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Sergey Venezky
STORIES ON METALS

ZINC

"VEIL" FOR STEEL

The Mystery Of Masako. - Idol of Dacia. - Evidence Of Marco Polo. - Fake silver or Indian tin? - Like a Phoenix. - The laurels awarded to the Champion. - The sun in the fog. - Long before the birth. - Silver patterns. - Allies become competitors. - A unique collection. - A negative role. - Stroll along the Neva river. - Three events in the last century. - A century of waiting. - The sacrifice of themselves. - Starting the fever. - The gun is charged. - Powder "philosopher's wool". - It's not El Greco! - Glass Agatha. - Raduga TV. - Why fight the rats? - Talking about Pansy? - Wealth needs to be protected. - From the bottom of the red sea. - News from space.

In the early 50-ies English archaeologist James Mellaart excavated in the Anatolian plateau in Turkey. Findings were little, and the scientist decided to stop seeking. Leaving AB the early 60-ies in the foothills of the North Caucasus was carried out archaeological excavations of the ancient settlement of Masako. A long time ago, about two and a half millennia BC, lived in these places tribes of nomadic pastoralists who used copper and bronze tools. Among the many found here small metal crafts, special interest was strongly oxidized greenish-brown small object in the form of tubes, apparently, having at one time adorned the neck of one of the local fashionistas. What attracted this modest decoration modern historians and archaeologists?

Spectral analysis showed that the material from which was made the tube, is clearly dominated by zinc. Is this metal was known here almost five thousand years ago?

From zinc ores person familiar with ancient times: in ancient times, more than three thousand years ago, many people were able to smelt brass - an alloy of copper with zinc. But in its pure form zinc long was given into the hands of chemists and metallurgists: extract the metal from its oxide proved to be difficult. To break the ties that bind zinc with oxygen, needed high temperature significantly above the temperature of its boiling point, so the vapors of zinc, meeting with oxygen in the air, turned back in the oxide.

To break this vicious circle for a long time could not. Yet the ancient masters of India and China around the fifth century B.C. learned condensing vapors of zinc without air in earthen vessels, and obtain in this way the bars bluish-white metal. After a few centuries the art of smelting zinc captured and some European countries. So, in Transylvania, on the territory of today's Romania, where in the beginning of our era was the Roman province of Dacia, was found by a metal idol cast from an alloy rich in zinc (over 85%). But later the secret to obtain the metal was lost. Until the second half of the seventeenth century zinc were brought to Europe from the East and was considered a great rarity.

That's why finding Masako was so surprised and caught the attention of archaeologists. Had to repeat the analysis, but the lines of the spectrum reaffirmed that the test object consists of zinc with only a small admixture of copper. Perhaps, zinc hack has a later origin and happened to be among the really ancient articles? But this version has almost disappeared after having been specified conditions findings: zinc decoration was found at the depth corresponding to the III Millennium BC, where could hardly get a more "young" objects. It is possible that the decoration of Masako is the most ancient of all known zinc products.

What name is given to zinc, is not yet opened it!the middle Ages have left us a lot of mention of zinc. Description melting this metal can be found in Chinese and Indian sources VII - VIII centuries. The famous Venetian traveler Marco Polo, who visited at the end of the XIII century Persia, told in his book about how he got zinc Persian masters. However, zinc metal began to be called only in the XVI century, after the term appeared in the writings of Paracelsus - known scholar of the Renaissance. What names did not know the metal before: fake silver, Spelter, Turkey, spouter, Indian tin, concerta. Entrenched behind him the Latin name "zinc" is translated as "white bloom" (according to one version it was derived from the old Germanic word "zinc", meaning, in particular "thorn in the eye").

In 1721, a German chemist and Metallurgist Johann Friedrich Henkel (he studied the young M.V. Lomonosov in the period of stay in Freiberg) managed to separate the zinc from the mineral Galea. Henkel "burned" Galma, and the "ash" received a shiny metallic zinc, which he in his writings likened Phoenix risen from the ashes.

The first European zinc smelter was built in the English city of Bristol in 1743 - four years after John champion took the patent for distillation is a method of obtaining zinc from oxidized ores. In principle Bristol technology is not much different from that enjoyed by the ancient nameless metallurgists, but because they were deprived of the opportunity to patent their way, Laura, inventor of the industrial production process of zinc went to the Champion. After about two decades champion, who continued steadfastly "training" in the field of smelting zinc, managed to develop another process in which raw materials were serving not oxidized and sulphide ores.

