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Sergey Venezky
STORIES ON METALS

NIOBIUM

FORTY-FIRST

Where you are registered? - Without incident. - Neighbors intrigued. - Sending from the coast of Colombia. - 150 years later. - Two open. - "To inflict upon him a new interrogation..." - In honor of the goddess of sorrow. - "Columbite" make peace with God. - Water will not spill. - The game is worth the candle. - There is a silver lining. - Recognition. - Important things. - Helps emptiness. - Not afraid of frost. - Error leads to discovery. - Without any resistance. - The record has to give. - How to catch two birds with one stone? - Opponent zirconium. - In the fight against gas. - Responsible medical officer. - Currency transactions. - Prediction comes true.

By the middle of the last century, was discovered already several dozen chemical elements. But, alas, they did not possess their own angle or permanent residence. And only in 1869, when Dmitry Ivanovich Mendeleyev was built multi-storey building his Periodic system, all open to the time the items he finally found refuge.

When the distribution of the residential area merits future tenants before science and technology, and work experience were not taken. It takes into account only the personal qualities (primarily atomic mass), the inclinations, the similarity with the nearest neighbors. Important role played and communication (of course, chemical). To avoid potential problems of residents with different personalities and views on life were placed as far as possible from each other.

In the fifth house (i.e. in the fifth group) on the fifth floor (more precisely, in the fifth period) in the apartment No. 41 settled the tenant with a beautiful name - Niobium. Who is he? Where are you from?

...In the middle of XVII century in the basin of Colombia (North America) was found heavy black mineral with Golden flecks of mica. Together with other stones, collected in various parts of the New world, this mineral (later called columbite) was sent to England in the British Museum. Nearly 150 years lay the stone under glass at the booth Museum, the number in the list of exhibits a sample of iron ore. But in 1801 already known at that time chemist Charles Hatchett interested in this beautiful mineral. The analysis showed that the stone is actually contained iron, manganese, oxygen, but along with them there was an unknown element, forming a substance with the properties of acid oxide. New item Hatchet called columbium.

A year later the Swedish scientist Andrew Gustav Ekeberg in some Scandinavian minerals found another new element, named after the mythological hero of the tantalum. The name apparently symbolized the difficulties ("torment of Tantalus"), which experienced chemists, trying to dissolve the oxide of a new element in acids. Properties of tantalum and Colombia were completely identical, and many scientists, including the famous Jena Jacob Berzelius decided that we are dealing not with two different elements, and with one and the same - tantalum.

In the future, Berzelius doubted the correctness of this view. In a letter to his disciple German chemist Friedrich the wöhler's he wrote: "I Send you back your X, I asked how he could, but from whom I received evasive answers. "You're a Titan?" - I asked. He replied: "wöhler told you that I'm not the Titan. I also installed it. "You're Zirconia?" "No, " he answered. - I dissolved in the soda, what does zirconium earth". "You tin?" "I contain tin, but very little" - "You tantalum?" - "I related, " he answered. But I gradually dissolved in sodium hydroxide and precipitate from the yellow-brown. - "Why are you the devil thing?" I asked. It seemed to me then that he said, "I was not given a name". By the way, I'm not quite sure if I heard it, because he was on my right, and I am very hard of hearing in the right ear. Because your hearing is better than mine, I'll send this Tomboy back to inflict upon him a new interrogation..."

Columbia or niobium?But the wöhler's failed to understand the relationship of elements, open Hatchet and Ekeberg. Until 1844 the German chemist Heinrich rose after a laborious search, which left half a dozen years, was able to prove that the mineral columbite contains two distinct elements - tantalum and Colombia, which rose gave a new name - "niobium" (in Greek mythology the goddess of sorrow and sufferings of Niobe the daughter of Tantalus). However, in some countries (USA, England) was long preserved the original name of the element - Colombia - and only in 1950, the international Union of pure and applied chemistry decided to do away with this variety of opinions and suggested chemists around the world to call this element niobium.

The first time American and British chemists tried to overturn this decision, which seemed unfair to them, but the sentence was final and were not subject to appeal. Had columbium" to come to terms with this stroke of fate, and in the chemical literature of the USA and England were the new symbol "Nb".

Cohabitation of niobium and tantalum in nature, due to their extraordinary chemical similarity, for a long time hindered the development of the industry of these metals. Only in 1866, the Swiss chemist Jean Charles Glisser de Marignac developed the first industrial method of separating chemical twins. He took advantage of the different solubility of some compounds of these metals: a comprehensive fluoride, tantalum is not soluble in water, a similar connection niobium sufficiently soluble in it. In the improved method of Marignana used until recently, but now they have been replaced by new, more efficient ways - selective extraction, ion exchange, distillation halides.

In the late nineteenth century, the French chemist Henri Moissan received net niobium electrothermal by restoring the niobium oxide with carbon in the electric furnace.

