Cobalt

Cobalt is not found naturally occurring in its pure state, however compounds of cobalt are common.  Cobalt is typically produced as a by-product from copper and nickel mining.  It is also present in meteorites.

Cobalt is located between iron and nickel in the periodic table and shares many of the same physical and chemical properties. Cobalt is a relatively hard, brittle, transition metal.  It is ductile but only moderately malleable.  Cobalt is one of only three naturally occurring magnetic metals.  The other two being iron and nickel.  When Cobalt is alloyed with iron, nickel and other metals, it forms Alnico, a material with exceptional magnetic strength.

The main use of cobalt is in the cobalt based super alloys.  The high temperature stability of this range of cobalt alloys makes them suitable for use in turbine blades and jet air craft engines.  Other cobalt-based alloys exhibit good corrosion and wear resistance and are used for prosthetic parts such as hip and knee replacements.

Cobalt is also used in magnetic steels, stainless steels, and when cobalt is alloyed with chromium and tungsten, it produces a material suitable for use in high-speed, heavy duty, high temperature cutting tools.  Due to cobalt’s resistance to oxidation and it hardness, it is also used in electroplating.

A radioactive isotope, cobalt-60, is a source of gamma radiation and consequently is used as a radiotherapeutic agent in the treatment of cancer. Cobalt salts have been used over several centuries for the production of the brilliant blue colour often found in porcelain, pottery and paints.

Further properties of Cobalt have been outlined below:

• Cobalt Melting point 1768 °C
• Cobalt Density 8900  kgm^-3
• Cobalt Young’s modulus 209 GPa
• Cobalt Poisson’s ratio 0.31
• Cobalt Electrical Resistivity 6 x 10^-8 Wm
• Cobalt Thermal Conductivity 100 W m^-1 K^-1