Did you know that some refractory metals have a melting point of over 2000°C? These super tough metals play an essential part in almost every industry. But what exactly are they?
Refractory metals are defined as a group of metals that have a spectacularly high melting point, as well as a general resistance to damage from wear, corrosion, or deformation. They are widely used across a number of industries.
Here’s your guide to refractory metals.
Which Metals Are Refractory Metals?
In industry settings, the five metals commonly considered refractory are:
- Niobium (Nb)
- Rhenium (Re)
- Molybdenum (Mo)
- Tantalum (Ta)
- Tungsten (W)
Tungsten is widely considered to be the toughest of the refractory metals. There are some others that haven’t made it on to this main refractory metals list, like Cromium, and Osmium, these fall under broader definitions.
Because their melting point is so high, it’s common to see refractory metals processed as powders like Tantalum powder instead of being made by casting.
Properties of Refractory Metals
The main property of refractory metals is their impressive heat resistance. The main five metals can withstand heat well over 2,000°C (3623°F). They remain incredibly hard and strong at high temperatures.
They are also a number of other refractory metal properties.
Resistance to Thermal Shock
Thermal shock can damage metals that have been repeatedly heated and then cooled. One refractory metals benefit is that they are incredibly resistant to this.
Their high melting point stops them from cracking at high temperatures or high pressure.
Resistance to Creep
‘Creep’ is the term given to the deformation of metals. Most metals are affected by creep, but refractory metals remain a class apart in this aspect.
Refractory metals will retain their shape incredibly well when heated to super-high temperatures or exposed to high pressures.
Refractory metals are incredibly dense, meaning they are incredibly heavy.
This is why Tungsten is often used for electrical conductors because its density allows it to carry electrical currents incredibly well without sustaining very much damage.
Resistance to Corrosion
The elements that make up refractory metals form a protective layer that makes the metals resistant to corrosion. This sets them apart from most other metals.
The only drawback they have is that they react with oxygen, and so can oxidize at high temperatures.
Applications of Refractory Metals
Refractory metal applications are numerous. Each metal has properties that are best suited to particular applications.
- Tungsten – radiation shields, ignition systems for cars, lamp filaments, rocket nozzles, heating elements.
- Tantalum – cutting tools, surgical implants, heat exchangers, and furnace components.
- Molybdenum – nuclear control rods, superconductors, missiles, and grinding wheels.
These are only a selected handful of the many applications of these extraordinary metals and a glimpse into why refractory metal uses are so varied.
That’s your brief guide to refractory metals. Hopefully, now you know a little bit more about what they are and how they’re used.
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