MECH2305 - Powder Metallurgy

Power metallurgy

Metal is formed through heating compacted metals

Applications of powder metallurgy

1. Offers cost effective alternative

2. Materials that are too difficult to form other ways

3. Materials with better performance

5 Steps of powder metallurgy

1. Blending - Mix powders, lubricants and binders

2. Compaction - Form green part

3. Burn out - Part is heated to remove lubricants and binders

4. Sintering - Heated to high temperatures to diffuse

5. Secondary operations - Machine etc if neccessary

5 Powder characteristics

1. Morphology (smallest particle to largest)

2. Size

3. Density

4. Flowability

5. Compressability

Blending

Powers are all blended together

Compaction

High pressure applied to form the “green part” which has enough strength to be handled

Sintering

Heat treatment to bond particles, increasing strength and hardness

Ceramic vs Metal Powders

Ceramic powders do not deform, need additives to ensure bond.

PM advantages

1. Can have better properties

2. High material efficiency

3. Can form from difficult materials (ceramics)

PM disadvantages

1. High tooling and equipment costs

2. Metal powders are dangerous

3. Variations in density of the part

4. Expensive metallic powders required