Spotlight on Tantalum: Wire, Foil, Sheet and More for Research

Tantalum combines a very high melting point with good ductility in its annealed state. It melts at 3,017 °C and can be drawn into fine wire and rolled into foil as thin as 0.008 mm. Its strong resistance to corrosion and ability to retain useful mechanical properties at high temperatures make it useful in research involving aggressive chemicals, high temperatures and vacuum conditions. 

This overview looks at the properties that make tantalum useful, its research applications, and the forms and purities supplied by Advent Research Materials.

What makes tantalum different

Tantalum has atomic number 73 and a density of 16.69 g/cm³. Its most useful property is its high resistance to corrosion. When exposed to oxygen, tantalum forms a thin, protective oxide layer on its surface. This passive layer helps protect the metal from further chemical attack and contributes to tantalum's resistance to many corrosive environments, including those encountered in some medical applications. Its resistance is not universal, however, and conditions such as hydrofluoric acid and strongly alkaline environments can attack tantalum.

Tantalum also has a very high melting point of 3,017 °C. At elevated temperatures, however, it can absorb gases including oxygen, nitrogen and hydrogen, which can affect its mechanical properties and cause embrittlement. High-temperature tantalum work is therefore commonly carried out under vacuum or in a controlled inert atmosphere rather than in air.

Where tantalum is used in research

• Biomedical research. Porous tantalum is used in some implant applications because its interconnected structure can support bone ingrowth and its surface is well tolerated by the body. Tantalum coatings are also studied for modifying the surfaces of titanium and other implant materials.
• Capacitors and anodic oxide research. Tantalum is used in capacitors because anodising can form a thin Ta₂O₅ dielectric layer on the metal surface. Tantalum wire and other forms are therefore useful in research into anodic oxide formation, dielectric behaviour and breakdown.
• Corrosion-resistant equipment. Tantalum's resistance to many corrosive chemicals makes it useful for laboratory components and materials research involving aggressive chemical environments. Tantalum sheet and foil can also be formed into components where corrosion resistance is important.
• High-temperature and vacuum work. Tantalum's high melting point and useful strength at elevated temperatures make it suitable for components such as heat shields, heating elements and sample supports used under controlled atmospheres or in vacuum systems.
• Semiconductor and thin-film research. Tantalum and tantalum nitride are used in thin-film research and semiconductor processing, including work on diffusion-barrier and conductive layers. Tantalum films can be deposited using techniques such as sputtering.

Choosing the right form

Advent supplies tantalum in seven forms. The most suitable form depends on the dimensions, shape and mechanical properties required for the application.

• Foil: from 0.008 mm to 0.20 mm thick. Thinner gauges are supplied as rolled, while gauges from 0.050 mm are annealed.
• Ribbon: 0.025 mm thick, as rolled, at 99.95% purity.
• Sheet: from 0.25 mm to 2.0 mm thick, annealed.
• Wire: from 0.05 mm to 2 mm diameter. Most sizes are annealed, with a 0.125 mm hard-temper option also available.
• Insulated wire: 0.125 mm bare tantalum wire with quadruple PTFE insulation, for applications where the tantalum conductor needs electrical insulation.
• Rod: 4 mm, 6 mm, 10 mm and 20 mm diameter, supplied unannealed.
• Woven mesh or gauze: 50 mesh per inch, made from 0.075 mm wire with a 0.43 mm aperture.

Annealed tantalum is softer and more ductile, making it easier to form. Hard-temper and as-rolled material has greater hardness and strength, which can be useful where the material needs to retain its shape or withstand tension.

Choosing the right purity

Advent's tantalum products are available in several purity levels, depending on the form and size. Standard tantalum is supplied at 99.9% purity, while selected products are available at higher purities.

The catalogue includes 99.95% tantalum for the ribbon and 2 mm wire, 99.96+% for one 0.4 mm wire size, and 99.996+% for one 1 mm wire size. The woven mesh or gauze is supplied at 99.85%.

For research where material composition is an important part of the experimental specification, check the purity and form of the individual product before ordering. The appropriate grade will depend on the requirements of the experiment, including any limits on metallic impurities.

Frequently asked questions

Why is tantalum so corrosion resistant?

Tantalum forms a thin protective oxide layer on its surface when exposed to oxygen. This passive layer helps prevent further corrosion in many chemical environments, although tantalum can be attacked under specific conditions, including exposure to hydrofluoric acid and strongly alkaline solutions.

Can tantalum be heated in air?

Tantalum can be exposed to air at lower temperatures, but at elevated temperatures it can absorb oxygen and nitrogen. This can change its mechanical properties and cause embrittlement. Vacuum or a controlled inert atmosphere is therefore normally preferred for high-temperature tantalum work.

Which tantalum form is suitable for microelectrodes?

Fine tantalum wire can be suitable for some microelectrode applications because it is available in small diameters and can be formed into fine structures. The required diameter, insulation, geometry and surface condition will depend on the application.

Can I order other tantalum sizes or purities?

Some tantalum sizes and specifications may be available to order specially. Contact Advent Research Materials with your required form, dimensions and purity to discuss your requirements.