are good ductility and fusibility. But that's not all.
The physical properties of iron also include its ferromagnetism. What it is? Iron, whose magnetic properties we can observe in practical examples every day, is the only metal that has such a unique distinguishing feature. This is due to the fact that this material is able to be magnetized under the influence of a magnetic field. And after the termination of the action of the latter, iron, the magnetic properties of which have just been formed, remains a magnet for a long time. This phenomenon can be explained by the fact that in the structure of this metal there are many free electrons that are able to move.
In terms of chemistry
This element belongs to the metals of medium activity. But the chemical properties of iron are typical for all other metals (except those that are to the right of hydrogen in the electrochemical series). It is capable of reacting with many classes of substances.
Let's start simple
Ferrum interacts with oxygen, nitrogen, halogens (iodine, bromine, chlorine, fluorine), phosphorus, carbon. The first thing to consider is reactions with oxygen. When ferrum is burned, its oxides are formed. Depending on the conditions of the reaction and the proportions between the two participants, they can be varied. As an example of such interactions, the following reaction equations can be given: 2Fe + O 2 = 2FeO; 4Fe + 3O 2 \u003d 2Fe 2 O 3; 3Fe + 2O 2 \u003d Fe 3 O 4. And the properties of iron oxide (both physical and chemical) can be varied, depending on its variety. These reactions take place at high temperatures.
The next is the interaction with nitrogen. It can also occur only under the condition of heating. If we take six moles of iron and one mole of nitrogen, we get two moles of iron nitride. The reaction equation will look like this: 6Fe + N 2 = 2Fe 3 N.
When interacting with phosphorus, a phosphide is formed. To carry out the reaction, the following components are necessary: for three moles of ferrum - one mole of phosphorus, as a result, one mole of phosphide is formed. The equation can be written as follows: 3Fe + P = Fe 3 P.
In addition, among reactions with simple substances, interaction with sulfur can also be distinguished. In this case, sulfide can be obtained. The principle by which the process of formation of this substance occurs is similar to those described above. Namely, an addition reaction occurs. All chemical interactions of this kind require special conditions, mainly high temperatures, less often catalysts.
Also common in the chemical industry are reactions between iron and halogens. These are chlorination, bromination, iodination, fluorination. As is clear from the names of the reactions themselves, this is the process of adding chlorine / bromine / iodine / fluorine atoms to ferrum atoms to form chloride / bromide / iodide / fluoride, respectively. These substances are widely used in various industries. In addition, ferrum is able to combine with silicon at high temperatures. Due to the fact that the chemical properties of iron are diverse, it is often used in the chemical industry.
Ferrum and complex substances
From simple substances, let's move on to those whose molecules consist of two or more different chemical elements. The first thing to mention is the reaction of ferrum with water. Here are the main properties of iron. When water is heated together with iron, it is formed (it is called so because, when interacting with the same water, it forms a hydroxide, in other words, a base). So, if you take one mole of both components, substances such as ferrum dioxide and hydrogen are formed in the form of a gas with a pungent odor - also in molar proportions of one to one. The equation for this kind of reaction can be written as follows: Fe + H 2 O \u003d FeO + H 2. Depending on the proportions in which these two components are mixed, iron di- or trioxide can be obtained. Both of these substances are very common in the chemical industry and are also used in many other industries.
With acids and salts
Since ferrum is located to the left of hydrogen in the electrochemical series of metal activity, it is able to displace this element from compounds. An example of this is the substitution reaction that can be observed when iron is added to an acid. For example, if you mix iron and sulphate acid (aka sulfuric acid) of medium concentration in the same molar proportions, the result will be iron sulfate (II) and hydrogen in the same molar proportions. The equation for such a reaction will look like this: Fe + H 2 SO 4 \u003d FeSO 4 + H 2.
When interacting with salts, the reducing properties of iron are manifested. That is, with the help of it, a less active metal can be isolated from salt. For example, if you take one mole and the same amount of ferrum, then you can get iron sulfate (II) and pure copper in the same molar proportions.
Significance for the body
One of the most common chemical elements in the earth's crust is iron. we have already considered, now we will approach it from a biological point of view. Ferrum performs very important functions both at the cellular level and at the level of the whole organism. First of all, iron is the basis of such a protein as hemoglobin. It is necessary for the transport of oxygen through the blood from the lungs to all tissues, organs, to every cell of the body, primarily to the neurons of the brain. Therefore, the beneficial properties of iron cannot be overestimated.
