Zirconium is a refractory metal, which occurs naturally in the Earth’s crust, exclusively in the form of ores and compounds. As a pure element, zirconium has an atomic number of 40, and appears on the Periodic Table of the Elements under the symbol Zr. Thanks to its incredible corrosion-resistance, high temperature tolerances and physical properties, zirconium is used in a huge variety of applications across various industries, including the nuclear power industry and aerospace engineering. One of the most important used for zirconium is in laboratory crucibles, where its unique properties make it ideal for acting as a chemical crucible for fusion reactions. But why would you choose a zirconium crucible?
What are the Advantages of a Zirconium Crucible?
A zirconium crucible has multiple advantages over other crucible types, like steel, platinum, porcelain, glass or nickel. While more expensive than glass, steel or nickel, the advantages offered by this zirconium crucibles make it much more cost-effective, and it is significantly less expensive than platinum and other noble metals, with other material advantages. These advantages include:
Zirconium Crucibles Have a Longer Life Expectancy Than Other Crucible Types
As mentioned above, a zirconium crucible is more expensive than a nickel, steel, porcelain or glass crucible, which may seem like a disadvantage – until you consider the number of fusion reactions which can be carried out in each crucible. Comparing zirconium to nickel, the zirconium crucibles have around 20 times the longevity of the nickel crucibles, recovering their higher cost many times over.
Compared to glass and porcelain, which are very brittle and easily destroyed, a zirconium crucible benefits from greater strength and durability, and is much less likely to break. While it may have a slightly shorter life expectancy than a platinum crucible, the vastly larger cost of platinum means that a zirconium crucible is much more cost-effective in the long run than any of the other crucible materials.
Zirconium Crucibles are Highly Resistant to Oxidation
When a zirconium crucible is heated, a creamy-coloured passivation layer will form, which is extremely resistant to oxidation, corrosion and attack by both acids and alkalis. This passivation layer means that zirconium is ideal for full-heat fusion reactions, and won’t decay under the heat or oxidise over time. It also won’t react with the chemicals in the crucible – bar one, described below.
Zirconium Crucibles are Extremely Resistant to Corrosion by Most Acids and Alkalis
Zirconium is almost completely resistant to corrosion by acids and alkalis, thanks in part to the protective passivation layer formed on a zirconium crucible – except for one. While it is resistant to corrosion by almost every other form of acid and alkali, zirconium is corroded by hydrofluoric acid, so zirconium crucibles are not ideal for use with this acid. However, hydrofluoric acid is relatively uncommon for a reagent, and the corrosion by it is more than compensated for by the resistance to other acids and alkalis.
Zirconium Crucibles are Completely Resistant to Solvents (Except Hydrofluoric Acid)
As mentioned above, a zirconium crucible is resistant to corrosion by the vast majority of acids and alkalis – but an additional advantage of this material in crucible construction is that the material is resistant to attack by almost all solvents – again, with the exception of hydrofluoric acid. This means that many reactions can be carried out using solvents which would be prohibitive in a steel, nickel or porcelain crucible, further boosting the cost-effectiveness of a zirconium crucible – a zirconium crucible has the versatility to deal with almost any chemicals and solvents, driving down the number of crucibles you need and cutting costs for your lab.
Zirconium Crucibles Don’t Have the High Costs and Security Problems Inherent to Platinum Crucibles
While more expensive than glass, porcelain, steel or nickel, zirconium is much less pricey than its primary competitor, platinum. Platinum is a precious metal, to the point that additional laboratory security measures may need to be taken to protect the valuable stock of platinum crucibles from theft. This pushes up the cost of the platinum crucibles well beyond the actual – considerable – unit price of the crucible itself.
However, zirconium crucibles don’t have the same problem, with a much lower unit cost and no need for additional security, as they won’t be targeted for theft.
Zirconium Crucibles Won’t Alloy with More Easily Reduced Metals
Thanks to the high temperatures that occur inside a laboratory crucible, it is possible for easily-reduced metals to be temporarily liberated from their compounds, at which point they may alloy with the crucible metal, if it is steel or nickel, contaminating and altering the reaction, usually rendering it useless and causing the crucible to be discarded.
However, thanks to its extremely resistant passivation layer and the underlying qualities of the zirconium used in a zirconium crucible, this won’t occur when a zirconium crucible holds the reaction, making these crucibles ideal for holding many reactions which are beyond the capabilities of other crucible types.
Zirconium Crucibles Virtually Eliminate Sample Contamination
With no reaction with the samples within, no corrosion and no reaction with solvents, zirconium crucibles virtually eliminate sample contamination, resulting in more precise reactions and purer results than would be possible with a more reactive crucible, like a steel or nickel vessel.
What is Zirconium?
Zirconium is a relatively uncommon element, occurring as a transition metal with the symbol Zr and the atomic number 40. Zirconium only occurs in the Earth’s crust in the form of compounds and ores, the most prominent of which is zircon, which gives the element its name. A soft, shiny, silvery metal which is malleable and ductile at room temperature, zirconium is resistant to corrosion by almost every acid and alkali, and has excellent heat resistance, making it ideal for use in a zirconium crucible.
At low temperatures, it super conducts, and zirconium/niobium superconductors are commonly seen in MRI scanners and other applications.
Where is Zirconium Found?
Most of the zircon ore which will later be reduced to zirconium is mined in Australia and South Africa, with these nations providing circa 60% of the world’s zirconium. Smaller deposits are mined in Brazil, India, Russia and the United States of America, as well as other nations. Zirconium is estimated to make up a component of the Earth’s core at a proportion of roughly 130mg/kg, and occurs only in ore form. It must be purified before it can be used to make crucibles.
What are Zirconium Crucibles Used For?
A zirconium crucible is used to hold reacting chemicals in a laboratory setting, and must therefore be able to resist high temperatures, a large range of acids and alkalis, oxidation, reduction, alloying with other metals and other chemical and physical stresses that may compromise the chemical reaction.
Zirconium fulfils all of these purposes, making it the ideal material for your crucibles.
If you’d like more information on the zirconium crucible range available from Special Metals UK, you can get in touch with the team at Special Metals by calling our telephone number, 01268 820409, or by using the Enquiry form on this page at any time! With decades of experience, the team at Special Metals UK will be happy to answer any questions you may have, or provide any advice you may need to help you choose the best possible crucible material for your business. Get in touch with us today!