A solution and solid state study of niobium complexes University of ...

Chapter 2
Ferroniobium acts as a grain refiner to increase tensile strength at additions as low
as 0.02 wt %. Normal usage is 0.03 – 0.1 wt %. 7
Addition of niobium to zirconium increases the mechanical strength and corrosion
resistance of the metal. The main reason for the addition of niobium to zirconium is
for use in the cladding of nuclear fuel rods. This is due to the low thermal-neutron
cross section of both metals (Nb, 1.15 barn; Zr, 0.184 barn). The fuel rods need to
be cladded to prevent the leakage or corrosion of the rods into the reactor itself. A Zr
– 1 wt % Nb alloy has been used as primary cladding in Canada and a Zr – 2.5 wt %
Nb alloy has been used to replace Zircaloy-2 as the cladding in Candu-PHW
(pressurized hot water) and has led to a 20 % reduction in wall thickness of
cladding. 8
Superconductivity is a term used to describe the lack of electrical resistance at very
low temperatures and it is displayed by niobium and many of its alloys. This makes
the alloys of great interest for electronic devices, power generation and other
applications. Niobium-titanium alloys are used for most superconducting devices due
to the ease of its conversion into magnet wire, which is its most common application.
Where the use of higher magnetic fields is necessary, niobium-tin alloys are used.
The intermetallic nature of this alloy makes production difficult and improved
methods of fabrication should lead to wider use. Niobium becomes superconducting
at 9.15 K, Nb-Ti at 9.5 K and Nb-Sn at 18 K. 7
Niobium oxide is the intermediate product used in the manufacturing of high-purity
niobium metal, ferro-niobium, nickel niobium and niobium carbide. The leading
applications of high purity niobium oxide (> 99.9 %) are ceramics and optical glass.
In the field of electro ceramics, niobium based perovskites are expected to exceed
the traditional titanate/zirconate based ceramics because of their lower sintering
temperature. Classic examples of ceramics comprising of niobium are
[Pb3MgNb2O9], [Pb3NiNb2O9] and [Pb2FeNbO6]. When the silica in glass is replaced
by niobium oxide the refractive index is increased. This means that thinner and
lighter lenses can be produced for the same focal length. It is also a very important
material for the electronics industry.
7 Kirk-Othmer, Encyclopedia of Chemical Technology, 5 th Ed., Wiley and Sons, New Jersey, 610, 2007.
8 B. A. Cheadle, W. J. Langford, R. I. Coote, Nucl. Eng. Int., 50, 24, 289, 1979.
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