In addition to the fact that it affects blood formation, ferrum is also important for the full functioning of the thyroid gland (this requires not only iodine, as some believe). Iron also takes part in intracellular metabolism, regulates immunity. Ferrum is also found in especially large quantities in liver cells, as it helps to neutralize harmful substances. It is also one of the main components of many types of enzymes in our body. The daily diet of a person should contain from ten to twenty milligrams of this trace element.
Foods rich in iron
There are many. They are of both plant and animal origin. The first are cereals, legumes, cereals (especially buckwheat), apples, mushrooms (white), dried fruits, rose hips, pears, peaches, avocados, pumpkin, almonds, dates, tomatoes, broccoli, cabbage, blueberries, blackberries, celery, etc. The second - liver, meat. The use of foods high in iron is especially important during pregnancy, as the body of the developing fetus requires a large amount of this trace element for proper growth and development.
Signs of iron deficiency in the body
Symptoms of too little ferrum entering the body are fatigue, constant freezing of hands and feet, depression, brittle hair and nails, decreased intellectual activity, digestive disorders, low performance, and thyroid disorders. If you notice more than one of these symptoms, you may want to increase the amount of iron-rich foods in your diet or buy vitamins or supplements containing ferrum. Also, be sure to consult a doctor if any of these symptoms you feel too acute.
The use of ferrum in industry
The uses and properties of iron are closely related. Due to its ferromagnetism, it is used to make magnets - both weaker for domestic purposes (souvenir fridge magnets, etc.), and stronger - for industrial purposes. Due to the fact that the metal in question has high strength and hardness, it has been used since ancient times for the manufacture of weapons, armor and other military and household tools. By the way, even in ancient Egypt meteorite iron was known, the properties of which are superior to those of ordinary metal. Also, such a special iron was used in ancient Rome. They made elite weapons from it. Only a very rich and noble person could have a shield or sword made of meteorite metal.
In general, the metal that we are considering in this article is the most versatile among all the substances in this group. First of all, steel and cast iron are made from it, which are used to produce all kinds of products necessary both in industry and in everyday life.
Cast iron is an alloy of iron and carbon, in which the second is present from 1.7 to 4.5 percent. If the second is less than 1.7 percent, then this kind of alloy is called steel. If about 0.02 percent of carbon is present in the composition, then this is already ordinary technical iron. The presence of carbon in the alloy is necessary to give it greater strength, thermal stability, and rust resistance.
In addition, steel can contain many other chemical elements as impurities. This is manganese, and phosphorus, and silicon. Also, chromium, nickel, molybdenum, tungsten and many other chemical elements can be added to this kind of alloy to give it certain qualities. Types of steel in which a large amount of silicon is present (about four percent) are used as transformer steels. Those containing a lot of manganese (up to twelve to fourteen percent) find their use in the manufacture of parts for railways, mills, crushers and other tools, parts of which are subject to rapid abrasion.
Molybdenum is introduced into the composition of the alloy to make it more thermally stable - such steels are used as tool steels. In addition, in order to obtain well-known and often used stainless steels in everyday life in the form of knives and other household tools, it is necessary to add chromium, nickel and titanium to the alloy. And in order to get shock-resistant, high-strength, ductile steel, it is enough to add vanadium to it. When introduced into the composition of niobium, it is possible to achieve high resistance to corrosion and the effects of chemically aggressive substances.
The mineral magnetite, which was mentioned at the beginning of the article, is needed for the manufacture of hard drives, memory cards and other devices of this type. Due to its magnetic properties, iron can be found in the construction of transformers, motors, electronic products, etc. In addition, ferrum can be added to other metal alloys to give them greater strength and mechanical stability. The sulfate of this element is used in horticulture for pest control (along with copper sulfate).
They are indispensable in water purification. In addition, magnetite powder is used in black and white printers. The main use of pyrite is to obtain sulfuric acid from it. This process occurs in the laboratory in three stages. In the first stage, ferrum pyrite is burned to produce iron oxide and sulfur dioxide. At the second stage, the conversion of sulfur dioxide into its trioxide occurs with the participation of oxygen. And at the final stage, the resulting substance is passed through in the presence of catalysts, thereby obtaining sulfuric acid.
