Transcript Chapter 13: Types and Applications of Materials

Chapter 13: 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?
Chapter 13 - 1
Classification of Metal Alloys
Metal Alloys
Ferrous
Steels
Steels
<1.4wt%C
<1.4
wt% C
Nonferrous
Cast Irons
Cast
Irons
3-4.5
wt%C
3-4.5 wt% C
microstructure: ferrite,
graphite/cementite
T(ºC)
1600
d
L
1400
1200
g
austenite
g+L
a800
ferrite
600
0
(Fe)
L+Fe3C
1148ºC
4.30
1000
400
Adapted from Fig.
13.1, Callister &
Rethwisch 4e.
727ºC
Eutectoid:
0.76
1
2
Eutectic:
g+Fe3C
Fe3C
cementite
a+Fe3C
3
4
Adapted from Fig. 10.28, Callister &
Rethwisch 4e. (Fig. 10.28 adapted
from Binary Alloy Phase Diagrams,
2nd ed., Vol. 1, T.B. Massalski (Ed.-inChief), ASM International, Materials
Park, OH, 1990.)
5
6
Co , wt% C
6.7
Chapter 13 - 2
Steels
High Alloy
Low Alloy
low carbon Med carbon
<0.25 wt% C 0.25-0.6wt% C
high carbon
0.6-1.4wt% C
heat
plain
treatable
Cr,V
Cr, Ni
Additions none
none
none
Ni, Mo
Mo
Example 1010 4310
1040
4340 1095
Hardenability 0
+
+
++
++
TS
0
+
++
+
EL
+
+
0
Name
plain
Uses
auto
struc.
sheet
HSLA
bridges
towers
press.
vessels
plain
crank
shafts
bolts
hammers
blades
pistons
gears
wear
applic.
wear
applic.
tool
Cr, V,
Mo, W
4190
+++
++
-drills
saws
dies
increasing strength, cost, decreasing ductility
Based on data provided in Tables 13.1(b), 13.2(b), 13.3, and 13.4, Callister & Rethwisch 4e.
stainless
Cr, Ni, Mo
304, 409
varies
varies
++
high T
applic.
turbines
furnaces
Very corros.
resistant
Chapter 13 - 3
Refinement of Steel from Ore
Coke
Iron Ore
gas
refractory
vessel
layers of coke
and iron ore
air
slag
Molten iron
Limestone
BLAST FURNACE
heat generation
C+O2 CO2
reduction of iron ore to metal
CO2 + C  2CO
3CO + Fe2O3 2Fe+3CO2
purification
CaCO3  CaO+CO2
CaO + SiO2 + Al2O3  slag
Chapter 13 - 4
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 (1.00 - 1.65%)
40xx Mo (0.20 ~ 0.30%)
43xx Ni (1.65 - 2.00%), Cr (0.40 - 0.90%), Mo (0.20 - 0.30%)
44xx Mo (0.5%)
where xx is wt% C x 100
example: 1060 steel – plain carbon steel with 0.60 wt% C
Stainless Steel >11% Cr
Chapter 13 - 5
Cast Irons
• Ferrous alloys with > 2.1 wt% C
– more commonly 3 - 4.5 wt% C
• Low melting – relatively easy to cast
• Generally brittle
• Cementite decomposes to ferrite + graphite
Fe3C  3 Fe (a) + C (graphite)
– generally a slow process
Chapter 13 - 6
Fe-C True Equilibrium Diagram
T(°C)
1600
Graphite formation
promoted by
1400
• Si > 1 wt%
1200
• slow cooling
L
g
Austenite
Liquid +
Graphite
g +L
1153°C
4.2 wt% C
1000
g + Graphite
a+g
800
0.65
740°C
600
Adapted from Fig. 13.2,
Callister & Rethwisch 4e.
[Fig. 13.2 adapted from
Binary Alloy Phase
Diagrams, 2nd ed.,
Vol. 1, T.B. Massalski (Ed.in-Chief), ASM International,
Materials Park, OH, 1990.]
400
(Fe)
a + Graphite
0
1
2
3
4
90
C, wt% C
Chapter 13 - 7
100
Types of Cast Iron
Adapted from Fig.
13.3(a) & (b),
Callister &
Rethwisch 4e.
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
Chapter 13 - 8
Types of Cast Iron (cont.)
White iron
• < 1 wt% Si
• pearlite + cementite
• very hard and brittle
Adapted from Fig.
13.3(c) & (d),
Callister &
Rethwisch 4e.
Malleable iron
• heat treat white iron at 800-900ºC
• graphite in rosettes
• reasonably strong and ductile
Chapter 13 - 9
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 4e.
Chapter 13 - 10
Production of Cast Irons
Adapted from Fig.13.5,
Callister & Rethwisch 4e.
Chapter 13 - 11
Limitations of Ferrous Alloys
1) Relatively high densities
2) Relatively low electrical conductivities
3) Generally poor corrosion resistance
Chapter 13 - 12
Nonferrous Alloys
• Cu Alloys
• Al Alloys
-low r: 2.7 g/cm3
Brass: Zn is subst. impurity
(costume jewelry, coins,
-Cu, Mg, Si, Mn, Zn additions
corrosion resistant)
-solid sol. or precip.
