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Refractory Metals

Refractory Metals

Date posted: May 25, 2016 // Refractory Metals

An Introduction to Refractory Metals and Their Uses in Industry

A total of 12 elements in the periodic table are classified as refractory metals, although this depends upon the precise definition used. One authority claims that the term should only be applied to those with a melting point greater than 1 900°C, which restricts the number that qualify and, for instance, excludes tungsten and chromium. By contrast, an alternative definition classifies them more broadly and includes any metallic element that has a melting point beyond the range displayed by the elements iron, cobalt and nickel.

Of the total number of elements identified under the latter definition, only a relatively small percentage has any significant industrial application. These are restricted to five, of which the refractory metals niobium molybdenum, tantalum and rhenium also conform to the narrower definition, while tungsten is the only one excluded. In practice, the number of current commercial uses for tantalum is relatively small. Apart from their very high melting points, greater than 2 000°C for the five named here, these elements are also notable for their extreme hardness at room temperature and resistance to corrosion, and these are further reasons for their usefulness.

One of the industries that make widespread use of these elements is the automotive industry. The drivers of modern cars are, quite literally, surrounded by various components that have been made from one or more of these tough refractory metals or that have at least been manufactured using tools that were made from them.  The drill used to extract the oil needed to manufacture petrol and diesel, as well as their subsequent processing, would have also relied on such materials. Molybdenum, for instance, has been used as an additive to enhance the lubricating properties of motor oils and extend engine life.

Other products in which these substances play a prominent role include lighting, where the elements tungsten, molybdenum and tantalum are used to create filaments and other components that are required to operate at high temperatures. Within the semi-conductor industry, the alloy known as TZM (Tantalum Zirconium Molybdenum) is also widely used. While surface coatings applied by physical vapour deposition (PVD) commonly employ ceramics and copper, they also use certain refractory metals, including niobium, chromium, tungsten, tantalum and molybdenum.

At LIT Africa, we specialise in the supply of a wide range of industrial and commercial materials and components, many of which are required to survive extreme conditions. In addition to architectural glass products resistant to heat, fire and ionising radiation, we also supply many of the specialised components used in welding, coating, high temperature furnaces, the manufacturing of semiconductors, engine technology, and in most applications for which parts made from refractory metals are important.