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Sergey Venezky
STORIES ON METALS

CHROME

MYSTERIOUS X

Chinese grammar. - "Siberian red lead. - It all started with the washing up. - Gray needles in the crucible. - Each gives advice. - Solar flares. - Fortune favors. - "Provocative" behavior. - New mystery. - The monument of the "stainless steel". - "The concert is cancelled. - Tea ice cream? - The steel is covered with "scales". - The first patent. - Turtle pace. - Interesting conversation. - "Cocktail" of metals. - Chrome boots. - The gods shed blood. - A way out. - A new specialty. - Out of competition. - Unexpected difficulties. - "Take fire". - Armor for diamond. - Arithmetic considerations. - "The British know a lot about..."

Browse through any metals reference book, and among the numerous steel grades time you will not meet such which includes the letter "X": 18CR10NITI, HM, HY, SHKH15, CHWF, HST, HF, SOHMA etc. For the uninitiated in this field for a man of such "secret code" understandable not more than Chinese characters. But, as a musician, reading notes, hears lurking in their music, and metallurg easily understand these at seemingly random combinations of letters and numbers. Even a cursory glance is enough to see the total for the listed grades of steel: they are all in varying quantities contain the element chromium (as evidenced by the letter "X").

The steel grade, the name of which includes the letter

Together with their "colleagues" in the alloying - Nickel, tungsten, molybdenum, vanadium, titanium, zirconium, niobium and other elements - chrome allows you to melt the steel for various purposes. Used in modern engineering steel has a lot to be able to resist the enormous pressures to resist chemical aggressors, without fatigue, to withstand prolonged overload, have good machinability, do not be afraid nor heat nor cold. This wide range of properties of steel contributes and chrome.

More than two centuries ago, in 1766, St. Petersburg Professor of chemistry at the Johann Gottlob Leman, visiting the Urals, found on the Berezovsky gold mine, near Ekaterinburg (now Sverdlovsk), a new mineral, which turned out to be quite a lot of lead. A few years later, Berezovsky mines described in his book "a Journey through various provinces of the Russian state" naturalist and traveler academician Peter Simon Pallas. "Berezovsky mine, " wrote he, " consists of four mines, which have been developed since 1752. In them along with gold mined silver and lead ores, and also find a wonderful red lead mineral, which was not detected any more in a single mine in Russia. This lead ore can be different colors (sometimes similar to the color of cinnabar), heavy and translucent... Sometimes a little irregular pyramids of this mineral are disseminated in quartz like a little Rubina. When you cut it into powder it gives a beautiful yellow paint...".

The mineral was named "Siberian red lead. Subsequently he was given the name "krakout".

A sample of this mineral was in the late eighteenth century brought Pallas in Paris. Crocoite interested in the famous French chemist Louis Nicolas Vauclin. His career began washing dishes at the pharmacy. Soon the capable young man noticed and made his assistant, the young but already occupied a respectable position in science chemist and politician Antoine françois Fourcroy. In 1796 Vauclin subjected crocoite chemical analysis. "All samples of this substance, which are available in several mineralogical cabinets of Europe, " wrote Vauclin in its report, were obtained from this (i.e. Berezovsky. - S. C.) gold mine. Before the mine was very rich in this mineral, however, say that a few years ago, the reserves of the mineral in the mine was exhausted and now this mineral buy their weight in gold, especially if it is yellow. The mineral samples that do not have the correct shape or split into pieces, suitable for use in painting, where they are appreciated for its yellow-orange color, not changing in the air... Beautiful red color, clarity and crystal form of the Siberian red mineral made mineralogists to engage with nature and the place where it was found; a large proportion of the associated lead ore, of course, were forced to assume the presence of lead in the mineral..."

In 1797 Vauclin repeated the analysis. Powdered crocoite he was placed in a solution of potassium carbonate and boiled. As a result of experience he has received carbon lead and the yellow solution, which contained potassium salt then unknown acid. When added to a solution of mercury salt formed a red precipitate after the reaction with a lead salt, a yellow precipitate, and the introduction of tin chloride were stained with a solution of green. After deposition of hydrochloric acid lead Vauclin the filtrate is boiled away, and released red crystals (chromic anhydride) was mixed with coal, was placed in a graphite crucible and heated to a high temperature. Compounds of chromium have bright colouringWhen the experience was over, the scientist discovered in the crucible many gray fused metal needles. So was first isolated a new element. Fourcroy suggested calling the element chromium (Greek "chromium" - painting) because of the bright variety of colors of its compounds. Incidentally, the syllable "chrome" in the sense of "colored" includes many terms that are not associated with the element chromium: the word "chromosome", for example, in Greek means "body, which is painted" to obtain a color image using the device chromoscope; photographers well known film "the wide latitude sensitivity", "panchromatic", "orthros" bright education in the Solar atmosphere astrophysics called chromospheric flares, etc.

