When people say “Zirconium”, they are often erroneously talking about the brilliant, diamond-like gems more accurately known as cubic zirconia – but a less well-known, much more important material is pure zirconium – an elemental transition metal and a vital material for much of industry and engineering. At Special Metals UK, we provide a range of zirconium products ranging from zirconium bars and zirconium sheets, to zirconium rods, zirconium crucibles and zirconium plate.
The zirconium available from Special Metals UK is made to a high standard or purity and reliability, so you can always rely on us to meet your requirements.
What is Zirconium?
Zirconium, discovered in 1789, is a pure element represented on the Periodic Table of Elements by the symbol Zr and the atomic number 40. As a pure chemical element, Zirconium cannot be made by combining other elements as it is one of the primary chemical building blocks of reality. In some rare cases, zirconium is produced as the result of nuclear fission, but this is an extremely unreliable way to obtain the element!
Zirconium must be purified from ores and compounds mined from the Earth’s crust, the most common of which is zircon, from which the element receives its name. These ores must be reduced, and, in many cases, the small amounts of hafnium which occur alongside the zirconium must be completely removed, leaving pure elemental zirconium. This process is expensive and difficult, but it is very worth it – elemental zirconium is an extremely versatile, valuable material.
A transition metal, zirconium is malleable and soft at room temperature and pressure when in its pure form – but if impure, it becomes brittle and hard.
What are the Characteristics of Zirconium?
Zirconium is a lustrous, silver coloured transition metal, and a solid at room temperature. Under normal conditions, it is malleable and ductile, able to be worked by conventional metalworking techniques to create a variety of components.
Zirconium is has an extremely high melting point, remaining solid up until 1,855°C – a much higher melting point than other metals. In fact, a zirconium vessel could hold completely liquid steel without melting, making this transition metal very useful in high-heat applications, such as crucibles and refractories.
Zirconium is also extremely resistant to corrosion, with a powerful resistance to attack by any common acid or alkali – with the notable exception of hydrofluoric acid. This attribute is thanks to a nanometre-thin passivation layer which forms on the surface of the zirconium anywhere that it comes into contact with oxygen. This protective, inert layer of zirconium oxide acts as a protective coating, nonreactive when exposed to acids and alkalis, and effectively endowing zirconium with incredible corrosion resistance.
Zirconium can be alloyed with other metals to improve the corrosion resistance and melting point of these metals, and this is commonly seen in the superalloys used in jet turbines and rocketry. Alternatively, zirconium can be used to create compounds which display impressive mechanical and chemical properties.
What is Zirconium Used For?
Zirconium is used for a range of applications. In alloy form, it is used in superalloys and the construction of missile components, and in space vehicles which require high resistance to heat. In powder form, it is commonly a constituent of explosives and primers for explosives, and its immense heat resistance makes it ideal for use in furnaces, smelters and other extremely high-heat applications.
One of the most famous and crucial of these high-temperature applications is in the nuclear power industry, where zirconium cladding is used to shield fuel rods. The very low neutron-capture cross section ability of zirconium means that the high-energy neutrons which propagate the nuclear chain reaction are unable to penetrate the cladding, and therefore that the reaction can be controlled and the fuel introduced when it is appropriate to do so, avoiding the reaction becoming too powerful at any one time.
Another important use for elemental zirconium is in zirconium crucibles – thanks to their very high melting point and resistance to corrosion by most common acids, alkalis and solvents, a zirconium crucible is the ideal crucible in which to carry out chemical reactions and combinations, with no contamination and a significantly better shelf life than the competition materials.
Where is Zirconium Found?
Zirconium is found in the Earth’s crust – and, interestingly, in minerals on the Moon – in the form of ores and compounds which must be mined and purified. By weight, zirconium makes up 130mg/kg of the Earth’s crust, so while it isn’t the most abundant Element on Earth (that accolade goes to oxygen) it is still economically important.
Zirconium is always mined in ore form, and the most common ore is Zircon. Zircon is predominantly mined in South Africa and Australia, with around 60% of the world’s total zirconium production occurring there.
The remaining 40% takes place in Brazil, India, Russia and the United States of America, with small, less economically significant amounts being mined and processed in other nations, like China, Indonesia and Mozambique.
Who Discovered Zirconium?
The minerals which contain zirconium, including zircon, jargoon, hyacinth and ligure, among others, were known in prehistory and are mentioned in biblical writings, but these minerals were not known to contain a new element until 1789, when the chemist Martin Heinrich Klaproth inspected a Sri Lankan jargoon and discovered a new metal which he named “zirkonerde”.
However, it was many more years before Jons Jakob Berzelius was able to isolate the metal in an impure form, marking the world’s first glimpse of elemental zirconium metal.
What “Zirconium” Means
Unlike many elements, “Zirconium” didn’t get its name from Latin or Greek, it wasn’t named after its discoverer, and its name doesn’t describe its properties. Instead, the word zirconium comes from zircon, the most common and most well-known ore containing the metal. Zircon takes its name from the ancient Persian word zargun, which means “gold-coloured”. So the modern day element is actually named after the ancient word for its ore!
Why is Zirconium Used in Fuel Rods in Nuclear Power?
A question we often see at Special Metals UK is the question of why zirconium is so commonly used in the nuclear power industry. Zirconium – once all the hafnium has been successfully removed from it – is used as cladding for nuclear fuels, protecting it from the reaction until it is needed. This is largely due to two attributes of zirconium, which make it especially useful in nuclear reactors.
Low Neutron Capture Cross-Section
The most important attribute of zirconium for its use in nuclear fuel cladding is its very low neutron capture cross-section ability, which means that the high-energy neutrons which drive the nuclear chain reaction cannot penetrate the cladding to cause a fission reaction in the clad fuel.
This stops the chain reaction growing out of control, and ensures that the nuclear reactor works only at the rate which its operators decide.
It is vitally important to remove all the hafnium from the material before it is used in nuclear fuel cladding. This is often a complex procedure, as hafnium is a very closely related element with many similar properties to zirconium, bar one: it has a very high neutron capture cross-section, making it extremely ineffective as a shield against the high-energy neutrons found in a nuclear reaction. Once it is all removed, all that is left is zirconium, a much, much more effective cladding material.
Very High Melting Point
The other key feature of zirconium that makes it work for nuclear cladding is its high melting point – as high as 1,855°C – which means that it can hold up to the conditions within the reactor, at temperatures where even steel would run like water.
Can Zirconium Combine with Other Elements?
Despite appearing to be nonreactive, thanks to its passivation layer, zirconium will combine readily with other elements in the right conditions – the fact that it is only ever found in compounds in the Earth’s crust should attest to that! Zirconium is commonly made into compounds including zirconia and other ceramics, as well as being combined with various elements to create explosive primers and other industrial components.
At high temperatures, zirconium will also react with water – bear this in mind when choosing a high-temperature-capable material from Special Metals UK!
Get in Touch with Special Metals UK for Zirconium Today!
If you are interested in the zirconium available from Special Metals UK, or you would like more information on this remarkable metal and its applications, you can get in touch with us at any time on our telephone number, 01268 820409, or use the contact form on this page to send us a message!
The experts at the Special Metals head office will be happy to help you find the metal solution to suit your needs, no matter what they are!
We look forward to speaking to you!