Rana zia ur rehman Graduate Researcher at KAIST (Korea Advanced of Science & Technology) My Email ID: ranazia517@gmail.com

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http://www.ts.mah.se/utbild/mt7150/051212%20ceramics.pdf

3. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Ceramic Defined
An inorganic compound consisting of a metal (or
semi metal) and one or more nonmetals‑
• Important examples:
– Silica - silicon dioxide (SiO2), the main ingredient in
most glass products
– Alumina - aluminum oxide (Al2O3), used in various
applications from abrasives to artificial bones
– More complex compounds such as hydrous
aluminum silicate (Al2Si2O5(OH)4), the main
ingredient in most clay products

4. 4
• To be most frequently silicates, oxides, nitrides and
carbides
• Typically insulative to the passage of electricity and heat
• More resistant to high temperatures and harsh
environments than metals and polymers
• Hard but very brittle
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5. What are they?
• A compound of metallic and nonmetallic
elements, for which the inter atomic
bonding is predominantly ionic.
• They tend to be oxides, carbides, etc of
metallic elements.
• The mechanical properties are usually
good: high strength, especially at elevated
temperature.
• However, they exhibit low to nil-ductility,
and have low fracture toughness.

6. 6
• ceramics that are predominantly ionic in nature
have crystal structures comprised of charged ions,
where positively-charged (metal) ions are called
cations, and negatively-charged (non-metal) ions
are called anions – the crystal structure for a given
ceramic depends upon two characteristics:
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7. 7
1. the magnitude of electrical charge on eachcomponent
ion, recognizing that the overallstructure must be
electrically neutral
2. the relative size of the cation(s) and anion(s),which
determines the type of interstitial site(s) for the
cation(s) in an anion lattice
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Rock salt structure(AX)(NaCl ) Fluorite structure(AX2)(CaF2)
Perovskite structure(ABX3)(BaTiO3) Spinel structure(AB2X4)(MgAl2O4)
http://www.eng.uwo.ca/es021/ES021b_2007/Lecture%20Notes/Chap%2012-13%20SN%20-%20Ceramics.pdf

9. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Ceramic Products
• Clay construction products - bricks, clay
pipe, and building tile
• Refractory ceramics ceramics capable of‑
high temperature applications such as
furnace walls, crucibles, and molds
• Cement used in concrete - used for
construction and roads
• Whiteware products - pottery, stoneware,
fine china, porcelain, and other tableware,

10. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Ceramic Products (continued)
• Glass bottles, glasses, lenses, window‑
pane, and light bulbs
• Glass fibers - thermal insulating wool,
reinforced plastics (fiberglass), and fiber
optics communications lines
• Abrasives - aluminum oxide and silicon
carbide
• Cutting tool materials - tungsten carbide,
aluminum oxide, and cubic boron nitride

11. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Ceramic Products (continued)
• Ceramic insulators applications include‑
electrical transmission components, spark
plugs, and microelectronic chip substrates
• Magnetic ceramics – example: computer
memories
• Nuclear fuels based on uranium oxide (UO2)
• Bioceramics - artificial teeth and bones

12. Dept of Mat Eng 12
CLAY PRODUCTS
-earthenware e.g. plant pot
(dirty red brown, very cheap,
opaque)
-stoneware e.g. coffee mug,
plate, bowl
(cheap, heavy, opaque)
earthenware stoneware porcelain bone china
-porcelain e.g. table wares
plate, souvenirs
(clean, light, translucency)
-bone china e.g. table wares,
souvenirs
(very clean, very expensive,
very good translucency,
light, mostly ivory colour)

13. Dept of Mat Eng 13
REFRACTORY
• A material to use in high temperature furnaces.
• Consider Silica (SiO2) - Alumina (Al2O3) system.
mullite, alumina, and crystobalite (made up of SiO2)
tetrahedra as candidate refractories.
Refractory

14. Dept of Mat Eng 14
• Glasses are non-
crystalline silicates
containing with other
oxides , e.g., CaO, Na2O,
K2O and Al2O3.
• Mostly glasses are
transparent and easy to
fabricate or form.
• Glass-ceramics are glasses
which are transformed to
crystalline state with fine
polycrystalline grains.
• High strength,
high thermal conductivity,
high thermal shock
resistance ,e.g., Pyrex
GLASS

