Application of iron: from foundation reinforcement to magnetic drive

• Designation - Fe (Iron);
• Period - IV;
• Group - 8 (VIII);
• Atomic mass - 55.845;
• Atomic number - 26;
• Atomic radius = 126 pm;
• Covalent radius = 117 pm;
• Electron distribution - 1s22s22p63s23p63d64s2;
• melting temperature = 1535°C;
• boiling point = 2750°C;
• Electronegativity (according to Pauling/according to Alpred and Rochow) = 1.83/1.64;
• Oxidation state: +8, +6, +4, +3, +2, +1, 0;
• Density (no.) = 7.874 g/cm3;
• Molar volume = 7.1 cm3/mol.

Iron compounds:

• Iron(II) oxide
• Iron(II) hydroxide
• Iron(III) oxide
• Iron(III) hydroxide
• Iron salts

Iron is the most abundant metal in the earth's crust (5.1% by mass) after aluminum.

On Earth, free iron is found in small quantities in the form of nuggets, as well as in fallen meteorites.

Industrially, iron is mined from iron ore deposits from iron-containing minerals: magnetic, red, brown iron ore.

It should be said that iron is part of many natural minerals, causing their natural color. The color of minerals depends on the concentration and ratio of iron ions Fe2+/Fe3+, as well as on the atoms surrounding these ions. For example, the presence of impurities of iron ions affects the color of many precious and semi-precious stones: topazes (from pale yellow to red), sapphires (from blue to dark blue), aquamarines (from light blue to greenish blue), etc.

Iron is found in the tissues of animals and plants; for example, about 5 g of iron is present in the body of an adult. Iron is a vital element; it is part of the hemoglobin protein, participating in the transport of oxygen from the lungs to tissues and cells. With a lack of iron in the human body, anemia (iron deficiency anemia) develops.

Iron in D.I. Mendeleev’s Periodic Table of Chemical Elements, numbered “26”, belongs to the transition metals (See Atoms of transition elements).

Rice. The structure of the iron atom.

The electronic configuration of the iron atom is 1s22s22p63s23p63d64s2 (see Electronic structure of atoms). In the formation of chemical bonds with other elements, 2 electrons located on the outer 4s level + 6 electrons of the 3d sublevel (8 electrons in total) can participate, therefore, in compounds, iron can take oxidation states +8, +6, +4, +3, +2, +1, (the most common are +3, +2). Iron has average chemical activity.

Rice. Iron oxidation states: +2, +3.

Physical properties of iron:

• silver-white metal;
• in its pure form it is quite soft and plastic;
• has good thermal and electrical conductivity.

Iron exists in the form of four modifications (they differ in the structure of the crystal lattice): α-iron; β-iron; γ-iron; δ-iron.

When was it open

The history of man's acquaintance with iron begins with Space. Judging by the ancient (for example, ancient Egyptian) names of the element, it was meteorite iron. Hittite texts refer to him as "fallen from the sky."

Man has been using metal for 6 thousand years.

Archaeologists have unearthed tools used by the ancient Sumerians and Egyptians. They are made from meteorite iron.

Iron products conquered the world. The poems of Homer's Iliad are dedicated to metal, and it is mentioned by Aristotle and Strabo.

The ancient name of iron is due to its celestial origin: “sider” (“starry”).

Scientists are constantly exploring the potential of metal. Thus, in 1868, the Russian scientist D.K. Chernov discovered crystalline modifications of matter.

How they searched for iron ore

In the middle of the century, metal products were highly valued, they were cherished and also passed on by inheritance.

The path to becoming a cauldron or an ax in those days was very long and long: iron had to be found and then processed.

The business began with a search for places where metal ores lay. The search was helped by the experience that people have accumulated over many centuries. First of all, these are deposits that reach the surface of the earth.

Throughout Europe, iron was found in the form of lumps of ore:

1. greenish - at the bottom of lakes;

2. reddish - under the turf;

3. reddish - in forest swamps.

The bottom of the clear lakes was scanned from boats, or they dived into the muddy water in search of pieces of ore, which they scooped out with scoops.