First Voclano not like the proposed name, because he discovered the metal had a modest gray color and didn't seem to justify its name. But Fourcroy managed to persuade Varlena, and, after the French Academy of Sciences on the entire form has registered his discovery, chemists around the world have made the word "chrome" in the lists of known elements.

A few months later Varlena new item found in the same crocoite German chemist Martin Heinrich works, which had by this time on his scientific account three open view of the element uranium, zirconium and titanium (later joined by cerium). But the glory of the discoverer of chromium on the right came Voclano.

It took more than half a century, to distinguish the new metal in its purest form: it was done in 1854 the German scientist Robert Wilhelm Bunsen, who chromium chloride electrolysis.

Unlike many other metals, chromium fortune immediately showed favor. High melting point, great hardness, the ability to easily form alloys with many elements, particularly iron, are interested primarily metallurgists. Years did not dampen this interest: in our days metallurgy continues to be a critical consumer of chromium, although for this element and its compounds found many other useful lessons.

Chrome has all the characteristic of a metal is a good conductor of heat and electric current, is characteristic of most metals Shine. A curious peculiarity of chromium: at a temperature of about 37°C, it behaves clearly "defiant" - many of its physical properties sharply, abruptly changing. At this point temperature internal friction chromium peaks, and the modulus of elasticity decreases to minimum values. As suddenly changes the electrical conductivity, linear expansion coefficient, thermoelectric power.

At a temperature of 37°C physical properties of chromium abruptly changed

While scientists tried to find an explanation for this anomaly, chromium asked another riddle.

Physicists have long known pattern: the magnetic structure of the material is strictly complies with its crystal lattice. However, studies of ultra-pure chromium showed that to him this regularity is not relevant.

Even minor impurities make chrome is very fragile, therefore, as a structural material of its practically not used, but as alloying element he has long enjoyed the honor of metallurgists. Small additions give it steel hardness and wear resistance. Such properties inherent in ball-bearing steel, which, along with chromium (up to 1.5%), includes carbon (about 1%). Formed therein, the chromium carbides are characterized by exceptional hardness - they allow the metal confident to resist one of the most dangerous enemies - wear.

Who does not know of the magnificent sculpture V.I. Mukhina's worker and kolkhoz woman"? A majestic monument, which in 1937 was decorated with the Soviet pavilion at the world exhibition in Paris, and now stands at the entrance to the Exhibition of achievements of national economy in Moscow, made of stainless steel containing about 18% chromium and 10% Nickel. But stainless steel carbon harmful: carbidopa inclinations of chromium leads to the fact that large quantities of this element in contact carbides, released at the grain boundaries of steel, and the grains themselves are poor chrome and can't bravely to defend against the onslaught of acid and oxygen. Therefore, the carbon content in the stainless steel must be kept to a minimum (not more than 0.1%).

Original steel containing chromium and aluminum has created the Japanese steelmakers: it hundreds of times more dampens sound vibrations than conventional structural steel. Window frames and doors of the "quiet" were completely silent, even if they pop it out there. Sheet made of this steel, falling on the cement floor, does not emit any sounds. The new material is appreciated by engineers who are forced every day to listen to "concerts", performed at the workshop "percussion instruments".

At high temperatures, the steel can be coated with "scales" scale. In some machines, the workpieces are heated to hundreds of degrees. To steel, from which these details did not suffer onlinealprazolam, enter 25-30 % chromium. Such steel can withstand temperatures up to 1000°C!

Alloys of Nickel and chromium - nichrome - successfully serve as heating elements: they have a very high electrical resistance and therefore, when current passes through the metal gets very hot. Additive to Nickel-chromium alloys, cobalt and aluminum gives the metal the ability to carry heavy loads at 650-900°C; from such heat-resistant alloys are produced, for example, blades of gas turbines. Chrome is a part of many other alloys, which can be judged by their names: chromel, chromel, promensil. Alloy tomogram (it consists of cobalt, molybdenum and chromium) harmless to human body and therefore is used in reconstructive surgery. For dentures designed alloy of cobalt and chromium, which is many times cheaper than gold and also has a lower thermal conductivity: the owner of such a prosthesis can drink hot tea or eat ice cream without feeling discomfort.

Chrome harmless to the human body and therefore is used in reconstructive surgery

The main part produced in the world chrome ore arrives today on Ferroalloy plants, where melted various grades of ferrochromium and metallic chromium. First ferrochrome was obtained in 1820 the restoration of a mixture of oxides of iron and chromium charcoal into the crucible. In 1854 managed to get clean chrome metal by electrolysis of aqueous solutions of chromium chloride. To this time belong the first attempts to produce carbon ferrochrome in the blast furnace. In 1865, was issued the first patent on the chrome steel. The demand for ferrochrome began to grow rapidly.

