Zirconium: Zirconium is a chemical element whose chemical symbol is Zr. Its atomic number is 40. It is a silver-white high melting point metal with a light gray color. The density is 6.49 g/cm 3. The melting point is 1852 ± 2 ° C, the boiling point is 4377 ° C. The valence is +2, +3 and +4. The first ionization energy is 6.84 eV. The surface of zirconium is easy to forms an oxide film with a luster, so the appearance is similar to steel. It is corrosion-resistant and soluble in hydrofluoric acid and aqua regia. It reacts with non-metallic elements and many metal elements at high temperatures to form solid solution compounds. applications of zirconium: nuclear energy property, excellent corrosion resistance, high melting point, high strength and hardness, super conduct at low temperatures.