1. ENGR 241 – Introduction To Manufacturing Chapter 17: Powder Processing

2. Powder Metallurgy Consists in compacting metal powders into an specific shape (dies), and heating them (without melting) to impart strength.

3. Powder Metallurgy Process Steps powder production blending compaction sintering finishing operations

4. Powder Production Atomization liquid-metal broken up by jets of gas, air or water. Reduction fine metallic oxides are turned into metallic particles. Electrolytic Deposition metal immersed in aqueous solutions or fused salts.

5. Powder Production (Cont.) Carbonyls reaction with carbon monoxide Comminution mechanical pulverization Mechanical Alloying impact alloying

6. Blending of Metal Powders Use to impart special physical and mechanical properties/characteristics Uniformity Lubricants (improve flow) Pyrophorism (high surface-area to volume ratio).

7. Compaction of Metal Powders Powders are pressed into shapes (dies) using hydraulic or mechanical presses. Green compacts (pre-forms at room temp) 24% porosity (in theory) MIM

8. Sintering Compressed metal powders heated in a controlled atmosphere. Bonding of particles. Temperature, time, and atmosphere. Usually carried at 70 to 90% of the melting point of the metal or alloy.

9. Finishing Operations Impregnating (oil) Infiltration (porosity) Heat treatment Machining Grinding Plating Forging (Coining)