15. Dept of Mat Eng 15
ABRASIVES
• Tools:
--for grinding and polishing
--for cutting
--for oil drilling
Abrasive bladesoil drill bits
• Solutions:
--coated single crystals or
polycrystalline diamonds or SiC or
corundum ( aluminum oxide) in a metal
or resin matrix. (blades)
--coated single or polycrystalline crystals
on paper or cloth. (sand paper)
--loose abrasive grains. (for polishing)
coated single
crystal diamonds
polycrystalline
diamonds in a
resin matrix.
•Because of their hardness,
high wear resistance,
high toughness

16. Whiteware:
 CrockeryCrockery
 Floor and wall tilesFloor and wall tiles
 Sanitary-wareSanitary-ware
 Electrical porcelainElectrical porcelain
 Decorative ceramicsDecorative ceramics

17. Cements
• Used to produce concrete roads, bridges,
buildings, dams.

18. 18
• Include point defects and impurities
• Non-stoichiometry refers to a change in composition
• the effect of non-stoichiometry is a redistribution of the
atomic charges to minimize the energy
• Charge neutral defects include the Frenkel defects(a
vacancy- interstitial pair of cations) and Schottky defects
(a pair of nearby cation and anion vacancies)
• Defects will appear if the charge of the impurities is not
balanced
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19. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Imperfections in
Crystal Structure of Ceramics
• Ceramics contain the same imperfections in
their crystal structure as metals vacancies,‑
displaced atoms, interstitialcies, and
microscopic cracks
• Internal flaws tend to concentrate stresses,
especially tensile, bending, or impact
– Hence, ceramics fail by brittle fracture much more
readily than metals
– Performance is much less predictable due to
random imperfections and processing variations

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• Extreme hardness
– High wear resistance
– Extreme hardness can reduce wear caused by friction
• Corrosion resistance
• Heat resistance
– Low electrical conductivity
– Low thermal conductivity
– Low thermal expansion
– Poor thermal shock resistance
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 Low ductility
– Very brittle
– High elastic modulus
 Low toughness
– Low fracture toughness
– Indicates the ability of a crack or flaw to produce a
catastrophic failure
 Low density
– Porosity affects properties
 High strength at elevated temperatures
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22. 22
Property Ceramic Metal Polymer
Hardness Very High Low Very Low
Elastic modulus Very High High Low
Thermal expansion High Low Very Low
Wear resistance High Low Low
Corrosion resistance High Low Low
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23. 23
Property Ceramic Metal Polymer
Ductility Low High High
Density Low High Very Low
Electrical conductivity Depends High Low
on material
Thermal conductivity Depends High Low
on material
Magnetic Depends High Very Low
on material
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• Traditional Ceramics
 the older and more generally known
types (porcelain, brick, earthenware,
etc.)
 Based primarily on natural raw
materials of clay and silicates
 Applications;
building materials (brick, clay pipe,
glass)
household goods (pottery, cooking
ware)
manufacturing ( abbrasives,
electrical devices, fibers) Traditional Ceramics

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• Advanced Ceramics
 have been developed over the past
half century
 Include artificial raw materials,
exhibit specialized properties,
require more sophisticated
processing
 Applied as thermal barrier coatings
to protect metal structures, wearing
surfaces,
 Engine applications (silicon nitride
(Si3N4), silicon carbide (SiC),
Zirconia (ZrO2), Alumina (Al2O3))
bioceramic implants

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• Oxides: Alumina, zirconia
• Non-oxides: Carbides, borides, nitrides, silicides
• Composites: Particulate reinforced, combinations of oxides and
non-oxides
CERAMIC
S
Oxides
Nonoxides
Composite

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• Oxide Ceramics:
 Oxidation resistant
 chemically inert
 electrically insulating
 generally low thermal conductivity
 slightly complex manufacturing
 low cost for alumina
 more complex manufacturing
higher cost for zirconia.
zirconia

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• Non-Oxide Ceramics:
 Low oxidation resistance
 extreme hardness
 chemically inert
 high thermal conductivity
 electrically conducting
 difficult energy dependent
manufacturing and high cost.
Silicon carbide cermic foam filter (CFS)
http://images.google.com.tr/imgres?imgurl=http://www.made-in-
china.com/image/2f0j00avNtpdFnLThyM/Silicon-Carbide-Ceramic-Foam-
Filter-CFS-.jpg&imgrefurl

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• Ceramic-Based Composites:
 Toughness
 low and high oxidation resistance
(type related)
 variable thermal and electrical
conductivity
 complex manufacturing processes
 high cost.
Ceramic Matrix Composite (CMC) rotor
http://images.google.com.tr/imgres?
imgurl=http://www.oppracing.com/images/cmsuploads/Large_Images/brakete
ch%2520cmc%2520rotor%2520oppracing%2520cbr1000rr.jpg&imgrefurl

