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Engineering Materials

Chapter 1Introduction and

History on Materials Evolution

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工程材料課程ppt講義有部分是授課教師選用教科書內圖片及Wiley出版公司提供之ppt講義，配合教師自行增加之內容編撰而成，圖片及部分ppt版權屬Wiley出版公司。

工程材料課程所有講義嚴格僅限供修課同學為著上課以及研讀之目的在ecourse教學平台下載使用。

嚴禁轉發非修課同學及校外任何人士。違反者將違反相關智財權法。

Prof. J.N. Aoh CCU ME 09.16.2021

Chapter 1 - Introduction

• What is materials science? • Why should we know about it?• Materials drive our society-

• Stone Age– Bronze Age :Tm– Brass– Iron Age :Tm– : cast iron/wrought iron/steels– Now?

• Silicon Age? Semiconductor Age?• Polymer Age? Nano Age?

1.1 Historical perspective

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Historical evolution of engineering materials

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Stone age (-3300 BC)

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Pottery age

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Black potteryPainted pottery

Firing temperature of ancient kilns(窯)

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Smelting furnace for bronze alloy

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Bronze Phase Diagram

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Brass phase diagram

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Cu Zn

Blast furnace for iron making

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中鋼高爐

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Iron-carbon phase diagram

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1.2 Materials Science and engineering

Atomic structures Crystal structures MicroscopicMacroscopic Material properties Processing Performance

The four components of the discipline of materials science and engineering and their interrelationship.

Aluminum oxides with different light-transmittance characteristics.

A consequence of differences in structure of these materials due to materials processing.

What are these different Aluminum oxide structures?

Single crystal (transparent)

Polycrystalline (translucent)

Polycrystalline porous (translucent)

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1. Application Determine required Properties

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

forming, joining, annealing.

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

Material: structure, composition.2. Properties Identify candidate Material(s)

3. Material Identify required Processing

The Materials Selection Process

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Atoms Structure

Crystal

Properties

Microstructure Component

Thermo-mechanical Treatments

Phases Defects+

• Casting• Metal Forming• Welding• Powder Processing• Machining

• Vacancies• Dislocations• Twins• Stacking Faults• Grain Boundaries• Voids• Cracks

+ ResidualStress

Processing determines shape and microstructure of a component

相

缺陷

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ex: hardness vs structure of steel• Properties depend on microstructure

ex: microstructure vs cooling rate of steel• Processing can change microstructure

Structure, Processing, & Properties

Har

dnes

s (B

HN

)

Cooling Rate (ºC/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(d)

30 μm(c)

4 μm

(b)

30 μm

(a)

30 μm

ex: 碳鋼的硬度與其顯微結構(相)的關係

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Why study engineering materials for mechanical engineers?

• Machine design and components design always involve materials selection.

• Materials (mechanical) properties must match in-service conditions of machines and components.

• Materials properties may be enhanced by processing and treatment.

• Basic knowledge on the relationship between (micro)structure and the mechanical properties of the materials.

• Case study- Librty ship WWII(later in Chap 10)

1.4 CLASSIFICATION OF MATERIALS

• Metals• Ceramics• Polymers• Composites

Metals

Ceramics

Polymers

Semi-conducotrs

Metallic Bond

Ionic Bond

Covalent Bond

Com

posi

tes

Advanced materials:•Semiconductors•Biomaterials•Functional materials•Smart materials

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• Metals: Metallic bonding– Strong, ductile– High thermal & electrical conductivity– Opaque, reflective.

• Polymers: Plastics, rubber, PE,PVC, etc.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)

• Composites: composed of two or more materials, such as metals, ceramics, and polymers. Carbon Fiber Reinforced Polymers (CFRP)- combination of properties of materials

- best characteristics of each of the component materials

1.4 Classification of Materials

Classification of Materials

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Figure 1.3 Bar chart of room-temperature density values for various metals, ceramics, polymers, and composite materials.

Figure 1.4 Bar chart of room-temperature stiffness (i.e., elastic modulus) values for various metals, ceramics, polymers, and composite materials.

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Figure 1.5 Bar chart of room-temperature strength (i.e., tensile strength) values for various metals, ceramics, polymers, and composite materials.

Figure 1.6 Bar chart of room-temperature resistance to fracture for various materials.

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1.5 ADVANCED MATERIALS (functional materials)

•Semiconductors•columns IIIA-VA

•Biomaterials•Compatible to body tissues

•Smart materialsUsually sensor or actuator •Shape memory alloys•Piezoelectric ceramics•Optical fibers

•Nanomaterials usually < 100nm,1 nano= 10?

• Carbon nanotube (CNT)• Graphene

三五族

Semiconductors-silicon wafer/ chips/ IC

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Shape memory alloys, Ni-Ti Alloys

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Piezoelectric ceramics

Adapted from Fig. 19.36, Callister & Rethwisch 9e. (© 1989 by Addison-Wesley Publishing Company, Inc.)

Piezoelectricity– application of stress induces voltage (sensor)– application of voltage induces dimensional change (Actuator)

σ

σstress-free with applied

stress

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Piezoelectric effect

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Sensor

Nanomaterials--examples

• Graphite• Graphene• Carbon Nanotube• CNT

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碳米碳管簡介 (Carbon nano-tube)

‧First found in 1991‧ideal CNT consists of hollow tube formed by graphene sheet‧Single walled carbon nanotube, SWNT –one layer of graphene‧Multi-walled carbon nanotube, MWNT—multilayer of graphene‧SWNT diameter usually 1－6 nm，smallest dia. --0.5 nm‧SWNT length up to several hundred nm to mm

Example on biomaterialsHip fracture and hip implant

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Example on biomaterials– Hip Implant

Adapted from Fig. 22.26, Callister 7e.

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Hip Implant• Key problems to overcome

– fixation agent to hold acetabular cup

– cup lubrication material– femoral stem – fixing agent

(“glue”)– must avoid any debris in cup– Lifetime: at least 10 years

Femoral Stem(Ti-alloy)

Ball (Ti-alloy)

AcetabularCup (Ti-alloy) and

Liner(polymers)

Adapted from chapter-opening photograph, Chapter 22, Callister 7e.

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Biomaterials for human tissues

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目前無法顯示此圖像。

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Thermal properties• Space Shuttle Tiles:

-- Silica fiber insulationoffers low heat conduction.

100μm

an uncoated tile can be held by its edges with an ungloved hand seconds after removal from the oven while its interior still glows red.

90 percent of the tile is void and the remaining 10 percent is material.

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Thermal properties

Space shuttle Columbia

• The Space Shuttle Columbia disaster occurred on February 1, 2003, when Columbia disintegrated over Texas and Louisiana as it reentered Earth's atmosphere, killing all seven crew members.

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Magnetic property• Magnetic Permeability

vs. Composition:-- Adding 3 atomic % Si

makes Fe a betterrecording medium!

• Magnetic Storage:-- Recording medium

is magnetized byrecording head.

Magnetic Field

Mag

netiz

atio

n Fe+3%Si

Fe