If Bristol factory issued annually 200 tonnes of zinc, in our days, the world melting this metal is measured in millions of tons. The scale of production, it ranks third among non-ferrous metals, second only to recognized giants of non - ferrous metals, aluminium and copper. However, zinc has one distinct advantage over most industrial metals - low cost due to ease of access (its cheaper on the world market only iron and lead). Along with the old distillation process, zinc plants widely used electrolytic method in which zinc is deposited on the aluminum cathodes, and then re-melted in induction furnaces.

Interestingly, the famous English inventor Henry Bessemer, best known for the creation of a steelmaking Converter, in 1868, has designed a solar oven, which was able to melt the zinc and copper. The furnace, however, was technically imperfect, besides the natural conditions of Albion is clearly not favored its practical application.

His career zinc, as mentioned, began long before the birth: the metallurgy of the ancient world, throwing into the fire with coal and copper gray stones containing zinc compounds, got brass is an excellent alloy with high strength and ductility, corrosion resistance and beautiful color, more colors, depending on the zinc content and other components. Unlike normal red copper, brass, Russia called yellow copper: with the increasing content of zinc alloy color varies from reddish to light yellow. Brass with a small addition of aluminum has a nice Golden color and is used nowadays for making decorations and artwork. Aristotle wrote about copper, which differs from gold only taste". Obviously, the "Golden copper" - not that other, as brass.

For a long time it was believed that the monument to Minin and Pozharsky, built in the beginning of the last century on the red square in Moscow, made of bronze. But recent restoration work has made adjustments to this question: as it turned out, the material for the wonderful creations of the sculptor I.P. Martos was not bronze, and brass.

In India there is the village of Bidart, famous for its decorative products, which local craftsmen made of an alloy of copper, zinc and tin. Castings - jugs, plates, figurines - coated with a special solution, after which the metal is completely black. Then the artists put on different patterns or designs, resembling an inlaid silver. These patterns will never fade, which explains the popularity of products from the Bidart not only in India but also abroad.

Typically, the zinc and copper are alloys as allies, complementing and enriching each other. But recently they were in the position of competing firms, and zinc in the literal sense supplanted copper alloy. It happened in the United States, where until recently the penny is the smallest coin is minted from an alloy containing 95% copper and 5% zinc. A few years ago decided to change the composition of the alloy. It will include the same components but in a different ratio of 97.6% zinc and 2.4% copper. This "permutation" is due to the fact that zinc is much cheaper than copper, and therefore the innovation proposal financiers promises the Treasury of great benefit.

There are a lot of zinc alloys (with minor additions of aluminum, copper, magnesium), characterized by good casting properties and low melting point. One of them cast a complex thin-walled parts and other precise products, including miniature typographic characters. In the middle of the last century under the project of the Russian sculptor I.P. Vitali were cast and installed in the St George hall of the Grand Kremlin Palace in Moscow eighteen zinc columns with decorative ornaments and statues, crowned with Laurel wreaths.

A unique collection zinc die casting offers one of the residents of the GDR. Now a quarter of a century he pours himself from zinc small, no more than 5 inches tall, figures of people and animals. The collection includes about a thousand interesting compositions. Perhaps the most impressive of them is dedicated occurred in 1813, near Leipzig battle where Napoleon's army, has not recovered even after the battle of Borodino, suffered a major defeat by the armies of Russia, Prussia, Austria and Sweden. The song "Battle of Nations" consists of about one thousand items - figures of soldiers and horses, guns, wagons.

Hobby German collector largely contributes to the relatively low melting point of zinc is about 420°C. Many of the properties of the metal depends on its purity. As a rule, it is easily soluble in acids, but if you bring purity to "five nines" (99.99 percent), the same acid can no longer cope with him even when overheated. Purity is used for zinc will not only chemical invulnerability, but also high plasticity: this metal is easily drawn into fine threads. But the usual technical zinc shows a rather capricious nature: he agrees to skate in the ribbon, sheets and plates only in a certain temperature range from 100 to 150°C. at normal temperatures and above 250°C up to the melting point of this metal is very fragile - it can easily be crushed.

