ems test 3.pdf

Chapter 11 -

Reminders

Exam II: Wednesday March 25th

Quiz: Wednesday March 18th

Material: Chapters 6 - 10

1

Chapter 11 -

ISSUES TO ADDRESS...

Chapter 11: Applications and Processing of Metal Alloys

How are commercial alloys classified and what are their common applications? What are some of the common fabrication techniques

for metals? How do they alter the properties? What heat treatment procedures are used to improve the

mechanical properties of both ferrous and nonferrousalloys?

2

Chapter 11 -Fig_11-1

Chapter 11 -

How much steel is produced in the US?

A. 5,000 metric tonsB. 100,000 metric tonsC. 1 million metric tonsD. 5 million metric tonsE. 100 million metric tons

Chapter 11 -

Chapter 11 -americanresources.org

Chapter 11 -

World primary Titanium sponge production volumes increased by 11% to 222 thousand tons in 2013 compared with production in 2012. New production capacities are to be introduced by Ukraine and Canada. Commercial aerospace industry supports the market with high demand for titanium. In Singapore, on the contrary, a TiO2 plant was closed in 2013 due to high prices and sluggish distribution channels.

http://mcgroup.co.uk/researches/titanium

Chapter 11 -

Wide spread use of steel due to:

iron-containing compounds are abundantin the Earths crust

Relatively economical extraction, refining, alloying and fabrication

Ferrous alloys are extremely versatile

Disadvantage: corrosiondensity

Sao Francisco Craton, Minas Gerais, Brazil8

Chapter 11 -

Chapter 11 -

Adapted from Fig. 11.1, Callister & Rethwisch 9e.

Classification of Metal AlloysMetal Alloys

Steels

Ferrous Nonferrous

Cast Irons

Chapter 11 -Based on data provided in Tables 11.1(b), 13.2(b), 11.3, and 11.4, Callister & Rethwisch 9e.

SteelsLow Alloy High Alloy

low carbon

Chapter 11 -

Ferrous AlloysIron-based alloys

Nomenclature for steels (AISI/SAE)10xx Plain Carbon Steels11xx 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

13

PresenterPresentation NotesSAE: Society of automotive engineersAISI: The American Iron and Steel Insititute

Chapter 11 -

Ferrous Alloys:Advanced High Strength Steels (AHSS)

AISI: www.steel.org (2006)14

PresenterPresentation NotesSAE: Society of automotive engineersAISI: The American Iron and Steel Insititute

Chapter 11 -

Typical: C: 0.05 - 0.15 Mn: 1.0 2.0Others: Si, Cr, Ni, Mo, Nb, V

0.15C, 1.5 Mn, 1.5 SiWQ from 775oC

V 9 %; C 0.45

V 30 %; C 0.17

C = 0.06

810 oC

750 oC

A.De et al. Adv. Mat. Proc. 2003

Dual Phase Steels

Ferrite-martensitemicrostructures

Chapter 11 -

Davies (1978)

Strengthening in DP Steels

Strength increase follows rule of mixtures for composites: T = Vff + VMM

16

Chapter 11 -

Cast Irons Ferrous alloys with > 2.14 wt% C

more commonly 3 - 4.5 wt% C Low melting relatively easy to cast Generally brittle Cementite is a metastable compound, it can

decompose to ferrite + graphiteFe3C 3 Fe () + C (graphite)

generally a slow process

17

PresenterPresentation NotesSo phase diagram for this system is different (Fig 12.4)

Chapter 11 -

Fe-C True Equilibrium Diagram

Graphite formation promoted by

Si > 1 wt%

slow cooling

Fig. 11.2, Callister & Rethwisch 9e.[Adapted from Binary Alloy Phase Diagrams, T. B. Massalski (Editor-in-Chief), 1990. Reprinted by permission of ASM International, Materials Park, OH.]

1600

1400

1200

1000

800

600

4000 1 2 3 4 90

L

+L

+ Graphite

Liquid +Graphite

(Fe) C, wt% C

0.65

740C

T(C)

+ Graphite

100

1153CAustenite 4.2 wt% C

+

18

PresenterPresentation NotesCast irons have graphite

Chapter 11 -

Types of Cast IronGray iron graphite flakes gray fracture surface weak & brittle in tension stronger in compression excellent vibrational dampening wear resistantDuctile (or Nodular) iron add Mg and/or Ce graphite as nodules not flakes matrix often pearlite or ferrite Valves, pump bodies,

crankshafts, gears.

Figs. 11.3(a) & (b), Callister & Rethwisch 9e.[Courtesy of C. H.Brady and L. C. Smith,National Bureau ofStandards, Washington,DC (now the NationalInstitute of Standardsand Technology, Gaithersburg, MD]

19

PresenterPresentation NotesCe: cerium

Chapter 11 -

Production of Cast Irons

Fig.11.5, Callister & Rethwisch 9e.(Adapted from W. G. Moffatt, G. W. Pearsall, and J. Wulff, The Structure and Properties of Materials, Vol. I, Structure, p. 195. Copyright 1964 by John Wiley & Sons, New York. Reprinted by permission of John Wiley & Sons, Inc.)

20

Chapter 11 -

Types of Cast Iron (cont.)

White iron < 1 wt% Si pearlite + cementite very hard and brittle Fracture surface:

white appearance

Malleable iron heat treat white iron at 800-900 C graphite in rosettes within ferrite matrix reasonably strong and ductile

Figs. 11.3(c) & (d), Callister & Rethwisch 9e.

Courtesy of A

mcast Industrial C

orporation

Reprinted w

ith permission of the

Iron Castings Society, D

es Plaines, IL

21

Chapter 11 -

Types of Cast Iron (cont.)Compacted graphite iron graphite nodules and flakes some Mg or Ce added but less than

used in nodular cast irons relatively high thermal conductivity good resistance to thermal shock lower oxidation at elevated

temperatures diesel engine blocks

Fig. 11.3(e), Callister & Rethwisch 9e.

Courtesy of Sinter-C

ast, Ltd.

22

Chapter 11 -

Limitations of Ferrous Alloys

1) Relatively high densities2) Relatively low electrical conductivities3) Generally poor corrosion resistance

23

Chapter 11 -

Classification scheme for nonferrous alloys

Fig. 11.6

24

Chapter 11 -Based on discussion and data provided in Section 11.3, Callister & Rethwisch 9e.

Nonferrous Alloys

NonFerrous Alloys

Al Alloys-low : 2.7 g/cm3-Cu, Mg, Si, Mn, Zn additions -solid sol. or precip.

strengthened (struct. aircraft parts)

Mg Alloys-very low : 1.7g/cm3- Powder ignites easily - Steering wheel, laptop

Refractory metals-high melting Ts-Nb, Mo, W, Ta Noble metals

-Ag, Au, Pt -oxid./corr. resistant

Ti Alloys-relatively low : 4.5 g/cm3

vs 7.9 for steel-reactive at high Ts-space applic.

Cu AlloysBrass: Zn is subst. impurity(costume jewelry, coins)

corrosion resistant)

Bronze : Sn, Al, Si, Ni are subst. impurities(stronger,

(bushings)

Cu-Be: precip. hardened for strength

25

PresenterPresentation NotesBushing,Landing gear Pt - platinum

Chapter 11 -Table. 11.7

Temper Designation Scheme for Aluminum Alloys

Aluminum (Al) alloys are classified as either cast or wrought. Cast Al alloys: e.g., 295.0, 356.0 Temper designation indicates the mechanical and/or heat treatment the alloy

has been subjected to.

