Niobium Information
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Niobium Element
Niobium, also known as
columbium, is a chemical element with the symbol Nb (formerly Cb) and atomic
number 41. Niobium is a light grey, crystalline, and ductile transition metal.
Pure niobium has a hardness similar to that of pure titanium,[2][contradictory]
and it has similar ductility to iron. Niobium oxidizes in the 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, hence the former name "columbium". Its name comes from
Greek mythology, specifically Niobe, who was the daughter of Tantalus, the
namesake of tantalum. The name reflects the great similarity between the two
elements in their physical and chemical properties, making them difficult to
distinguish.[3]
The English chemist Charles
Hatchett reported a new element similar to tantalum in 1801 and named it
columbium. In 1809, the English chemist William Hyde Wollaston wrongly
concluded that tantalum and columbium were identical. The 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.
Niobium and its compounds may
be toxic (niobium dust causes eye and skin irritation) , but there are no reports
of human being poisoned by it. Apart from measuring its concentration, no
research on niobium in humans has been undertaken.
Niobium, when inhaled, is
retained mainly in the lungs, and secondarily in bones. It interferes with
calcium as an activator of enzyme systems. In laboratory animals, inhalation of
niobium nitride and/or pentoxide leads to scarring of the lungs at exposure
levels of 40 mg/m3.
It was not until the early 20th
century that niobium was first used commercially. 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. The temperature
stability of niobium-containing superalloys is important for its use in jet and
rocket engines.
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