Getting iron
This metal is mainly mined from its two main minerals: magnetite and hematite. This is done by reducing iron from its compounds with carbon in the form of coke. This is done in blast furnaces, the temperature in which reaches two thousand degrees Celsius. In addition, there is a way to reduce the ferrum with hydrogen. This does not require a blast furnace. To implement this method, special clay is taken, mixed with crushed ore and treated with hydrogen in a shaft furnace.
Conclusion
The properties and uses of iron are varied. This is perhaps the most important metal in our lives. Having become known to mankind, he took the place of bronze, which at that time was the main material for the manufacture of all tools, as well as weapons. Steel and cast iron are in many ways superior to the alloy of copper and tin in terms of their physical properties, resistance to mechanical stress.
In addition, iron is more common on our planet than many other metals. it in the earth's crust is almost five percent. It is the fourth most abundant chemical element in nature. Also, this chemical element is very important for the normal functioning of the organism of animals and plants, primarily because hemoglobin is built on its basis. Iron is an essential trace element, the use of which is important for maintaining health and normal functioning of organs. In addition to the above, it is the only metal that has unique magnetic properties. Without ferrum it is impossible to imagine our life.
Iron is one of the most common metals in the earth's crust after aluminum. Its physical and chemical properties are such that it has excellent electrical conductivity, thermal conductivity and ductility, has a silvery white color and high chemical reactivity to quickly corrode at high humidity or high temperatures. Being in a finely dispersed state, it burns in pure oxygen and ignites spontaneously in air.
The beginning of the history of iron
In the third millennium BC. e. people began to mine and learned to process bronze and copper. They were not widely used due to their high cost. The search for new metal continued. The history of iron began in the first century BC. e. In nature, it can only be found in the form of compounds with oxygen. To obtain a pure metal, it is necessary to separate the last element. For a long time it was not possible to melt the iron, since it had to be heated to 1539 degrees. And only with the advent of cheese-blowing furnaces in the first millennium BC, this metal began to be obtained. At first, it was brittle and contained a lot of slag.
With the advent of forges, the quality of iron improved significantly. It was further processed in a blacksmith, where slag was separated by hammer blows. Forging has become one of the main types of metal processing, and blacksmithing has become an indispensable branch of production. Iron in its purest form is a very soft metal. It is mainly used in an alloy with carbon. This additive enhances such a physical property of iron as hardness. Cheap material soon penetrated widely into all spheres of human activity and made a revolution in the development of society. Indeed, even in ancient times, iron products were covered with a thick layer of gold. It had a high price compared to the noble metal.
iron in nature
One aluminum in the lithosphere contains more than iron. In nature, it can only be found in the form of compounds. Trivalent iron, reacting, stains the soil brown and gives the sand a yellowish tint. Iron oxides and sulfides are scattered in the earth's crust, sometimes there are accumulations of minerals, from which the metal is subsequently mined. The content of ferrous iron in some mineral springs gives the water a special flavor.
Rusty water flowing from old water pipes is colored by the trivalent metal. Its atoms are also found in the human body. They are found in hemoglobin (an iron-containing protein) in the blood, which supplies the body with oxygen and removes carbon dioxide. Some meteorites contain pure iron, sometimes whole ingots are found.
What are the physical properties of iron?
It is a ductile silvery-white metal with a grayish tint, having a metallic luster. It is a good conductor of electricity and heat. Due to its plasticity, it lends itself perfectly to forging and rolling. Iron does not dissolve in water, but liquefies in mercury, melts at 1539 and boils at 2862 degrees Celsius, has a density of 7.9 g/cm³. A feature of the physical properties of iron is that the metal is attracted by a magnet and, after the annulment of the external magnetic field, retains magnetization. Using these properties, it can be used to make magnets.
Chemical properties
Iron has the following properties:
- in air and in water it easily oxidizes, becoming rusty;
- in oxygen, the heated wire burns (in this case, scale is formed in the form of iron oxide);
- at a temperature of 700-900 degrees Celsius, it reacts with water vapor;
- when heated, it reacts with non-metals (chlorine, sulfur, bromine);
- reacts with dilute acids, resulting in iron salts and hydrogen;
- does not dissolve in alkalis;
- it is able to displace metals from solutions of their salts (an iron nail, in a solution of copper sulfate, is covered with a red bloom - this is copper);
- in concentrated alkalis, when boiled, the amphotericity of iron is manifested.
