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Sergey Venezky
STORIES ON METALS

MOLYBDENUM

ALLY IRON

Without condiments will not do! - Under a false name. - The error of the ancient Greeks. - At the Mint. - In protest. - "Skyscraper" in 1600 floors. - Crash on level ground. - Dream hairdressers. - Reliable support. - "Take the burden on yourself ..." - Glass changes colour. - "Parts" of man. - True friends. - Mystery of the samurai sword. - Tank becomes invulnerable. - Razor blade. - Kindred spirits. - Not afraid of frost. - Loved the beans. - What is the "Union red"? - All the "blame" is molybdenum? - Uninvited guests. - Modest place. - The"war" metal. - High in the mountains. - Millions of meters. - Where the key to the chest?

To prepare a tasty dish, the chef adds a variety of spices. To smelt steel with valuable properties, the steel-maker introduces a variety of alloying elements.

Seasoning for alloyseach spice has its own goal. Some improve the taste of food, others make it fragrant and delicious, others give it a sharp, fourth... Hard to count all purpose spices. But it is even more difficult to enumerate all the wonderful properties that acquires steel with the addition of chromium, titanium, Nickel, tungsten, molybdenum, vanadium, zirconium, and other elements.

One of the most faithful allies-iron - molybdenum - and dedicated to this story.

...Molybdenum was discovered in 1778 by the Swedish chemist Carl Wilhelm Scheele. The element name comes from the Greek word "molybdos". That a newborn baby was baptized a Greek name, it is not surprising - many chemists before open to name their items looked in Greek "the saints". Surprising in the Russian translation of "molybdos" means... "lead". What made this item to hide under a false name? Why lead molybdenum owes its name?

And the box was just opened. The fact that even the ancient Greeks was known mineral of lead is Galena, which they called "molybdenum". In nature, there is another mineral, molybdenite, as two drops of water similar to Galena. This similarity and introduced the Greeks misleading: they believed that they were dealing with the same mineral molibdenos. The same opinion was held at that time, scientists and other countries. That's why Scheele, discovered this mineral is unknown "land", without much deliberation called it "molybdenum".

Now I had to extract the new metal. Although Scheele had already gained world fame and was a member of the Royal Swedish Academy of Sciences, he continued to work in modest pharmacy, where he spent his chemical studies. But the pharmacy was not a furnace, in which molybdenum earth, calcined coal, would have recovered to the metal. Scheele remembered that suitable for this purpose, the furnace is at the Mint in Stockholm, where he worked his friend Peter Jakob Helm, and appealed to him for help. Expectations: Helm soon was able to select an item in the form of metal powder, however, heavily soiled carbides.

Almost forty years later, when neither Scheele, nor Gelma was no longer alive, their famous compatriot Jens Jakob Berzelius managed to get more or less pure molybdenum and determine many of its properties.

Like so many of his brothers in the Periodic table, molybdenum absolutely does not tolerate extraneous impurities and, as if in protest, fundamentally alters the properties. Thousands and even ten-thousandths of a percent of oxygen or nitrogen to give the molybdenum greater fragility. That is why in many manuals of chemistry, published in the early twentieth century, it was argued that the molybdenum almost not machinable. In fact, pure molybdenum, despite high hardness, is quite a plastic material, which is relatively easily rolled and forged.

The first entry in the "work-book" molybdenum appeared several centuries ago, when the mineral molybdenite began to be used as leads. (Interestingly, in Greek pencil and is now called "molybdos".) Like graphite, molybdenite consists of many scales, whose dimensions are so small that if you put them one on another, the height of the "skyscraper" from 1600 floors-scales will be equal to... 1 micron. Thanks to these scales molybdenite can write and draw on paper it leaves greenish-gray trail.

Nowadays you will not meet molybdenum of pencils: pencil industry exclusively possessed graphite. But molybdenum disulfide (chemical name molybdenite) has found himself another application. However, before I talk about it, will tell you a little story.