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• Amorphous
 the atoms exhibit only short-range
order
 no distinct melting temperature (Tm)
for these materials as there is with
the crystalline materials
 Na20, Ca0, K2O, etc
Amorphous silicon and thin film PV cells
CERAMIC
S
amorphous
crystalline
http://images.google.com.tr/imgres?imgurl=http://simeonintl.com/sitebuilder/images/A-Si_Solar-
510x221.jpg&imgrefurl=http://simeonintl.com/Solar.html&usg=__ktCHUAO742PE0hh3U1fGw8go
PrM=&h=221&w=510&sz=17&hl=tr&start=68&sig2=9OC7pTtJz2SuK_AKdrqTAA&um=1&tbnid=x
QRh5yfCftf89M:&tbnh=57&tbnw=131&prev=/images%3Fq%3Damorphous%2Bceramic%26ndsp
%3D18%26hl%3Dtr%26rlz%3D1G1GGLQ_TRTR320%26sa%3DN%26start%3D54%26um
%3D1&ei=9Kv1SrTfAoej_gbrz6WtAw

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• Crystalline
 atoms (or ions) are arranged in a
regularly repeating pattern in three
dimensions (i.e., they have long-
range order)
 Crystalline ceramics are the
“Engineering” ceramics
– High melting points
– Strong
– Hard
– Brittle
– Good corrosion resistance
a ceramic (crystalline) and a glass (non-crystalline)

34. MECHANICAL PROPERTIES OF CERAMICS
STRESS-STRAIN BEHAVIUR of selected materials
Al2
O3
thermoplast
ic
http://www.keramvaerband.de/brevier_engl/5/5_2.htm
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35. MECHANICAL PROPERTIES OF CERAMICS
Flexural Strength
The stress at fracture using
this flexure test is known as
the flexural strength.
Flexure test :which a rod
specimen having either a
circular or rectangular cross
section is bent until fracture
using a three- or four-point
loading technique
Callister, W., D., (2007), Materials Science And Engineering, 7th Edition,
35
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36. For a rectangular cross section, the flexural strength σfs is equal to,
L is the distance between support points
When the cross section is circular,
R is the specimen radius
Stress is computed from,
• specimen thickness
•the bending moment
•the moment of inertia of the cross section
MECHANICAL PROPERTIES OF CERAMICS
Callister, W., D., (2007), Materials Science And Engineering, 7th
Edition,
36
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37. MECHANICAL PROPERTIES OF
CERAMICS
Callister, W., D., (2007), Materials Science And Engineering, 7th
Edition,
37
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38. MECHANICAL PROPERTIES OF CERAMICS
Hardness
Hardness implies a high
resistance to deformation and is
associated with a large modulus of
elasticity.
In metals, ceramics and most
polymers, the deformation
considered is plastic deformation of
the surface. For elastomers and
some polymers, hardness is defined
at the resistance to elastic
deformation of the surface.
Technical ceramic
components are therefore
characterised by their stiffness
and dimensional stability.
Hardness is affected from
porosity in the surface, the grain
size of the microstructure and the
effects of grain boundary phases.
http://www.dynacer.com/hardness.htm
http://www.keramvaerband.de/brevier_eng/5/3/%_3_5.htm
http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Hardness.htm
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39. Material Class Vickers Hardness (HV) GPa
Glasses 5 – 10
Zirconias, Aluminium Nitrides 10 - 14
Aluminas, Silicon Nitrides 15 - 20
Silicon Carbides, Boron
Carbides
20 - 30
Cubic Boron Nitride CBN 40 - 50
Diamond 60 – 70 >
Test procedures for determining the hardness according to Vickers,
Knoop and Rockwell.
Some typical hardness values for ceramic materials are provided below:
MECHANICAL PROPERTIES OF
CERAMICS
The high hardness of technical ceramics results in favourable wear resistance.
Ceramics are thus good for tribological applications.
http://www.dynacer.com/hardness.htm
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40. MECHANICAL PROPERTIES OF
CERAMICS
Elastic modulus
The elastic modulus E [GPa] of almost
all oxide and non-oxide ceramics is
consistently higher than that of steel.
This results in an elastic deformation of
only about 50 to 70 % of what is found
in steel components.
The high stiffness implies, however,
that forces experienced by bonded
ceramic/metal constructions must
primarily be taken up by the ceramic
material.
http://www.keramverband.de/brevier_engl/5/3/4/5_3_4.htm
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41. MECHANICAL PROPERTIES OF CERAMICS
Density
The density, ρ (g/cm³) of
technical ceramics lies
between 20 and 70% of the
density of steel.
The relative density, d [%],
has a significant effect on
the properties of the
ceramic.
http://www.keramverband.de/brevier_engl/5/3/4/5_3.htm
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42. MECHANICAL PROPERTIES OF CERAMICS
A comparison of typical mechanical characteristics of some ceramics with grey
cast-iron and construction steel
http://www.keramverband.de/brevier_engl/5/5_2.htm
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43. MECHANICAL PROPERTIES OF
CERAMICS
Porosity
Technical ceramic materials have
no open porosity.
Porosity can be generated through
the appropriate selection of raw
materials, the manufacturing
process, and in some cases
through the use of additives.
This allows closed and open pores
to be created with sizes from a few
nm up to a few µm. http://www.ucl.ac.uk/cmr/webpages/spotlight/articles/colombo.htm
Change in elastic modulus with the amount of
porosity in SiOC ceramic foams obtained from a
preceramic polymer
http://www.keramverband.de/brevier_engl/5/3/5_3_2.htm
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44. MECHANICAL PROPERTIES OF CERAMICS
Strength
The figure for the strength of
ceramic materials, [MPa] is
statistically distributed depending
on
•the material composition
•the grain size of the initial
material and the additives
•the production conditions
•the manufacturing process
Strength distribution within batches
http://www.keramverband.de/brevier_engl/5/3/3/5_3_3.htm
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45. MECHANICAL PROPERTIES OF CERAMICS
Toughness
Ability of material to resist
fracture
affected from,
•temperature
•strain rate
•relationship between the strenght
and ductility of the material and
presence of stress concentration
(notch) on the specimen surface
http://www.subtech.com/dokuwiki/doku.php?id=fracture_toughness
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46. MECHANICAL PROPERTIES OF
CERAMICS
Some typical values of
fracture toughness for
various materials
http://en.wikipedia.org/wiki/Fracture_toughness
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47. Stress-Strain Behaviour
0.00100.00080.00060.00040.00020.0000
0
100
200
300
Bending Strain
BendingStress,MPa
Aluminum Oxide
Soda-Lime Glass