In modern chemical current sources zinc plates play a negative role - provide the electrode with a minus sign, where the oxidation of the metal. For the first time zinc tried their hand in this field in the year 1800, when the Italian scientist Alessandro Volta created a galvanic element ("volt column"). Two years later, with the enormous galvanic battery, composed of 4200 copper and zinc circles, Russian physicist V. Petrov first got an electric arc.

In 1838, a Russian electrical engineer BS Jacobi has designed a ship - boat with an electric motor, fed by current from a galvanic battery. For some time the boat sailed up and down the Neva river, carrying up to fourteen passengers. However, this engine was very inefficient, which gave the German chemist Justus Libicu ground to say: "it is Much more profitable right to burn coal for heat or care, than to spend the coal mining of zinc, and then burning it in the batteries to get a job in the motor". Not found then attempts to use electric traction batteries on land. The famous English physicist James Prescott Joule if one day, whether in jest or seriously noticed that it is cheaper to feed the horse, than to change the zinc in the electric battery.

Nowadays, this idea has found a second wind: on the roads of many countries already scurrying thousands of electric vehicles and their designers when choosing a driving force tend to give preference to zinc-air batteries, which replace dozens of horses, allowing them to pass without "feeding", i.e. without charging, over hundreds of kilometers. Tiny power sources of this type are used in hearing AIDS, time indicators, exposure meters, calculators. In conventional flat battery flashlight under the paper jacket has three zinc cylinder: "burning down" (i.e. oxidized), zinc creates a current that kindles the light of the flashlight. For a more solid device reliable power sources capable of simultaneously powering tens devices are batteries with electrodes made of silver and zinc. This battery worked, for example, on Board of one of the Soviet satellites.

Recent energy crisis has forced the search for energy sources many large scientific and industrial organization. But from professional inventors do not lag behind and fans. So, a watchmaker from the English town of Kidderminster decided to use for this purpose... the usual lemon. Inserted zinc and copper plates with the findings, the inventor got the original electric battery. In the reaction of citric acid with copper and zinc were current, which in a few months ate a tiny motor, which resulted in movement of an advertising sign in the window of the watch shop. What is not an invention? But here's the problem: according to experts, to provide current, for example, only one TV, you need a battery of several million lemons.

Lemons for electrodes

More powerful vegetable source current proposed American biochemist, Nobel laureate Melvin Calvin. He has developed a solar battery in which the current creates a joint effort of the zinc oxide and the chlorophyll of plants. From the surface of the green electroplastic the size of a small room, you can collect "harvest" the current capacity of 1 kilowatt.

Apparently, in the near future, maybe at the end of our century, we will witness new developments of solar-power plant, but now let us return again in the past century to meet three important events of direct relevance to zinc.

The first of them occurred in 1850: Frenchman Gilles proposed an original method of making printing clichés. On a zinc plate with acid-resistant paint manually put the picture and then the surface of the metal protravlivanie nitric acid. While the painted areas remained unharmed, and in places where there was no paint, acid "ate" the zinc, forming a recess. The image was embossed and printed on paper appeared in the picture. In further sellotape (so at first called this way) was considerably improved and turned into zincography, with which printing machines all over the world daily reproduce the myriad of drawings and photographs in books, Newspapers, magazines.

In 1887, the famous German scientist Heinrich Rudolf Hertz discovered the phenomenon of the photoelectric effect - the emission of a substance of electrons under the action of light. A year later the photoelectric effect has been thoroughly studied by the Russian physicist A. G. Stoletov, which was conducted in the laboratory of Moscow University of fine experience, which entered the history of science. To the negative pole of a galvanic battery he joined a zinc plate, and the positive metal net, placing it in front of the plate at some of her distance. Naturally, this open circuit current is not passed and arrow galvanometer standing still on zero up until the scientist is not sent on a zinc plate bright beam of light - arrow immediately to budge. This meant that the chain went current. Stoletov has further strengthened the lighting plate and the arrow moved on, indicating that the increase in current. As soon as the light was turned off, the current in the circuit has disappeared and arrow again came to a standstill at zero. This device essentially was the first photocell device, which is essential to modern technique.

In the same year, when Stoletov made his historical experience, the zinc plate was "aiding" interesting inventions: German engineer Berliner, who worked in the United States, has created a device for sound playback - gramophone, proposing to use as spokanites zinc disc, covered with a thin layer of wax. With the disk you can remove the metal copy of the matrix for mass production of phonograph records. The world's first LP, manufactured by Berliner, preserved in the National Museum in Washington. In 1907 in Paris CDs with recordings of Enrico Caruso, Francesco Tamagno, Adelina Patti and other prominent singers were solemnly placed in galvanized hermetic enclosures for long-term storage. To open the cases envisaged in 100 years, i.e. in 2007.