Nowadays, the production of metal niobium is a complex multistage process. First niobium ore is enriched. The obtained concentrate alloys with different fluxes (caustic soda, hydrosulfite or soda), then leached, resulting in falls insoluble precipitate of hydroxide niobium and tantalum. Then the twins are separated, and the niobium is in the form of the oxide or chloride. The recovery of these compounds at high temperatures is possible to obtain powdery niobium, who need to turn in a compact metal suitable for processing.

This is achieved as follows. From the powder under high pressure is pressed so-called rods (procurement) rectangular or square cross section. Rods is sintered in vacuum in several stages, and at the final stage reaches a temperature of 2350°C. In further niobium enters the vacuum arc furnace, which completes the whole cycle of transformation niobium ore into metal.

A few years ago, the industry has mastered the electron-beam melting of niobium, eliminating the labor-intensive intermediate operation as pressing and sintering. In this method, the powdered niobium direct a powerful stream of electrons. The powder begins to melt, and metal drops fall on niobium ingot, which as penetration of the powder increases and gradually removed from the working chamber.

As you can see, niobium goes a long way to go before the ore becomes a metal. And still the game is worth the candle: today niobium very necessary industry. And he began his career in... dumps.

Paradoxically, but in those days it was considered only harmful mixture to the tin and in the extraction of this metal huge amounts of niobium were thrown into the landfill. The same is to be considered attained when the industrial world became interested in tantalum, and niobium remained indifferent: during the processing of tantalum niobium ore "empty" rock went to the dump. But there is a silver lining, and subsequently, when niobium was appreciated by the person, these waste products became the richest "field" niobium ores.

After 1907, the German chemist Werner von Bolton managed to get this metal in compact form, niobium, like many other refractory brethren, he tried his hand in the production of light bulbs as a material for the filaments. But as you know, caught here only tungsten, and the rest had to find luck on another field.

By 1925, are the first attempts to use niobium as an alloying element in the U.S. studies have been conducted on the replacement of tungsten contained in high speed steel. These experiments were unsuccessful, but it was different: niobium came in sight of the metallurgists.

In 1930 the total world supply of products from niobium (sheet, wire, and other) was just... 10 pounds . But soon came the recognition, and with it rose sharply and the production of this metal. Niobium was able to prove that he can rightfully be called the "vitamin" steel. Additive him to chromium steel has improved its plasticity, increased corrosion resistance. It was found that the introduction of stainless steel niobium (up 1%) prevents the precipitation of chromium carbides at the grain boundaries and, therefore, eliminates intergranular corrosion. Additive him to structural steel significantly improves impact resistance at low temperatures; steel acquires the ability to easily withstand variable load, which is of great importance, for example, in the aircraft industry.

An important role was destined to play the niobium in the welding business. Up until the weld was subjected to only normal steel, no hassles, this process is not represented. But when the welders had to deal with a special alloy steels complex chemical composition, for example from stainless steel, it was found that the weld loses many valuable properties possessed by the weld metal. How to improve the quality of the seam? Tried to change the construction of the welding apparatus has not helped. Changed the composition of the electrode - to no avail. Tried to welding in an atmosphere of inert gases - no effect. Then came to the aid of niobium. Steel, which was introduced this item, it was possible to weld without having to worry about the quality of the weld: it is in no way inferior to the next layer of metal is not subjected to welding.

Until recently, great difficulties arose when necessary to obtain a strong connection refractory metals such as niobium-molybdenum. Rescued... emptiness. It turned out that in a vacuum melting point of many substances is significantly lower than in normal conditions. Scientists were quick to take advantage of this circumstance to overcome the barrier of "incompatibility": welding of refractory metals in vacuum gave excellent results.

As alloying element niobium is widely known in nonferrous metallurgy. So, aluminum, easily soluble in alkali, does not react with them, if there was a 0.05% niobium. Copper and its alloys with the addition of this element to acquire hardness, titanium, molybdenum and zirconium are more durable and heat resistant. At low temperatures, many alloys and steel, fragile as glass. It was found that the niobium able to deliver them from this drawback. A small addition of niobium allows the metal to retain its strength even when vosmidesyatikratnoe frost. This quality is especially important for parts of a jet aircraft flying at high altitudes.

The niobium readily reacts with other elements. When one of the American companies produced a batch of supposedly ultra-pure niobium, customers were very surprised that it does not melt at 2500°C., although the melting point of pure niobium is slightly lower. Laboratory analysis has helped to establish that this "clean" niobium contained small amounts of zirconium. So sudden was opened swargarohini niobium-zirconium alloy.

A number of valuable qualities give the niobium and the addition of other metals. Tungsten and molybdenum increases the resistance of the metal niobium, aluminum makes it stronger, copper improves its conductivity. Pure niobium conducts electric current is ten times worse than copper. The alloy of niobium with 20% copper has high electrical conductivity and at the same time he is twice stronger and harder than pure copper. In Alliance with tantalum niobium able to withstand sulfuric and hydrochloric acids even at 100°C.

