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:

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