Niobium workpieces have small thermal neutron absorption cross section, good corrosion resistance and high high temperature strength. They can be used as packaging materials for reactor structural materials and fuel, and can also be used as additives for nuclear fuel. Niobium has high superconducting transition temperature, and niobium compounds and alloys can make superconducting materials. Niobium has good thermionic emission performance, and can be used to make getter and rectifier of vacuum tube. Niobium and niobium alloys have high melting point and still have high strength at 1650 ℃. However, niobium pentoxide oxide film without protective effect is easy to form at high temperature. Therefore, in addition to improving the oxidation resistance of the basic alloy, it is also necessary to apply protective coating to ensure the high-temperature performance of the metal. Niobium is a gray white metal, melting point 2468 ℃, boiling point 4742 ℃, density 8.57 g / cm3. Niobium is stable in air at room temperature and is not completely oxidized when it is red hot in oxygen. Niobium has strong activity at high temperature and can react with elements such as oxygen, nitrogen, hydrogen and carbon, so it becomes hard and brittle. Therefore, sintering should be carried out in vacuum.