Tungsten

Notable characteristics

Pure tungsten is a hard metal of color active of the gray steel to the white tin. One can cut it using a hacksaw when it is very pure, but it is breakable and difficult to work when it is impure, and one normally works it by forging, extrusion, or stretching. This element has highest Point melting (3422°C) of all metals, weakest Steam pressure and largest force of traction of all metals to an higher temperature with 1650°C. Its resistance to the Corrosion is excellent and it can be only slightly attacked by the mineral acid. Metal tungsten forms a layer of protective oxide when it is exposed to the air. When one adds it in small quantity to steel alloys, it increases the hardness of this one.

Applications

Tungsten is metal used in large number of uses, of which most important is the tungsten carbide (W₂C, WC), which is used for the manufacture of the wearing parts in the metallurgy, mining and oil industry. Tungsten is largely used in the filaments of the electric bulbs and of the television stations, like like electrode, because one can make of them very fine filaments having a very high melting point.

Others utilizations :

Its point melting very high makes it particularly adequate for the space applications and those which ask for the use of very high temperatures.
the hardness and the density of this metal make it ideal to make metal alloys used in the armament, the wells of heat, like like weight and counterweight. It was used, for example, by the Israeli army in the Gaza Strip to the autumn 2006
the parts wearing used, for example in the tools at high-speed, often use steel and tungsten alloy which can go until 18 % of tungsten.
Of composed of tungsten is used as catalyst, pigment inorganic. The tungsten disulfide is used like stable Lubrifiant above 500°C.
the sodium tugstate (CASE: ) belonged to the reagent of Folin Denis
Since his coefficient of Dilatation is equivalent to that of glass borosilicate, it is used to make joinings glass on metal.
Of the superalloys containing of tungsten is used to make blades of turbine, steel tools, as well as platings.
It is used as refractory electrode in the Soudage TIG.
the arcing contacts of circuit breakers with high voltage also partially consist of tungsten in order to tolerate the high temperature of an electric arc.
DIME (Dense Inert Metal Explosive), new very powerful armament to destroy a human target while causing damage in a very limited ray of a few meters.

History

The first to have supposed the existence of tungsten (of the Swedish tung sten meaning “heavy stone”) is Peter Woulfe, in 1779, whereas it examined Wolframite.

It determined whereas this mineral was to contain another substance. In 1781, Carl Wilhelm Scheele establishes that a new acid could be formed starting from tungstenite. Scheele and Berman suggested that it was to be possible to obtain a new metal by reducing this acid. The brothers Jose and Fausto Elhuyar discovered, in 1783, a new acid derived from wolframite identical to the tungstic acid. In Spain, a little later the same year, the two brothers succeeded in isolating tungsten by reducing the acid with coal. The discovery of the element was allotted to them.

Occurrence

One finds tungsten in the Wolframite which is a manganese and iron tungstate, FeW O ₄/MnWO₄), Scheelite (tungstate of Calcium, CaWO₄), Ferbérite and Hübnérite. One finds important deposits of these minerals in Bolivia, California, China, Colorado E. - U., Portugal, Russia, and the South Korea. China produces 75% of the world provisioning. Metal is produced commercially by reduction of tungsten oxide by Hydrogène or Carbone.

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