It happened on the Simferopol highway during tests of an experimental batch of cars "Zaporozhets". All went well, but suddenly at full speed one of the cars rolled over on completely level ground. Fortunately, sitting in the car people escaped, as they say, with a fright. The cause of the accident was a mystery up until the car was not dismantled bones. It turned out that one of the gears in the gearbox, which was free to rotate on a steel sleeve, firmly welded to it. Of course, such a "brake" triggered instantly.

To such accidents do not happen again in the future, it was necessary to find a suitable lubricant. Here and remembered the molybdenite, or rather on its ability to split into separate microscopic scales. They were supposed to serve as a solid lubricant for the moving parts of the transmission.

Standing for a moment to lower the steel workpiece in a liquid containing only 2% of molybdenum disulfide, and the surface is covered with a thin layer of excellent solid lubricant. However, this grease has an insidious enemy - high temperature. When heated molybdenum disulfide is starting to turn into molybdenum trioxide, which, though not harm the surfaces of the parts, but does not, unfortunately, lubricating properties. How to avoid this?

It turned out that before applying disulfide layer item must be processed in a hot phosphate bath. In this case, the disulfide particles penetrate into the fine pores of the phosphate coating and the surface formed by the thinnest oil film that can withstand enormous loads of several tons per square centimeter. Sleeve covered with this film experienced in heavy modes and no case of welding. Since then, the "Cossacks" traveled our country far and wide, but the unfortunate site of transmission was not let down never, no more.

The miraculous properties of molybdenum are used in the art of hairdressingcreate a lubricating film is not limited to the beneficial effect of molybdenum disulfide on a steel surface: if you handle molybdenite cutting tool, it will become more resistant, more durable. When this wonderful property molybdenite learned some hairdressers, they with enviable efficiency rushed to implement it in practice.

But back to the molybdenum. Due to the refractoriness and low coefficient of thermal expansion of the metal is widely used in electrical, electronics, engineering high temperatures. Hooks on which hung a tungsten filament in an ordinary electric light bulb, made of molybdenum; if the glass rod lamp was soldered give light to the tungsten wire, glass soon be cracked due to its thermal expansion, and molybdenum when heated almost does not expand and therefore does not cause the glass no concern. From it produce anodes, grids and other details of the radio, x-ray tubes. As a constructional material for molybdenum has found application in nuclear power reactors. Molybdenum spiral well established as a powerful heaters vacuum resistance furnaces where they develop a very high temperature. Among the exhibits of the Polytechnic Museum in Moscow you can see a small molybdenum boat with grown in artificial crystal alumina-yttrium garnet.

The U.S. created the original glass that changes color depending on... the time of day. Sunlight glass turns blue, and dark - transparent again. This effect is due to the addition of molybdenum, which is either injected into the molten glass, either in the form of a thin transparent film glued between two layers of glass.

Heat-resistant molybdenum alloys proved to be an excellent material for critical parts of rockets, rocket engines, the edges of the wings of supersonic aircraft. And in medicine has found application alloy kamagra consisting of cobalt, molybdenum and chromium: this alloy is manufactured "parts" for man." Yes, don't be surprised) Nomogram easy to get along with human body tissues, and surgeons have successfully used them to replace damaged joints.

Even in Babylon during the construction of homes builders armirovali clay cane, and in Ancient Greece iron bars strengthened marble columns in the construction of palaces and temples. This principle formed the basis for the creation of a new class of advanced structural materials called composite because they represent the composition of two or more dissimilar components. Each of them is doing his job: some, for example, resist high heat, wear or corrosive environments, and the other confidently resist stretching. This division of labor allows a lot of ease in many designs, especially for aviation and space technology. Varying the ratio of components, it is possible to obtain materials with desired strength, heat resistance, elastic modulus and other desired properties. For a number of ductile metals (Nickel, cobalt, titanium and others) in the role of reinforcement, which assumes too much for them tensile load, can speak confidently molybdenum wire: this "stuffing" the strength characteristics of the material can be increased many times.

