Math Is Fun Forum

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 51,538

Niobium

Niobium

Gist

Niobium is a chemical element with the symbol Nb and atomic number 41. It's a soft, gray-white, ductile transition metal known for its resistance to corrosion due to a protective oxide layer. Niobium is also a refractory metal, meaning it has a high melting point and resistance to heat and wear. It's commonly used in steel alloys, particularly high-strength, low-alloy steels, and in superalloys for high-temperature applications.

Niobium, with the symbol Nb and atomic number 41, is a lustrous, greyish, ductile transition metal. It's known for its high melting point, corrosion resistance, and superconductivity at low temperatures. Niobium is commonly found in the mineral niobite (formerly columbite) and is used in alloys, particularly to strengthen steel and in superconducting applications like MRI scanners. 

Niobium is primarily used to enhance the properties of steel and other alloys, making them stronger, more durable, and resistant to corrosion and high temperatures. It's also used in superconducting magnets, medical devices, and is a component in some jewelry.

Summary

Niobium is a chemical element; it has symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has similar ductility to iron. Niobium oxidizes in Earth's atmosphere very slowly, hence its application in jewelry as a hypoallergenic alternative to nickel. Niobium is often found in the minerals pyrochlore and columbite. Its name comes from Greek mythology: Niobe, daughter of Tantalus, the namesake of tantalum. The name reflects the great similarity between the two elements in their physical and chemical properties, which makes them difficult to distinguish.

English chemist Charles Hatchett reported a new element similar to tantalum in 1801 and named it columbium. In 1809, English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium. In 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element (as distinguished from tantalum), and for a century both names were used interchangeably. Niobium was officially adopted as the name of the element in 1949, but the name columbium remains in current use in metallurgy in the United States.

It was not until the early 20th century that niobium was first used commercially. Niobium is an important addition to high-strength low-alloy steels. Brazil is the leading producer of niobium and ferroniobium, an alloy of 60–70% niobium with iron. Niobium is used mostly in alloys, the largest part in special steel such as that used in gas pipelines. Although these alloys contain a maximum of 0.1%, the small percentage of niobium enhances the strength of the steel by scavenging carbide and nitride. The temperature stability of niobium-containing superalloys is important for its use in jet and rocket engines.

Niobium is used in various superconducting materials. These alloys, also containing titanium and tin, are widely used in the superconducting magnets of MRI scanners. Other applications of niobium include welding, nuclear industries, electronics, optics, numismatics, and jewelry. In the last two applications, the low toxicity and iridescence produced by anodization are highly desired properties.

Details

Niobium (Nb) is a chemical element, refractory metal of Group 5 (Vb) of the periodic table, used in alloys, tools and dies, and superconductive magnets. Niobium is closely associated with tantalum in ores and in properties.

Due to the great chemical similarity of niobium and tantalum, the establishment of the individual identities of the two elements was very difficult. Niobium was first discovered (1801) in an ore sample from Connecticut by the English chemist Charles Hatchett, who called the element columbium in honour of the country of its origin, Columbia being a synonym for the United States. In 1844 a German chemist, Heinrich Rose, discovered what he considered to be a new element occurring along with tantalum and named it niobium after Niobe, the mythological goddess who was the daughter of Tantalus. After considerable controversy it was decided that columbium and niobium were the same element. Eventually international agreement (about 1950) was reached to adopt the name niobium, though columbium persisted in the U.S. metallurgical industry.

Niobium is roughly 10 times more abundant in the crust of the Earth than is tantalum. Niobium, more plentiful than lead and less abundant than copper in the Earth’s crust, occurs dispersed except for relatively few minerals. Of these minerals, the columbite–tantalite series, in which columbite (FeNb2O6) and tantalite (FeTa2O6) occur in highly variable ratios, is the main commercial source. Pyrochlore, a calcium sodium niobate, is also the principal commercial source. Natural niobium occurs entirely as the stable isotope niobium-93.

The production procedures for niobium are complex, the major problem being its separation from tantalum. Separation from tantalum, when necessary, is effected by solvent extraction in a liquid-liquid process; the niobium is then precipitated and roasted to niobium pentoxide, which is reduced to niobium powder through metallothermic and hydriding processes. The powder is consolidated and purified further by electron-beam melting. Vacuum sintering of powder is also used for consolidation. Niobium can also be obtained by either electrolysis of fused salts or reduction of fluoro complexes with a very reactive metal such as sodium.

The pure metal is soft and ductile; it looks like steel or, when polished, like platinum. Although it has excellent corrosion resistance, niobium is susceptible to oxidation above about 400° C (750° F). Niobium can best be dissolved in a mixture of nitric and hydrofluoric acids. Completely miscible with iron, it is added in the form of ferroniobium to some stainless steels to give stability on welding or heating. Niobium is used as a major alloying element in nickel-based superalloys and as a minor but important additive to high-strength, low-alloy steels. Because of its compatibility with uranium, resistance to corrosion by molten alkali-metal coolants, and low thermal-neutron cross section, it has been used alone or alloyed with zirconium in claddings for nuclear reactor cores. Cemented carbides used as hot-pressing dies and cutting tools are made harder and more resistant to shock and erosion by the presence of niobium. Niobium is useful in constructing cryogenic (low temperature) electronic devices of low power consumption. Niobium-tin (Nb3Sn) is a superconductor below 18.45 Kelvins (K), and niobium metal itself, below 9.15 K.

Compounds of niobium are of relatively minor importance. Those found in nature have the +5 oxidation state, but compounds of lower oxidation states (+2 to +4) have been prepared. Quadruply charged niobium, for example, in the form of the carbide, NbC, is used for making cemented carbides.

Element Properties

atomic number  :  41
atomic weight  :  92.906
melting point  :  2,468° C (4,474° F)
boiling point  :  4,927° C (8,901° F)
specific gravity  :  8.57 (20° C)
oxidation states  :      +2, +3, +4, +5.

Additional Information:

Appearance

A silvery metal that is very resistant to corrosion due to a layer of oxide on its surface.

Uses

Niobium is used in alloys including stainless steel. It improves their strength, particularly at low temperatures. Alloys containing niobium are used in jet engines and rockets, beams and girders for buildings and oil rigs, and oil and gas pipelines.

This element also has superconducting properties. It is used in superconducting magnets for particle accelerators, MRI scanners and NMR equipment.

Niobium oxide compounds are added to glass to increase the refractive index, which allows corrective glasses to be made with thinner lenses.

Biological role

Niobium has no known biological role.

Natural abundance

The main source of this element is the mineral columbite. This mineral also contains tantalum and the two elements are mined together. Columbite is found in Canada, Brazil, Australia, Nigeria and elsewhere. Some niobium is also produced as a by-product of tin extraction.

---

It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.