Niobium is a kind of silver grey rear high-melting-point metal with relatively soft texture and ductility. At normal temperature, niobium cannot react with the air, and cannot be completely oxidized in oxygen in the red hot state. Niobium can be directly and chemically combined with sulfur, nitrogen and carbon at high temperature. Niobium cannot react with inorganic acid or alkali, and is insoluble in aqua regia but is soluble in hydrofluoric acid. Niobium features extremely good superconductivity, high melting point, corrosion resistance, wear resistance, etc.