Tantalum

Tantalum is gray, dense, ductile, very hard, easily fabricated, and highly conductive of heat and electricity. The metal is renowned for its resistance to corrosion by acids; in fact, at temperatures below 150 °C tantalum is almost completely immune to attack by the normally aggressive aqua regia.

It can only be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulfur trioxide. Tantalum's high melting point of 3290 K (boiling point 5731 K) is exceeded only by tungsten and rhenium.

The major use for tantalum, as the metal powder, is in the production of electronic components, mainly capacitors and some high-end audio grade resistors. Tantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum foil as one plate of the capacitor, the oxide as the dielectric, and an electrolytic solution as the other plate.

Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminum electrolytic capacitor), a high capacitance can be achieved in a small volume. Because of the size and weight advantages, tantalum capacitors are attractive for portable telephones, pagers, personal computers, and automotive electronics.

Tantalum is also used to produce a variety of alloys that have high melting points, are strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of super alloys for jet engine components, chemical process equipment, nuclear reactors, and missile parts. Because of its ductility, Ta can be drawn into fine wires or filaments, which are used for evaporating metals such as aluminum.

Due to it resists attack by body fluids and is nonirritating, tantalum is widely used in making surgical instruments and implants. The oxide is used to make special high refractive index glass for camera lenses. The metal is also used to make vacuum furnace parts.