Uses of Niobium

The Krupp work had shown interesting improvements in acid resistance resulting from molybdenum and copper additions, and the use of 2-3% Mo for more difficult acid conditions was soon established. Other early additions were made to overcome susceptibility to intercrystalline corrosion, culminating in the general use, by the early thirties, of titanium additions for carbide stabilisation, followed shortly after by the alternative use of niobium. 

It is somewhat less corrosion resistant than tantalum, and like tantalum suffers from hydrogen embrittlement if it is made cathodic by a galvanic couple or an external e.m.f., or is exposed to hot hydrogen gas. The metal anodises in acid electrolytes to form an anodic oxide film which has a high dielectric constant, and a high anodic breakdown potential. This latter property coupled with good electrical conductivity has led to the use of niobium as a substrate for platinum-group metals in impressed-current cathodic-protection anodes. 

Investigations into the use of niobium and tantalum complexes as Lewis acids [99]... 

Some positive steps were made in this direction through the use of niobium-based alloys. In 1973 the alloy Nb3Ge was found to have a Tc = 23 K, which remained the highest attainable critical temperature until 1986. In 1986 two IBM scientists in Zurich, the German, Johannes Georg Bednorz and the Swiss, Karl Alex Muller found that a ceramic oxide based on lanthanum, barium and copper (of stoichiometry... 

Introduction.—The compilation of the inorganic chemistry of niobium and tantalum has been revised.341 Reviews have appeared on the physicochemical properties of tantalum compounds and alloys,498,499 on the extraction, properties, and uses of niobium and tantalum,500 and on the structures of their compounds determined by diffraction methods.339 The half-life of 182Ta has been determined as 114.74 + 0.08 days.501... 

The method described above has been found suitable for the synthesis of Nb(NCSe)4(CioH8N2)2, Nb(NCS)4(dmbipy)2, and Nb(NCSe)4(dmbipy)2, where dmbipy is4,4 -dimethyl-2,2 -bipyridine. These niobium (IV) compounds can also be prepared from the hexakis(isothiocyanate)niobate(V) complex. The sensitivity of the materials to air and moisture makes the method somewhat more time-consuming, but the use of niobium tetrachloride as a starting material is avoided. The tantalum(V) complexes, Ta(NCS)6(CioH8N2)... 

Another popular use of niobium alloys is in the making of jewelry. These alloys are lightweight and hypoallergenic. The term hypoallergenic means that they do not cause skin reactions. People who wear pierced earrings or similar forms of jewelry will not develop skin problems from niobium alloy jewelry. 

Tribological Background for Use of Niobium Carbide as Cutting Tools... 

Tribological Background for the Use of Niobium Carbide (NbC) as Cutting Tools and For Wear Resistant Tribosystems Mathias Woydt and Hardy Mohrbacher... 

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