Tungsten, like all the elements having a
higher atomic number than iron (Z>26), cannot be formed by nuclear fusion
processes in stars, as is the case for those elements with a lower atomic
number, but originates only by neutron or proton absorption of already existing
bigger nuclei. These capture processes with extremely high fluxes of
neutrons and protons occur exclusively in massive stars (>8 times the solar
mass) during the end of their life cycle. Massive stars end in a supernova
explosion whereby certain amounts of their mass are distributed to the
surrounding space, including also the tungsten atoms formed.
The name Wolfram is closely related to
today’s important tungsten mineral wolframite. In the Middle Ages (16th century)
tin miners in the Saxony-Bohemian Erzgebirge in Germany reported about a mineral
which often accompanied tin ore (tinstone). From experience, it was known
that the presence of this mineral reduced the tin yield during smelting.
Foam appeared on the surface of the tin melt and a heavy deposit formed in the
smelting stove, which retained the valuable tin. "It tears away the
tin and devours it like a wolf devours a sheep", a contemporary wrote in
the symbolic language of those times. The miners gave this annoying ore
German nicknames like "wolffram", "wolform",
"wolfrumb" and "wolffshar" (because of its black colour and
hairy appearance). Georgius Agricola was the first to report about
this new fossil (Spuma Lupi) in his book “De Natura Fossilium”, published
in 1546.
The name Tungsten came from the other
important tungsten ore, which is now called scheelite. In 1750, this
heavy mineral was discovered in the Bispberg´s iron mine in the Swedish
province Dalecarlia. The first person who mentioned the mineral was Axel
Frederik Cronstedt in 1757, who called it Tungsten {composed of the two Swedish
words tung (heavy) and sten (stone)} due to its density close to 6.
In 1781, the outstanding Swedish chemist
Carl Wilhelm Scheele published the results of his experiments on the mineral
tungsten in Kongl. Vetenskaps- Academiens Nya Handlingar, with the title:
“The Constituents of Tungsten”. In this work he demonstrated that the
mineral contains lime and a still unknown acid, which he called tungstic
acid. Torbern Bergman, professor in Uppsala,
suggested preparing the corresponding metal by charcoal reduction of the
obtained acid.
In 1781/1782, the Spanish nobleman, Juan
José de D´Elhuyar studied metallurgical chemistry with Prof Bergman and
gathered information about the work on the mineral tungsten. Back to Spain in 1783,
Juan José analyzed a wolfram species from a tin mine in Zinnwald/Saxony, and
showed it to be an iron and manganese salt of a new acid. He also
concluded that wolfram contained the same acid as Scheele had gained from
tungsten. He then reduced the oxide to the new metal by heating it with
charcoal, as had been recommended by his teacher Bergman.
His discovery, jointly with his
brother Fausto Jermin, was published in 1783 by the Royal Society of
Friends of the Country in the City of Victoria (“Analysis quimico del volfram,
y examen de un Nuevo metal, que entra en su composition por D Juan Joséf y Don
Fausto de Luyart de la Real Sociedad Bascongada”). The new metal was
named VOLFRAM after the mineral used for analysis.
Thereafter, an increasing number of
scientists explored the new chemical element and its compounds. However,
the price for the metal was still very high and the time was not yet ripe for
promising applications.
In 1847, a patent was granted to the
engineer Robert Oxland. This included the preparation of sodium
tungstate, formation of tungstic acid, and the reduction to the metallic form
by oil, tar or charcoal. The work constituted an important step in modern
tungsten chemistry, and opened the way to industrialisation.
First, tungsten-containing steels were
patented in 1858, leading to the first self-hardening steels in 1868.
High speed steels with tungsten additions up to 20% were first
exhibited at the World Exhibition in Paris
in 1900, and revolutionized engineering practice in the early 20th century.
Such steels (Taylor- and White) are still used today in practically every
machine shop of the world.
The first tungsten light bulbs were
patented in 1904, and rapidly replaced the less efficient carbon filament lamps
on the lighting market. Since then, tungsten filaments have illuminated
the world and have revolutionized artificial lighting in general.
To produce drawing dies with diamond-like
hardness but improved toughness was the driving force for the development of
cemented carbides in the 1920s. At this time, no one, even the most optimistic,
could imagine the enormous breakthrough for this material in the tooling
industry. After WW2, a huge market opened in the growing economies and
cemented carbides contributed as tool materials and construction parts for
their industrial development.
In
1944, K C Li, President of Wah Chang Corporation in the US, published a
picture in the Engineering & Mining Journal entitled: “40 Years Growth of
the Tungsten Tree (1904 – 1944)” illustrating the fast development of the
various tungsten applications in the field of metallurgy and chemistry.
To compare the evolution of a technology
with the growth of a tree was a unique idea which has since been
developed and expanded from 1850. This 150 years’ time span reveals a
fascinating picture of scientific and technological evolution.
The tree has grown to reach today a
peculiar form, which is dominated by an increasingly thick bole (cemented
carbides) with two main branches (steel and mill products). The chemicals
branch seems somehow atrophied but still has a large number of small
leaves. Due to the unique properties of tungsten, it can be assumed that
in future a steady further growth will occur, given the appropriate market
opportunities.
For the full story on the History of
Wolfram and Tungsten, click to read the article in Newsletters June and December 2005. Further information is given in
the Tungsten Brochure (2009).The Trewhiddle Tungsten Bloom
The ITIA does not often receive calls from
TV producers but there was excitement over the discovery of a lump of metal
found in the West of England, after an article was published in “Materials
World” in February 2004.
There was speculation that this lump was
tungsten metal, pre-dating its presumed discovery in 1783, and a further twist
to the story suggests the involvement of that scientist, man of letters,
bankrupt and thief, Rudolph Erich Raspe (1737-1794), the author of “The Travels
of Baron Munchausen”.
没有评论:
发表评论