26

Chapter 11 -

Metal Fabrication How do we fabricate metals?

Example: Steelmaking

Extract metal from ore https://www.youtube.com/watch?v=9l7JqonyoKA

Recycling through scrap remelting https://www.youtube.com/watch?NR=1&v=T1CJ5NP

W8MU&feature=endscreen

27

Chapter 11 -

Metal Fabrication How do we fabricate metals?

Blacksmith - hammer (forged) Cast molten metal into mold

Forming Operations Rough stock formed to final shape

Hot working vs. Cold working Deformation temperature

high enough for recrystallization

Large deformations

Deformation belowrecrystallization temperature

Strain hardening occurs Small deformations

28

Chapter 11 -

FORMING

roll

AoAd

roll

Rolling (Hot or Cold Rolling)(I-beams, rails, sheet & plate)

Ao Ad

force

dieblank

force

Forging (Hammering; Stamping)(wrenches, crankshafts)

often atelev. T


Metal Fabrication Methods (i)

ram billet

container

containerforce die holder

die

Ao

Adextrusion

Extrusion(rods, tubing)

ductile metals, e.g. Cu, Al (hot)

tensile force

AoAddie

die

Drawing(rods, wire, tubing)

die must be well lubricated & clean

CASTING MISCELLANEOUS

29

Chapter 11 -

FORMING CASTING

Metal Fabrication Methods (ii)

Casting- mold is filled with molten metal metal melted in furnace, perhaps alloying

elements added, then cast in a mold common and inexpensive gives good production of shapes weaker products, internal defects good option for brittle materials

MISCELLANEOUS

30

Chapter 11 -

Sand Casting(large parts, e.g.,auto engine blocks)

Metal Fabrication Methods (iii)

What material will withstand T >1600Cand is inexpensive and easy to mold?

Answer: sand!!!

To create mold, pack sand around form (pattern) of desired shape

Sand Sand

molten metal

FORMING CASTING MISCELLANEOUS

31

Chapter 11 -

Metal Fabrication Methods (v)

Continuous Casting-- simple shapes

(e.g., rectangular slabs, cylinders)

molten

solidified

FORMING CASTING MISCELLANEOUS

Die Casting-- high volume-- for alloys having low melting

temperatures

https://www.youtube.com/watch?v=BX8w-GUPz1w

Investment Casting:

32

Chapter 11 -

MISCELLANEOUSCASTING

Metal Fabrication Methods (vi)

Powder Metallurgy(metals w/low ductilities)

pressure

heat

point contact at low T

densificationby diffusion at higher T

area contact

densify

Welding(when fabrication of one large part is impractical)

Heat-affected zone:(region in which themicrostructure has beenchanged).

Fig. 11.10, Callister & Rethwisch 9e.[From Iron Castings Handbook, C.F. Walton and T.J. Opar (Ed.), Iron Castings Society,Des Plaines, IL,1981.]

piece 1 piece 2

fused base metal

filler metal (melted)base metal (melted)

unaffectedunaffectedheat-affected zone

FORMING

33

Chapter 11 -

Heat treating following prior processing affects final properties.

Effect of prior processing can be canceled out.

Thermal processing to soften (e.g. full anneal) or strengthen material (e.g. precipitation strengthening).

Thermal Processing of Metals

34

Chapter 11 -

Annealing: Heat to Tanneal, then cool slowly.

Based on discussion in Section 11.7, Callister & Rethwisch 9e.

Thermal Processing of Metals

Types of Annealing

Stress Relief: Reducestresses resulting from:

- plastic deformation - nonuniform cooling - phase transform.

Normalize (steels): Deformsteel with large grains. Then heattreat to allow recrystallization and formation of smaller grains.

Full Anneal (steels): Make soft steels for good forming. Heat to get , then furnace-coolto obtain coarse pearlite.

Spheroidize (steels): Make very soft steels for good machining. Heat just

below Teutectoid & hold for15-25 h.

35

Chapter 11 -

a) Full Annealingb) Quenching

Heat Treatment Temperature-Time Paths

c)

c) Tempering (Tempered Martensite)

P

B

A

A

a)b)

Fig. 10.25, Callister & Rethwisch 9e. [Adapted from H. Boyer (Editor), Atlas of Isothermal Transformation and Cooling Transformation Diagrams, 1977. Reproduced by permission of ASM International, Materials Park, OH.]

36

Chapter 11 -

Hardenability -- Steels Hardenability measure of the ability to form martensite Jominy end quench test used to measure hardenability.

Fig. 11.12, Callister & Rethwisch 9e. (Adapted from A.G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1978.)

24C water

specimen (heated to phase field)

flat ground

Rockwell Chardness tests

https://www.youtube.com/watch?v=nEV6RqDr9CA

37

Chapter 11 -

Hardenability -- Steels Hardenability measure of the ability to form martensite Jominy end quench test used to measure hardenability.

Plot hardness versus distance from the quenched end.

Fig. 11.12, Callister & Rethwisch 9e. (Adapted from A.G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1978.)

Fig. 11.13, Callister & Rethwisch 9e.

24C water

specimen (heated to phase field)

flat ground

Rockwell Chardness tests

Har

dnes

s, H

RC

Distance from quenched end38

Chapter 11 -

The cooling rate decreases with distance from quenched end.

Fig. 11.14, Callister & Rethwisch 9e. [Adapted from H. Boyer (Ed.), Atlas of Isothermal Transformation and Cooling Transformation Diagrams, 1977. Reproduced by permission of ASM International, Materials Park, OH.]

Reason Why Hardness Changes with Distance

distance from quenched end (in)Har

dnes

s, H

RC

20

40

60

0 1 2 3

600

400

200A M

0.1 1 10 100 1000

T(C)

M(start)

Time (s)

0

0%100%

M(finish)

39

Chapter 11 -

Hardenability vs Alloy Composition Hardenability curves for

five alloys each with, C = 0.4 wt% C

"Alloy Steels"(4140, 4340, 5140, 8640)-- contain Ni, Cr, Mo

(0.2 to 2 wt%)-- these elements shift

the "nose" to longer times (from A to B)

-- martensite is easierto form

Fig. 11.15, Callister & Rethwisch 9e. (Adapted from figure furnished courtesy Republic Steel Corporation.)

Cooling rate (C/s)

Har

dnes

s, H

RC

20

40

60

100 20 30 40 50Distance from quenched end (mm)

210100 3

41408640

5140

50

80

100

%M4340

T(C)

10-1 10 103 1050

200

400

600

800

Time (s)

M(start)M(90%)

BA

TE

40

PresenterPresentation NotesMo- Molybdenum

Chapter 11 -

Internal wing structure on Boeing 767

Aluminum is strengthened with precipitates formedby alloying.

Adapted from Fig. 11.26, Callister & Rethwisch 8e. (Fig. 11.26 is courtesy of G.H. Narayanan and A.G. Miller, Boeing Commercial Airplane Company.)

1.5m

Precipitation Strengthening

Adapted from chapter-opening photograph, Chapter 11, Callister & Rethwisch 3e. (courtesy of G.H. Narayanan and A.G. Miller, Boeing Commercial Airplane Company.)

Precipitates are developed by heat treating.42

Chapter 11 -

Particles impede dislocation motion. Ex: Al-Cu system Procedure:

0 10 20 30 40 50wt% Cu

L+L

+

+L

300

400

500

600

700

(Al)

T(C)

composition range available for precipitation hardening

CuAl2

A

Fig. 11.25, Callister & Rethwisch 9e. (Adapted from J.L. Murray, International Metals Review 30, p.5, 1985. Reprinted by permission of ASM International.)

