name: Niobium carbide
Chemical formula: NbC
Molecular weight :104.923
Relative density: 8.47
Lattice constant: a=0.447nm
Melting point :3500℃
Density: 7.6g/cm³(25℃)
Microhardness :>23.5 Gpa(>2400 kg/mm2), harder than corundum
Elastic modulus :338000 N/mm2
Coefficient of thermal expansion :6.65×10^(-6)/K
Thermal conductivity :14 w/(m·K)
Heat of formation :-140.7 kJ/mol
Specific heat capacity: 36.8J /(mol·K)
Resistivity :35μΩ·cm
Physical and chemical properties: Niobium carbide is green cubic crystal, metallic luster, belongs to sodium chloride cubic crystal system. Insoluble in hot and cold hydrochloric acid, sulfuric acid, nitric acid, soluble in hot hydrofluoric acid and nitric acid mixed solution.
Application field:
1) refractory high temperature materials; Good chemical stability, high temperature performance, is a kind of high melting point, high hardness material, widely used in refractory high temperature materials; It is stable at 1000~1100℃, and is rapidly oxidized to niobium pentoxide above 1100℃. Niobium carbide is easily fused in titanium carbide, zirconium carbide, tungsten carbide and other compounds, and together to form an isocrystalline solid solution mixture.
2) As a carbide carbide additive, it is a ternary, quaternary carbide solid solution component, such as WC-NbC-C ternary system. It can also be used as purple artificial gemstone.
3) Niobium carbide is a terene and quaternary carbide solid solution component, combined with tungsten carbide and molybdenum carbide, used for hot forging die, cutting tool, jet engine turbine blade, valve, tail dress and rocket nozzle coating.
4) For the production of wear-resistant film and semiconductor film. It can also be used as a raw material for the production of molybdenum carbide, and can be used for the manufacture of chromium-free special alloys and engineering ceramics.
① Application in composite materials:
Multi-phase ceramics: As one of the raw materials of multi-phase ceramic materials, niobium carbide made of multi-phase ceramic materials with its high hardness, high melting point, excellent chemical stability and electrical conductivity, often used in wear-resistant parts, cutting tools and electrodes and other fields.
Cemented carbide: not only can be used as an inhibitor of cemented carbide grain growth, but also can form a third dispersion phase with other carbides in addition to WC and Co, which significantly improves the thermal hardness and thermal shock resistance, thermal pressure resistance, and oxidation resistance of cemented carbide. Niobium carbide has the advantages of increasing the hardness of alloy and improving the fracture toughness of alloy, so it can be used to prepare carbide cutting tool materials with excellent cutting properties. In addition, niobium carbide can also be processed into purple artificial gems
Surfacing electrode: The hard niobium carbide hard phase enters the structure of the surfacing layer, so that the welding layer has a better wear-resistant skeleton, and the wear resistance is greatly improved. The wear resistance of this kind of wear-resistant alloy is 1.2-1.8 times higher than that of quenched 45 steel (HRC50) and 2.4-3.6 times higher than that of Fe-Cr-C-B type abrading alloy. At the same time, the wear-resistant surfacing layer can be surfaced on the workpiece surface without preheating, and the fine cracks generated on the surface can release the stress of the surfacing layer and will not spread to the base material. In addition, a trace amount of niobium carbide is added to the steel strengthening phase in the process of steelmaking, which can achieve the effect of precipitation strengthening and fine crystal strengthening, thereby improving the comprehensive mechanical properties of steel.
Aerospace components: Used as the preparation materials for many aerospace equipment components such as turbine rotors, gas rudders, blades, engine nozzle linings and nuclear reactor structures.
② Application in coating materials:
Die steel surface coating: niobium carbide as a metal carbide, with high hardness, heat resistance and wear resistance. Therefore, coating it on steel shows that it can improve the wear resistance of the die surface.
Metal workpiece coating: composite niobium carbide layer on the surface of the metal workpiece matrix, so that the surface hardness is greatly improved, can reach more than HV2800, while improving the working temperature and tissue density of the workpiece, thereby extending its service life. Niobium carbide coating can be achieved on the surface of cast iron piston ring by chemical liquid deposition treatment, and the coating is firmly combined with the substrate. The coated piston ring not only has a good pocket oil storage structure, but also has the advantages of high hardness, which can significantly reduce the sliding friction coefficient of non-lubricating medium and diesel oil lubrication, greatly improve its wear resistance, but also reduce the friction loss of diesel engine and improve the performance of diesel engine.
Other niobium carbide coatings: The use of niobium carbide coatings on spacecraft high-temperature components can significantly increase their service life. In the electronics industry, the intermediate layer material of the electron emission tube uses ultra-fine cobalt-containing niobium carbide, which has a significant effect on improving the emissivity of the gate surface, reducing the gate temperature and reducing the gate thermal emission, thus prolonging the life of the electron emission tube.
③ Application in metal niobium production: Our country mainly uses indirect reduction method to produce metal niobium, first the output of niobium carbide as a reducing agent, and niobium pentoxide to produce crude metal niobium, and then refined into high purity metal niobium. In addition, niobium carbide can also directly reduce niobium pentoxide to produce pure metal niobium.
Market analysis of key countries and regions:
Europe and America: At present, the niobium carbide industry in Europe and the United States (including Western Europe, North America, South America, etc.) has entered the late stage of rapid development or early maturity, especially the niobium carbide industry in the United States, Brazil, Germany, the United Kingdom, Switzerland, Canada and other regions is gradually mature, product quality is high, supply is sufficient or excess, market demand is gradually saturated or declining, the entire industry is in a highly competitive situation.
Storage conditions: inert gas anti-static packaging, should be sealed in a dry, cool environment, should not be exposed to the air for a long time.
