Explanation

Tin (element symbol Sn) is a silver white metal with a density of 7.3 g/cm at room temperature 3， The melting point is 231.9 ° C. Tin will form a dense oxide film at room temperature to prevent further oxidation, but it will rapidly oxidize and volatilize at high temperature. Tin has isomorphic transformation, which belongs to α Tin, also known as gray tin, its crystal structure is diamond type. However, between 13.2 ° C and melting point, tin has a tetragonal crystal structure, called β Tin is also called white tin. When α Tin conversion β When tin is used, it will appear powder. This phenomenon of transformation from metal tin block to metal tin powder is called "tin plague". Tin has high resistance to atmospheric corrosion and is almost insensitive to weak organic acids. Therefore, it is often used to make tinplate, also known as "tinplate", as a food packaging materials. Pure tin is also used as a coating for certain mechanical parts. Although the strength and hardness of tin are relatively low, tin has good processing properties and can be made into materials of various shapes such as tubes, foils, wires, strips, plates, bars, etc. Tin can also be made into powder for powder metallurgy and other applications. Tin and some low melting point metals, such as lead, bismuth, cadmium, etc., can form a series of fusible alloy, such as tin lead alloy, tin bismuth alloy, tin cadmium alloy, etc., and can also be used to manufacture tin solder. As an alloy element, tin is also widely used, such as in titanium alloy and zirconium alloy. Niobium tin imermetallif compound (Nb3Sn) is a low temperature superconducting material, while tin silver amalgam is used as a dental materials.

Classification