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Metal- TUNGSTEN

Tungsten is known as one of the toughest things found in nature. It is super dense and almost impossible to melt. Pure tungsten is a silver-white metal and when made into a fine powder can be combustible and can spontaneously ignite. Natural tungsten contains five stable isotopes and 21 other unstable isotopes.

It is used in many different ways because it is very strong and durable. It is very resistant to corrosion and has the highest melting point and highest tensile strength of any element. Its strength comes when it is made into compounds, though. Pure tungsten is very soft.
The first use of tungsten was more than 350 years ago. Chinese porcelain makers used a tungsten pigment that was a unique peach color. Most tungsten resources are found in China, South Korea, Bolivia, Great Britain, Russia and Portugal, as well as in California and Colorado. Though it is found in these many places, 80 per cent of the world’s supply is controlled by China.

The element naturally occurs in the minerals scheelite, wolframite, huebnertie and ferberite. It is harvested from the minerals by reducing tungsten oxide with hydrogen or carbon. Once it is sourced, tungsten is often mixed into alloys. The hardest alloys are shaped using diamonds. Diamonds are the only things harder than some tungsten alloys.

Applications:
Tungsten wire can also be used to make direct heating cathodes and grids of electronic oscillating tubes and indirect heating cathode heaters in various electronic instruments. The properties of tungsten make it suitable for TIG welding and other electrode materials.
Tungsten disulfide is used as a lubricant and catalyst in the preparation of synthetic gasoline, bronze-coloured tungsten oxide is used in painting, and calcium or magnesium tungsten is commonly used in phosphors.
Tungsten-containing steels include tungsten steel and tungsten-cobalt magnetic steel with high magnetization and coercive force. These steels are mainly used to manufacture various tools, such as drills, and milling cutters.

Tungsten's thermal expansion is similar to borosilicate glass, thus it is used to make glass-to-metal seals. Tungsten is also used in jewellery as a gold or platinum substitute because its density is similar to gold.
Because tungsten oxides have two unique properties—intercalation and polycondensation—there is a great opportunity for tungsten to be used in a fuel cell or energy-saving technologies in the future.



Credits: Sabitha

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