1. Chapter 11: Types and Applications of Materials
ISSUES TO ADDRESS...
• How are metal alloys classified and what are their common applications ?
• How do we classify ceramics?
• What are some applications of ceramics?
• What are the various types/classifications of polymers?

2. Classification of Metal Alloys
Adapted from Fig. 13.1, Callister & Rethwisch 3e.
Ferrous
Nonferrous
Steels
<1.4 wt% C
Steels
Cast Irons
3-4.5 wt% C
Cast Irons
<1.4wt%C
3-4.5
wt%C
microstructure: ferrite,
graphite/cementite Fe 3 C
cementite
1600
1400
1200
1000
800
600
400 1 2 4 5 6
6.7 L g
austenite +L
+Fe3C a
ferrite +
L+Fe3C d
(Fe)
Co , wt% C
Eutectic:
Eutectoid:
0.76
4.30
727°C
1148°C
T(°C)
Adapted from Fig , Callister & Rethwisch 3e. (Fig adapted from Binary Alloy Phase Diagrams, 2nd ed., Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.)

3. Steels Low Alloy High Alloy low carbon <0.25 wt% C Med carbon
high carbon
wt% C
plain
HSLA
heat
treatable
tool
stainless
Name
Additions
none
Cr,V
Ni, Mo
Cr, Ni Mo
Cr, V,
Mo, W
Cr, Ni, Mo
Example
1010
4310
1040 43 40
1095
4190
304, 409
Hardenability + ++
+++
varies TS - + ++
varies EL + + - - -- ++
Uses
auto
bridges
crank
pistons
wear
drills
high T
struc.
towers
shafts
gears
applic.
saws
applic.
sheet
press.
bolts
wear
dies
turbines
vessels
hammers
applic.
furnaces
increasing strength, cost, decreasing ductility
blades
Very corros.
resistant
Based on data provided in Tables 13.1(b), 13.2(b), 13.3, and 13.4, Callister & Rethwisch 3e.

4. Refinement of Steel from Ore
Iron Ore
Coke
Limestone
3CO +
Fe2O3
2Fe
+3CO2 C + O2
CO2
2CO
CaCO3
CaO+CO2
CaO + SiO2 + Al2O3
slag
purification
reduction of iron ore to metal
heat generation
Molten iron
BLAST FURNACE
air
layers of coke
and iron ore
gas
refractory
vessel

5. Ferrous Alloys Iron-based alloys • Steels • Cast Irons
Nomenclature for steels (AISI/SAE)
10xx Plain Carbon Steels
11xx Plain Carbon Steels (resulfurized for machinability)
15xx Mn ( %)
40xx Mo (0.20 ~ 0.30%)
43xx Ni ( %), Cr ( %), Mo ( %)
44xx Mo (0.5%)
where xx is wt% C x 100
example: steel – plain carbon steel with 0.60 wt% C
Stainless Steel -- >11% Cr
• Steels
• Cast Irons

6. Cast Irons Ferrous alloys with > 2.1 wt% C
more commonly wt% C
Low melting – relatively easy to cast
Generally brittle
Cementite decomposes to ferrite + graphite
Fe3C  3 Fe () + C (graphite)
generally a slow process
So phase diagram for this system is different (Fig 12.4)

7. Fe-C True Equilibrium Diagram
1600
1400
1200
1000
800
600
400 1 2 3 4 90 L g +L
 + Graphite
Liquid +
Graphite
(Fe)
C, wt% C
0.65
740°C
T(°C)
 + Graphite
100
1153°C
Austenite
4.2 wt% C
a + g
Graphite formation promoted by
Si > 1 wt%
slow cooling
Cast irons have graphite
Adapted from Fig. 13.2, Callister & Rethwisch 3e.
[Fig adapted from Binary Alloy Phase Diagrams, 2nd ed.,
Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.]

