first lesson ceramics introduction
TRANSCRIPT
-
7/28/2019 First lesson Ceramics Introduction
1/28
1
Definition of ceramicsDefinition of ceramics
from the Greek word keramikos burntstuff; desirable properties are normally
achieved through a high-temperature heattreatment process called firing orsintering
Source: http://www.alphafiredarts.com/claystudio.html
-
7/28/2019 First lesson Ceramics Introduction
2/28
2
Traditional CeramicsTraditional Ceramics
Source: http://203.148.253.29/annaart/
Source:http://www.aqualon.ashland.com/industries/Specialties_S
olutions/Applications/Ceramics/Traditional_Ceramics_and
_Glazes.aspx
Source:
http://www.indiamart.com/topma
rble-granite/building-hardware.html
-
7/28/2019 First lesson Ceramics Introduction
3/28
3
Definition of ceramicsDefinition of ceramics
solid compounds that are formed by theapplication ofheat, and sometimes heat andpressure, comprising:
a. at least one nonmetal or a nonmetallicelemental solid (NMES) and
b. One or more of a metal/s, nonmetal or
NMES/s
Ex. SiO2 (silica), TiO2, SiC, BaTiO3, YBa2Cu3O7,Ti3SiC2
*Oxides, nitrides, borides, carbides and silicides
of all metals and NMES are ceramics. Silicates
are also, by definition, ceramics.
-
7/28/2019 First lesson Ceramics Introduction
4/28
4
Engineering/Engineered CeramicsEngineering/Engineered Ceramics
Source:
http://www.newworldencyclopedia.or
g/entry/Image:Shuttle_STS-45.jpg
Source:
http://www.avure.com/iso/applic
ations/advanced-ceramics.asp
Source: http://www.hannongroup.com/
Source: http://www.amazon.com/Ceramic-
Hex-Bolt-Length-Pack/dp/B000FN1DVW
-
7/28/2019 First lesson Ceramics Introduction
5/28
5
General properties of ceramics:General properties of ceramics:
1. generally stiff and strong (comparable tometals)
2. very hard3. extremely brittle and susceptible to fracture
4. insulative to heat and electricity
5. more resistant to high temperatures andharsh environments (compared to metals
and polymers)6. may be transparent, translucent or opaque
-
7/28/2019 First lesson Ceramics Introduction
6/28
6
RoomRoom--temperature elastic modulus comparisontemperature elastic modulus comparison
-
7/28/2019 First lesson Ceramics Introduction
7/28
7
RoomRoom--temperature tensile strength comparisontemperature tensile strength comparison
-
7/28/2019 First lesson Ceramics Introduction
8/28
8
RoomRoom--temperature electrical conductivity comparisontemperature electrical conductivity comparison
-
7/28/2019 First lesson Ceramics Introduction
9/28
9
Optical propertyOptical property
Disk specimens of aluminum oxide (Al2O3)
-
7/28/2019 First lesson Ceramics Introduction
10/28
10
Crystalline vs. amorphous solidsCrystalline vs. amorphous solids
Crystalline solid
solids that exhibit long-range order
Amorphous, glassy or noncrystalline solid solids which lack periodicity
-
7/28/2019 First lesson Ceramics Introduction
11/28
11
Basic terminologiesBasic terminologies
Single crystal
solids in which the periodic arrangement of atomsis perfect and extends throughout the entirety of thespecimen without interruption
Polycrystalline solid
composed of a collection of many single crystals,termed grains, separated from one another byareas of disorder known as grain boundaries
Microstructure
describes the shape and size of the grains,together with the presence of porosity, second
phases, etc., and their distribution
-
7/28/2019 First lesson Ceramics Introduction
12/28
12
-
7/28/2019 First lesson Ceramics Introduction
13/28
13
Bonding in ceramicsBonding in ceramics
atomic bonding ranges from purely ionic to totallycovalent (degree depends on theelectronegativities, X of the atoms)
( )( ) 10025.0exp1% 2 = BA XXcharacterionic
-
7/28/2019 First lesson Ceramics Introduction
14/28
14
Ceramic crystal structuresCeramic crystal structures
for predominantly ionic materials, crystalstructure is composed of metallic cationsand nonmetallic anions
characteristics of the component ions whichinfluence the crystal structure:
a. magnitude of the electrical charge (crystalmust be electrically neutral)
b. relative sizes of cations, rC and anions, rA
stable ceramic structures: anionssurrounding a cation are in contact with thatcation
-
7/28/2019 First lesson Ceramics Introduction
15/28
15
Ceramic crystal structuresCeramic crystal structures
for a specific coordination number, there is acritical rC/rA ratio for which cation-anion contact isestablished
-
7/28/2019 First lesson Ceramics Introduction
16/28
16
-
7/28/2019 First lesson Ceramics Introduction
17/28
17
Most common coordination numbers for ceramics
are 4, 6 or 8.
-
7/28/2019 First lesson Ceramics Introduction
18/28
18
Sample problemSample problem
Show that the minimum cation-to-anion radiusratio for the coordination number 3 is 0.155
-
7/28/2019 First lesson Ceramics Introduction
19/28
21
AXAX--Type crystal structuresType crystal structures
equal number of cations and anions
Rock salt structure
- cation and anion CN is 6
- thought of as two
interpenetrating FCC lattices- ex. NaCl, MgO, MnS, LiF,and FeO
-
7/28/2019 First lesson Ceramics Introduction
20/28
22
AXAX--Type crystal structuresType crystal structures
Cesium Chloride structure
- cation and anion CN is 8- anions: cube corners;
cation: cube center
- ex. CsCl
-
7/28/2019 First lesson Ceramics Introduction
21/28
23
AXAX--Type crystal structuresType crystal structures
Zinc blende structure
- cation and anion CN is 4(all ions are tetrahedrallycoordinated)
- bonding is often highlycovalent
- ex. ZnS, ZnTe, SiC
-
7/28/2019 First lesson Ceramics Introduction
22/28
24
AAmmXXpp --Type crystal structuresType crystal structures
when cation and anion
charges are not the same AmXp, where m and/or p
1 CN = 8 ex. CaF2, UO2, PuO2, and
ThO2
-
7/28/2019 First lesson Ceramics Introduction
23/28
25
AAmmBBnnXXpp --Type crystal structuresType crystal structures
for compounds with two
types of cations
ex. BaTiO3 (perovskitestructure)
-
7/28/2019 First lesson Ceramics Introduction
24/28
26
-
7/28/2019 First lesson Ceramics Introduction
25/28
27
CloseClose--packed anion structurepacked anion structure
Ceramic crystal structures depend on:
stacking of the close-packed anion layers
manner in which the interstitial sites are filled withcations
-
7/28/2019 First lesson Ceramics Introduction
26/28
28
Sample problemSample problem
On the basis of ionic radii, what crystalstructure would you predict for FeO?
-
7/28/2019 First lesson Ceramics Introduction
27/28
-
7/28/2019 First lesson Ceramics Introduction
28/28
32
Sample problemSample problem
On the basis of crystal structure, compute thetheoretical density for sodium chloride.