A wide variety of applications found molybdenum compounds. Thanks to him, enamel acquire a high covering capacity. Molybdenum dyes used in the manufacture of ceramics and plastics, leather, fur and textile industries. Molybdenum oxide serves as a catalyst in petroleum cracking and other chemical processes In analytical chemistry for nearly a century and a half working ammonium molybdate is an important reagent with which chemists determine the phosphorus content in ores, steel, alloys and other materials.

As you can see, there is a molybdenum enough. But we have talked only about the side practice of this metal and did not say a word about his main profession. Remember, in the beginning of this essay molybdenum was called faithful ally of iron. That's about the friendship of iron, molybdenum and we will tell you more - in fact, three quarters of all mined on earth molybdenum consumes metals special steels. In our country steel containing this element was first produced in 1886 at the Putilov plant in St. Petersburg. However, the use of molybdenum to improve the properties of steel has a much more ancient history.

The mystery of the samurai swordLong time no one could solve the mystery of great acuteness of samurai swords. Many generations of metallurgists unsuccessfully tried to smelt steel, similar to the one from which in the XI-XIII centuries produced melee weapon in the land of the Rising Sun. In the end, the secret has been uncovered: the mysterious steel, along with other elements, contain molybdenum, which has managed to simultaneously increase the hardness and toughness of the metal, while usually the increase in hardness is accompanied by an increase in fragility.

The combination of high hardness and toughness is crucial for armor steel. Armor Anglo-French tanks, which appeared in 1916 on the battlefields of the first world war, was made of hard, but brittle manganese steel. Alas, this massive shell thickness 75 mm shells German artillery was transpierced, like butter. But it was necessary to add to steel only 1.5-2% molybdenum, as the tanks were out, despite the fact that the thickness of the armour plate was reduced almost threefold.

What is the explanation of this truly miraculous rebirth armor? The fact that molybdenum retards the grain growth during solidification of steel and thereby gives it a fine uniform structure, providing a high metal properties. Most alloy steels inherent in the so-called fragility after the holidays. Steel, containing molybdenum, are not susceptible to this disease, so that they may be subjected to heat treatment without any fear of internal stresses. Molybdenum improves the hardenability of steel. This alloy element in steel is also characterized by a considerable strength at high temperatures and greater creep resistance. A similar effect on steel properties has and tungsten, but the effect of molybdenum, for example, on the strength of the metal is much more efficient: 0.3% molybdenum can be replaced 1% tungsten metal more scarce.

Molybdenum steel is not only armor, but the barrels of guns and rifles, parts of aircraft and cars, steam boilers and turbines, cutting tools and razor blades. Beneficial molybdenum and properties of cast iron: increases the strength of the metal increases its durability.

High alloying ability of molybdenum due to the fact that it has the same crystal lattice as iron. The radius of the atoms is also very close to each other. Well, kindred souls easily find a common language. However, molybdenum friendly not only with iron. Alloys of molybdenum, chromium, cobalt, Nickel possess excellent kislotoupornogo and used for the production of chemical equipment. For some alloys the same elements characterized by a large abrasion resistance. Alloys of molybdenum with tungsten can replace platinum. For the manufacture of electrical contacts using the alloys of this element with copper and silver.

In refrigeration is widely used liquefied gases, in particular nitrogen. To keep it in liquid state, needs frost - almost 200 degrees. At this temperature the usual steel becomes brittle as glass. Containers for storage of liquid nitrogen made of special cold-resistant steel, but it has long suffered one significant drawback: the welds on it had a low strength. To eliminate this drawback helped molybdenum. Before the composition of the welding consumables used in welding, consisted of chromium, which, as it turned out, led to the cracking of the edges of the seam. Studies have allowed to establish that the molybdenum, conversely, prevents the formation of cracks. After numerous experiments, it was found the optimal composition of the additive: it must contain 20% molybdenum. And welds now easily transfer dvuhsotgrammovy frost, as well as steel.

Molybdenum has steel and other assistance: if you mix fine molybdenum powder with ascorbic acid (vitamin C), a mixture is formed, which protects the steel and other metal products from corrosion. As you can see, vitamins are useful not only people, but also metals.

