Tungsten - Refractory metalOne of a group of elements, collectively known as refractory metals, whether in the form of plates, powdered, or fashioned to form a rod, tungsten is perhaps best known as the metallic element with the highest melting point in this group. All the members of this group display the characteristic of an exceptionally high melting point, although to a lesser degree than tungsten. Commonly, the group is claimed to consist of five members, the others being listed as niobium, molybdenum, tantalum, and rhenium, all of which have melting points in excess of 2200 °C. However, some believe the entry point should be 2120 °C, which results in a broader definition and a group that now has an additional nine elements, among them chromium, zirconium, vanadium, and titanium.

Of considerable importance to modern materials science, tungsten rod, the powdered form of the metal, and various alloys are now being used in a growing range of applications. With its incredibly high melting point of around 3410 °C, it is, for example, the ideal choice of material from which to construct the containers and related equipment necessary for the smelting of other metals. Not surprisingly, this resistance to high temperatures means that the refractory metal itself is unsuitable for smelting, so sintering, with the addition of binders such as nickel or copper, is necessary when used for the manufacture of components. For such components, its exceptional strength and resistance to chemical and environmental corrosion are added benefits.

Among the more common applications for a tungsten rod is in a specialised welding technique known as TIG, or tungsten inert gas welding, as well as in the manufacture of high-temperature heating elements. The main virtue of the metal in welding is that it provides a virtually permanent electrode in suitably skilled hands. Though now being gradually phased out, in the form of a fine wire, the metal is still used to produce what was once the most effective and durable form of filament suitable for use in electric light globes of all shapes, sizes, and wattage. Anyone who has accidentally touched one after a few minutes of operation will be well aware of the sort of temperature that even a fine strand of this metal is able to withstand.

The high density of tungsten rod has prompted the military to investigate its use as a weapon. When the size of a telegraph pole and ejected from an orbiting platform, the resulting projectile could attain Mach 10 without burning up, and deliver an impact comparable to a nuclear explosion, far more cheaply, with no radioactive fallout, and without violating existing treaties banning orbital weaponry. Fortunately, the current cost of placing them in obit remains prohibitive, although the concept clearly illustrates the exceptional properties of this remarkable metal.

Tungsten rod is offered either in its pure form or alloyed with other metals such as thorium, which acts to improve ignition and provides a more stable arc when used in the high-power arc lighting for theatrical, military and similar purposes. These products, and various tools made from this and other refractory metals, are available in South Africa from LIT Africa.