| Identifiers | |
|---|---|
| |
| ChemSpider |
|
| ECHA InfoCard | 100.031.913 |
| EC Number |
|
| |
| Properties | |
| NbC | |
| Molar mass | 104.917 g/mol |
| Density | 7.820 g/cm3 |
| Melting point | 3,608 °C (6,526 °F; 3,881 K) |
| Structure | |
| Cubic (rock salt structure),Fm3m,cF8) | |
| Related compounds | |
Related Refractory ceramic materials | zirconium nitride,tantalum carbide,zirconium carbide |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Niobium carbide (NbC andNb2C) is an extremelyhardrefractoryceramic material, commercially used intool bits for cutting tools. It is usually processed bysintering and is a frequent additive as grain growth inhibitor incemented carbides. It has the appearance of a brown-gray metallic powder with purple lustre. It is highlycorrosion resistant.
Niobium carbide can be produced by the heating of niobium oxide in a vacuum at 1800 °C and adding coke.
Niobium carbide has aYoung's modulus of approximately 452 GPa, and a shear modulus of 182 GPa.[1] It has a Poisson's ratio of 0.227.[1]
Niobium carbide is a frequent intentional product inmicroalloyed steels due to its extremely low solubility product inaustenite, the lowest of all therefractory metal carbides. This means that micrometre-sized precipitates of NbC are virtually insoluble in steels at all processing temperatures and their location at grain boundaries helps prevent excessive grain growth in these steels. This is of enormous benefit, and the cornerstone of microalloyed steels, because it is their uniform, very fine grain size that ensures both toughness and strength. The only commonly occurring compound with a lower solubility and hence, greater potential for restricting the grain growth of steels istitanium nitride.
Depending on grain size, niobium carbide may burn at 200-800 °C in air. A layer of niobium carbide can be created bychemical vapor deposition.Zirconium carbide and niobium carbide can be used as refractory coatings innuclear reactors.
Niobium carbide occurs naturally as Niobocarbide. This is an extremely rare mineral, and has been found in Sverdlovsk Oblast, Russia.[2]
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