Niobium (Nb) is a grey transition metal that is routinely used as an essential alloying element in high-volume mid-value steelmaking, alongside lower throughput superalloy production for extremely valuable high-technology applications. Among the many benefits of niobium is the fact that it only takes small amounts to dramatically alter the performance properties of an alloyed system. As little as 0.02 wt% can significantly enhance corrosion resistance and strength in steels. This makes niobium an increasingly vital component in a wide range of application areas.

Chemical Properties of Niobium

Atomic Number 41
Atomic Mass 92.906
Density 8.57 g/cm3
Melting Point 2477°C
Coefficient of Thermal Expansion 7.1 x 10-6 / K at 25°C

Niobium is useful as an alloying element for a number of reasons. Firstly, it belongs to the refractory metals group and is subsequently associated with extremely high thermodynamic stability. It shares several properties with other refractories like molybdenum; namely comparable atomic mass and similar melting points. Secondly, it readily forms strong carbides and nitrides within microalloyed steels which improves key properties like strength, toughness, and formability.

As a consequence of these extremely desirable qualities, the majority of globally-produced niobium is used for steels and superalloys. However, there are some applications where pure niobium excels.

Common Niobium Applications

Among the most common applications of niobium are high-strength low-alloy (HSLA) steels and superalloys. However, at H.C. Starck Solutions, we supply a range of specialist applications rather than the standard industries. These include:

Oxide Coatings

Niobium oxide coatings can significantly improve the electrochemical corrosion and wear resistance of glass. This is ideal for enhanced longevity of various components such as camera lenses and touch screens. Performance-enhancing niobium oxide films are deposited via sputtering using high-purity, low-defect niobium sputter targets.

Cathodic Protection Systems

Active steel surfaces (pipelines, underwater storage, etc.) often require protection from complex forms of electrochemical corrosion, such as pitting—where chlorides in seawater attack flaws in the material. Niobium coatings can be used to protect the base metal by acting as a sacrificial coating, corroding in lieu of the underlying steel.

Sodium Vapor Lamps

Gas-discharge lamps based on sodium vapour emit nearly monochrome yellow light by passing a current between two electrodes and ionizing neon and argon within the discharge tube, then finally vaporising metallic sodium. It is the sodium that shines this characteristic yellow. Low- and high-pressure sodium-vapour (LPS/HPS) have been used as the predominating technology for street lights for decades.  The tough sealing demands of HPS lamps often use niobium seals to combat the corrosive effects of sodium at high-pressure and temperature.

Superconductors

Niobium and niobium based alloys form the basis for a large number of superconductor wire applications.  These materials are processed from large diameter rod (e.g., approximately 25mm) to extremely fine wire filaments finer than 10 mm.  These wires are used in fusion energy, high energy physics, MRI, and other applications where high magnetic field strengths are required.

Interested in niobium?

Contact a member of the H.C. Starck Solutions team today if you would like to learn about the range of niobium alloys that we supply across a growing global marketplace.