Iron ore was also found in brown vegetation. The meadow turf was cut, the swamp layers were torn off, and the ore nest was taken out with shovels. Sometimes such a meadow was covered with thousands of holes.

A little later, ore began to be mined in mines that reached depths of up to 500 meters.

Iron ore was lifted from the mines using lifting mechanisms, and groundwater was pumped out with hand pumps.

Physico-chemical characteristics

Iron is not a particularly hard metal (4-5 on the Mohs scale).

Physical and chemical properties are determined by impurities and microclimate:

• Reacts with metals at elevated temperatures.
• Pure iron is ductile and does not oxidize in water or air.
• When exposed to dry air (not hotter than 200°C), it becomes covered with a matte oxide film. It prevents metal corrosion.
• Endowed with magnetic properties. By this characteristic, iron can be easily distinguished from other metals.

A substance with the formula FeO•nH2O is ordinary rust.

• The crystal lattice is cubic, but changes structure depending on temperature.
• Iron, elevated temperatures plus water form sulfides, halides, phosphides, titanides, nitrides.
• Insoluble in alkalis.
• Interaction with acids depends on concentration. Dilute ones dissolve the metal, concentrated ones create an oxide film-shield.

Hydrothermal spring with ferruginous water.
Iron oxides color water brown. Wet or hot iron becomes covered with rust. Carbon makes it brittle. These disadvantages limit the use of the metal.

Advantages and disadvantages

There are many advantages, but no less disadvantages.

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Malleability makes it possible to produce decorative products.

Iron in nature

Iron is the fourth most abundant element on the planet and the second among metals (after aluminum). But the content is uneven: 86% of the reserves are concentrated in the planet’s core, the rest is shared by the mantle and crust.

Native iron is rare in nature; it is almost always minerals.

Native iron

There are three hundred of them, the most famous and rich in iron (% content in composition):

• Magnetite (magnetic iron ore) – 72.
• Hematite (red iron ore) – 70.
• Lepidocrocite, goethite – 63 each.
• Limonite (brown iron ore) – 62.
• Siderite (spar iron ore) – 48.

Iron is found in all living organisms.

The second source is meteorites.

A quarter of the mass of stone meteorites and 91% of iron meteorites is iron.

Feature properties

One of the physical properties of iron is ferromagneticity. In practice, the magnetic properties of this material are often encountered. This is the only metal that has such a rare feature.

Under the influence of a magnetic field, iron is magnetized. The metal retains its formed magnetic properties 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.

Receiving technology

Iron ore (magnetite and hematite) is sent to work: to a processing or metallurgical plant.

Iron ore

Pig iron is smelted in a blast furnace. At 1610°C, the mixture (sinter, pellets) with flux is loaded and blown with hot air. This allows you to remove impurities and separate slag.

The main methods of producing steel:

1. Martenovsky. Molten cast iron, ore, and scrap are melted at 2100°C.

If necessary, alloying additives are added at the end of the melt.

1. Oxygen converter . The cast iron mass in the furnace is blown with air under pressure. A mixture of oxygen and air or pure oxygen is used (for steels with premium characteristics).
2. Electric melting. Cast iron is burned in an electric furnace at 2250°C. The method is used for smelting alloy and other special grades of steel.
3. Straight. The iron-rich pellets are loaded into the furnace. Blow with hydrogen at 1050°C.

Hardening steel—heating until hot and cooling—makes it ductile and hard.

The production of pure metal is based on the electrolysis of molten salts of the substance.

An iron alloy containing less than 2% carbon is steel. More than 2% carbon is cast iron.

History of steel production

BC. Wrought iron was already being produced everywhere in Europe. Many magnificent Greek and Roman buildings were built of stone using butterfly-shaped iron tools covered with lead. In 500 BC. e. The Etruscans who lived on the west coast of Italy produced more than 4.5 thousand kilograms of iron per year.

Iron was forged in a forge, and charcoal was used to keep the fire going. The fire was fanned using special bellows made from animal skins. Later, the small stone furnaces were dismantled and mass iron smelting began. Ore was delivered to the furnaces on sailing ships. Due to the fact that the ore processing method used by the Etruscans was ineffective, its reserves were quickly depleted. In addition, charcoal production has sharply reduced the number of forests in western Italy.

