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Chapter 13 - 1
ISSUES TO ADDRESS...
• How are metal alloys classified and what are their common applications ?
Chapter 13: Types and Applications of Metals, Ceramics,
and Polymers
• How do we classify ceramics?
• What are some applications of ceramics?
• What are the various types/classifications of polymers?
Chapter 13 - 2
Adapted from Fig. 10.28, Callister & Rethwisch 3e. (Fig. 10.28 adapted from Binary Alloy Phase Diagrams, 2nd ed., Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.)
Adapted from Fig. 13.1, Callister & Rethwisch 3e.
Classification of Metal AlloysMetal Alloys
Steels
Ferrous Nonferrous
Cast Irons
<1.4wt%C 3-4.5wt%CSteels
<1.4 wt% CCast Irons3-4.5 wt% C
Fe3C
cementite
1600
1400
1200
1000
800
600
4000 1 2 3 4 5 6 6.7
L
gaustenite
g+L
g+Fe3Ca
ferritea+Fe3C
a+g
L+Fe3C
d
(Fe) Co , wt% C
Eutectic:
Eutectoid:0.76
4.30
727°C
1148°C
T(°C) microstructure: ferrite,graphite/cementite
Chapter 13 - 3Based on data provided in Tables 13.1(b), 13.2(b), 13.3, and 13.4, Callister & Rethwisch 3e.
Steels
Low Alloy High Alloy
low carbon <0.25 wt% C
Med carbon0.25-0.6 wt% C
high carbon 0.6-1.4 wt% C
Uses auto struc. sheet
bridges towers press. vessels
crank shafts bolts hammers blades
pistons gears wear applic.
wear applic.
drills saws dies
high T applic. turbines furnaces
Very corros. resistant
Example 1010 4310 1040 4340 1095 4190 304, 409
Additions noneCr,V Ni, Mo
noneCr, Ni Mo
noneCr, V, Mo, W
Cr, Ni, Mo
plain HSLA plainheat
treatableplain tool stainlessName
Hardenability 0 + + ++ ++ +++ variesTS - 0 + ++ + ++ variesEL + + 0 - - -- ++
increasing strength, cost, decreasing ductility
Chapter 13 - 4
Refinement of Steel from Ore
Iron OreCoke
Limestone
3CO + Fe2O3 ®2Fe+3CO2
C+O2 ®CO2
CO2 +C® 2CO
CaCO3 ® CaO+CO2
CaO + SiO2 + Al2O3 ® slag
purification
reduction of iron ore to metal
heat generation
Molten iron
BLAST FURNACE
slagair
layers of coke and iron ore
gasrefractory vessel
Chapter 13 - 5
Ferrous Alloys
Iron-based alloys
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 100example: 1060 steel – plain carbon steel with 0.60 wt% C
Stainless Steel -- >11% Cr
• Steels• Cast Irons
Chapter 13 - 6
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 () + C (graphite)
– generally a slow process
Chapter 13 - 7
Fe-C True Equilibrium Diagram
Graphite formation promoted by
• Si > 1 wt%
• slow cooling
Adapted from Fig. 13.2, Callister & Rethwisch 3e. [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.]
1600
1400
1200
1000
800
600
4000 1 2 3 4 90
L
g +L
+ Graphite
Liquid +Graphite
(Fe) C, wt% C
0.65
740°C
T(°C)
+ Graphite
100
1153°CgAustenite 4.2 wt% C
+ a g
Chapter 13 - 8
Types of Cast Iron
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
Adapted from Fig. 13.3(a) & (b), Callister & Rethwisch 3e.
Chapter 13 - 9
Types of Cast Iron (cont.)
White iron• < 1 wt% Si• pearlite + cementite• very hard and brittle
Malleable iron• heat treat white iron at 800-900ºC• graphite in rosettes• reasonably strong and ductile
Adapted from Fig. 13.3(c) & (d), Callister & Rethwisch 3e.
Chapter 13 -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.
Chapter 13 - 11
Production of Cast Irons
Adapted from Fig.13.5, Callister & Rethwisch 3e.
