Using Niobium and Tantalum in Superconducting Products

H.C. Starck Solutions offers tantalum and niobium rod and sheet for low temperature superconductor (LTS) wire manufacturing processes, where cryogenic cooling is required to keep the material below it's critical temperature (Tc).

The company also provides extrusion services for extruding large-diameter wire bundles for final redrawing by customers. Tantalum (Ta) and niobium (Nb) materials exhibit special properties, which make them a suitable option for the following superconducting applications:

  • Particle accelerators
  • MRI and NMR medical equipment
  • Magnetic levitation
  • Nuclear fusion research equipment
  • Mass spectroscopy

H.C. Starck Solutions' tantalum and niobium sheet and rod have been used in large-scale scientific projects to develop fusion reactors for clean energy production, and large particle accelerator experiments. Superconductors are critical to these types of experiments, which involve suspending and controlling high-energy plasmas.

Unique Properties for Manufacturing Superconductor Products

During the production of superconducting wire, care is taken to ensure that both the rods and sheets have rigorously controlled chemical composition, mechanical properties, and surface roughness. This is important to enable easy processing and help achieve a superconductor wire of high quality.

The sheets are often used as a diffusion barrier between tin and copper, and the rods are primarily used for producing Nb3Sn superconducting wires. These wires are used in high magnetic field applications.

Tantalum is mainly used in superconductors to create a reliable and stable diffusion barrier between the tin and copper matrix. This diffusion barrier begins as a sheet of tantalum whose width is reduced to just a fraction of its original width during the course of the drawing process.

Care must be taken to ensure that the tantalum layer is not damaged, and there must not be any direct contact between the tin and copper. This is the reason why the original surface quality, thickness uniformity, mechanical properties, and microstructure hold a major significance. If these properties are not controlled properly, it would lead to poor magnetic properties, reduced yields, and several other unwanted effects.

Niobium properties are as important as the properties of tantalum, but for slightly different reasons. This is where H.C. Starck Solutions stands out. The company has developed processes that facilitate stringent control of all key properties and parameters. H.C. Starck Solutions continues to make advancements with optimization of mechanical or microstructural properties at its sophisticated R&D facilities.

H.C. Starck Solutions supplies quality niobium and tantalum sheet and rod for high performance superconducting wires. Figure 1 shows the EBSD map and pole figure of niobium rods in cross-section.

EBSD map and pole figure of niobium rods in cross- section

Figure 1. EBSD map and pole figure of niobium rods in cross- section

Specifications of niobium and tantalum rods are as follows:

  • Microstructural control
  • Conforms to ASTM B392 (Nb) and B365 (Ta)
  • Consistent mechanical properties and chemistry
  • Maximum length: 2.5 to 7.5m
  • Diameters: 10 to 100mm

Specifications of niobium and tantalum sheets are as follows:

  • Consistent chemistry
  • Excellent surface quality
  • Mechanical properties tuned to customer requirements
  • Conforms to ASTM B393 (Nb) and B708 (Ta)
  • Sheet: 0.25 o 2.5mm thick, up to 1m wide
  • Other dimensions can be availed on request

Billet Extrusion

H.C. Starck Solutions provides billet extrusion services for LTS wires (Figure 2). The 5,500mt press is integrated with advanced controls for optimum reductions and precise dimensional control. The high tonnage leads to excellent wire properties and enhanced superconducting wire yields.

H.C. Starck provides billet extrusion services for LTS wires

Figure 2. Billet extrusion

Billet extrusion is performed under the following conditions:

  • Extrusion temperature: Wide range, controlled atmosphere
  • Press Force: 5,500 tons
  • Input billet diameter: 152 to 432mm (6 to 17”) diameters

Conclusion

Tantalum and niobium are low-temperature superconducting materials that will continue to be utilized in large and powerful particle accelerator programs. The high-quality niobium and tantalum sheet and rod supplied by H.C. Starck Solutions is perfect for manufacturing superconductor products.

H.C. Starck Fabricated Products

This information has been sourced, reviewed and adapted from materials provided by H.C. Starck Solutions.

For more information on this source, please visit H.C. Starck Solutions.

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