Zr - ZirconiumSee metal norms for Zirconium
|Chemical Element||Zirconium||Melting Point °C||1852|
|Chemical Symbol||Zr||Boiling Point °C||4377|
|Atomic Number||40||Density g/cm3||6.5|
Zirconium is a strong, durable metal. It is hard, lustrous and silvery in colour. Zirconium is a transition metal and is a member of Group 4 of the Periodic Table, the 18th most abundant element within the Earth’s crust. Zirconium reacts rapidly with oxygen within the air, forming a tough zirconium oxide layer on its surface protecting it from further reaction. This oxide layer makes zirconium very corrosion resistant. Zirconium does not dissolve in acids (except hydrofluoric acid) or alkalis. Powdered Zirconium is black, and it will burn in air if ignited, and zirconium dust is regarded as a dangerous fire hazard.
Zirconium was discovered in 1789 by German chemist, Martin Heinrech Klaproth, who at the time was analysing a zircon, which is a semi-precious gem. Zircon, along with hyacinth, jacinth and jargon, were known during biblical times and were thought to be inferior kinds of diamond. This was proven to be untrue with the discovery of zirconium. This was not Klaproth’s only discovery that year, as he also discovered uranium, both later to be linked to the nuclear power industry. Klaproth was unable to isolate the metal himself and, unfortunately, did not live to see this achievement. It was not until 1824 that the element was isolated, by the Swedish chemist Jons Jacob Berzelius.
In order to reach metallic form, zircon sand is reduced via a solvent process using magnesium and chlorine to create low hafnium zirconium sponge for the nuclear industry. Consequently, producing companies are few, grouped around the historic nuclear energy producing nations of France (Cezus-Areva), USA (Wah Chang) and Russia (Chepetsky Mechanical Works). China is a new addition to this club, but is not expected to produce consistent nuclear grade material before 2015. The quantity of zirconium available to the market in metal form is about 6,000 mt per year.
In the minor metals industry, the growth of non-nuclear applications has been the main driver. Metal produced via the Van Arkel method, which results in crystal bars of high grade zirconium, are required in small amounts for super alloys, while 4% zirconium content of Zr sponge is required in titanium alloy (6Al-2Sn-4Zr-2Mo) for aerospace parts. Zirconium is also used in some aluminium alloys for aerospace, as well as in the car industry for engine blocks, while an alloy of CuCrNiZr is used to replace BeCu in contacts. An alloy called Liquidmetal™ used in tennis rackets and other sports equipment is said to contain more than 60% zirconium.
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- Stwertka, Albert. A Guide to the Elements, 3rd Edition, Oxford University Press, 2012