Manufacturing Processes for Engineering Materials (5th Edition in …ma.gnu.ac.kr/course/mp/11_Powder_Ceramic.pdf · 2019-11-14 · Manufacturing Processes 22 • Produced in extremely

© Pearson & GNU Su-Jin Kim

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Manufacturing Processes


Powder metallurgy(분말야금)

Ceramics(세라믹)

Glasses(유리)

Associate Professor Su-Jin Kim

School of Mechanical Engineering

Gyeongsang National University

http://ma.gnu.ac.kr/

http://engine.gnu.ac.kr/

http://www.gnu.ac.kr/


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OCW

• Metal powder and powder metallurgy SME:

https://youtu.be/O7U4HWjYcqo

• Powder Metallurgy 1:

http://www.youtube.com/watch?v=n_FW7Q2xO5

o

• Powder Metallurgy 2:

http://www.youtube.com/watch?v=iQIsk44JUYs

&feature=related


http://www.youtube.com/watch?v=n_FW7Q2xO5o

http://www.youtube.com/watch?v=iQIsk44JUYs&feature=related


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OCW

• Ceramic Manufacturing Process: https://youtu.be/wLLFHKPMutc

• Glass Window: https://youtu.be/IjNusHQOhTM

• Glass bottle: https://youtu.be/A1W3_OCZRX0

https://youtu.be/wLLFHKPMutc

https://youtu.be/IjNusHQOhTM

https://youtu.be/A1W3_OCZRX0


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Contents

Powder Metallurgy(분말야금)1. Powder production2. Blending or mixing3. Compaction4. Sintering

Ceramic1. Mixing particles with additives2. Shaping3. Drying & Firing

Glass1. Plate, Tubing2. Blowing, Pressing


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High temp & Hard

High temp hard materials : Ceramics and Tungsten W

•High melting point : Casting (X)

•Low ductility = Brittle : Deforming (X)

•High hardness : Machining (X)

Suggested process : Powder – Forming – Sintering (O)


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Powder Metallurgy Usage

• Automobile small gears

• Tungsten (W) weapons of military

• Cutting tools

• High temperature wear resistance

http://www.hmptech.com

http://www.hmptech.com/


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Powder Metallurgy

1. Powder production(분말)

2. Blending or mixing(혼합)

3. Compaction(압축)

4. Sintering(소결)

5. Finishing operations(마무리가공)

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

Powder metallurgy : https://youtu.be/O7U4HWjYcqo

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



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Powder Production

Size and shape of particles affect the processing characteristics of the powder.

Atomization (입자화)

• Liquid-metal stream is broken into powder by water jet.

Reduction (환원)

• Metallic oxides are reduced to the metallic state.

GE: https://youtu.be/CIPkbkhFZqk

https://youtu.be/CIPkbkhFZqk


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Blending metal powders (혼합)

• 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. binders are used for sufficient green strength


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Compaction(압축) of metal powders

• Powders are pressed into shapes using dies and press machine.

• Obtain the required shape, density and particle-to-particle contact.


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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.


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Sintering

• Sintering (소결) 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.


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Metal Injection Molding (MIM)

1. Mixing: metal + polymer

2. Injection monding

3. Debinding

4. Sintering

• Ceramic Injection Molding (CIM)

1. Mixing: ceramic + polymer

…


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Design for Powder Metallurgy

• Simple & uniform shape

• Easy ejection from die

• Large tolerance reduce cost

• Avoid sharp radius


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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.


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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 Al2O3, Zirconia ZrO2

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

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

4. Silica SiO2

5. Nanophase ceramic


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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.


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Ceramic process

1. Crushing raw materials into very fine particles (분말)

2. Mixing particles with additives (혼합)

3. Shaping (성형)

4. Drying (건조)

5. Baking in fire (굽기)

6. Finishing (마무리)

Toilet: https://youtu.be/x61lDo0zJTo

https://youtu.be/x61lDo0zJTo


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Particle mixing

Crushing and screening to desired particle size

Mixing particles & water: produces a "slip"


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Clay forming

Form a "green" component: Extrude into a pipe,

Slip casting

Drying: layer size and spacing decrease.

Drying too fast causes sample to warp or crack due to non-uniform shrinkage


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Firing

• Temperature raised to (900-1400°C)

• Liquid glass forms from clay and flows between SiO2

particles (quartz) melts at lower temperature

21


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Manufacturing Processes 22

• Produced in extremely large quantities.

• Portland cement:

- mix clay and lime bearing materials

- calcinate (heat to 1400°C)

- primary constituents:

tri-calcium silicate

di-calcium silicate• Adding water

- produces a paste which hardens

- hardening occurs due to hydration (chemical reactions

with the water).

• Forming: done usually minutes after hydration begins.

Cementation (시멘트)


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Glass

• Glass (유리) is an amorphous solid(비정질고체) with the structure of a liquid.

• All glasses contain at least 50% silica SiO2.

• They are resistant to chemical attacks and ranked by their resistance to acid, alkali or water corrosion.


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Properties of glass

• Consider to be linearly elastic and brittle.

• Bulk formed glass has low strength(<40 MPa) due to microcracks on the surface, but the strength of glass fiber is about 2 GPa stronger than steel.

• Low thermal conductivity and high electric resistance.

• Thermal expansion coefficient is lower than metals and plastics.

• Optical properties can be modified by varying their composition and treatment.


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Glass forming process (유리성형)

Formed at high temperature

Flat sheet (유리판): Float method

Glass tubing (유리관)

Blowing (블로잉)

Pressing (프래싱)

Spinning (스피닝)

Fiber drawing (유리섬유인발)


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Float method

Rolling(압연): Molten glass passes trough a pair of rollers

Float method(플로팅공정): Molten glass floats on a molten tin(주석) an then moves over rollers and is cut to glass plates.

Plate glass: http://www.youtube.com/watch?v=PSurxsGQL90

Molten Tin

Molten Glass

http://www.youtube.com/watch?v=PSurxsGQL90


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Blowing

Tubing(유리관인발): air is blown through the mandrel to make the tube

Blowing(블로우): glass bottle is made by blowing

Bottle: http://www.youtube.com/watch?v=NVKcISj2LfA&feature=related

http://www.youtube.com/watch?v=NVKcISj2LfA&feature=related


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Pressing

Pressing(프래싱): Molten glass is pressed into shape between molds.

Products: plates, dishes, cheap glasses

Block: http://www.youtube.com/watch?v=pEd2Oni88uY

http://www.youtube.com/watch?v=pEd2Oni88uY


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Fiber drawing

Grass fiber drawing(유리섬유) and winding up

Documents

Manufacturing Processes for Engineering Materials (5th Edition in …ma.gnu.ac.kr/course/mp/11_Powder_Ceramic.pdf · 2019-11-14 · Manufacturing Processes 22 • Produced in extremely