Bronze : Sn, Al, Si, Ni are
strengthened (struct.
subst. impurities
aircraft parts
(bushings, landing
& packaging)
gear)
• Mg Alloys
NonFerrous
Cu-Be:
-very low r: 1.7g/cm3
Alloys
precip. hardened
-ignites easily
for strength
-aircraft, missiles
• Ti Alloys
• Refractory metals
-relatively low r: 4.5 g/cm3
-high melting T’s
vs 7.9 for steel
• Noble metals -Nb, Mo, W, Ta
-reactive at high T’s -Ag, Au, Pt
-oxid./corr. resistant
-space applic.
Based on discussion and data provided in Section 13.3, Callister & Rethwisch 4e.
Chapter 13 - 13
Classification of Ceramics
Ceramic Materials
Glasses
Clay Refractories
products
Abrasives Cements
Advanced
ceramics
-optical
-whiteware -bricks for -sandpaper -composites -engine
-composite -structural high T
-cutting
-structural
rotors
(furnaces) -polishing
reinforce
valves
-containers/
bearings
Adapted from Fig. 13.7 and discussion in
-sensors
household
Section 13.4-10, Callister & Rethwisch 4e.
Chapter 13 - 14
Ceramics Application: Die Blanks
• Die blanks:
-- Need wear resistant properties!
• 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.
die
Ao
die
Ad
tensile
force
Adapted from Fig. 14.2(d),
Callister & Rethwisch 4e.
Courtesy Martin Deakins, GE
Superabrasives, Worthington,
OH. Used with permission.
Chapter 13 - 15
Ceramics Application:
Cutting Tools
• 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.
-- polycrystalline diamonds
resharpen by microfracturing
along cleavage planes.
oil drill bits
blades
Single crystal
diamonds
polycrystalline
diamonds in a resin
matrix.
Photos courtesy Martin Deakins,
GE Superabrasives, Worthington,
OH. Used with permission.
Chapter 13 - 16
Ceramics Application: Sensors
• Example: ZrO2 as an oxygen sensor
Ca 2+
• Principle: Increase diffusion rate of oxygen
to produce rapid response of sensor signal to
change in oxygen concentration
• Approach:
A substituting Ca2+ ion
removes a Zr 4+ ion and
an O2- ion.
Add Ca impurity to ZrO2:
-- increases O2- vacancies
-- increases O2- diffusion rate
• Operation:
-- voltage difference produced when
sensor
gas with an
reference
O2- ions diffuse from the external unknown, higher
gas at fixed
O2surface through the sensor to the oxygen content
oxygen content
diffusion
reference gas surface.
-- magnitude of voltage difference
 partial pressure of oxygen at the
+
voltage
difference
produced!
external surface
Chapter 13 - 17
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):
2200
T(°C)
2000
3Al2O3-2SiO2
Liquid
(L)
1800
mullite
alumina + L
mullite
+L
crystobalite
+L
1600
1400
mullite
+ crystobalite
0
20
alumina
+
mullite
40
60
80
100
Composition (wt% alumina)
Fig. 10.26, Callister &
Rethwisch 4e. (Fig. 10.26
adapted from F.J. Klug and
R.H. Doremus, J. Am. Cer.
Soc. 70(10), p. 758, 1987.)
Chapter 13 - 18
Advanced Ceramics:
Materials for Automobile Engines
• Advantages:
– Operate at high
temperatures – high
efficiencies
– Low frictional losses
– Operate without a cooling
system
– Lower weights than
current engines
• Disadvantages:
– Ceramic materials are
brittle
– Difficult to remove internal
voids (that weaken
structures)
– Ceramic parts are difficult
to form and machine
• Potential candidate materials: Si3N4, SiC, & ZrO2
• Possible engine parts: engine block & piston coatings
Chapter 13 - 19
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
Chapter 13 - 20
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
Chapter 13 - 21
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:
1. Secondary – van der Waals forces
2. Mechanical – penetration into pores/crevices
•
•
Films – produced by blown film extrusion
Foams – gas bubbles incorporated into plastic
Chapter 13 - 22
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
UHMWPE
• Important applications
– bullet-proof vests
– golf ball covers
– hip implants (acetabular cup)
Adapted from chapteropening photograph,
Chapter 22, Callister 7e.
Chapter 13 - 23
Advanced Polymers
Thermoplastic Elastomers
Styrene-butadiene block copolymer
hard
component
domain
styrene
butadiene
Fig. 13.13(a), Callister &
Rethwisch 4e.
soft
component
domain
Fig. 13.14, Callister & Rethwisch 4e. (Fig. 13.14
adapted from the Science and Engineering of
Materials, 5th Ed., D.R. Askeland and P.P.
Phule, Thomson Learning, 2006.)
Chapter 13 - 24
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
Chapter 13 - 25
ANNOUNCEMENTS
Reading:
Core Problems:
Self-help Problems:
Chapter 13 - 26