Nickel Chinese name mu, English name: Nickel, element symbol is Ni, atomic number 28 in the periodic table, relative atomic mass 58.69, is a Group VIII metal. The density is 8.9 g/cm3, the melting point is 1455 ° C, and the boiling point is 2730 ° C. Nickel is a kind of silver-white metal. It is easily oxidized by air in the air, and some oxide film is formed on the surface. Therefore, the nickel that people see often has a black color. Nickel is hard, has good ductility, is magnetic and corrosion resistant, and is highly polished. Nickel is also very rich in the earth's crust. It exists in the form of nickel silicate or sulfur, arsenic, and nickel compounds in nature. Nickel is often used in the manufacture of stainless steel, alloy structural steel and other steel fields, electroplating, high nickel-based alloys and batteries, etc. It is widely used in various military manufacturing industries such as aircraft and radar, civil machinery manufacturing and electroplating industry.