Tantalum is one of the rarest elements on earth in both pure and alloy forms. At the same time, it is needed in a wide variety of applications. First discovered in 1802, it was originally thought to be a niobium allotrope which is chemically similar to tantalum. However tantalum was determined to be an element of its own, one of the most corrosion-resistant metals available, with a rarity similar to that of uranium.
Chemical Properties of Tantalum
|Atomic Mass||180.94788 u|
|Melting Point||3,017 °C|
|Co-efficient of Thermal Expansion||10-6/K|
With its grey finish, tantalum is similar in color to platinum. It has a density of 16.6 g/cm3; double that of steel. It is highly ductile at room temperature and has the fourth highest melting point of all known metals at 3017°C (5463°F).
Tantalum is used in a wide range of alloys to increase strength, ductility, and melting point. Tantalum can be used in a range of forms suited to different industrial applications such as powder which can be used in electrical capacitors and sheet to line columns and vessels in chemical applications, and as vacuum furnace parts. When it is drawn into a thin wire, tantalum is used as a filament for metals which evaporate such as aluminum. In addition to these forms, tantalum can also be used as rods/wires, tubes, strips, foils, and oxides.
Tantalum has excellent corrosion resistance to most acids (a notable exception is hydrofluoric) in a wide range of concentrations and temperatures. Its corrosion resistance is similar to glass in many of these acids. Consequently, it is used in chemical processing equipment where hot, highly corrosive environments are encountered. Heat exchangers, bayonet heaters, tank liners, valve liners, feed lances, rupture disks, and various other components are fabricated from tantalum.
The semiconductor market is built on the foundation of silicon chip manufacturing technology. Integrated circuits (ICs) are produced with nanoscale feature sizes and the optimization of electron conduction between nanometer-scale features is critical. Tantalum can be used in logic chips and DRAMS to facilitate the use of copper as interconnects as, unlike copper, tantalum atoms do not diffuse into silicon at the temperatures these chips operate at.
High-purity tantalum and tantalum nitrides are grown on top of the copper chips to stop electromigration of the copper atoms, meaning the semiconductor devices remain reliable for longer. At H.C. Starck Solutions, we supply sputter target blanks which are often used to generate barrier layers in modern ICs.
Tantalum is extremely biocompatible and does not produce toxic products or trigger adverse immunological responses when exposed to body or bodily fluids. This means that tantalum works well for medical applications that require pairing with living tissue such as medical implants and prosthetics.
Military and Aerospace
Nickel based superalloys are used extensively in gas turbine engines for commercial and military aircraft where they are exposed to extremely high temperatures and stresses. Tantalum additions to these superalloys help improve high temperature strength. Parts and components made from these tantalum containing superalloys can operate at higher internal combustion temperatures resulting in enhanced thrust efficiencies and lower fuel consumption.
Refractory furnace trays and boats are routinely used to hold semi-finished goods during extremely high temperature processes like sintering. Tantalum is an exceptional material for furnace applications, retaining good dimensional stability at process temperatures with excellent resistance to creep deformation ensuring long service.
Superconducting wires intended for use in nuclear applications often incorporate tantalum diffusion barriers designed to resist internal diffusion and impart enhanced mechanical properties to the superconducting element. This is useful for large-scale scientific initiatives such as nuclear fusion research.
Tantalum has exceptional storage capacities with the ability to store more charge per gram than any other comparable metals. For this reason, tantalum is well-suited to the production of electrical capacitors and resistors whilst being able to hold large amounts of charge in a small component. This has meant manufacturers have been able to make electrical parts and devices much smaller.