Lecture 2 - Powder Metallurgy

Why Powder Metallurgy is Important
• PM parts can be mass produced to net shape or near net shape
• PM process wastes very little material - ~ 3%
• PM parts can be made with a specified level of porosity, to
produce porous metal parts
– Filters, oil?impregnated bearings and gears
• Difficult to fabricate parts can be shaped by powder metallurgy
– Tungsten filaments for incandescent lamp bulbs are made by PM
• Certain alloy combinations and cermets can only be made by
PM
• PM production can be automated for economical production

Limitations and Disadvantages
• High tooling and equipment costs
• Metallic powders are expensive
• Problems in storing and handling metal powders
– Degradation over time, fire hazards with certain metals
• Limitations on part geometry because metal powders do
not readily flow well
• Variations in density density may be a problem, especially for
complex geometries
Production of Metallic Powders
• Any metal can be made into powder form
• Three principal methods by which metallic
powders are commercially produced
1. Atomization
2. Chemical
3. Electrolytic
• In addition, mechanical milling is occasionally
used to reduce powder sizes