An important role in the development of production of ferrochrome played electric current, or rather the electrothermal method of producing metals and alloys. In 1893 a French scientist Moissan was melted in an electric furnace carbon ferrochromium containing 60% chromium and 6% carbon.

In pre-revolutionary Russia Ferroalloy industry has been developing at a snail's pace. Only a tiny amount of ferrosilicon and ferromanganese blast furnace smelted southern plants. In 1910, on the banks of the river Satka (South Urals) was built a little electrometallurgical plant "Thresholds", which began to produce ferrochrome, EB then and ferrosilicon. But about the needs of their industry could not be and speeches: Russia's need for the ferroalloys accounted for almost completely cover import them from other countries.

The young Soviet state could not depend on capitalist countries in such major industries as the production of quality steels, which is the main consumer of ferroalloys. In order to realize the ambitious plans for the industrialization of our country, was required steel - structural, tool, stainless, ball bearing, automotive. One of the most important components of these steel - chrome.

Already in 1927-1928 began the design and construction of Ferroalloy plants. In 1931 he entered the order of the Chelyabinsk plant of ferroalloys, which became the first of our Ferroalloy industry. One of the founders of Soviet high-quality metallurgy member of the Academy of Sciences of the USSR B. C. Emelyanov in these years was in Germany, where he was sent to study the experience of foreign experts.

In his memoirs he tells of a curious conversation that took place from his one of metallurgists: "In 1933 in a small German factory I asked the chief engineer:

- To whom do you sell manufactured at the plant ferrochrome?

He began to enumerate:

- About five percent of the total production we supply the nearby chemical plants, two percent of us buys a factory Becker, about three percent...

Interrupting him, I asked:

- Well, do you have many buys the Soviet Union?

And the Soviet Union while. Seventy-five to eighty percent of our products we send to your plants. Yes we are working on Ural chrome ore".

Yes, at that time, our chrome ore was exported not only in Germany, but in Sweden, Italy, USA. And they we had to buy ferrochrome. But when after the Chelyabinsk in 1933 were built two Ferroalloy plant in Zaporozhye and Zestaponi, our country not only ceased to import the major ferroalloys, including ferrochrome, but was able to export them abroad. Quality metallurgy of the country was almost entirely provided with the necessary materials domestic production.

In 1936, in Kazakhstan, in the district of Aktobe, were found huge deposits of chromite - basic industrial raw materials for the production of ferrochrome. In the war on the basis of this field was built Aktobe Ferroalloy plant, which later became the largest enterprise for the production of ferrochrome and chrome all brands.

Very rich chrome ore Ural: it is no coincidence that here was found the mineral in which Voclano managed to open chrome. There are deposits of this element and in many other countries. And while traveling on the moon was the Soviet Lunokhod of his instruments have established the presence of chromium in the area of the Sea of Rains. But if to the Sea of Rains quite far to the red sea, as they say, at hand. Here, near the banks of Sudan French scientists have discovered a kind of pit, the depth of which reached 2200 meters, and the water at this depth was very hot. Researchers have fallen into the abyss to the submersible, but soon had to return because the steel wall of the device quickly warmed to 43°C. the water Samples taken at this depth, showed that the hole is almost filled with hot liquid ore: content in water chromium, iron, gold, manganese and many other metals were unusually high. It is quite possible that in the coming years, experts will be engaged in the development of these "cocktails" of metals.

The chromites are widely used in the refractory industry. Magnesiochromite brick is an excellent refractory material for lining open-hearth furnaces and other metallurgical units. This material has high heat resistance, they are not afraid of multiple abrupt changes in temperature.

Chemists use chromites to obtain bichromate potassium and sodium, as well as chrome alum, which is used for tanning of the skin, giving it a beautiful Shine and strength. This skin is called chromium, and boots from it chrome.

Every evening over Moscow flash ruby stars of the Kremlin. In the world of precious stones ruby belongs to the second place after diamond. According to the ancient Indian tradition rubies formed from the drops of blood shed by the gods: "Fall heavy drops of blood on the bosom of the river, in deep water, the reflection of the beautiful palm trees. And called the river since Ramanagara, and has lit up since these drops of blood, turned into stones ruby, and they burned with a dark fairy fire, hot on the inside, and panizales water these fiery rays...", tells of the origin of the ruby ancient Oriental legend. In these days technology is a wonderful red stone has been greatly simplified and the gods do not have to shed his sacred blood: for the alumina introduce metered additions of chromium oxide, and are obliged ruby crystals with her charming color. But artificial rubies are valued not only for their beautiful appearance: born with their help, the laser beam can literally work wonders. Like magic beam created by the hyperboloid of engineer Garin and rich imagination Alexei Tolstoy, the laser beam can cut any metals with the same ease with which the scissors cut paper, or flash in diamonds, rubies and other "hard nuts" fine holes, not showing any respect for their world famous hardness.