Precipitation Hardening


-- Pt B: quench to room temp.(retain solid solution)

-- Pt C: reheat to nucleatesmall particles within phase.

Other alloys that precipitationharden: Cu-Be Cu-Sn Mg-Al

Temp.

Time

-- Pt A: solution heat treat(get solid solution)

Pt A (soln heat treat)

B

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Pt B

C

Pt C (precipitate )

43

PresenterPresentation NotesBe- Beryllium

Chapter 11 -

2014 Al Alloy:

Maxima on TS curves. Increasing T accelerates

process.

Fig. 11.28, Callister & Rethwisch 9e. [Adapted from Metals Handbook: Properties and Selection: Nonferrous Alloys and Pure Metals, Vol. 2, 9th ed., H. Baker (Managing Ed.), 1979. Reproduced by permission of ASM International, Materials Park, OH.]

Influence of Precipitation Heat Treatment on TS, %EL

precipitation heat treat time

tens

ile s

treng

th (M

Pa)

200

300

400

100 1min 1h 1day 1mo 1yr

204C149C

Minima on %EL curves.

%E

L10

20

30

0 1min 1h 1day 1mo 1yr

204C 149C

precipitation heat treat time

44

Chapter 11 -

Ferrous alloys: steels and cast irons Non-ferrous alloys:

-- Cu, Al, Ti, and Mg alloys; refractory alloys; and noble metals. Metal fabrication techniques:

-- forming, casting, miscellaneous. Hardenability of metals

-- measure of ability of a steel to be heat treated.-- increases with alloy content.

Precipitation hardening--hardening, strengthening due to formation of

precipitate particles.--Al, Mg alloys precipitation hardenable.

Summary

45

Chapter 12 -

Chapter 12: Structures & Properties of Ceramics

ISSUES TO ADDRESS... How do the crystal structures of ceramic materials

differ from those for metals? How do point defects in ceramics differ from those

defects found in metals? How are impurities accommodated in the ceramic lattice?

How are the mechanical properties of ceramics measured, and how do they differ from those for metals?

In what ways are ceramic phase diagrams different from phase diagrams for metals?

1

Chapter 12 -

Bonding:-- Can be ionic and/or covalent in character.-- % ionic character increases with difference in

electronegativity of atoms. Degree of ionic character may be large or small:

Atomic Bonding in Ceramics

SiC: smallCaF2: large

2

Chapter 12 -

Factors that Determine Crystal Structure1. Relative sizes of ions Formation of stable structures:

--maximize the # of oppositely charged ion neighbors.


- -

- -+

unstable

- -

- -+

stable

- -

- -+

stable2. Maintenance of

Charge Neutrality :--Net charge in ceramic

should be zero.--Reflected in chemical

formula:

CaF2: Ca2+

cationF-

F-

anions+

AmXpm, p values to achieve charge neutrality 3

PresenterPresentation NotesF: fluorineCa: Calcium

Chapter 12 -

Coordination Number increases with

Coordination Number and Ionic Radii

Adapted from Table 12.2, Callister & Rethwisch 9e.

2

rcationranion

Coord. Number

< 0.155

0.155 - 0.225

0.225 - 0.414

0.414 - 0.732

0.732 - 1.0

3

4

6

8

linear

triangular

tetrahedral

octahedral

cubic




ZnS (zinc blende)

NaCl(sodium chloride)

CsCl(cesium chloride)

rcationranion

To form a stable structure, how many anions cansurround around a cation?

4

PresenterPresentation NotesZnS: Zinc sulphideCoordination number: number of anion near neighbors for a cationCl: chlorine

Chapter 12 -

Computation of Minimum Cation-Anion Radius Ratio

Determine minimum rcation/ranion for an octahedral site (C.N. = 6)

a = 2ranion

5

Chapter 12 -

On the basis of ionic radii, what crystal structurewould you predict for FeO?

Answer:

550014000770

anion

cation

...

rr

=

=

based on this ratio,-- coord # = 6 because

0.414 < 0.550 < 0.732

-- crystal structure is NaClData from Table 12.3, Callister & Rethwisch 8e.

Example Problem: Predicting the Crystal Structure of FeO

Ionic radius (nm)0.0530.0770.0690.100

0.1400.1810.133

Cation

Anion

Al3+

Fe2+

Fe3+

Ca2+

O2-

Cl-

F-6

Chapter 12 -

Rock Salt StructureSame concepts can be applied to ionic solids in general. Example: NaCl (rock salt) structure

rNa = 0.102 nm

rNa/rCl = 0.564

cations (Na+) prefer octahedral sites


rCl = 0.181 nm

7

Chapter 12 -

MgO and FeO

O2- rO = 0.140 nm

Mg2+ rMg = 0.072 nm

rMg/rO = 0.514

cations prefer octahedral sites

So each Mg2+ (or Fe2+) has 6 neighbor oxygen atoms


MgO and FeO also have the NaCl structure

8

Chapter 12 -

AX Crystal Structures


Cesium Chloride structure:

Since 0.732 < 0.939 < 1.0, cubic sites preferred

So each Cs+ has 8 neighbor Cl-

AXType Crystal Structures include NaCl, CsCl, and zinc blende

9

Chapter 12 -

ABX3 Crystal Structures


Perovskite structure

Ex: complex oxide BaTiO3

10

Chapter 12 -

Silicate CeramicsMost common elements on earth are Si & O

SiO2 (silica) polymorphic forms are quartz, crystobalite, & tridymite

The strong Si-O bonds lead to a high melting temperature (1710C) for this material

Si4+

O2-

Figs. 12.9 & 12.10, Callister & Rethwisch 9e crystobalite

11

PresenterPresentation NotesCrystobalite: Tridymite: Silicate:

Chapter 12 -

Polymorphic Forms of CarbonDiamond tetrahedral bonding of

carbon hardest material known very high thermal

conductivity small crystals used to

grind/cut other materials diamond thin films

hard surface coatings used for cutting tools, medical devices, etc. Fig. 12.16, Callister &

Rethwisch 9e.

12

Chapter 12 -

Polymorphic Forms of Carbon (cont)Graphite layered structure parallel hexagonal arrays of

carbon atoms

weak forces between layers planes slide easily over one another -- good

lubricant


13

Chapter 12 -

Polymorphic Forms of Carbon (cont)Fullerenes and Nanotubes

Fullerenes spherical cluster of 60 carbon atoms, C60 Like a soccer ball

Carbon nanotubes sheet of graphite rolled into a tube Ends capped with fullerene hemispheres

Adapted from Figs. 12.18 & 12.19, Callister & Rethwisch 8e.

14

Chapter 12 -

Factors that Determine Crystal Structure1. Relative sizes of ions Formation of stable structures:

--maximize the # of oppositely charged ion neighbors.


- -

- -+

unstable

- -

- -+

stable

- -

- -+

stable2. Maintenance of

Charge Neutrality :--Net charge in ceramic

should be zero.CaF2: Ca

2+cation

F-

F-

anions+

AmXpm, p values to achieve charge neutrality

rcationranion

determinescrystal structure

15

PresenterPresentation NotesF: fluorineCa: Calcium

Chapter 12 -

Vacancies-- vacancies exist in ceramics for both cations and anions

Interstitials-- interstitials exist for cations-- interstitials are not normally observed for anions because anions

are large relative to the interstitial sites

Fig. 12.18, Callister & Rethwisch 9e.(From W.G. Moffatt, G.W. Pearsall, and J. Wulff, The Structure and Properties of Materials, Vol. 1, Structure, p.78. Copyright 1964 by John Wiley & Sons, New York. Reprinted by permission of John Wiley and Sons, Inc.)

Point Defects in Ceramics (i)

Cation Interstitial

Cation Vacancy

Anion Vacancy 16

PresenterPresentation NotesCation:

Chapter 12 -

Frenkel Defect-- a cation vacancy-cation interstitial pair.

Shottky Defect-- a paired set of cation and anion vacancies.

Equilibrium concentration of defects

Point Defects in Ceramics (ii)

Shottky Defect:

Frenkel Defect

Fig. 12.19, Callister & Rethwisch 9e.(From W.G. Moffatt, G.W. Pearsall, and J. Wulff, The Structure and Properties of Materials, Vol. 1, Structure, p.78. Copyright 1964 by John Wiley & Sons, New York. Reprinted by permission of John Wiley and Sons, Inc.)

17

Chapter 12 -

Ceramic Phase DiagramsMgO-Al2O3 diagram:

Fig. 12.23, Callister & Rethwisch 9e. [Adapted from B. Hallstedt,Thermodynamic Assessment of the System MgOAl2O3, J. Am. Ceram. Soc., 75[6], 1502 (1992). Reprinted by permission of the American Ceramic Society.]

18

Chapter 12 -

Mechanical PropertiesCeramic materials are more brittle than metals.

Why is this so? Consider mechanism of deformation

In crystalline, by dislocation motion In highly ionic solids, dislocation motion is difficult

few slip systems resistance to motion of ions of like charge (e.g., anions)

past one another bend test to measure room-T flexural strength.

FL/2 L/2

= midpoint deflection

cross section

R

b

d

rect. circ.

location of max tension19

Chapter 12 -

SUMMARY Interatomic bonding in ceramics is ionic and/or covalent. Ceramic crystal structures are based on:

-- maintaining charge neutrality-- cation-anion radii ratios.

Imperfections-- Atomic point: vacancy, interstitial (cation), Frenkel, Schottky-- Impurities: substitutional, interstitial-- Maintenance of charge neutrality

Room-temperature mechanical behavior flexural tests

20

Chapter 13 - 1

Chapter 13: Applications and

Processing of Ceramics


How do we classify ceramics?

What are some applications of ceramics?

How is processing of ceramics different than for metals?

Chapter 13 - 2

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-sensors

Adapted from Fig. 13.1 and discussion in

Section 13.2-8, Callister & Rethwisch 8e.

Classification of Ceramics

Ceramic Materials

Chapter 13 - 3

tensile force

Ao

Addie

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. 11.8(d),

Callister & Rethwisch 8e.

Courtesy Martin Deakins, GE

Superabrasives, Worthington,

OH. Used with permission.

Ceramics Application: Die Blanks

Chapter 13 - 4

Tools:-- for grinding glass, tungsten,

carbide, ceramics

-- for cutting Si wafers

-- for oil drilling

bladesoil drill bits

Single crystal

diamonds

polycrystalline

diamonds in a resin

matrix.

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 - 5

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. 12.27, Callister &

Rethwisch 8e. (Fig. 12.27

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 - 6

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 - 7

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 - 8

Blowing of Glass Bottles:

GLASS

FORMING

Adapted from Fig. 13.8, Callister & Rethwisch 8e. (Fig. 13.8 is adapted from C.J.

Phillips, Glass: The Miracle Maker, Pittman Publishing Ltd., London.)

Ceramic Fabrication Methods (i)

Gob

Parison mold

Pressing operation

Suspended parison

Finishing mold

Compressed air

Fiber drawing:

wind up

PARTICULATE

FORMING

CEMENTATION

-- glass formed by application of

pressure

-- mold is steel with graphite

lining

Pressing: plates, cheap glasses

Chapter 13 - 9

Sheet Glass Forming

Sheet forming continuous casting

sheets are formed by floating the molten glass on a pool of molten tin

Adapted from Fig. 13.9,


Chapter 13 -10

Quartz is crystallineSiO2:

Basic Unit: Glass is noncrystalline (amorphous) Fused silica is SiO2 to which no

impurities have been added

Other common glasses contain impurity ions such as Na+, Ca2+,

Al3+, and B3+

(soda glass)



Glass Structure

Si04 tetrahedron4-

Si4+

O2-

Si4+

Na+

O2-

Chapter 13 - 11

Specific volume (1/r) vs Temperature (T):

Glasses: -- do not crystallize

-- change in slope in spec. vol. curve at

glass transition temperature, Tg-- transparent - no grain boundaries to

scatter light

Crystalline materials: -- crystallize at melting temp, Tm-- have abrupt change in spec.

vol. at Tm



Glass Properties

T

Specific volume

Supercooled Liquid

solid

Tm

Liquid(disordered)

Crystalline (i.e., ordered)

Tg

Glass

(amorphous solid)

Chapter 13 -

Production Processes

12

https://www.youtube.com/watch?v=yvqLtTUlZcA

Glass bottles:

https://www.youtube.com/watch?v=dw7623hu7wM

Glass windows:

Chapter 13 -14

Mill (grind) and screen constituents: desired particle size

Extrude this mass (e.g., into a brick)

Dry and fire the formed piece

ram billet

container

containerforce

die holder

die

Ao

AdextrusionAdapted from

Fig. 12.8(c),

Callister &

Rethwisch 8e.

Ceramic Fabrication Methods (iia)

GLASS

FORMING

PARTICULATE

FORMING

CEMENTATION

Hydroplastic forming:

Chapter 13 -15

Mill (grind) and screen constituents: desired particle size

Slip casting operation

Dry and fire the cast piece

Ceramic Fabrication Methods (iia)

solid component

Adapted from Fig.

13.12, Callister &

Rethwisch 8e. (Fig.

13.12 is from W.D.

Kingery, Introduction

to Ceramics, John

Wiley and Sons,

Inc., 1960.)

hollow component

pour slip

into mold

drain

moldgreen ceramic

pour slip into mold

absorb water into mold

green ceramic

GLASS

FORMING

PARTICULATE

FORMING

CEMENTATION

Slip casting:

Mix with water and other constituents to form slip

Chapter 13 -16

Typical Porcelain Composition

(50%) 1. Clay

(25%) 2. Filler e.g. quartz (finely ground)

(25%) 3. Fluxing agent (Feldspar)

-- aluminosilicates plus K+, Na+, Ca+

-- upon firing - forms low-melting-temp. glass

https://www.youtube.com/watch?v=9lD999ZjD7E

Porcelain

Porcelain Production:

Chapter 13 -17

Drying: as water is removed - interparticle spacings decrease shrinkage .

Adapted from Fig.

13.13, Callister &

Rethwisch 8e. (Fig.

13.13 is from W.D.

Kingery, Introduction

to Ceramics, John

Wiley and Sons,

Inc., 1960.)

Drying and Firing

Drying too fast causes sample to warp or crack due to non-uniform shrinkage

wet body partially dry completely dry

Firing:-- heat treatment between

900-1400C

-- vitrification: liquid glass forms

from clay and flux flows between SiO2 particles. (Flux

lowers melting temperature). Adapted from Fig. 13.14, Callister & Rethwisch 8e. (Fig. 13.14 is courtesy H.G. Brinkies, Swinburne

University of Technology, Hawthorn Campus,

Hawthorn, Victoria, Australia.)