Niobium is an indispensable part of alloys for turbine blades of jet engines, where the metal to retain its strength at high temperatures. From NB alloys and pure niobium made some parts of supersonic airplanes, space rockets, satellites.

Worker niobiumMore recently, the phenomenon of superconductivity was only interested in physics. Now superconductivity already crossed the borders of laboratories and begins to invade technique, where its practical application window of opportunity. What is the essence of this phenomenon?

More than 70 years ago it was discovered that at very low temperatures in some metals, alloys and chemical compounds, the current begins to flow without any losses - resistance disappears. But the metal must be cooled almost to absolute zero, i.e. to -273°C. Very high (if only here this term), and thus relatively easily achievable transition temperature to the superconducting state (18K, or -265°C) is characterized by stunned niobium connection niobium and tin. Made out of superconducting magnetic coils create a huge magnetic field: a magnet the size of a little more than usual cans, in which the winding tape is of such compounds, can create a field of 100 thousand Oersted (for comparison, the magnetic field of the Earth is only a few Oersted).

For a long time stunned niobium was considered a record for the temperature threshold of superconductivity, but in 1974 he was forced to cede the title to another member of the family of niobium - his germanide, i.e. the connection with Germany. Now record the critical temperature, below which there is the effect of superconductivity, is approximately 23 To (or -250°C). In experiments conducted by American scientists, through a square centimeter of film from Germania niobium was able to pass current in a million amps. This means that for electricity of an average city's enough to be two small, pencil-thin, superconducting tubes.

Niobium is widely used in engineering and in pure form. Extremely high corrosion resistance of this metal led to its application in chemical engineering. Interestingly, in the manufacture of equipment and pipelines means of hydrochloric acid production niobium not only serves as a structural material, but also plays the role of catalyst, giving the opportunity to get a more concentrated acid. The catalytic ability of niobium is used in other processes, for example in the synthesis of alcohol from butadiene.

Very honorable and niobium in nuclear reactors, where he works side by side with Zirconia, sometimes quite successfully competing with him. Like zirconium, niobium has a neutron transparency (i.e. the ability to pass neutrons) and along with it a very high melting temperature, a significant resistance, strong chemical resistance and the excellent mechanical properties. In addition, niobium almost does not react with molten alkali metals. Liquid sodium and potassium, used as coolants in nuclear reactors of some types may be freely circulate through the niobium tubes without causing them any harm. For niobium is characterized by low artificial (induced) radioactivity, so it is possible to make containers for radioactive waste storage or installation.

We should mention another interesting property of this metal: it's a great getpagetitle. So, at ordinary temperature in 1 gram of niobium can be dissolved more than 100 cubic centimeters of hydrogen, even at 500°C the solubility of hydrogen in niobium is about 75 cubic centimeters per gram. This property of metal used in the manufacture of high-vacuum electron tubes. When pumping lamps in them is still a certain amount of gases that interfere with work. Niobium deposited on parts of lamps, like a sponge, absorbs these gases, thereby providing a very high vacuum. Details of vacuum tubes, made of niobium, more economical than tantalum or tungsten, and are much longer. Thus, the service life of a powerful generator of lamps with niobium cathode reaches 10 thousand hours.

As tantalum, niobium absolutely not irritating to the tissues of the human body, fused with him and remains inert even after prolonged exposure to a fluid environment of the body. Because of these properties niobium drew the attention of surgeons and now can rightfully consider themselves responsible medical officer.

Recently, rumor has it that niobium has decided to engage seriously... currency transactions. In fact, due to lack of silver American financiers assume for the manufacture of metal money be used instead of niobium, as the cost of niobium approximately corresponds to the value of silver.

If we trace in different literature sources for data about the content of niobium in the earth's crust, it appears that over the past few decades it constantly... increases. Of course, the actual reserves of this metal on the planet remain almost constant, while the number of elds it is increasing all the time. In recent years, significant new deposits of niobium ores found in Africa. The largest supplier of concentrates niobium on the world market is Nigeria, where there are huge accumulations of columbite.

In our country genuine pantry minerals is considered the Kola Peninsula. For centuries, the lands of this region was known as barren and useless, although in 1763, M. C. Lomonosov predicted: "In many proofs conclude that in the Northern depths lengthy and richly reigns nature and the shores of the White sea should not be scarce minerals. During the years of Soviet power there are plenty of important fields, found dozens of valuable minerals, including poparic containing up to 8% of niobium. Interestingly, this mineral, found a great researcher of the Kola Peninsula academician A.E. Fersman in the Khibiny mountains, nor in any other places of the globe is not found.

...So you met with the tenants No. 41 on the door which hangs a plaque with the inscription "Niobium".

 

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