Metals are generally considered to be very strong but not all metals are equal in strength, as some are much stronger than others when it comes to their Compressive, Impact, Tensile or Yield Strength. In this article, we look at Tungsten, the strongest natural occurring metal, its origin, uses and where it is found in abundance.
Tungsten (Wolfram) – Introduction
Tungsten also known as Wolfram, is a special metal known for its uniqueness and heat resistant qualities. It has a high melting point as well as the highest tensile strength of all the pure metals.
Tungsten requires a temperature of about 5700 °C to boil – this is the same amount of temperature on the sun’s surface. Also, with a density of 19.25 g/cm3, this metal is amongst the heaviest metals in existencewhere today. Its electrical conductivity at 0 °C is about 28% when compared to silver, which itself has the highest conductivity of all metals.
The discovery of tungsten dates as far back as the 17th century, when miners in the Erz Mountains of Saxony noticed that certain ores disturbed the reduction of cassiterite (a tin mineral) and induced slagging. According to an acient writing, ”They tear away the tin and devour it like a wolf devours a sheep”, prompting the miners to give this annoying ore German nicknames like “wolfert” and “wolfrahm” (which means wolf froth).
In 1758, however, a Swedish chemist and mineralogist by the name, Axel Fredrik Cronstedt, discovered and described an unusually heavy mineral that he called “tung-sten”(Swedish for heavy stone). Cronstedt was convinced that this mineral contained a new and yet-to-be discovered element.
Another Swede named, Carl Wilhelm Scheele in 1781, while working as a pharmacist and private tutor in Uppsala and Köping, succeeded in isolating the oxide (tungsten trioxide).
Also while working independently in 1783, two Spanish chemists, the brothers Elhuyar de Suvisa, were able to reduce the mineral wolframite to tungsten metal. 1816 saw Jöns Jacob Berzelius and much later, Friedrich Wöhler in 1824 while describing the oxides and bronzes of tungsten, gave the new metal the name “wolfram”. While this established itself in Germany and Scandinavia, the Anglo-Saxon countries like America and Britain still prefers Cronstedt’s “tungsten”.
However, the first attempt to produce tungsten steel were made in 1855, but due to the high cost of tungsten steel, industrial use was not possible.
The 19th century further saw the revolution of the industrial application of tungsten steel. This saw to the the alloying and hardening of steels, leading to rapid growth and widespread application followed the invention, and the launch of high speed steels by Bethlehem Steel, which place at the Paris World Exhibition.
A major breakthrough in tungsten application was also recorded in 1903, made by W. D. Coolidge. He successfully prepared a ductile tungsten wire by doping tungsten oxide before reduction. The resulting metal powder was pressed, sintered and forged to thin rods. Very thin wire was then drawn from these rods. This was the beginning of tungsten powder metallurgy, which was instrumental in the rapid development of the lamp industry.
Another milestone reached in tungsten application, was in 1923, which marks the invention of hardmetal (combining WC and Cobalt by liquid phase sintering) by K. Schröter and the corresponding application for a patent which was granted to Osram Studiengesellschaft in Berlin and licensed to Krupp in Essen in 1926.
Nowadays, hardmetal (cemented carbide) is the main application for tungsten, while Jön Jacob Berzelius’s symbol W prevails as its chemical symbol and stands at 74 in the periodic table of elements.
Uses And Applications
– Filaments for electric lamps
– electrical and electronic contacts, wire, rods and so on.
– Inert gas welding electrodes. – Metal evaporation work.
– As an alloy (steels) it is used for high-speed steel tools, weights and counterbalances, radiation shielding, cutting/grinding tools.
– Heavy metals.
– Electronic applications such as electric contacts points for automobile distributors, heat sinks, electrochemical machining and electrodes for electrical
-discharge machining (EDM).
– X-ray targets.
– Windings and heating elements for electric furnaces.
– Space missiles, rocket nozzles and high-temperature applications as a coating.
– As yarn it is used for reinforcement in metal, ceramic and plastic composites.
– Magnetrons for microwave ovens. – Television sets.
– Chemical catalysts.
– Metalworking, mining, cutting tools bits, heat- and erosion-resistant parts, coatings, seal rings and petroleum.
– Calcium and magnesium tungstates are widely used in fluorescent lighting.
– Other tungsten salts are used in tanning industries.
– Tungsten disulphide is used as a dry high temperature lubricant (stable to 500∞C).
– Tungsten bronzes and other compounds are used as pigments for paints.
– The military uses tungsten to make bullets and missiles used in “kinetic bombardment.” This type of attack uses a super dense material to breach armor instead of explosives.
Where It Is Found
According to an article published in 2014 by the British Broadcasting Corporation(BBC), titled, Tungsten, the perfect metal for bullet and missiles, the largest producer of tungsten in the world is China with 80% of this metal under their control. South Korea, Bolivia, Great Britain, Russia and the U.S. also have a significant amount of this resource, while Canada, Kazakhstan and many others are also host to this great metal.
China aside being the leading producer of tungsten, they are also the world’s leading consumer of the metal and they control the price too. China currently produces 60,000 of the world’s 72,000 tons per year.