The first steel was created by the Celts around 200 AD. e. They cut the wrought iron into thin strips and placed them in a container with burnt bones and charcoal, after which they heated the whole thing in a furnace for 10-12 hours at very high heat. As a result, the metal surface was enriched with carbon. Then they welded these strips together through forging and thus created knives. These knives became the predecessors of the blades that we mistakenly call Damascus.

The Celtic process for making steel in 1050 was copied by the Vikings and Germans. Since then, steel blades have been produced in these countries, the manufacturing method of which was strictly classified. Damascus steel was produced in Pakistan and sent in the form of damask steel to Syria, where the famous Damascus blades were made. The process of producing Damascus steel is very complex because it had to be heated to a very high temperature, and if the temperature was exceeded, the material could break.

Over time, the melting temperature of iron in furnaces became higher and higher, so the resulting iron contained 3-4% carbon.

It was fragile and suitable only for casting. It was impossible to make knives and parts for transport from it. In addition, by this time a huge part of the forests in Europe had been cut down for construction purposes and the production of charcoal.

Then the King of England issued a decree that no more forests could be cut down, and steel producers had to come up with a way to process coal into coke. In England, they developed a method for tinning steel by mixing molten iron with iron silicate and iron oxide. Iron silicate is one of the components of wrought iron.

Coal-fired furnaces were called the furnace. One worker had to stir the resulting mixture, which created carbon dioxide, so the melting point of the iron became higher, and the tinning process began.

Large pieces weighing from 90 kg to 130 kg were placed inside. Another worker, using a pair of large tongs, took these pieces and placed them under a press to squeeze out the iron silicate from them. After the press, the pieces were placed in a rolling mill, where they were formed into strips of cast iron.

These strips were cut into short pieces and joined together, after which they were placed in a recess filled with carbon and heated to welding temperature. After this, the strips of red iron were again sent to the rolling mill and graded iron was obtained. This method was used not only in Europe, but in the eastern United States.

To make steel, thin rolled products were placed in a cavity filled with carbon obtained from burning bones and heated at high temperatures for several days.

The carbon was absorbed by the iron, resulting in bubbly steel. Cement steel or tomlenka was called bubbly. This concept arose from the appearance of the strips recovered from the carbon pit, which were covered in bubbles. After this, the strips were folded together and forged, then folded again and forged, in this way high-quality steel was obtained.

England needed high-quality steel to create a fleet that could cross the ocean.

One enterprising Englishman noticed that glassblowers could achieve very high temperatures in their furnaces. He took strips of bubbled steel and placed them in a ceramic crucible, then placed the container in the glassblowing furnace. As a result, the steel melted, the iron silicate evaporated, but the carbon remained, resulting in very high quality steel. At that time, many people were watching the process, and he could not keep it a secret.

This method produced cast steel, from which a large number of old tools were made in the United States, labeled "cast steel."

Where is it used?

It’s hard to imagine everyday life without metal: iron is practical, reliable, and cheap. Perhaps someday it will be replaced by plastic. Today the advantages of iron material are at a premium.

Ultrapure iron

Industry

Iron has found uses in all forms. Alloys are the basis of materials in demand by industry. Powder is purchased in tons for welding, pyrotechnics, and printers. Compounds - the basis of mineral paints, pigments in the production of textiles and inks.

No industry can do without it:

• Mechanical engineering. The body of machines and mechanisms, especially for working in extreme conditions.
• Construction. Load-bearing structures of buildings, structures (bridges, mobile communication towers, etc.), fittings. Roofing material, corrugated sheets, metal tiles.
• Electrical engineering. Cores of electromagnets, armatures of electric machines, battery plates.
• Communications. Industrial and domestic pipelines for pumping steam, water, gas, and oil are made of steel and cast iron. This is the sheath of power cables.

Iron is the anode in iron-nickel, iron-air batteries. Household and professional tools are made from steel.