Chapter 13 -12
Limitations of Ferrous Alloys
1) Relatively high densities
2) Relatively low electrical conductivities
3) Generally poor corrosion resistance
Chapter 13 -13Based on discussion and data provided in Section 13.3, Callister & Rethwisch 3e.
Nonferrous Alloys
NonFerrous Alloys
• Al Alloys-low r: 2.7 g/cm3 -Cu, Mg, Si, Mn, Zn additions -solid sol. or precip. strengthened (struct.
aircraft parts & packaging)
• Mg Alloys-very low r: 1.7g/cm3 -ignites easily -aircraft, missiles
• Refractory metals-high melting T’s -Nb, Mo, W, Ta• Noble metals
-Ag, Au, Pt -oxid./corr. resistant
• Ti Alloys-relatively low r: 4.5 g/cm3
vs 7.9 for steel -reactive at high T’s -space applic.
• Cu AlloysBrass: 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
Chapter 13 -14
Glasses Clay products
Refractories Abrasives Cements Advanced ceramics
-optical -composite reinforce -containers/ household
-whiteware -structural
-bricks for high T (furnaces)
-sandpaper -cutting -polishing
-composites -structural
-engine rotors valves bearings
-sensorsAdapted from Fig. 13.7 and discussion in Section 13.4-10, Callister & Rethwisch 3e.
Classification of Ceramics
Ceramic Materials
Chapter 13 -15
tensile force
AoAddie
die
• 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.
Adapted from Fig. 14.2 (d), Callister & Rethwisch 3e.
Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission.
Ceramics Application: Die Blanks
Chapter 13 -16
• Tools: -- for grinding glass, tungsten, carbide, ceramics -- for cutting Si wafers -- for oil drilling
bladesoil drill bits
Single crystal diamonds
polycrystallinediamonds in a resinmatrix.
Photos courtesy Martin Deakins,GE Superabrasives, Worthington,OH. Used with permission.
Ceramics Application: Cutting Tools
• Materials:-- manufactured single crystal or polycrystalline diamonds in a metal or resin matrix.
-- polycrystalline diamonds resharpen by microfracturing along cleavage planes.
Chapter 13 -17
• Example: ZrO2 as an oxygen sensor
• Principle: Increase diffusion rate of oxygen to produce rapid response of sensor signal to change in oxygen concentration
Ceramics Application: Sensors
A substituting Ca2+ ion
removes a Zr 4+ ion and
an O2- ion.
Ca2+
• Approach: Add Ca impurity to ZrO2: -- increases O2- vacancies
-- increases O2- diffusion rate
reference gas at fixed oxygen content
O2-
diffusion
gas with an unknown, higher oxygen content
-+voltage difference produced!
sensor• 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
Chapter 13 -18
• 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):
Fig. 10.26, Callister & Rethwisch 3e. (Fig. 10.26 adapted from F.J. Klug and R.H. Doremus, J. Am. Cer. Soc. 70(10), p. 758, 1987.)
Refractories
Composition (wt% alumina)
T(°C)
1400
1600
1800
2000
2200
20 40 60 80 1000
alumina +
mullite
mullite + L
mulliteLiquid
(L)
mullite + crystobalite
crystobalite + L
alumina + L
3Al2O3-2SiO2
Chapter 13 -19
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 -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
Chapter 13 -2121
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 -2222
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 -2323
Advanced Polymers
• 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.
Ultrahigh Molecular Weight Polyethylene (UHMWPE)
Chapter 13 -2424
Advanced Polymers
styrene
butadiene
Thermoplastic Elastomers
Styrene-butadiene block copolymer
hard component
domain
soft component
domain
Fig. 13.14, Callister & Rethwisch 3e. (Fig. 13.14 adapted from the Science and Engineering of Materials, 5th Ed., D.R. Askeland and P.P. Phule, Thomson Learning, 2006.)
Fig. 13.13(a), Callister & Rethwisch 3e.
Chapter 13 -25
• 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
Summary
• Polymer applications -- elastomers -- fibers
-- coatings -- adhesives
-- films -- foams
-- advanced polymeric materials
Chapter 13 -26
Core Problems:
Self-help Problems:
ANNOUNCEMENTS
Reading: