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Sergey Venezky
STORIES ON METALS

ZIRCONIA

"CLOTHES ROD

Martin works makes a discovery. - What did you dream? - Without a job. - Constant companion. - Serious disagreements. - "Bathing" in alkalis. - Multifaceted activity. - Without the worries of overheating. - In search of a calling. - The fate of the "brothers". - No trespassing. - Reactor "Nautilus". - Merits and sins. - Problem after problem. - Wealth in the dumps. - On the ocean shore. - The oldest on Earth. - The tendency to "sprawl". - Side of the profession. - Nernst Lamp. - For all tastes. - What happens in Montlouis? - "The capital city of the sun". - Clear the misunderstanding.

In 1789 by the German chemist Martin Heinrich works by analyzing one of the varieties of the mineral zircon, discovered a new element, which he called zirconium. Due to the beautiful color - Golden, orange, pink - zircon in the era of Alexander the great was considered a precious stone. The name of the mineral comes, apparently, from the Persian word "zargun" Golden.

Zircon (in the literature there are other names of this mineral: hyacinth, jacinth, argon, jargon) used in the old days not only as decoration but also as an amulet, which is the "heart obvestila, and the sorrow and harmful thoughts drives away, mind and honor multiplies". One of the Russian doctors with professional awareness argued in his work on medicine that he who is the jewel scarlet with him is, terrible dreams and dashing will not see, will fasten his heart and honest people." (Ruby Russia called on many gemstones, including Ceylon hyacinth).

In free form zirconium was first isolated in 1824 Swedish chemist Jens Jakob Berzelius. However, to obtain pure zirconium in those days was not possible, and the physical properties of this metal for a long time have not been studied. For decades, zirconium, like many new metals, could not find something to do, while such well-known metals, such as iron, copper, lead, were able to show the good face and therefore does not suffer from a lack of offers.

Only at the beginning of our century, scientists were able to get free from impurities zirconium, and carefully examine the properties of this metal. It turned out that there is a constant companion - hafnium. More than 130 years chemists did not notice that the hafnium is present (and sometimes in fairly large quantities) in zirconium. This is explained by the striking similarity of their chemical properties. However, on some issues, these elements have serious disagreements, but this will be told a few below.

Pure Zirconia is outwardly similar to steel, but more durable metal having high ductility. One of the important properties of Zirconia - its exceptional resistance to many corrosive environments. For corrosion qualities zirconium exceeds such resistant metals, such as niobium and titanium. Stainless steel loses five percent hydrochloric acid at 60°C to about 2.6 millimeters per year, titanium is about 1 millimeter , and Zirconia - a thousand times less. Especially great is the resistance of the zirconium action of alkali; in this respect it is inferior even to the tantalum, which has rightfully earned a reputation as an outstanding fighter against chemical corrosion. Only the zirconium can afford long-term "bathing" in alkalis, ammonia, is highly corrosive environments, contraindications, without exception, all other metals.

Due to the high corrosion resistance of zirconium has found application in such a responsible medicine, as neurosurgery. From zirconium alloys produce hemostatic clamps, surgical instrument, and in some cases even thread for sutures in operations of the brain.

After scientists noticed that the addition of zirconium to become significantly improve many of its properties, zirconium was raised to the rank of valuable alloying element. The activity of the zirconium on the field is multi-faceted: it increases the hardness and strength of steel, improves its machinability, hardenability, weldability, positive effect on the fluidity of steel, grinds it contains sulfides, makes the structure of the metal fine-grained.

With the introduction of zirconium in structural steel significantly increases its scaling resistance: loss in weight of the steel containing 0.2 to 0.3% zirconium, after a three-hour exposure at 820°C in approximately six to seven times less than the same steel, but not stainless steel and zirconium.

Zirconium and significantly increases the corrosion resistance of the steels. So, after a three-month stay in the water structural steel loss in weight in terms of 1 square meter amounted to 16.3 grams, while the sample of the same steel, but with the addition of 0.2% zirconium, less only 7.6 grams.

Zirconium steel can be heated to high temperatures without fear of overheating. This allows to intensify the processes of forging, stamping, heat treatment, carburizing metal.

Dense fine-grained structure and high strength zirconium steel in combination with good fluidity enable to produce the castings with thinner walls than that of ordinary steel. For example, from steel with Zirconia were experienced cast thin-walled parts with a wall thickness of 2 mm; the wall thickness of these parts from the same steel, but not containing zirconium, was not less than 5 to 6 millimeters .

Zirconia has proven to be a good ally for many non-ferrous metals. The addition of this element to copper dramatically increases its strength and heat resistance, almost without reducing the conductivity. High strength and electrical conductivity has menatality alloy containing small amounts of zirconium. Introduction to aluminum alloys significantly increases their strength, ductility, corrosion resistance, heat resistance. Strength magneticone alloys with the addition of minor amounts of Zirconia increases approximately twice. Corrosion resistance of titanium alloy with zirconium in the five-percent hydrochloric acid at 100°C is ten times higher than that of commercially pure titanium. The addition of zirconium to the molybdenum improves the hardness of this metal. Zirconium is introduced into manganese brass, aluminum, Nickel, lead bronze.

And yet, no matter how important and honorable role of alloying element for steel and alloys, it could not satisfy the zirconium. He continued to search and found my true calling. But before I talk about it, back to its cradle in the chemical laboratory Martin Works.

In fact, in 1789 works discovered not only zirconium, but another great item, which was destined to play a prominent role in science and engineering XX century. This item was uranium.Metals-brothers - zirconium and uranium Neither the works nor anyone else could foresee what will be the fate of "brothers" - zirconium and uranium. Their paths diverged for a long time: within one and a half centuries there was nothing to link these elements. And only in these days after a long separation, they met again. At first knew only a very few scientists and engineers working in the field of nuclear energy, which, as we know, no trespassing. The meeting took place in nuclear reactors, where uranium is used as nuclear fuel, and zirconium was to serve as a wrapper for the uranium rods. However, for the sake of accuracy, we note that a few years ago, American scientists have tried to use Zirconia as a material for a nuclear reactor, which was installed on the first nuclear submarine of the U.S. "Nautilus". However, it soon became clear that zirconium is more profitable to do the stationary parts of the reactor core and the fuel cladding. Then the uranium and fell into the arms of zirconium.

The zirconium was not accidental: physicists knew that he, unlike many other metals, easily passes neutrons, and it is this property, called neutron transparency, must have material for buildings uranium rods. However, some metals are magnesium, aluminum, tin is in this respect similar to zirconium, but they are fusible and nikopachi. Zirconium, which melts only at 1850°C, heat load nuclear power completely on the shoulder.

However, the zirconium there are some sins that would prevent him from working in this important area. In fact, that is transparent to neutrons only Zirconia high purity. Here we have again to recall the hafnium metal, which according to their chemical properties can be called a twin zirconium. But the views on the neutron turned out to be the opposite: hafnium eagerly absorbs neutrons (hundreds of times stronger than Zirconia). Moreover, hafnium impurities even in homeopathic doses can damage the blood of zirconium and to deprive him of neutron transparency. Technical specifications for the so-called zirconium reactor purity admit the presence in it no more than a few hundredths of a percent hafnium. But such crumbs quite significantly - several times - reduce neutron transparency zirconium.

Because the nature of these metals usually are together to be completely free from hafnium zirconium is a task of enormous difficulty. Nevertheless, chemists and metallurgists had to tackle this problem, because the nuclear industry is in dire need of structural material.

When the problem was solved on the agenda stood another: to ensure that in the manufacture of structures made of pure zirconium in the process of welding it is not exposed to foreign atoms, which could be an insurmountable obstacle in the path of the neutrons and thus negate all the advantages of this metal. Moreover, the welding had to be done so as not to disturb the uniformity of metal: weld pool must have the same properties as welded material. Help was called an electron beam. The purity and accuracy of electron-beam welding has allowed to solve this problem - zirconium became the "clothing" of uranium rods.

But there was a sharp rise in the production of this metal: only a decade from 1949 to 1959 - world production of zirconium has increased a thousand times! In the course went large concentrations of zircon Sands, who previously served as waste in the extraction of other minerals. So, in California during the gold mining dredges in the beds of ancient rivers together with gold wash raised a significant amount of zircon, but due to the lack of demand was dropped into the dumps. In Oregon (USA) in the war was mined chromite, and along the way received a certain amount of zircon, which was not interested in then industry and because it is not exported from the place of production. When soon after the war began zirconium boom, all of these dumps were a tasty morsel.

Now large deposits of this valuable element develop in the United States, Australia, Brazil, India, West Africa; significant reserves of zirconium raw materials available and the Soviet Union. Excellent zirconium ore often serve as coastal Sands. In Australia, for example, zirconium placers extend nearly 150 miles along the ocean shore. And recently, in the Western part of this continent, near the town of Meekatharra, students of Geology, exploring the dry river flowed here once river, found in weathered sandy rocks zircon crystals, which were the most ancient on Earth. To this conclusion came Geophysics National University in Canberra, who determined that age was found zircon inclusions is calculated in 4.1-4.2 billion years: they are several hundred million years older than any other known mineral formations. In other words, found in Australia zircon was formed after only some 300 to 400 million years after the formation of our planet.

The need for zirconium is growing from year to year, since this material is gaining new specialty. His property is in a hot state greedily absorb gases used, for example, in electro-engineering, radio engineering.

Some metals, including zirconium, hydrogenation process, i.e. saturated with hydrogen, changing their crystal lattice and noticeable increase in volume is much greater than with conventional heating. On this property, "swelling" was founded invented by Soviet specialists, the original method of joining metal and other surfaces in cases where welding or brazing't help, for example when you want to make a double-layer pipe of various materials - fusible (aluminium, copper, plastics) and refractory (heat-resistant steel, tungsten, ceramic). What is the essence of the new way? If the cylinder from the prone to the "swelling" of the metal tightly to plant one on another two dissimilar pipes, and then subjecting the metal hydrogenation, "swelled", he firmly pripechatal these pipes to each other. So, for example, bushings, stainless steel and aluminum alloy, worn on the ring of zirconium, after hours in an atmosphere of hydrogen at 400°C "stuck together" is so firmly that they cannot be separated.

From a mixture of zirconium metal powder with flammable compounds produce flares, giving a large amount of light. Zirconium foil when burned gives one and a half times more light than aluminum. "Flash" with zirconium filling convenient because they take up very little space - they can be the size of a thimble. To zirconium alloys, all carefully eyeing the designers of rocket technology: it is quite possible that of heat-resistant alloys of this element will be executed with the front edge of spacecraft intended for regular flights in the universe.

Rain coats owe their resistance to salts of zirconium, which are part of a special emulsion for impregnation of fabrics. Salt of zirconium is also used for production of colored printing inks, special varnishes, plastics. As a catalyst zirconium compounds used in the production of high octane motor fuel. Sulfate compounds of this element are very good tanning properties.

A useful application found the zirconium tetrachloride. The conductivity of the plate of this substance varies depending on the pressure which it operates. This property has been used in the construction of universal gauge device for measuring pressure. At the slightest change in pressure changes the current in the circuit device, a scale calibrated in units of pressure. These gauges are very sensitive: they can be used to determine the pressure from statystyczny shares atmosphere to thousands of atmospheres.

For many radio devices - ultrasonic generators, stabilizers, frequency and others need a so-called piezoelectric crystals. In some cases they have to work at elevated temperatures. From this point of view, of great interest are the crystals of lead zirconate lead, which practically do not change their piezoelectric properties up to 300 °C.

Speaking of zirconium, not to mention its oxide is one of the most refractory substances of nature: its melting point is about 2900°C. the zirconium Oxide is widely used to obtain high strong refractory products, heat resistant enamel, refractory glass. Even more refractory material bored this metal. From it produce covers for thermocouples, which may be in the molten iron continuously for ten to fifteen hours, and in liquid steel two-three hours (quartz covers only withstand one or two dives no more than 20-25 seconds).

Zirconium oxide has the interesting property: strongly heated, it emits light is so intense, that can be used in illumination engineering. This property was noticed at the end of last century, the famous German physicist Walter Hermann Nernst. In constructed lamp (included in the history of technology as a Nernst lamp) rods bulbs were made of zirconium oxide. In laboratory experiments this substance is now sometimes used as a light source.

Obtaining zirconium using solar energyKind word recall zirconium oxide scientists Physical Institute. P.N. Lebedev physical Institute of the USSR Academy of Sciences (FIAN): based on oxides of zirconium and hafnium they managed to create an amazing crystals, which don't exist. Wholesale-rhinestone - name these handmade gems - not only quickly gained recognition jewelers, but has gained great popularity in the world of science and technology. It is enough to mention the fact that they successfully cope with the role of laser materials.

But French scientists use zirconium oxide as the starting material to obtain the metal with the help of solar energy. In the 50-ies in Montlouis - fortress, built in the XVII century in the Eastern Pyrenees at an altitude of 1500 meters above sea level, was built a solar oven, designed by a team of researchers led by Professor Felix Thrombus. Held in Montlouis Symposium on the use of solar energy to the participants demonstrated this oven in action.

"Slowly, almost imperceptibly, a special platform lifts a handful of white powder to the focus of a large parabolic mirror. Now the platform has reached the focus and before the eyes of scientists and engineers flashed blindingly bright white flame.

White powder is zirconium oxide... Placed in the focus of a parabolic mirror, where the temperature of the concentrated sunlight reaches 3000°C, the powder is melted. In this issue of the flash can only see through the dark glass. And a little bunch of hot substances, lying on the platform, looked like an erupting volcano some distant geological era.

Describes the process of obtaining the solar zirconium is one of the Symposium participants. Special reflector, consisting of many individual mirrors and reaching 12 meters in diameter, with photocell automatically turns towards the Sun. They reflected rays are discarded on a large parabolic mirror with a diameter of 10 meters . Heat capacity of this mirror, which concentrates the sun's rays in the mouth of an oven, equivalent to 75 kilowatts.

Ten kilometers from Montlouis, in the small mountain village of Odeio built another solar oven is the largest in the world. Those who come to the capital city of the sun" (as the locals proudly began to call Adao), meets an unusual landscape, similar to scenery for filming sci-Fi movie. Next to the old gabled Church stands the ultra-modern multi-storey building - Laboratory of solar energy. The entire North facade it is a huge parabolic mirror with a height of 40 and a width of 50 meters . On the opposite slope of the hill series hosted dozens of mirrors rather impressive size - heliostat. The sun's rays caught heliostats, first of all, head to the parabolic mirror, and then collected in a bundle, get into a melting furnace where a temperature of 3500°C. the Heat developed solar "Bunny" in the mouth of an oven, equivalent to 1000 kilowatts of electricity. The oven can produce up to 2.5 tons of zirconium per day.

The main advantage of solar ovens is that in the process of melting the metal does not get unnecessary impurities - they have nowhere to take. So get here metals and alloys are characterized by high purity and in constant demand. There is another powerful argument in favor of this method of melting: with the Sun not need to pay for the used energy generous shone freely gives it to the people.

In conclusion, let us dwell on the same misunderstanding. The crust contains more zirconium than, for example, copper, Nickel, lead or zinc. However, unlike these metals, zirconium called rare. Once this was due to a large dispersion of zirconium ores, the difficulty of extraction of zirconium, and the fact that in the technique of this metal was really "rare". Now, when the production of zirconium with steadily increasing every year and he finds new and emerging applications, the term "rare" for it has lost its meaning. But the past is the past, and to the question about the origin of the zirconium may proudly say "rare".

 

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