Si02 particle

(quartz)

glass formed around the particle

mic

rog

rap

h o

f p

orc

ela

in

70mm

Chapter 13 -18

Powder Pressing: used for both clay and non-clay compositions.

Powder (plus binder) compacted by pressure in a mold-- Uniaxial compression - compacted in single direction

-- Isostatic (hydrostatic) compression - pressure applied by

fluid - powder in rubber envelope

-- Hot pressing - pressure + heat

Ceramic Fabrication Methods (iib)

GLASS

FORMING

PARTICULATE

FORMING

CEMENTATION

Chapter 13 -19

Sintering



Aluminum oxide powder:-- sintered at 1700C

for 6 minutes.Adapted from Fig. 13.17, Callister

& Rethwisch 8e. (Fig. 13.17 is from

W.D. Kingery, H.K. Bowen, and

D.R. Uhlmann, Introduction to

Ceramics, 2nd ed., John Wiley and

Sons, Inc., 1976, p. 483.)

15mm

Sintering occurs during firing of a piece that has

been powder pressed

-- powder particles coalesce and reduction of pore size

Chapter 13 -20

Tape Casting Thin sheets of green ceramic cast as flexible tape

Used for integrated circuits and capacitors

Slip = suspended ceramic particles + organic liquid (contains binders, plasticizers)

Fig. 13.18, Callister &

Rethwisch 8e.

Chapter 13 -21

Hardening of a paste paste formed by mixing cement material with water

Formation of rigid structures having varied and complex

shapes

Hardening process hydration (complex chemical reactions involving water and cement particles)

Ceramic Fabrication Methods (iii)

GLASS

FORMING

PARTICULATE

FORMING

CEMENTATION

Portland cement production of:-- mix clay and lime-bearing minerals

-- calcine (heat to 1400C)

-- grind into fine powder

https://www.youtube.com/watch?v=m8U76Bm8kDY

Chapter 13 -22

Categories of ceramics: -- glasses -- clay products

-- refractories -- cements

-- advanced ceramics

Ceramic Fabrication techniques:-- glass forming (pressing, blowing, fiber drawing).

-- particulate forming (hydroplastic forming, slip casting,

powder pressing, tape casting)

-- cementation

Heat treating procedures-- glassesannealing-- particulate formed piecesdrying, firing (sintering)

Summary

Chapter 14 -

11.2, 11.7 (composition only), 11.19, 11.24, 11.D14Due: Wednesday April 8th, 2015

Homework IV Assignment

Homework V Assignment

Due: Wednesday April 15th, 2015

Exam III: Wednesday April 22nd, 2015

12.4, 12.5, 13.8, 13.21

1

Chapter 14 -

Coordination Number increases with

Coordination Number and Ionic Radii

Adapted from Table 12.2, Callister & Rethwisch 9e.

2

rcationranion

Coord. Number

< 0.155

0.155 - 0.225

0.225 - 0.414

0.414 - 0.732

0.732 - 1.0

3

4

6

8

linear

triangular

tetrahedral

octahedral

cubic




ZnS (zinc blende)

NaCl(sodium chloride)

CsCl(cesium chloride)

rcationranion

To form a stable structure, how many anions cansurround around a cation?

2

Chapter 14 -

ISSUES TO ADDRESS... What are the general structural and chemical

characteristics of polymer molecules? What are some of the common polymeric

materials, and how do they differ chemically?

How is the structure of polymers different than that in metals and ceramics ?

Chapter 14:Polymer Structures

3

Chapter 14 -

What is a Polymer?

Poly mermany repeat unit


C C C C C CHHHHHH

HHHHHH

Polyethylene (PE)ClCl Cl

C C C C C CHHH

HHHHHH

Poly(vinyl chloride) (PVC)HH

HHH H

Polypropylene (PP)

C C C C C CCH3

HH

CH3CH3H

repeatunit

repeatunit

repeatunit

4

Chapter 14 -

Natural Polymers Originally natural polymers were used

Wood Rubber Cotton Wool Leather Silk

Oldest known uses Rubber balls used by Incas Biblical reference to pitch(a natural polymer)

5

Chapter 14 -

Polymer CompositionMost polymers are hydrocarbons

i.e., made up of H and C Saturated hydrocarbons

Each carbon singly bonded to four other atoms Example:

Ethane, C2H6

C C

H

H H H

HH

6

Chapter 14 - 7

Chapter 14 -

Unsaturated Hydrocarbons Double & triple bonds somewhat unstable

can form new bonds Double bond found in ethylene - C2H4

Triple bond found in acetylene - C2H2

C CH

H

H

H

C C HH

8

Chapter 14 -

Chemistry and Structure of Polyethylene


Note: polyethylene is a long-chain hydrocarbon- paraffin wax for candles is short polyethylene

9

Chapter 14 -

Isomerism Isomerism

two compounds with same chemical formula can have quite different structures

for example: C8H18 normal-octane

2,4-dimethylhexane

C C C C C C C CH

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H H3C CH2 CH2 CH2 CH2 CH2 CH2 CH3=

H3C CH

CH3CH2 CH

CH2

CH3

CH3

H3C CH2 CH3( )6

10

Chapter 14 -

Bulk or Commodity Polymers

12

Chapter 14 -


Molecular Structures for Polymers

Branched Cross-Linked NetworkLinear

secondarybonding

15

Chapter 14 -

Polymers Molecular ShapeMolecular Shape chain bending and twisting

are possible by rotation of carbon atoms around their chain bonds note: not necessary to break chain bonds

to alter molecular shapeAdapted from Fig. 14.5, Callister & Rethwisch 9e.

16

Chapter 14 -

Chain End-to-End Distance, r


17

Chapter 14 -

Polymer Crystallinity Crystalline regions

thin platelets with chain folds at faces Chain folded structure


10 nm

18

Chapter 14 -

Crystallinity in Polymers Ordered atomic

arrangements involving molecular chains

Crystal structures in terms of unit cells

Example shown polyethylene unit cell


19

Chapter 14 -

Polymer Crystallinity (cont.)Polymers rarely 100% crystalline Difficult for all regions of all chains to

become aligned

Degree of crystallinity expressed as % crystallinity.-- Some physical properties

depend on % crystallinity.-- Heat treating causes

crystalline regions to grow and % crystallinity to increase.

Fig. 14.11, Callister 6e. (From H.W. Hayden, W.G. Moffatt, and J. Wulff, The Structure and Properties of Materials, Vol. III, Mechanical Behavior, John Wiley and Sons, Inc., 1965.)

crystalline region

amorphousregion

20

Chapter 14 -

Semicrystalline Polymers

Spherulite surface


Some semicrystalline polymers form spherulite structures

Alternating chain-folded crystallites and amorphous regions

Spherulite structure for relatively rapid growth rates

21

Chapter 14 -

MOLECULAR WEIGHT Molecular weight, M: Mass of a mole of chains.

Low M

high M

Not all chains in a polymer are of the same length i.e., there is a distribution of molecular weights

22

Chapter 14 -

MOLECULAR WEIGHT DISTRIBUTION


= numerical average

23

Chapter 14 -

Degree of Polymerization, DPDP = average number of repeat units per chain

C C C C C C C CH

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

C C C C

H

H

H

H

H

H

H

H

H( ) DP = 6

mol. wt of repeat unit iChain fraction28

Chapter 14 -

Copolymerstwo or more monomers

polymerized together random A and B randomly

positioned along chain alternating A and B

alternate in polymer chain block large blocks of A

units alternate with large blocks of B units

graft chains of B units grafted onto A backbone

A B

random

block

graft


alternating

29

Chapter 15 -

Chapter 15: Characteristics, Applications &

Processing of Polymers


What are the tensile properties of polymers and how are they affected by basic microstructural features?