8. Types of Cast Iron Gray iron graphite flakes weak & brittle in tension
Adapted from Fig. 13.3(a) & (b), Callister & Rethwisch 3e.
Gray iron
graphite flakes
weak & brittle in tension
stronger in compression
excellent vibrational dampening
wear resistant
Ductile iron
add Mg and/or Ce
graphite as nodules not flakes
matrix often pearlite – stronger but less ductile

9. Types of Cast Iron (cont.)
Adapted from Fig. 13.3(c) & (d), Callister & Rethwisch 3e.
White iron
< 1 wt% Si
pearlite + cementite
very hard and brittle
Malleable iron
heat treat white iron at ºC
graphite in rosettes
reasonably strong and ductile

10. Types of Cast Iron (cont.)
Compacted graphite iron
relatively high thermal conductivity
good resistance to thermal shock
lower oxidation at elevated temperatures
Adapted from Fig. 13.3(e), Callister & Rethwisch 3e.

11. Production of Cast Irons
Adapted from Fig.13.5, Callister & Rethwisch 3e.

12. Limitations of Ferrous Alloys
Relatively high densities
Relatively low electrical conductivities
Generally poor corrosion resistance

13. Nonferrous Alloys NonFerrous Alloys • Cu Alloys • Al Alloys
Brass: Zn is subst. impurity
(costume jewelry, coins,
corrosion resistant)
Bronze
: Sn, Al, Si, Ni are
subst. impurities
(bushings, landing
gear)
Cu-Be :
precip. hardened
for strength
• Al Alloys
-low r: 2.7 g/cm3
-Cu, Mg, Si, Mn, Zn additions
-solid sol. or precip.
strengthened (struct.
aircraft parts
& packaging)
NonFerrous
Alloys
• Mg Alloys
-very low r
: 1.7g/cm3
-ignites easily -
aircraft, missiles
• Ti Alloys
-relatively low r: 4.5 g/cm3
vs 7.9 for steel
-reactive at high T’s -
space applic.
• Refractory metals
-high melting T’s
-Nb, Mo, W, Ta
• Noble metals
-Ag, Au, Pt -
oxid./corr. resistant
Based on discussion and data provided in Section 13.3, Callister & Rethwisch 3e.

14. Classification of Ceramics
Ceramic Materials
Glasses
Clay
products
Refractories
Abrasives
Cements
Advanced
ceramics
-optical -
composite
reinforce
containers/
household
-whiteware
structural
-bricks for
high T
(furnaces)
-sandpaper
cutting
polishing
-composites
-engine
rotors
valves
bearings
-sensors
Adapted from Fig and discussion in Section , Callister & Rethwisch 3e.

15. Ceramics Application: Die Blanks
-- Need wear resistant properties!
tensile
force A o d
die
• Die surface:
-- 4 mm polycrystalline diamond
particles that are sintered onto a
cemented tungsten carbide
substrate.
-- polycrystalline diamond gives uniform
hardness in all directions to reduce wear.
Adapted from Fig (d), Callister & Rethwisch 3e.
Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission.

16. Ceramics Application: Cutting Tools
-- for grinding glass, tungsten,
carbide, ceramics
-- for cutting Si wafers
-- for oil drilling
• Materials:
-- manufactured single crystal or polycrystalline diamonds
in a metal or resin matrix.
oil drill bits
blades
Single crystal diamonds
-- polycrystalline diamonds
resharpen by microfracturing
along cleavage planes.
polycrystalline
diamonds in a resin
matrix.
Photos courtesy Martin Deakins,
GE Superabrasives, Worthington,
OH. Used with permission.

