Tantalum is a rare, gray-blue metal found in approximately 15% of the world’s pegmatites. Tantalum has a number of properties that make it a valuable commodity today, including:
• High boiling point (5,425°C, 9,797°F)
• High melting point (2,997°C, 5,427°F)
• Resistance to corrosion
• Ductility, i.e. it alloys well
• Low thermal expansion
• High capacitance
Tantalum can be drawn, due to its ductility, into fine wire and small tubing. Tantalum is almost completely immune to chemical attack at temperatures below 150°C (300°F), and is attacked only by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide. Alkalis attack it only slowly. At high temperatures, tantalum becomes much more reactive. The element has a melting point exceeded only by tungsten and rhenium. Tantalum is used to make a variety of alloys with desirable properties such as high melting point, high strength, good ductility, etc.
Tantalum can be alloyed with carbon, nitrogen, niobium, tungsten, molybdenum, titanium and many other metals. Tantalum is used to make electrolytic capacitors and vacuum furnace parts, which account for about 60% of its use. The metal is also widely used to fabricate chemical process equipment, nuclear reactors, aircraft, and missile parts. Tantalum is completely immune to body liquids and is a nonirritating material. It has, therefore, found wide use in making surgical appliances.
Tantalum pentoxide (Ta2O5) is a dielectric material and is used to make capacitors. It is also used to make special glass with a high index of refraction for optical and camera lenses. Another major application is to manufacture lithium tantalate in SAW (Surface Acoustic Wave) devices. A composite consisting of tantalum carbide (TaC) and graphite, with a melting point of 3,738°C (6,760°F), is one of the hardest materials known and is used on the cutting edges of high-speed machine tools.