48. Mechanical Properties of Various Ceramics
a
Sintered with about 5% porosity

49. Hardness of Ceramics

50. Effect of Porosity on Stiffness

51. Effect of Porosity on Strength

52. Fracture Toughness
Fracture Toughness (MPa√m)

53. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Compressive Strength of Ceramics
• The frailties that limit the tensile strength of
ceramic materials are not nearly so operative
when compressive stresses are applied
• Ceramics are substantially stronger in
compression than in tension
• For engineering and structural applications,
designers have learned to use ceramic
components so that they are loaded in
compression rather than tension or bending

54. ©2002 John Wiley & Sons,
Inc. M. P. Groover,
“Fundamentals of Modern
Methods to Strengthen Ceramic
Materials
• Make starting materials more uniform
• Decrease grain size in polycrystalline
ceramic products
• Minimize porosity
• Introduce compressive surface stresses
• Use fiber reinforcement
• Heat treat

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• Crushing &
Grinding (to get
ready ceramic powder
for shaping)
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• Ceramic powder is converted into a useful
shape at this step.
• Processing techniques
– Tape casting
– Slip casting
– Injection molding
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http://janereynoldsceramics.co.uk/images/ceramic1.jpg

58. 58
• Water must be removed from clay piece before
firing
• Shrinkage is a problem during drying. Because
water contributes volume to the piece, and the
volume is reduced when it is removed.
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REFERENCES
• http://www.azom.com/details.asp?ArticleID=2123
• www.accuratus.com/materials.html
• http://global.kyocera.com/fcworld/charact/heat/thermaexpan.html
• http://www.keramverband.de/brevier_engl/5/4/5_4.htm
• http://www.ts.mah.se/utbild/mt7150/051212%20ceramics.pdf
• http://www.virginia.edu/bohr/mse209/chapter13.htm
• http://ceramics.org/learn-about-ceramics/structure-and-properties-of-ceramics/
• http://www.keramverband.de/brevier_engl/5/5_1.htm
• http://me.queensu.ca/courses/MECH270/documents/Lecture20CeramicsA.pdf
• http://www.tarleton.edu/~tbarker/2033/Notes_Handouts/Powerpoint_notes/Cera
mic_Materials_Module_7.pdf
• http://users.encs.concordia.ca/~mmedraj/mech221/lecture%2018.pdf
• http://media-2.web.britannica.com/eb-media/85/1585-004-168972D1.gif
• http://global.kyocera.com/fcworld/first/process06.html