17. Ceramics Application: Sensors
A substituting Ca2+ ion
removes a Zr 4+ ion and
an O2- ion. Ca 2+
• Example: ZrO2 as an oxygen sensor
• Principle: Increase diffusion rate of oxygen to produce rapid response of sensor signal to change in oxygen concentration
• Approach:
Add Ca impurity to ZrO2:
-- increases O2- vacancies
-- increases O2- diffusion rate
• Operation:
-- voltage difference produced when O2- ions diffuse from the external surface through the sensor to the reference gas surface magnitude of voltage difference  partial pressure of oxygen at the external surface
reference
gas at fixed
oxygen content O 2-
diffusion
gas with an
unknown, higher - +
voltage difference produced!
sensor

18. Refractories
• Materials to be used at high temperatures (e.g., in high temperature furnaces).
• Consider the Silica (SiO2) - Alumina (Al2O3) system.
• Silica refractories - silica rich - small additions of alumina depress melting temperature (phase diagram):
Composition (wt% alumina)
T(°C)
1400
1600
1800
2000
2200 20 40 60 80
100
alumina +
mullite
+ L
Liquid
(L)
crystobalite
alumina + L
3Al2O3-2SiO2
Fig , Callister & Rethwisch 3e. (Fig adapted from F.J. Klug and R.H. Doremus, J. Am. Cer. Soc. 70(10), p. 758, 1987.)

19. Advanced Ceramics: Materials for Automobile Engines
Disadvantages:
Ceramic materials are brittle
Difficult to remove internal voids (that weaken structures)
Ceramic parts are difficult to form and machine
Advantages:
Operate at high temperatures – high efficiencies
Low frictional losses
Operate without a cooling system
Lower weights than current engines
Potential candidate materials: Si3N4, SiC, & ZrO2
Possible engine parts: engine block & piston coatings

20. Advanced Ceramics: Materials for Ceramic Armor
Components:
-- Outer facing plates
-- Backing sheet
Properties/Materials:
-- Facing plates -- hard and brittle
— fracture high-velocity projectile — Al2O3, B4C, SiC, TiB2
-- Backing sheets -- soft and ductile — deform and absorb remaining energy — aluminum, synthetic fiber laminates

21. Polymer Types – Fibers Fibers - length/diameter >100
Primary use is in textiles.
Fiber characteristics:
high tensile strengths
high degrees of crystallinity
structures containing polar groups
Formed by spinning
extrude polymer through a spinneret (a die containing many small orifices)
the spun fibers are drawn under tension
leads to highly aligned chains - fibrillar structure 21 21

22. Polymer Types – Miscellaneous
Coatings – thin polymer films applied to surfaces – i.e., paints, varnishes
protects from corrosion/degradation
decorative – improves appearance
can provide electrical insulation
Adhesives – bonds two solid materials (adherands)
bonding types:
Secondary – van der Waals forces
Mechanical – penetration into pores/crevices
Films – produced by blown film extrusion
Foams – gas bubbles incorporated into plastic 22 22

23. Advanced Polymers Ultrahigh Molecular Weight Polyethylene (UHMWPE)
Molecular weight ca. 4 x 106 g/mol
Outstanding properties
high impact strength
resistance to wear/abrasion
low coefficient of friction
self-lubricating surface
Important applications
bullet-proof vests
golf ball covers
hip implants (acetabular cup)
UHMWPE
Adapted from chapter-opening photograph, Chapter 22, Callister 7e. 23 23

24. Advanced Polymers Thermoplastic Elastomers
Styrene-butadiene block copolymer
hard component domain
styrene
soft component domain
butadiene
Fig (a), Callister & Rethwisch 3e.
Fig , Callister & Rethwisch 3e. (Fig adapted from the Science and Engineering of Materials, 5th Ed., D.R. Askeland and P.P. Phule, Thomson Learning, 2006.) 24

25. Summary • Ferrous alloys: steels and cast irons • Non-ferrous alloys:
-- Cu, Al, Ti, and Mg alloys; refractory alloys; and noble metals.
• Categories of ceramics:
-- glasses clay products
-- refractories cements
-- advanced ceramics
• Polymer applications
-- elastomers -- fibers
-- coatings -- adhesives
-- films -- foams
-- advanced polymeric materials