Manufacturing Processes Metal Powders, Ceramics, Glasses

Metals Powders, Ceramics, Glasses 

Manufacturing Processes 

© Pearson Pearson 

& GNU Su-Jin Su Jin Kim 


Metal Powders, Powders, 

Ceramics, Glasses

Contents 

Powder Metallurgy 

1. Powder production 

2. Blending or mixing 

3. Compaction 

4. Sintering 

Ceramic 

1. Mixing particles with additives 

2. Shaping 

3. Drying & Firing 

Glass 

1. Plate, Tubing 

2. Blowing, Pressing 




& GNU Su-Jin Su Jin Kim

Powder Metallurgy Usage 





http://www.hmptech.com

Powder Metallurgy 

1. Powder production 

2. Blending or mixing 

3. Compaction 

4. Sintering 

5. Finishing operations (Coining, Sizing, Machining, 

Infiltration) 





http://www.youtube.com/watch?v=1Mjsi2F2MrY

Powder Production 

1. Atomization 

• Produces liquid-metal stream by injecting molten metal. 

2. Reduction 

• Removal of oxygen involves gases such as reducing agents. 





Particle size and shape 

• Particle size is measured and controlled by screening. 

• Size distribution of particles affects the processing 

characteristics of the powder. 

• Particle shape influences on processing characteristics. 

It is expressed by aspect ratio or shape factor. 





Blending metal powders 

• Blending (mixing) powders is the second step, and the 

purposes are: 

1. to impart physical and mechanical properties and 

characteristics to the P/M part 

2. obtain uniformity from part to part 

3. lubricants are mixed to improve flow characteristics 

4. additives used to facilitate sintering 





Compaction of metal powders 

• Compaction are pressed into shapes using dies and 

presses. 

• Obtain the required shape, density and particle-toparticle 

contact. 





Compaction of metal powders 

• The density after compaction 

depends on: 

1. compaction pressure 

2. powder composition 

3. hardness of the powder 

• Higher the density, higher 

the strength and 

elastic modulus of the part. 





Pressure distribution in powder 

compaction 

• Pressure distribution along length of the compact. 

p 

μ : powder-wall friction coef 

k : the inter-particle friction coef 

x/D : length-to-diameter ratio 



x 

= 



p 

0 

e 

-4mkx 

D

Isostatic pressing 

• Powders are subjected to hydrostatic pressure in order 

to to achieve uniform compaction. 

• In cold isostatic pressing (CIP), metal powder is placed 

in a flexible rubber mold. 





Isostatic pressing 

• In hot isostatic pressing (HIP), a container is made of 

high-melting point sheet metal and the pressurizing 

medium is an inert gas. 

• It can produce compacts with uniform grain structure 

and density, irregardless of shape. 





Sintering 

• Sintering is where compacted metal powder is heated 

to below its melting point for the bonding of the 

individual metal particles. 

• Sintered density increases with temperature and time. 

• Volume shrink during sintering 





Sintering mechanisms 

• 1 st mechanism: As temperature increases, 2 particles 

will bond by diffusion. 

• 2 nd mechanism: Vapor-phase transport is due to 

material heated close to melting temperature. 





Design for Powder Metallurgy 

1. Simple & uniform shape 

2. Easy ejection from die 

3. large tolerance reduce cost 

4. Avoid sharp radius 





Economics of Powder Metallurgy 

• The cost depends on method of powder production, its 

quality and quantity purchased. 

• Due to high cost of punches, dies and equipment for 

P/M processing, production volume must be high. 

• P/M forging is used for critical applications where 

fatigue resistance are essential. 





Ceramics 

• Ceramics are compounds of metallic and non-metallic 

elements. 

• Bonding between atoms can be covalent and ionic. 

• Various types of ceramics are: 

1. Oxide ceramics O: Alumina Al 2 O 3 , Zirconia ZrO 2 

2. Carbides C: Tungstem carbides WC, Silicon carbide SiC 

3. Nitrides N: Cubic boron nitride cBN, Titanium nitride TiN, Sialon, Cermets 

4. Silica SiO 2 

5. Nanophase ceramic 





Ceramic usage 



Pottery 



Aerospace 

Memory 

Medical

Ceramic usage 





Electric resistance 

Wear resistance 

Art 

High temperature

General properties of ceramics 

• Ceramics are brittle, have high compressive strength and 

hardness at elevated temperatures, high elastic modulus, 

low toughness, low density, low thermal expansion, and low 

thermal and electrical conductivity. 

1. Mechanical properties 

• Sensitivity to cracks, impurities and porosity 

• Strength in tension is lower than compressive strength. 

2. Physical properties 

• Low specific gravity and have high melting temperatures. 





Ceramic process 

1. Crushing raw materials into very fine particles 

2. Mixing particles with additives 

3. Shaping 

4. Drying & Firing 

5. Finishing 





http://www.youtube.com/watch?v=_xx0qwFJ8nI&feature=related

Ceramic Shaping process 

1. Casting: slip casting 

2. Plastic forming: extrusion 

3. Pressing: dry pressing, wet pressing, isostatic pressing, 

jiggering, injection molding, hot pressing 





Ceramic Fiber Process 





Glass 

• Glass is an amorphous solid with the structure of a liquid. 

• All glasses contain at least 50% silica SiO 2. 

• They are resistant to chemical attacks and ranked by their 

resistance to acid, alkali or water corrosion. 





Mechanical properties 

• Consider to be linearly elastic and brittle. 

• Bulk formed glass has low strength(

Forming and Shaping Glass 

1. Flat sheet or plate made by float method 

2. Rods and tubing 





Float method 

http://www.seoulglass.com 

Tubing

Forming and Shaping Glass 

3. Discrete products 

– Blowing 

– Pressing 

– Centrifugal casting 

4. Glass fibers 

Pressing 





Blowing

Graphite 

• Graphite is a layered structure of carbon C. 

• It is brittle, electrical thermal conductor, has resistance 

to chemical thermal shock. 

• Low frictional properties allow it to be a solid lubricant, 

abrasive but a poor lubricant in a vacuum. 

• Special structure : Graphite fiber and Carbon nano tube. 





Diamond 

• Has a covalently bonded structure and is the hardest 

substance. 

• It is brittle and decompose in air at about 973 K. 

• Applications include cutting tools, window of laser.

Manufacturing Processes Metal Powders, Ceramics, Glasses

Create successful ePaper yourself

Delete template?

Save as template?