Productively molybdenum and agricultural field. Introduced in microscopic quantities in the soil or in food animals, some items literally work wonders. One of these wizards is molybdenum. Infinitesimally small doses of this trace element substantially increase the yield of many crops, improve their quality. Very partial to the molybdenum leguminous plants. Seeds of peas, treated with ammonium molybdate was on an ordinary field crops almost a third higher than normal. Concentrated in nodules of legumes, molybdenum promotes the absorption of their atmospheric nitrogen is essential for plant development. Thanks to the molybdenum increases the content of proteins, chlorophyll and vitamins in plant tissues. But this element is not everyone gives their favor: on some weeds he acts detrimental way.

Unusual studies have been conducted by Japanese scientists from Osaka University. Analyzing, using the most modern means of remains of burnt hair, they concluded that the color of hair depends on the presence of trace quantities of certain metals. So, blonde hair, for example, is rich in Nickel, gold - titanium. If the owners of fire-red hair dissatisfied by it, all the claims they must produce molybdenum: it was he, according to Japanese pigmentosa, and gives your hair this color. Therefore, if there was indeed exposed Sherlock Holmes "Union red", its logo rightfully could show off the character of molybdenum.

Union red could take as the emblem glyph of molybdenum

This element gave rise to the famous English scientist in the field of molecular biology Nobel prize winner F. Crick and his colleague Professor L. Orelli hypothesized extraterrestrial origin of life on earth. In the basis of the hereditary mechanism of all living creatures is, as you know, the same genetic code. According to biologists, this uniformity suggests that all life on Earth evolved from the same colony of microorganisms. And as an indispensable companion of biochemical processes is relatively rare on our planet molybdenum, it can be assumed that this original colony came to us from another celestial body, rich in molybdenum. The hypothesis is very interesting, although there are many vulnerabilities.

Unfortunately, sometimes the molybdenum is caught up in things that are beneficial not be called. On the negative side of his activities told the research of Soviet scientists conducted in one of the distant sea expedition.

At the end of 1966 from berths Vladivostok away "Mikhail Lomonosov". This special scientific ship was to examine different parts of the world ocean and to determine the degree of contamination of their radioactive substances. Not one month, the ship sailed in the ocean, and all this time on Board, like the border guards kept watch sensitive devices - Geiger counters, ready at any moment to detect the appearance of radioactive guests.

One day the ship was preparing to cross the equator in the most deserted part of the Pacific ocean. All day on the deck of the ship with great speed was spinning fan blades, swallowing thousands of cubic meters of sea air and directing it into the filters, which could delay the dust size even in hundredths of a micron. Periodically, the filters together with the accumulated dust and burned by using sensitive instruments was determined by the radioactivity of the resulting ash. Suddenly Geiger counters excited is not a joke: in the ashes was a radioactive isotope molybdenum-99 neodymium-147. These isotopes are very short time. So, the half-life of 99mo only 67 hours. Measurements and calculations, scientists have established the exact date of the appearance of uninvited guests - December 28, 1966. Indeed, as reported by the Xinhua news Agency, the China tested its nuclear weapons. For several days the wind has blown the resulting radioactive "shards" thousands of miles.

In fairness, it should be noted that in this dangerous play with fire molybdenum plays a very modest role. However in the near future, as we may hope, the powers of the world will achieve a complete ban on nuclear testing - then he no longer act in such a nefarious role and will be involved only useful for human activities. Well, that molybdenum right people for a variety of purposes, and hence in large enough quantities, you have already seen. What are the reserves of this element on our planet?

The share of molybdenum is only 0,0001% of all atoms of the earth's crust. Prevalence in nature it takes some elements of the table D. I. Mendeleev modest place - in the sixth decile, however, deposits of this metal are found in many places around the globe.

If in the beginning of our century the production of molybdenum was only a few tons, in the years of the first world war, the production of this metal has grown almost 50 times (armor they needed!). In the postwar period, the mining molybdenum ore fell sharply, but then, starting in about 1925, was observed the new growth of the production of molybdenum, which reached a maximum (30 thousand tons) in 1943, during the second world war. Not by chance, therefore, molybdenum is sometimes referred to as "military" metal.

