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| Atomic Number: | 40 | Atomic Symbol: | Zr | | Atomic Weight: | 91.22 | Electron Configuration: | 2-8-18-10-2 | | Shells: | 2,8,18,10,2 | Filling Orbital: | 4d2 | | Melting Point: | 1852oC | Boiling Point: | 4377oC | | Uses: | Used in alloys such as zircalloy which is used in nuclear
applications as it does not readily absorb neutrons.
Also baddeleyite is used in
lab crucibles. Also used as
zircon gemstone. |
History(Persian zargun, gold like) The name zircon probably originated
from the Persion word zargun, which describes the color of the gemstone now
known as zircon, jargon, hyacinth, jacinth, or ligure.
SourcesThis mineral, or its variations, are mentioned in biblical
writings. The mineral was not known to contain a new element until Klaproth, in
1789, analyzed a jargon from from Ceylon and found a new earth, which Werner
named zircon (silex circonius), and Klaproth called Zirkonertz (zirconia). The
impure metal was first isolated by Berzelius in 1824 by heating a mixture of
potassium and potassium zirconium fluoride in a small decomposition processs
they developed. Zirconium is found in abundance in S-type stars, and has been
identified in the sun and meteorites. Analysis of lunar rock samples obtained
during the various Apollo missions to the moon show a surprisingly high
zirconium oxide content, compared with terrestrial rocks.
PropertiesNaturally occurring zirconium contains five isotopes. Fifteen
other isotopes are known to exist. Zircon, ZrSiO4, the principal ore, is pure
ZrO2 in crystalline form having a hafnium content of about 1%. Sirconium also
occurs in some 30 other recognized mineral species. Zirconium is produced
commercially by reduction of the chloride with magnesium (the Kroll Process),
and by other methods. It is a grayish-white lustrous metal. When finely divided,
the metal may ignite spontaneously in air, especially at elevated temperatures.
The solid metal is much more difficult to ignite. The inherent toxicity of
zirconium compounds is low. Hafnium is invariably found in zirconium ores, and
the separation is difficult. Commercial-grade zirconium contains from 1 to 3%
hafnium. Zirconium has a low absorption cross section for neutrons, and is
therfore used for nuclear energy applications, such as for cladding fuel
elements. Commercial nuclear power generation now takes more than 90% of
zirconium metal production. Reactors of the size now being made may use as much
as a half-million linear feet of zirconium alloy tubing. Reactor-grade zirconium
is essentially free of hafnium. Zircaloy(R) is an important alloy developed
specifically for nuclear applications. Zirconium is exceptionally resistant to
corrosion by many common acids and alkalis, by sea water, and by other agents.
UsesIt is used extensively by the chemical industry where corrosive
agents are employed. Zirconium is used as a getter in vacuum tubes, as an
alloying agent in steel, in surgical appliances, photoflash bulbs, explosive
primers, rayon spinnerets, lamp filaments, etc. It is used in poison ivy lotions
in the form of the carbonate as it combines with urushiol. With niobium,
zirconium is superconductive at low temperatures and is used to make
superconductive magnets, which offer hope of direct large-scale generation of
electric power. Alloyed with zinc, zirconium becomes magnetic at temperatures
below 35 K. Zirconium oxide (zircon) has a high index of refraction and is used
as a gem material. The impure oxide, zirconia, is used for laboratory crucibles
that will withstand heat shock, for linings of metallurgical furnaces, and by
the glass and ceramic industries as a refractory material. Its use as a
refractory material accounts for a large share of all zirconium consumed.
CostZirconium of about 99.6% purity is available at a cost of about
$150/kg
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