Other areas

Metal is used in science, medicine, and everyday life:

• Cleaning of drains.
• Component of gart (printing font).
• Kitchen utensils, tableware.
• Doors, locks.
• Ultra-fine magnetite (metal oxide) powder is used to fill black-and-white printers.
• Furniture of avant-garde styles.
• Anemia is treated with iron supplements.
• Gardeners and builders destroy the fungus with a mixture of copper and iron sulfate (septate metal sulfate).

Artificial radioactive isotopes are a marker in the analysis of chemical, technological and biological processes.

Application

More than 90% of all metallurgical production is occupied by iron and its alloys.

Products made from steels and cast irons are an irreplaceable and major part of structural materials, including buildings, bridges, railways and much more.

Application of iron compounds:

• Divalent and trivalent iron is used as a coagulant in water treatment systems;
• the anodes in iron-nickel and iron-air batteries are made of the most famous ferrous metal;
• magnetite in the form of ultrafine powder is used in black and white laser printers;
• FeCl3 is used by radio amateurs (etching printed circuit boards);
• Magnetite is indispensable in the manufacture of memory media (hard drives).

Areas of application of iron

For most organisms, there is no life without iron; with its help, oxygen is delivered to every cell of the body. Lack of iron leads to chlorosis in plants and iron deficiency anemia in animals.

Cognitive: the belief that an apple when cut is darkened by the iron contained in it is a myth.

Biological effects

For humans, iron as a microelement (0.02%) is of special importance: it regulates cellular respiration and is part of the blood.

Health Importance

The adult human body contains 3.5 grams of iron. Of these, three quarters are included in the hemoglobin of the blood, the rest is distributed to other structures of the body.

Lack of microelement causes anemia in humans or animals, chlorosis in plants.

Nutrition

Iron is supplied to the body by food.

The foods richest in micronutrients are found in all food groups:

• Bread, cereals.
• Liver, meat.
• Eggs.
• Beets, leafy greens.
• Legumes.
• Dried fruits, nuts, seeds.

Foods contain different types of iron: heme and non-heme. Heme contains the “animal” assortment, while non-heme contains the plant variety.

Need

Daily iron requirement (mg):

• children – 4-18;
• women – 18;
• men – 10.

During pregnancy, the norm doubles. More is required for anemic people and donors.

It is easier for the body to absorb heme iron, so vegans or vegetarians need 30-33 mg daily.

The danger of oversupply

However, an excess of the substance is not welcome, since it “suppresses” the formation of antioxidants in the body.

The use of water with an iron content of more than 2 mg per liter is undesirable. If the metal content is more than 200 mg, the water is toxic.

According to Russian standards, a liter of water should contain no more than 0.3 mg of iron.

Bulat (steel): where did it come from and who used it

The first information about damask steel came 2,300 years ago from participants in the famous campaign of Alexander the Great to India.

The warriors said that Indian blades cut stones and cut light fabrics in the air.

Perhaps it was this information that Walter Scott used in his novel “The Talisman”.

It describes a contest of agility between Sultan Saladin and the English king Richard the Lionheart. Richard cut the spear of one of the knights into two pieces with his steel sword. In response, Saladin threw a blanket of the finest fabric into the air and cut it with his damask blade.

Damask steel actually first appeared in India.

The Indians sold wootz - “bread” made of steel - to the countries of the East. They were flat cakes with a diameter of 12.5 cm and a thickness of 0.25 cm. The woots weighed about 900 grams. Such a “bread” was cut in half, into equal parts, so that the buyer could examine the structure of the metal.

Indian craftsmen mastered the art of steel processing to perfection.

“There will never be a people who would be better versed in certain types of swords and their names than the inhabitants of India,” wrote Biruni, who saw with his own eyes the production of steel and swords. He was especially struck by the colored swords. The Indians rubbed polished iron with hot copper sulfate powder, after which they obtained swords of various colors - green, blue, white and with patterns.

Among the many Indian swords, Biruni was most deeply impressed by a sword called “Majli”, on which animals and trees were depicted. Its cost was equal to the price of the best elephant. But if human figures were depicted on the sword, such weapons were even more expensive.