On the territory of our country's largest Deposit of molybdenum ore was discovered in the North Caucasus in 1934 by the student geologist Faith Flerova found in the gorge of the river Baksan molybdenite. Faith wandered through the beam for several hours and was thoroughly tired. And all of a sudden! As tired as usual. Heart was beating at a furious pace, it took my breath away. The girl again and again felt the rough surface of a small quartz chip, conducted on thin fingers and toes remained gray-blue "moon" track. Took another two dozen steps and again swiftly bent down. Picked up the same stone. Took the lens and just stared at the piece of rock with metallic inclusions. Yes, there was no doubt: these metal inclusions in quartz is not that other, as molybdenite. Molybdenum ore!"

So in the book about Faith Flerova (L. Kaftanov. Faith Flerov. M.: Politizdat, 1971, S. 75-76.) describes the event that has become a landmark in the history of domestic rare-metal industry. After two years on the findings already built molybdenum mine. Unfortunately, the Faith was not destined to see here in the mountains rose, the town of Tyrnyauz that his birth was obliged she is a wonderful girl since the childhood dreamed to find the magic stone: in 1936 Faith was tragically killed in the mountains. The suspension bridge, on which she passed through the Baksan river, fell into the turbulent waters of a mountain river. The name of Faith Flerova are one of the areas of Tyrnyauz and peak, towering above the city. On one of the mountain slopes, away from noisy highways, there is a small obelisk. Slowly and majestically float above him the clouds, and nearby steel wire ropes sliding trolley with a magic stone.

Molybdenum ore processed primarily in the ferromolybdenum, which are used in metallurgy high-quality steels and special alloys. The first industrial experimental production of ferromolybdenum refer to the end of the last century. In 1890, was developed the method of producing alloy recovery of the molybdenum oxide. But these experiments practically limited to the production of ferromolybdenum in tsarist Russia. In 1929 silicothermic method was able to melt the alloy containing 50-65% molybdenum. Successful experiments VP elatina conducted in 1930-1931, has further allowed us to implement this method in the metallurgical industry.

But technology is needed not only molybdenum steel and products made of pure molybdenum. But it's a long time and not been able to produce. But why? Because relatively pure powder of this metal have learned to get a long time ago? Blame was refractoriness of molybdenum - she was not allowed to turn the powder into a monolithic metal by fusing. Had to look for other ways. In 1907 under laboratory conditions was first obtained molybdenum thread. For this purpose, the molybdenum powder mixed with an adhesive organic material and the prepared weight pushed through the matrix, hole. The resulting sticky thread was placed in an atmosphere of hydrogen and skipped through the thread electric current. As expected, the thread warmed up, organic matter burns away and the metal managed proplevitra and settle on a wire (hydrogen was very handy for molybdenum during heating is not oxidized).

Three years later a patent was issued on receipt of refractory metals, particularly molybdenum, powder metallurgy, which is used in our time. The metal powder is pressed, is sintered, and then subjected to rolling or drawing tape or wire ready for use in the technique.

In the USSR molybdenum wire began in 1928, and three years later, production was 20 million meters.

In recent years, for the production of molybdenum were used vacuum arc remelting, zone and electron beam melting with such assistants things got even more fun.

...We have already talked about the fact that the molybdenum ore deposits in the earth's crust is limited. So, maybe after some time they will be exhausted and mankind will be faced with the problem of where to get a much-needed metal?

No, until we can be sure of the fate of his descendants. Because, in addition to the earth's crust, a huge number of different elements contained in the waters of the oceans and seas. If marine wealth to be divided equally among all the inhabitants of our planet, each of us will become the owner of countless treasures. Suffice it to say that only one gold Neptune may issue from their pantries approximately three tons per capita. Now really is a gold mine! As for molybdenum, then we would have tons of one hundred per person.

People are still trying to find the keys to the blue chests of Neptune. But will pick up. Will definitely pick up.

 

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