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Methods
of powder production and compaction issues.
· Important first steps in powder metallurgy are the production of
the metal powders, the selection of particles by size, and their compaction
into the green pre-sintering shape.
· Three
methods for powder production are listed below.
* Hydrodynamic breakup for low melting point materials
* Reduction of oxide particles for
refractory materials (W, Mo) and for materials found as oxides (Fe, Ni, Co,
Cu).
* Electrolytic
deposition under selected current conditions.
· Mechanical or aerodynamic particle size
selection is used to obtain a narrow size distribution. Particle size ranges
may be used for the green product. For some powders, a polymeric binder may
be employed to make the green shape easier to handle. The polymer is burned
off in heating to the sintering temperature.
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