Niobium carbide

Gray odorless solid

Fixed

7.60 g · cm -3

3500 ° C

4300 ° C

Insoluble in water

Attention

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Niobium carbide is an inorganic compound of niobium and carbon to the sum of the group of formula NbC carbides.

Representation

Niobium carbide is represented by reacting niobium with carbon powder in vacuum or a protective hydrogen atmosphere.

Small amounts of the niobium carbide may small amounts of hydrocarbons ( for example toluene, methane, acetylene ) can be obtained with the addition of niobium wires at temperatures over 2500 ° C in a hydrogen atmosphere. Also possible is the preparation by reacting niobium oxides and carbon.

Properties and Uses

Niobium carbide is an iron- gray to dark gray powder that shines more or less metallic in a compact, sintered state. By tarnishing it is sometimes superficial brown to yellowish. It has a homogeneity range of NbC0, 7 to NbC0, 99 and oxidized at 800 ° C. It has a cubic crystal structure of the sodium chloride type with space group Fm3m. It has a Mohs hardness of 9 , thus a hard material and is soluble in a mixture of hydrofluoric acid and nitric acid. Nb2C with another niobium carbide ( CAS Number 12011-99-3 ) having a hexagonal crystal structure and a melting temperature of 3080 ° C is known.

Use

Niobium carbide is used as an additive to special steels ( it increases, the wear resistance, making these steels are used for example for piston rings ) are used for the coating of graphite, for nuclear reactors, and as sputtering for the production of semiconductor films.

Of niobium carbide and niobium (V ) oxide, niobium is recovered pure at 2,000 ° C.