The chromium oxide allowed the tractor to reduce considerably the time of running engines. Usually this operation, during which all rubbing parts have to get used to each other, lasted quite a long time and it is certainly not very organized workers tractor plants. A way out was found, when it was possible to develop a new fuel additive, comprising the chromium oxide. The secret actions of the additive is simple: the combustion of the fuel produces tiny abrasive particles of chromium oxide, which, settling on the inner walls of the cylinder and the other exposed to friction surfaces, quickly eliminate roughness, polished and tightly fit the part. This additive in combination with a new type of oil has allowed 30 times to reduce the duration of the test.

Not so long ago, the chromium oxide bought another interesting specialty: custom magnetic tape, a working layer which contains iron oxide, as usual, and chromium oxide. The change was successful - increased density, improved sound quality, the film became more reliable. New first received a residence permit in the magnetic memory blocks of electronic computing machines.

Materials and drugs, catalysts for chemical processes and metal plating - chrome everywhere is busy. On chrome coating should, perhaps, be a little more.

It has long been observed that chromium not only has a great hardness (in this respect it has no competitors among metals), but also resists oxidation in air, does not react with acids. A thin layer of this metal have tried the electrolytic deposition on the surface of products made of other materials, to protect them from corrosion, scratches and other injury. However, the chrome coating was porous, easily peeled off and did not justify the hopes pinned on them. Almost three quarters of a century fought scientists on the problem of chrome, and only in 20-ies of our century, the problem was solved. The cause of the failures was the fact that the electrolyte contains trivalent chromium, which could not create the desired floor. But it hexavalent fellow this task turned out to be on the shoulder. Since that time, the electrolyte began to use chromic acid - valence chromium is equal to 6. The thickness of the protective coating (for example, on some exterior parts of automobiles, motorcycles, bicycles) reaches 1 mm. But sometimes chrome finish used for decorative purposes, for finishing hours, door handles and other items not exposed to serious danger. In such cases, the product is applied a thin layer of chromium is 0.0002-0.0005 mm).

Lithuanian chemists have developed a way to create multi-layered "armor" for critical parts. The thinnest top layer of this coating (under the microscope the surface and in fact resembles chain mail) consists of chromium: during the service, he first takes the fire itself, but chromium is oxidized, held for many years. Meanwhile, the item safely carries your responsible service.

Until recently was chromasomal only metal parts, but now scientists have learned how to apply chrome armor and plastic products. Tested widely known polymer - polystyrene, dressed in black, became stronger, it was less scary these eternal enemies of structural materials, such as abrasion, bending, impact. Needless to say, increased service life of parts.

Chrome armor was useful even in such a hardness standard, which is considered a diamond. The fact that not all mined diamonds can be used for production machining tool: as a rule, natural diamonds have many subtle cracks that make the stones are not suitable for installation on cutters or drill bits: as soon as this tool was related to metal or hard rock, diamond crumbled to pieces. In addition, crystals of natural diamond would often jump out of the tool holder. To resolve this shortcoming, researchers have proposed to cover the diamond thin film of chromium, quite tightly connected with diamond, and copper holder.

The diamond is coated with a thin film of chromium

Metalized diamond was subjected to the tests. And what was found? The diamond is securely held in the tool, and the service life of the crystal was increased several times. When such a crystal is examined under the microscope, on one of the faces found quite a deep crack, cemented film that covered the stone. It was found that the chromium atoms will combine with the carbon of the diamond formed on the surface of solid carbide, and chromium penetrated into the crack, the walls of which are covered carbide armor. And a layer of pure chromium adjacent to the holder, formed with copper alloy, making the diamond firmly entrenched in the tool. So using chrome managed to kill two birds with one stone: the tool has become more durable as diamond - stronger than... diamond.

In 1974 in Dubna scientists of the joint Institute for nuclear research was obtained isotope transuranic element with atomic number 106. Crowned with success the reaction of nuclear synthesis occurred in the bombing of the lead target with accelerated ions of chromium. The lead more than once served as a target in these experiments, and chromium was chosen for purely arithmetical reasons, with 82 protons, which includes the nucleus of an atom of lead, 24 proton nucleus chromium was at the confluence of these cores need the number - 106. Although the isotope of this element lives just a few milliseconds, sensitive instruments recorded the birth of a new transuranic.

...Before you finish the story on chrome, we revisit the memories V.S. Emelyanov. "Two years ago, " wrote scholar in 1967, I learned things that touched me deeply news, remaining in our country - alas! - unnoticed. We sold a lot of ferrochrome England is a country which has always been the symbol of technological progress. And now England is buying our ferrochrome! The British see the sense in that buy."

 

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