Hardening, anisotropy, and annealing in polymers.

How does the elevated temperature mechanicalresponse of polymers compare to ceramics and metals?

What are the primary polymer processing methods?

1

Chapter 15 -

Mechanical Properties of Polymers Stress-Strain Behavior

Fracture strengths of polymers ~ 10% of those for metals Deformation strains for polymers > 1000%

for most metals, deformation strains < 10%

brittle polymer

plasticelastomer

elastic moduli less than for metals Adapted from Fig. 15.1,


2

Chapter 15 -

Mechanical Properties of Polymers Stress-Strain Behavior

www.packaging-gateway.com3

Chapter 15 -

Mechanisms of DeformationBrittle Crosslinked and Network Polymers

brittle failure

plastic failure

e

x

x

aligned, crosslinkedpolymer Stress-strain curves adapted from Fig. 15.1,


InitialNear

Failure

network polymer

(MPa)

4

Chapter 15 -

Mechanisms of Deformation Semicrystalline (Plastic) Polymers

brittle failure

plastic failure

(MPa)

x

x

crystallineblock segments

separate

fibrillar structure

near failure

crystallineregions align

onset of necking

undeformedstructure amorphous

regionselongate

unload/reload

Stress-strain curves adapted from Fig. 15.1, Callister & Rethwisch 9e. Inset figures along plastic response curve adapted from Figs. 15.12 & 15.13, Callister & Rethwisch 9e. (From SCHULTZ, POLYMER MATERIALS SCIENCE, 1st Edition, 1974. Reprinted by permission of Pearson Education, Inc., Upper Saddle River, NJ.)1974, pp 500-501.)

e

5

Chapter 15 -

Predeformation by Drawing Drawing(ex: monofilament fishline)

-- stretches the polymer prior to use-- aligns chains in the stretching direction

Results of drawing:-- increases the elastic modulus (E) in the

stretching direction-- increases the tensile strength (TS) in the

stretching direction-- decreases ductility (%EL)

Annealing after drawing...-- decreases chain alignment-- reverses effects of drawing (reduces E and

TS, enhances %EL) Contrast to effects of cold working in metals!

Adapted from Fig. 15.13, Callister & Rethwisch 9e.(From Schultz, Polymer Materials Science, 1st Edition, 1974. Reprinted by permission of Pearson Education, Inc., Upper Saddle River, NJ.)1974, pp 500-501.)

6

Chapter 15 -

Compare elastic behavior of elastomers with the:-- brittle behavior (of aligned, crosslinked & network polymers), and-- plastic behavior (of semicrystalline polymers)

(as shown on previous slides)

Stress-strain curves adapted from Fig. 15.1, Callister & Rethwisch 9e.Inset figures along elastomer curve (green) adapted from Fig. 15.15, Callister & Rethwisch 9e. (Fig. 15.15 adapted from Z. D. Jastrzebski, The Nature and Properties of Engineering Materials, 3rd edition. Copyright 1987 by John Wiley & Sons, New York. Reprinted by permission of John Wiley & Sons, Inc.)

Mechanisms of DeformationElastomers

initial: amorphous chains are kinked, cross-linked.

x

final: chainsare straighter,

stillcross-linked

elastomer

deformation is reversible (elastic)!

brittle failure

plastic failurex

x(MPa)

e

7

Chapter 15 -

Thermoplastics:-- little crosslinking-- ductile-- soften w/heating-- polyethylene, polypropylene

polycarbonate, polystyrene

Thermoplastics vs. Thermosets

8

Chapter 15 -

Thermosets:-- significant crosslinking

(10 to 50% of repeat units)-- hard and brittle-- do NOT soften w/heating-- vulcanized rubber, epoxies,

polyester resin, phenolic resin

Thermoplastics vs. Thermosets

9

Chapter 15 -

Decreasing T...-- increases E-- increases TS-- decreases %EL

Increasingstrain rate...

-- same effectsas decreasing T.

Adapted from Fig. 15.3, Callister & Rethwisch 9e. (Reprinted with permission from T. S. Carswell and H. K. Nason, Effect of Environmental Conditions on the Mechanical Properties of Organic Plastics, in Symposium on Plastics. Copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428.)

Influence of T and Strain Rate on Thermoplastics

20

40

60

80

00 0.1 0.2 0.3

4C

20C

40C

60C to 1.3

Plots forsemicrystalline PMMA (Plexiglas)

(MPa)

e

10

Chapter 15 -

Melting & Glass Transition Temps.What factors affect Tm and Tg?

Both Tm and Tg increase with increasing chain stiffness

Chain stiffness increased by presence of1. Bulky sidegroups2. Chain double bonds


Representative Tg values (C):PE (low density)PE (high density)PVCPSPC

- 110- 90+ 87+100+150

Selected values from Table 15.2, Callister & Rethwisch 9e.

11

Chapter 15 -

Stress relaxation test:-- strain in tension to e

and hold.-- observe decrease in

stress with time.

Relaxation modulus:

Time-Dependent Deformation

time

straintensile test

eo(t)

There is a large decrease in Erfor T > Tg. (amorphous

polystyrene)Fig. 15.7, Callister & Rethwisch 9e. (From A. V. Tobolsky, Properties and Structures of Polymers. Copyright 1960 by John Wiley & Sons, New York. Reprinted by permission of John Wiley & Sons, Inc.)

103

101

10-1

10-3

105

60 100 140 180

rigid solid (small relax)

transition region

T(C)Tg

Er (10 s)in MPa

viscous liquid (large relax)

12

Chapter 15 -

Polymer Formation There are two types of polymerization

Addition (or chain) polymerization

Condensation (step) polymerization (beyond scope)

13

Chapter 15 -

Addition (Chain) Polymerization

InitiationR: initiator or catalyst

Propagation

Termination

14

Chapter 15 -

Polymer AdditivesImprove mechanical properties, processability,

durability, etc. Fillers

Added to improve tensile strength & abrasion resistance, toughness & decrease cost

ex: carbon black, glass, limestone, talc, etc.

Plasticizers small molecules that take place between polymer chains-reduce secondary bonding Presence of plasticizer transforms brittle polymer to a

ductile one Commonly added to PVC - otherwise it is brittle

15

Chapter 15 -

Polymer Additives (cont.) Stabilizers

UV protectants Lubricants

Added to allow easier processing polymer slides through dies easier

Colorants Dyes and pigments

Flame Retardants Substances containing chlorine, fluorine, and boron

16

Chapter 15 -

Processing of Plastics Thermoplastic

can be reversibly cooled & reheated, i.e. recycled heat until soft, shape as desired, then cool ex: polyethylene, polypropylene, polystyrene.

Thermoset forms a molecular network (chemical reaction) degrades (doesnt melt) when heated a prepolymer molded into desired shape, then

chemical reaction occurs ex: urethane, epoxy

17

Chapter 15 -

Example: Two component epoxy glue

Thermoset

18

Chapter 15 -

Processing Plastics Compression MoldingThermoplastics and thermosets polymer and additives placed in mold cavity mold heated and pressure applied fluid polymer assumes shape of mold

Fig. 15.23, Callister & Rethwisch 9e. (From F. W. Billmeyer, Jr., Textbook of Polymer Science, 3rd edition. Copyright 1984 by John Wiley & Sons, New York. Reprinted by permission of John Wiley & Sons, Inc.)