Modern technology is used not only cast zinc, but zinc dust. So, the fireworks it helps to paint the flame blue. Metallurgists use it for extraction from cyanide solutions of gold and silver. Even when receiving the zinc can not do without this dust with a solution of zinc sulfate purified from copper and cadmium in the hydrometallurgical (electrolytic) production method. Metal bridges, construction of industrial buildings, large machines and mechanisms often paint gray paint protects the metal from corrosion; the paint structure also includes zinc dust.

As long as we have mentioned corrosion, it's time to talk about the most important "role" zinc: almost half of the world production of this metal is for the protection of steel from worst enemy - rust, devouring every year tens of millions of tons of iron. Galvanized buckets and troughs, the roofs and gutters serve for many years while on an ordinary sheet steel first rain can draw red stains.

Why is zinc entrusted with a difficult and honorable service for the protection of steel "boundaries?" He is not known as a staunch fighter against chemical aggressors, as, for example, chromium, Nickel or cobalt? It turns out that in this lies the answer to the question. Like a woman, in the words of one of the wise men, strong in their weakness, zinc protects the iron from corrosion, because he... powerless to resist it. Zinc is characterized by a higher chemical activity than iron, and when threatened oxidation it immediately exposes itself under attack: sacrificing himself, rescues from death iron. Not accidentally, this method of protection is sometimes referred to as "sacrificial".

Zinc protects the iron from corrosion, sacrificing himself

Even when zinc armour appears scratch, corrosion cannot do their rusty case: while on the surface of steel products there is a grain zinc, iron will not be destroyed. In this sense, Nickel or chrome plating, with high corrosion resistance, in practice sometimes are not so reliable: they perfectly serve only until the first injury, but the slightest, literally point, the gap arising on them, opens aggressive components access to iron, and it starts to rust "eyes" of Nickel or chromium, using its chemical integrity.

Given that zinc is besides considerably cheaper than other defenders of steel from corrosion, it will become clear why zinc coating steadily occupy the first place in the scale and importance among all of the metal coatings.

Recently, the zinc coating has expanded the scope of protection activities: they started to be applied on the surface of metallic structures with high thermal loads. So, before the construction of launch facilities for launching space rockets due to overheating, over time, lost their strength. To avoid this, the metal is now covered with a layer of zinc. Due to its low boiling point, it is during the starting "fever" quickly evaporates, absorbing a large amount of heat and thereby protecting the metal from overheating.

Galvanizing technology is quite simple. Most often for this purpose, steel sheets, pipes or parts are immersed directly in the molten zinc. But try to submerge in the melt, for example, the mast transmission line will have a "bath" in size with a huge swimming pool. In such cases, used by spraying using a variety of devices. Developed a special gun, rechargeable, metal wire and firing a jet of liquid metal, which, after drying, cover the surface of the metal uniform protective layer. And that cover was brilliant, apply electrolytic galvanizing method.

The multifaceted activity of the zinc and its compounds. In the middle ages Arab and Western European doctors have used for medicinal purposes '"white snow" - fluffy powder zinc oxide, which the alchemists called the "philosopher's wool". Ointment, baby powder, eye drops, containing in one form or another this item you can find today in any pharmacy. A rare woman does not use zinc oxide, may be unaware of this: but the powder is not that other, as the smallest powder zinc compounds with the addition of aromatic, coloring and other substances. With a very strong increase in the grains of powder remind hairy spider with splayed in all directions paws.

About two centuries ago in France and England appeared zinc white, which, unlike used long lead, were harmless to the human body and so quickly came into use. Soon new paint steel manufacturing and in other countries. So, in 1807, one of the journals published in Russia, has placed the article On the preparation of oxide of zinc oxide, which can replace a conventional white". Zinc can serve as strong evidence against artists who profit from counterfeit works under famous masters of the past. If experts examine the picture, allegedly belonging to brush Bruegel the Elder, Rubens, or El Greco, and the analysis of the colors indicates the presence of zinc oxide, there is no doubt: before you clear fake.