Feature Feature
One of the physical properties of iron is ferromagnetism. In practice, the magnetic properties of this material are encountered frequently. It is the only metal that has such a rare trait.
Under the influence of a magnetic field, iron is magnetized. The formed magnetic properties of the metal retains for a long time and remains a magnet itself. This exceptional phenomenon is explained by the fact that the structure of iron contains a large number of free electrons that can move around.
Reserves and production
One of the most common elements on earth is iron. In terms of content in the earth's crust, it ranks fourth. Many ores are known that contain it, for example, magnetic and brown iron ore. Metal in industry is obtained mainly from ores of hematite and magnetite using a blast furnace process. First, it is reduced with carbon in a furnace at a high temperature of 2000 degrees Celsius.
To do this, iron ore, coke and flux are fed into the blast furnace from above, and a stream of hot air is injected from below. The direct process for obtaining iron is also used. The crushed ore is mixed with special clay to form pellets. Then they are fired and treated with hydrogen in a shaft furnace, where it is easily restored. Solid iron is obtained, and then it is melted down in electric furnaces. Pure metal is recovered from oxides by electrolysis of aqueous solutions of salts.
Benefits of iron
The main physical properties of the iron substance give it and its alloys the following advantages over other metals:
Flaws
In addition to a large number of positive qualities, there are a number of negative properties of the metal:
- Products are subject to corrosion. To eliminate this undesirable effect, stainless steels are obtained by alloying, and in other cases, special anti-corrosion treatment of structures and parts is done.
- Iron accumulates static electricity, so products containing it are subject to electrochemical corrosion and also require additional processing.
- The specific gravity of the metal is 7.13 g/cm³. This physical property of iron gives structures and parts increased weight.
Composition and structure
According to the crystalline feature, iron has four modifications that differ in structure and lattice parameters. For the smelting of alloys, it is the presence of phase transitions and alloying additives that is essential. There are the following states:
- Alpha phase. It persists up to 769 degrees Celsius. In this state, iron retains the properties of a ferromagnet and has a body-centered cubic lattice.
- Beta phase. Exists at temperatures from 769 to 917 degrees Celsius. It has slightly different lattice parameters than in the first case. All the physical properties of iron remain the same, except for the magnetic ones, which it loses.
- Gamma phase. The structure of the lattice becomes face-centered. This phase appears in the range of 917-1394 degrees Celsius.
- Omega phase. This state of the metal appears at temperatures above 1394 degrees Celsius. It differs from the previous one only in the lattice parameters.
Iron is the most sought after metal in the world. More than 90 percent of all metallurgical production falls on it.
Application
People first began to use meteorite iron, which was valued more than gold. Since then, the scope of this metal has only expanded. Below is the application of iron, based on its physical properties:
- ferromagnetic oxides are used for the production of magnetic materials: industrial plants, refrigerators, souvenirs;
- iron oxides are used as mineral paints;
- ferric chloride is indispensable in amateur radio practice;
- iron sulfates are used in the textile industry;
- magnetic iron oxide is one of the important materials for the production of long-term computer memory devices;
- ultrafine iron powder is used in black and white laser printers;
- the strength of the metal allows you to make weapons and armor;
- wear-resistant cast iron can be used for the production of brakes, clutch discs, and parts for pumps;
- heat-resistant - for blast, thermal, open-hearth furnaces;
- heat-resistant - for compressor equipment, diesel engines;
- high-quality steel is used for gas pipelines, boiler bodies, dryers, washing machines and dishwashers.
Conclusion
By iron is often meant not the metal itself, but its alloy - low-carbon electrical steel. Obtaining pure iron is a rather complicated process, and therefore it is used only for the production of magnetic materials. As already noted, the exceptional physical property of a simple iron substance is ferromagnetism, that is, the ability to be magnetized in the presence of a magnetic field.
The magnetic properties of pure metal are up to 200 times higher than those of technical steel. This property is also affected by the grain size of the metal. The larger the grain, the higher the magnetic properties. Machining also has some effect. Such pure iron, which satisfies these requirements, is used to obtain magnetic materials.