19

Chapter 15 -

Processing Plastics Injection Molding

Fig. 15.24, Callister & Rethwisch 9e. (From F. W. Billmeyer, Jr., Textbook of Polymer Science, 3rd edition. Copyright 1984 by John Wiley & Sons, New York. Reprinted by permission of John Wiley & Sons, Inc.)

Thermoplastics and some thermosets when ram retracts, plastic pellets drop from hopper into barrel ram forces plastic into the heating chamber (around the

spreader) where the plastic melts as it moves forward molten plastic is forced under pressure (injected) into the mold

cavity where it assumes the shape of the mold

Barrelhttps://www.youtube.com/watch?v=eUthHS3MTdA

20

Chapter 15 -

Processing Plastics Extrusion

Fig. 15.25, Callister & Rethwisch 9e. (Reprinted with permission from Encyclopdia Britannica, 1997 by Encyclopdia Britannica, Inc.)

thermoplastics plastic pellets drop from hopper onto the turning screw plastic pellets melt as the turning screw pushes them

forward by the heaters molten polymer is forced under pressure through the

shaping die to form the final product

21

Chapter 15 -

Processing Plastics Blown-Film Extrusion

Fig. 15.26, Callister & Rethwisch 9e. (Reprinted with permission from Encyclopdia Britannica, 1997 by Encyclopdia Britannica, Inc.)

22

Chapter 15 -

Polymer Types FibersFibers - length/diameter >100 Primary use is in textiles. Fiber characteristics:

high tensile strengths high degrees of crystallinity Nylon:https://www.youtube.com/watch?v=yFEHKRdXb9Y

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

23

Chapter 15 -

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)

Films produced by blown film extrusion

Foams gas bubbles incorporated into plastic

https://www.youtube.com/watch?v=xjap74m4228

24

Chapter 15 -

Advanced Polymers

Molecular weight ca. 4x106 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)

25

Chapter 15 -

Advanced Polymers

styrene

butadiene

Thermoplastic Elastomers

Styrene-butadiene block copolymerhard

component domain

soft component

domainFig. 15.22, Callister & Rethwisch 9e.Fig. 15.21(a), Callister & Rethwisch 9e.

26

Chapter 15 -

Limitations of polymers:-- E, y, Tapplication are generally small.-- Deformation is often time and temperature dependent.

Thermoplastics (PE, PS, PP, PC):-- Smaller E, y, Tapplication-- Easier to form and recycle

Elastomers (rubber):-- Large reversible strains!

Thermosets (epoxies, polyesters):-- Larger E, y, Tapplication

Table 15.3 Callister & Rethwisch 9e:

Good overviewof applicationsand trade namesof polymers.

Summary

27

Chapter 15 -

Summary Polymer Processing

-- compression and injection molding, extrusion, blown film extrusion

Polymer melting and glass transition temperatures Polymer applications

-- elastomers -- fibers-- coatings -- adhesives-- films -- foams-- advanced polymeric materials

28

Chapter 16 - 1

Reminders

Homework V Assignment

Due: Wednesday April 15th, 2015

Exam III: Wednesday April 22nd, 2015Chapter 11, 12, 13, 14, 15, 16

12.4, 12.5, 13.8, 13.21

Chapter 16 - 2

ISSUES TO ADDRESS... What are the classes and types of composites?

What are the advantages of using composite materials?

How do we predict the stiffness and strength of the various types of composites?

Chapter 16: Composites

Chapter 16 - 3

Composite

Combination of two or more individual materials

Design goal: obtain a more desirable combination of properties e.g., low density and high strength

Chapter 16 - 4

Composite:-- Multiphase material

Phase types:-- Matrix - is continuous-- Dispersed - is discontinuous and

surrounded by matrix

Terminology/Classification

Adapted from Fig. 16.1(a), Callister & Rethwisch 9e.

Chapter 16 - 5

Matrix phase:-- Purposes are to:

- transfer stress to dispersed phase- protect dispersed phase from environment

-- Types: MMC, CMC, PMC

metal ceramic polymer

Terminology/Classification

Dispersed phase:-- Types: particle, fiber

Reprinted with permission fromD. Hull and T.W. Clyne, An Introduction to Composite Materials, 2nd ed., Cambridge University Press, New York, 1996, Fig. 3.6, p. 47.

woven fibers

cross section view

0.5mm

0.5mm

Chapter 16 - 6

Chapter 16 -

Chapter 16 -

Boeing 787 Dreamliner

8

http://www.reinforcedplastics.com/

http://www.boeing.com/

http://www.dailytech.com/

https://www.youtube.com/watch?v=f07HpUAuWgk

Chapter 16 - 9

Classification of Composites

Large-particle

Dispersion-strengthened

Particle-reinforced

Continuous(aligned)

Aligned Randomlyoriented

Discontinuous(short)

Fiber-reinforced

Laminates Sandwichpanels

Structural

Composites


Chapter 16 - 10

Classification: Particle-Reinforced (i)

Examples:

Fig. 11.19, Callister & Rethwisch 9e. (Copyright 1971 by United States Steel Corporation.)

- Spheroidite steel

matrix: ferrite ()(ductile)

particles: cementite(Fe

3C)

(brittle)60m

Fig. 16.4, Callister & Rethwisch 9e. (Courtesy of Carboloy Systems Department, General Electric Company.)

- WC/Co cemented carbide

matrix: cobalt (ductile, tough)

particles: WC (brittle, hard):

600m

Fig. 16.5, Callister & Rethwisch 9e. (Courtesy of Goodyear Tire and Rubber Company.)

- Automobile tire rubber

matrix: rubber (compliant)

particles: carbon black (stiff) 0.75m

Particle-reinforced Fiber-reinforced Structural

Chapter 16 - 11

Classification: Particle-Reinforced (ii)

Concrete gravel + sand + cement + water- Why sand and gravel? Sand fills voids between gravel particles

Reinforced concrete Reinforce with steel rebar or remesh- increases strength - even if cement matrix is cracked


http://www.rebartool.com/

Chapter 16 - 12

Elastic modulus, Ec, of composites:-- rule of mixture:

Application to other properties:-- Electrical conductivity, e: Replace Es in equation with es.-- Thermal conductivity, k: Replace Es in equation with ks.

Fig. 16.3, Callister & Rethwisch 9e. (Reprinted with permission from R. H. Krock, ASTM Proceedings, Vol. 63, 1963. Copyright ASTM International, 100 Barr Harbor Drive, West Conschohocken, PA 19428.)

Classification: Particle-Reinforced (iii)

upper limit: c m mE = V E + VpEp


Data: Cu matrix w/tungsten particles

0 20 40 60 80 100

150200250300350

vol% tungsten

E(GPa)

(Cu) (W)

Chapter 16 - 13

Classification: Fiber-Reinforced (i)

Fibers very strong in tension Provide significant strength improvement to the

composite Ex: fiber-glass - continuous glass filaments in a

polymer matrix Glass fibers

strength and stiffness Polymer matrix

holds fibers in place protects fiber surfaces transfers load to fibers


Chapter 16 - 14

Classification: Fiber-Reinforced (ii)

Fiber TypesParticle-reinforced Fiber-reinforced Structural

Fibers polycrystalline or amorphous generally polymers or ceramics Ex: alumina, aramid, boron, UHMWPE

Wires metals steel, molybdenum, tungsten

Chapter 16 - 15

Fiber Alignment

alignedcontinuous

aligned randomdiscontinuous


Transverse direction

Longitudinal direction

Chapter 16 - 16

Aligned Continuous fibers Examples:

From W. Funk and E. Blank, Creep deformation of Ni3Al-Mo in-situ composites", Metall. Trans. A Vol. 19(4), pp. 987-998, 1988. Used with permission.

