EGN3365 Chapter 1

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Chapter 1 - 1

Chapter 1 - Introduction

What is materials science?

Why should we know about it?

Materials drive our society Stone Age

Bronze Age

Iron Age

Now? Silicon Age?

Polymer Age?

Chapter 1 - 2

Example Hip Implant

With age or certain illnesses joints deteriorate.

Particularly those with large loads (such as hip).

Adapted from Fig. 22.25, Callister 7e.

Chapter 1 - 3

Example Hip Implant

Requirements

mechanical strength (many cycles)

good lubricity

biocompatibility

Adapted from Fig. 22.24, Callister 7e.

Chapter 1 - 4

Example Hip Implant

Adapted from Fig. 22.26, Callister 7e.

BlackTypewriterHistorically, development and advancement of societies have been intimately tied to the members ability to produce and manipulate materials to fill their needs. In fact, early civilizations have been designated by the level of their materials development (Bronze, Steel, Iron)

BlackTypewriterThe earliest humans had access to only a very limited number of materials, those that occur naturally: stone, wood, clay, skins, and so on. With time they discovered techniques for producing materials that had properties superior to those of the natural ones. Furthermore, it was discovered that the properties of a material could be altered by heat treatments and by the addition of other substances. At this point, materials utilization was totally a selection process that involved deciding from a given, rather limited set of materials the one best suited for an application by virtue of its characteristics

BlackTypewriter

BlackTypewriterAt this point, materials utilization was totally a selection process that involved deciding from a given, rather limited set of materials the one best suited for an application by virtue of its characteristics.

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Chapter 1 - 5

Hip Implant

Key problems to overcome

fixation agent to hold acetabular cup

cup lubrication material

femoral stem fixing agent

must avoid any debris in cup

Femoral Stem

Ball

AcetabularCup and Liner

Adapted from chapter-opening photograph, Chapter 22, Callister 7e. (Photograph courtesy of Zimmer, Inc., Warsaw, IN, USA.)

Chapter 1 - 6

Example Develop New Types of Polymers

Commodity plastics large volume ca. $0.50 / lbEx. Polyethylene

PolypropylenePolystyreneetc.

Engineering Resins small volume > $1.00 / lbEx. Polycarbonate

NylonPolysulfoneetc.

Can polypropylene be upgraded to properties (and price) near those of engineering resins?

Chapter 1 - 7

ex: hardness vs structure of steel Properties depend on structure

Data obtained from Figs. 10.31(a) and 10.32 with 4 wt% C composition, and from Fig. 11.15, Callister & Rethwisch 9e. Micrographs adapted from (a) Fig. 10.19; (b) Fig. 9.30; (c) Fig. 10.33; and (d) Fig. 10.21, Callister & Rethwisch 9e. (Figures 10.19, 10.21, & 10.33 copyright 1971 by United States Steel Corporation. Figure 9.30 courtesy of Republic Steel Corporation.)

ex: structure vs cooling rate of steel Processing can change structure

Structure, Processing, & Properties

Ha

rdn

ess

(B

HN

)

Cooling Rate (C/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(d)

30m(c)

4m

(b)

30m

(a)

30m

Chapter 1 - 8

Types of Materials Metals:

Strong, ductile

High thermal & electrical conductivity

Opaque, reflective.

Polymers/plastics: Covalent bonding sharing of electrons Soft, ductile, low strength, low density

Thermal & electrical insulators

Optically translucent or transparent.

Ceramics: ionic bonding (refractory) compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides)

Brittle, glassy, elastic

Non-conducting (insulators)

BlackHighlight

BlackTypewriterMaterials Science involves investigating the relationships that exist between the structures and properties of materials. Materials Engineering is, on the basis of these structureproperty correlations, designing or engineering the structure of a material to produce a predetermined set of properties.

BlackTypewriterProcessing:Structure:Properties:Performance:

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Chapter 1 - 9

1. Pick Application Determine required Properties

Processing: changes structure and overall shapeex: casting, sintering, vapor deposition, doping

forming, joining, annealing.

Properties: mechanical, electrical, thermal,magnetic, optical, deteriorative.

Material: structure, composition.

2. Properties Identify candidate Material(s)

3. Material Identify required Processing

The Materials Selection Process

Chapter 1 - 10

ELECTRICAL

Electrical Resistivity of Copper:

Adding impurity atoms to Cu increases resistivity.

Deforming Cu increases resistivity.

Fig. 18.8, Callister & Rethwisch 9e. [Adapted from: J.O. Linde, Ann Physik 5, 219 (1932); and C.A. Wert and R.M. Thomson, Physics of Solids, 2nd edition, McGraw-Hill Company, New York, 1970.]

T (C)-200 -100 0

1

2

3

4

5

6

Re

sis

tivity,

(10

-8O

hm

-m)

0

Chapter 1 - 11

THERMAL Space Shuttle Tiles:

-- Silica fiber insulationoffers low heat conduction.

Thermal Conductivityof Copper:-- It decreases when

you add zinc!

Fig. 19.4W, Callister 6e. (Courtesy of Lockheed Aerospace Ceramics Systems, Sunnyvale, CA)(Note: "W" denotes fig. is on CD-ROM.)

Fig. 19.4, Callister & Rethwisch 9e. [Adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), ASM International, 1979, p. 315.]

Composition (wt% Zinc)

The

rma

l C

ond

uct

ivity

(W

/m-K

)

400

300

200

100

00 10 20 30 40

100m

Chapter-opening photograph, Chapter 17, Callister & Rethwisch 3e. (Courtesy of LockheedMissiles and SpaceCompany, Inc.)

Chapter 1 - 12

MAGNETIC Magnetic Permeability

vs. Composition:-- Adding 3 atomic % Si

makes Fe a betterrecording medium!

Adapted from C.R. Barrett, W.D. Nix, andA.S. Tetelman, The Principles of EngineeringMaterials, Fig. 1-7(a), p. 9, 1973.Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey.

Fig. 20.23, Callister & Rethwisch 9e.(Courtesy of HGST, a Western Digital Company.)

Magnetic Storage:-- Recording medium

is magnetized byrecording head.

Magnetic Field

Magnetiz

atio

n Fe+3%Si

Fe

BlackHighlight

BlackTypewriterProcessing -> Structure -> Properties -> Performance

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Chapter 1 - 13

Transmittance:-- Aluminum oxide may be transparent, translucent, or

opaque depending on the materials structure (i.e., single crystal vs. polycrystal, and degree of porosity).

Fig. 1.2, Callister & Rethwisch 9e.(Specimen preparation,P.A. Lessing)

single crystalpolycrystal:no porosity

polycrystal:some porosity

OPTICAL

Chapter 1 - 14

DETERIORATIVE Stress & Saltwater...

-- causes cracks!

Fig. 17.21, Callister & Rethwisch 9e. (from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc., 1975.)

Heat treatment: slowscrack speed in salt water!

Adapted from Fig. 11.20(b), R.W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials" (4th ed.), p. 505, John Wiley and Sons, 1996. (Original source: Markus O. Speidel, Brown Boveri Co.)

held at

160C for 1 hr

before testing

increasing load

cra

ck s

pe

ed

(m

/s) as-is

10-10

10-8

Alloy 7178 tested in

saturated aqueous NaCl

solution at 23C

Chapter 1 - 15

Use the right material for the job.

Understand the relation between properties,structure, and processing.

Recognize new design opportunities offeredby materials selection.

Course Goals:

SUMMARY