12.  Metallurgical and chemical powder industries

12.1  Powder metallurgy

Metal powders are used to manufacture parts by sintering. For this purpose, they must meet certain criteria in terms of granular distribution, shape, specific surface area, chemical composition, and so on. Particle size and shape depend on both their chemical nature and the method used to obtain the powder medium. Powder production involves both chemical and mechanical processes, including grinding.

Mechanical grinding is the most widely used technique for producing hard metal and oxide powders. It is performed using hammer or ball mills, with grinding times ranging from one to one hundred hours. Fragile metals are easily reduced to small granules, but ductile metals give rise to small flakes, unsuitable for the manufacture of sintered...