Traditional and engineering ceramics Traditional and engineering ceramics Suranaree University of Technology October 2007 T. Udomphol Chapter 1 Traditional ceramics Clay Silica Feldspar + + 2 3 2 2 2 3 2 2 6 . . 6 . . SiO O Al O Na SiO O Al O K 2 SiO O H SiO O Al 2 2 3 2 2 . 2 . • Structural clay products : bricks, sewer pipe, roofing tile • EX: Triaxial bodies: Whiteware, porcelain, chinaware, sanitary ware. Reactions of a triaxial body
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Traditional and engineering ceramicsTraditional and engineering ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional ceramics Clay Silica Feldspar+ +
2322
2322
6..
6..
SiOOAlONa
SiOOAlOK2SiOOHSiOOAl 2232 2.2.
• Structural clay products : bricks,
sewer pipe, roofing tile
• EX: Triaxial bodies:Whiteware,
porcelain, chinaware, sanitary ware.
Reactions of a triaxial body
Traditional and engineering ceramicsTraditional and engineering ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional ceramics
Triaxial whiteware chemical composition
Traditional and engineering ceramicsTraditional and engineering ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Electron micrograph of an electrical
insulator porcelain (etched 10 s, 0oC,
40% HF, silica replica)
quartz Mullite needles
High silica glass
Traditional and engineering ceramicsTraditional and engineering ceramics
Traditional ceramics
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Slip casting processMaster and plaster moulds
Fresh cast
Dry
Slip casting
Colour paintFire
Suranaree University of Technology October 2007
http://www.lindawilsonceramics.co.za/3.html
Pottery
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Slip casting processSlip casting process Sanitaryware
Slip casting in plaster moulds and demoulding
www.3emmegi.com
Suranaree University of Technology October 2007
Slip preparation
in ball millOHOHCaSOOHCaSO Co
223
221
4
150
24 .2. + →
Hemihydrate plaster – produced from gymsum
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Engineering ceramics • Contain more of pure compounds of oxides,
carbides, nitrides.
• Ex: Al2O3, Si3N4, SiC, ZrO2 , refractory
oxides
Mechanical properties of engineering ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Engineering ceramics Alumina
• Refractory tubing
• High purity crucibles for high temp
• High quality electrical applications
(low dielectric loss and high resistivity)
• Spark plug insulator
Microstructure of sintered, powdered aluminium
oxide doped with magnesium oxide
Alumina tubes
www.sentrotech.com
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Engineering ceramics Silicon nitride (Si3N4)
• Dissociate at T > 1800oC.
• Cannot be directly sintered � reaction bonding.
Silicon nitride for engineering applications
Silicon powder
N2 flow
nitriding
Microporous Si3N4
High strength
nonporous Si3N4
Hot pressing with
1-5%MgO
www.defazio-rotary.com
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Engineering ceramics Silicon carbide (SiC)
• Hard refractory carbide.
• Form skin of SiO2 at high temp.
• Resistance to oxidation at high temp.
• Can be sintered 2100oC with 0.5-1%B.
• Fibrous reinforcement in ceramic-
matrix composite material.
SiC fibre reinforced Titanium matrix
www.stork.com
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
Traditional and engineering ceramicsTraditional and engineering ceramics
Engineering ceramics Zirconia (ZrO2)
• Polymorphic: tetragonal � monoclinic.
• Mixed with CaO, MgO and Y2O3 � Partially stabilized zirconia (PSZ).
1170oC
Volume expansion
Heat treatment Cubic structure
www.azom.com
Zirconia
Mechanical properties of ceramicsMechanical properties of ceramics
Suranaree University of Technology October 2007
T. Udomphol
Chapter 1
• Brittle
• High strength (varying from 0.7 – 7000 MPa)
• Better compressive strength than tensile (5-10 times)