Without zinc oxide is not cost companies producing rubber and linoleum. Long familiar with the zinc and glass: in 1851 at the world exhibition in London, great interest was aroused by the novelty of the glass industry - zinc crystal possessing a special smoothness and Shine. Nowadays artists and glassmakers have adopted the zinc sulfide, allowing you to paint decorative glass rich palette of colors and shades, turn it into a Jasper or marble, agate or lapis lazuli.

In 20-ies of our century crystal of zinc oxide made a successful debut in radio communications: managed to install then record the range of reception of radio signals. Has been working for compounds of this element and in television technology: the three primary colors on the TV screen blue, green and red occur due to the fluorescent properties of sulfide, selenide and zinc phosphate activated by silver, manganese or other additives. Artificial crystal zinc selenide play a responsible role in building the future of laser TV: screen color laser TV will reach several square meters - bright colorful image will cover the entire wall in the apartment of the future. Zinc compounds possess semiconductor properties, which also promises great prospects.

Zinc is necessary for growthzinc needs not only technology - in small doses, it is necessary alive and vegetable organisms. The daily need for this essential trace element ranges from 5 to 20 milligrams. Especially great is the demand for it people experience, often looking in the glass: alcohol how would displaces zinc from the body. Surveys of people with dwarfism, held in Iran and Egypt, showed that stunting is caused, in particular, the low content of zinc in the consumption of food. But rats-females, from the diet which he was completely excluded, soon became evil draconian. Acquired trait was then transferred to the offspring, and the most successful in this respect "the weaker sex".

Some invertebrate marine animals zinc performs the same function as the iron in human blood: in the ashes of molluscs was sometimes up to 12 zinc. In appreciable quantities is contained in the venom of snakes, especially vipers and cobras. Scientists suggest that this element protects the snake from its own poison.

The important role played by zinc in the plant world. Wheat, for example, may die, if it does not end up in the soil. Pretty much zinc in grapes, oranges, pears, are tomatoes, onions, salad, rich in them mushrooms - boletus, chanterelles, boletus.

Long ago it was noticed that many plants prefer to settle near those or other mineral deposits. So, wild violet and field Pansy tend to lands containing zinc. About this attraction knew ancient professionals, use it to find hidden in the depths of minerals and modern geologists.

The most common mineral of zinc are sphalerite, which is also called zinc blende. For what sins have received the stone is insulting nickname? Apparently, this is due to the fact that the admixture of the various elements of mineral paint in various colors - easy to get confused and take sphalerite for something else. The Altai mountains are often catches the so-called "burundanga ore, representing a mixture of zinc blende and brown spar. These striped stones really like forest animal.

As a rule, in the nature of the zinc is in the form of polymetallic ores containing lead, copper, iron, many rare metals. One of the European deposits of zinc and lead was the cause of the education of the whole state. It happened in the last century, when, after the defeat of the Napoleonic Empire part part of her land had to move away to the winner countries. In the section "land property" between the Netherlands and Prussia, a dispute arose due to the County Marina, located on the border of these States. Finally, in 1816, a compromise solution was adopted: part of the County became part of the Netherlands, part - part of Prussia, and the portion on which was located rich in zinc and lead mines (because of them and broke fuss), was declared neutral. So there was a tiny Republic of Morena, occupies just 3.3 square kilometers and consisted of only a few hundred inhabitants. But the sovereignty of the country and its mineral resources need to be protected. To protect the Republic army was created in... one soldier - he acted for a soldier, and commander-in-chief. (Unlikely in the presence of someone dared to say that one man is no man.) By the mid 80-ies of the last century, the reserves of zinc and lead ores have been non-existent, but the state of Marine lasted until 1920, and then became part of Belgium.

Recently, the specialists ' attention was attracted by the unusual nature of wealth: in the hollows of the red sea, at a depth of about two kilometers, discovered deposits of semi-ores of zinc, copper, silver. Did the project create a special vessel, on Board of which the bottom is lowered pipe through it for the ore in the form of pulp will come from the depths of the sea on Board the vessel. Here she will become rich in zinc ore concentrate.

So, zinc ore mined not only on land but also underwater, but the properties of this metal and its alloys are studied not only on earth but also in space: among the experiments, prepared the Bulgarian scientists-scientists to conduct aboard the Soviet space station Salyut was growing crystals of zinc and obtaining its alloy with iron. What will please us the cosmic zinc?

 

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