-- Metal: (Ni3Al)-(Mo)by eutectic solidification.

Classification: Fiber-Reinforced (iii)


matrix: (Mo) (ductile)

fibers: (Ni3Al) (brittle)

2m

-- Ceramic: Glass w/SiC fibersformed by glass slurryEglass = 76 GPa; ESiC = 400 GPa.

From F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, 2000. Used with permission of CRCPress, Boca Raton, FL.

Chapter 16 - 17

Discontinuous fibers, random in 2 dimensions Example: Carbon-Carbon

-- carbon fibers embedded in polymer resin matrix,

-- uses: disk brakes, gas turbine exhaust flaps, missile nose cones.

Other possibilities:-- Discontinuous, random 3D-- Discontinuous, aligned

Adapted from F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, 2000. (a) Fig. 4.24(a), p. 151; (b) Fig. 4.24(b) p. 151. (Courtesy I.J. Davies) Reproduced with permission of CRC Press, Boca Raton, FL.

Classification: Fiber-Reinforced (iv)


(b)

fibers lie in plane

view onto plane

C fibers: very stiff very strong

C matrix: less stiff less strong

(a)

500 m

Chapter 16 - 18

Composite Stiffness:Longitudinal Loading

Continuous fibers - Estimate fiber-reinforced composite modulus of elasticity for continuous fibers

Longitudinal deformation

c = mVm + fVf and ec = em = ef

volume fraction isostrain

Ecl = EmVm + Ef Vf Ecl = longitudinal modulus

c = compositef = fiberm = matrix

Chapter 16 -Fig_16-9

Chapter 16 - 20

Composite Production Methods (i)


Pultrusion Continuous fibers pulled through resin tank to impregnate fibers with

thermosetting resin Impregnated fibers pass through steel die that preforms to the desired shape Preformed stock passes through a curing die that is

precision machined to impart final shape heated to initiate curing of the resin matrix

Chapter 16 - 21

Composite Production Methods (ii) Filament Winding

Continuous reinforcing fibers are accurately positioned in a predetermined pattern to form a hollow (usually cylindrical) shape

Fibers are fed through a resin bath to impregnate with thermosetting resin Impregnated fibers are continuously wound (typically automatically) onto a

mandrel After appropriate number of layers added, curing is carried out either in an

oven or at room temperature The mandrel is removed to give the final product

Fig. 16.15, Callister & Rethwisch 9e. [From N. L. Hancox, (Editor), Fibre Composite Hybrid Materials, The Macmillan Company, New York, 1981.]

Chapter 16 - 22

Laminates --- stacked and bonded fiber-reinforced sheets

- stacking sequence: e.g., 0/90Adapted from Fig. 16.16, Callister & Rethwisch 8e.

Classification: StructuralParticle-reinforced Fiber-reinforced Structural

Sandwich panels-- honeycomb core between two facing sheets

- benefits: low density, large bending stiffness

honeycombadhesive layer

face sheet

Fig. 16.18, Callister & Rethwisch 9e. (Reprinted with permission from Engineered Materials Handbook, Vol. 1, Composites,ASM International, Materials Park, OH, 1987.)

Chapter 16 - 23

Composites types are designated by:-- the matrix material (CMC, MMC, PMC)-- the reinforcement (particles, fibers, structural)

Composite property benefits:-- MMC: enhanced E, , creep performance-- CMC: enhanced toughness-- PMC: enhanced E/, y, TS/

Particulate-reinforced:-- Types: large-particle and dispersion-strengthened-- Properties are isotropic

Fiber-reinforced:-- Types: continuous (aligned)

discontinuous (aligned or random)-- Properties can be isotropic or anisotropic

Structural:-- Laminates and sandwich panels

Summary

RemindersChapter 11: Applications and Processing of Metal AlloysSlide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Classification of Metal AlloysSteelsFerrous AlloysFerrous Alloys:Advanced High Strength Steels (AHSS)Slide Number 15Slide Number 16Cast IronsFe-C True Equilibrium Diagram Types of Cast IronProduction of Cast IronsTypes of Cast Iron (cont.)Types of Cast Iron (cont.)Limitations of Ferrous AlloysClassification scheme for nonferrous alloysNonferrous AlloysSlide Number 26Metal FabricationMetal FabricationMetal Fabrication Methods (i)Metal Fabrication Methods (ii)Metal Fabrication Methods (iii)Metal Fabrication Methods (v)Metal Fabrication Methods (vi)Thermal Processing of MetalsThermal Processing of MetalsHeat Treatment Temperature-Time PathsHardenability -- SteelsHardenability -- SteelsReason Why Hardness Changes with DistanceHardenability vs Alloy Composition Precipitation StrengtheningPrecipitation HardeningInfluence of Precipitation Heat Treatment on TS, %ELSummaryChapter 12: Structures & Properties of CeramicsAtomic Bonding in CeramicsFactors that Determine Crystal StructureCoordination Number and Ionic RadiiComputation of Minimum Cation-Anion Radius RatioExample Problem: Predicting the Crystal Structure of FeORock Salt StructureMgO and FeOAX Crystal StructuresABX3 Crystal StructuresSilicate CeramicsPolymorphic Forms of CarbonPolymorphic Forms of Carbon (cont)Polymorphic Forms of Carbon (cont) Fullerenes and NanotubesFactors that Determine Crystal StructurePoint Defects in Ceramics (i)Point Defects in Ceramics (ii)Ceramic Phase DiagramsMechanical PropertiesSUMMARYHomework IV AssignmentCoordination Number and Ionic RadiiChapter 14:Polymer StructuresWhat is a Polymer?Natural PolymersPolymer CompositionSlide Number 7Unsaturated HydrocarbonsChemistry and Structure of PolyethyleneIsomerismBulk or Commodity PolymersMolecular Structures for PolymersPolymers Molecular ShapeChain End-to-End Distance, rPolymer CrystallinityCrystallinity in PolymersPolymer Crystallinity (cont.)Semicrystalline PolymersMOLECULAR WEIGHTMOLECULAR WEIGHT DISTRIBUTIONDegree of Polymerization, DP CopolymersChapter 15: Characteristics, Applications & Processing of PolymersMechanical Properties of Polymers Stress-Strain BehaviorMechanical Properties of Polymers Stress-Strain BehaviorMechanisms of DeformationBrittle Crosslinked and Network Polymers Mechanisms of Deformation Semicrystalline (Plastic) Polymers Predeformation by DrawingMechanisms of DeformationElastomersThermoplastics vs. ThermosetsThermoplastics vs. ThermosetsInfluence of T and Strain Rate on Thermoplastics Melting & Glass Transition Temps.Time-Dependent DeformationPolymer FormationAddition (Chain) PolymerizationPolymer AdditivesPolymer Additives (cont.)Processing of PlasticsSlide Number 18Processing Plastics Compression MoldingProcessing Plastics Injection MoldingProcessing Plastics ExtrusionProcessing Plastics Blown-Film ExtrusionPolymer Types FibersPolymer Types MiscellaneousAdvanced PolymersAdvanced PolymersSummarySummary

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