Patterns and drawings on metal were the main distinguishing feature of damask swords.

On some damask steel the patterns were visible to the naked eye immediately after polishing. On others they appeared only after etching with plant juice.

The pattern could be large or small.

Another place where excellent damask steel was produced was the city of Damascus. In the Middle Ages, swords came from Damascus to different countries. They could even be seen in African tribes. Damascus steel later became known as Damascus steel.

How people of the Middle Ages managed to create damask blades from stainless steel, which was unusually strong, was a mystery.

Various scientists in many countries tried to unravel the mystery of damask steel. The famous English physicist Mikhail Faraday tried to obtain damask steel by adding aluminum and platinum to steel.

In the end, the secret of damask steel was revealed by the Ural metallurgist Pavel Anosov. After many years of searching, trial and error, in 1837 he managed to make a damask blade in the city of Zlatoust. Anosov knew that damask steel production still existed in Moscow in the 16th-17th centuries.

He was familiar with the documents of that time, where there were entries: “Saber strip, blue damask steel, Moscow forged,” “Russian saber strip with fullers for damask steel.” By the end of the 17th century, the art of making damask steel fell into decline and was gradually forgotten. And now, more than two hundred years later, damask steel appeared in Zlatoust. “The strip of damask steel bent without the slightest damage and produced a clear and high ringing sound. The polished end crushed the best English chisels, while the loosened end easily accepted impressions and cut off cleanly and evenly,” Anosov wrote in the Mining Journal.

The damask blade prepared in Zlatoust had a golden tint and a large mesh or cranked pattern.

Experts believed that such a pattern was a sign of the highest grade of damask steel. The blade, made at the Zlatoust factory, cut through nails and bones without damaging the blade. With the help of these blades it was possible to perform the same trick with a thin blanket of gas that Saladin struck King Richard with.

People struggled with the riddle of damask steel for so long that they were extremely surprised when Anosov reported that damask steel is “iron and carbon and nothing more; it’s all about the purity of the starting materials, the cooling method, the crystallization.”

Bulat turned out to be a high-carbon steel without any special impurities, being a product of natural crystallization of steel obtained by combining iron and carbon.

The essence of the formation of damask steel was the saturation of the alloy with a large amount of carbon (about 1.3-1.5%). During slow cooling, a compound of iron and carbon was formed and found in some excess - the so-called cementite, which did not dissolve, as happens in ordinary steel, but remained in the iron as if in suspension. Layers of cementite were enveloped in slowly cooling soft iron.

Therefore, with a high carbon content, which gives the metal hardness, damask steel retains high flexibility and elasticity, which is not characteristic of ordinary steel. Due to the presence of layers of brittle cementite, forging damask steel must be done extremely carefully, with blows of a light hammer, with repeated heating to a critical temperature, that is, to a red-hot temperature. If it is raised higher, damask steel will lose its basic properties and its characteristic pattern. The process of making damask steel is labor-intensive, time-consuming and requires high skill.

While developing the process for producing damask steel, Anosov simultaneously invented a new method for producing steel by fusing unusable iron and steel scraps in clay pots, that is, crucibles, using high temperature air furnaces.

Having established the production of crucible steel in the Urals, Anosov reported that it was in no way inferior to English cast steel.

Nowadays, damask steel is not produced. The fact is that it was a product of handicraft production, and in general had only one use - for the manufacture of edged weapons. But modern technology has found many ways to produce steel of a wide variety of grades with various properties that damask steel did not possess.

Modern technology needs metals and alloys to operate at pressures of hundreds and thousands of atmospheres and in deep vacuum, when the pressure is close to zero. Cold-resistant steels must maintain strength at temperatures close to absolute zero (-273°C). Nuclear reactors require a metal with the highest magnetic conductivity; jet and rocket engines require steel that can maintain strength at very high temperatures and heavy loads.

The first mention of steel goes back to the distant 8-12 centuries BC. Even then, the troops of the Indian king Porus had strong and sharp weapons.

Indian craftsmen managed to obtain high-carbon steel, called damask steel. Its production was difficult and the production secret remained undisclosed.