Introduction to Material Science (for Engineers)

MEE 1109 Intoduction toMechanical Engineering

Materials Science

It all about the raw materials and how they are processed

That is why we call it materials ENGINEERING

Minor differences in Raw materials or processing parameters can meanmajor changes in the performanceof the final material or product

The selection of materials for design requires that many aspects be considered.

Doing Materials!

Our Role in Engineering Materials then is to understand the application and specify the appropriate material to do the job as a function of: Strength: yield and ultimate

Ductility, flexibility

Weight

Cost: Lifecycle expenses, Environmental impact*

* Economic and Environmental Factors often are the most important when making the final decision!

«Desired» material properties

Resistant to static loads.

Resistant to variable loads (good fatigue strength)

Resistance to corrosion.

Resistance to wear.

Resistant to high temperatures.

Not embrittlement in low temperatures

Lightweight.

Good thermal and electrical conductivity/ in some cases poor thermal and electrical conductivity .

Producibility and formability.

Low cost.

Good appearance

And Remember: Materials “Drive” our Society!

Ages of “Man” we survive based on the materials we control Stone Age – naturally occurring materials

Special rocks, skins, wood

Bronze Age Casting and forging

Iron Age High Temperature furnaces

Steel Age High Strength Alloys

Non-Ferrous and Polymer Age Aluminum, Titanium and Nickel (superalloys) – aerospace Silicon – Information Plastics and Composites – food preservation, housing, aerospace and higher

speeds

Exotic Materials Age? Nano-Material and bio-Materials – they are coming and then …

COMPOSITES

List the Major Types of MATERIALSThat You Know:

METALS

CERAMICS/Glasses

POLYMERS

COMPOSITES

ADVANCED MATERIALS( Nano-materials, electronic materials)

Introduction, cont.

Metals Steel, Cast Iron,

Aluminum, Copper, Titanium, many others

Ceramics Glass, Concrete,

Brick, Alumina, Zirconia, SiN, SiC

Polymers Plastics, Cotton

(rayon, nylon), “glue”

Composites Glass Fiber-

reinforced polymers, Carbon Fiber-reinforced polymers, Metal Matrix Composites, etc.

Thoughts about these “fundamental”

Materials

Metals:

Strong, ductile

high thermal & electrical conductivity

opaque, reflective.

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

non-conducting (insulators)

Polymers/plastics: Covalent bonding sharing of e’s

Soft, ductile, low strength, low density

thermal & electrical insulators

Optically translucent or transparent.

A Timeline of Human Materials “Control”

Structural Steel in Use: The Golden Gate Bridge

Periodic Table of Elements: The Metals

Structural Ceramics

Periodic table ceramic compounds are a combination of one or more metallic elements (in light color) with one or more nonmetallic elements (in dark color).

Alüminyum metaldir, fakat oksijenle yapmış olduğu Al2O3 bileşiği bir seramiktir. Al2O3 ‘in alüminyuma göre yüksek sıcaklık gibi değişik çevre şartlarında istikrarlı bir kimyasal yapıya ve yüksek bir ergime sıcaklığına (2020 °C) sahip olması gibi üstünlükleri vardır (alüminyumun ergime sıcaklığı 660 °C’ dir).

* Al2O3 bu özelliğinden dolayı yüksek sıcaklıkta refrakter malzeme olarak kullanılır.* Si3N4 silisyumnitrür yeni üretilen seramiklerdendir ve otomobil motorlarının yüksek sıcaklık bölgelerinde kullanılmaya adaydır. * B4C borkarbür- zırh malzemesi olarak kullanılmaktadır.* TiN titanyum nitrür-sert ve aşınmaya dayanıklı takım malzemesi olarak kaplanmaktadır.

Optical Properties of Ceramic are controlled by “Grain Structure”

MAE 224: ENGINEERING MATERIALS

1.Introduction 19

Figure 1.2 – Alumina (Al2O3) – single crystal and polycrystal

SINGLE

CRYSTAL POLYCRYSTAL

POLYCRYSTAL

+ PORES

Grain Structure is a function of “Solidification” processing!

Seramikler metaller gibi kristalin yapıya sahip olabilirler; fakat kristalin yapıya sahip olmayan amorf yapıya sahip olan pek çok seramik de vardır. Örneğin; cam. Mesela, pencere camı %72 SiO2

ve geri kalanı Na2O ve CaO’ dir.

Polymers are typically inexpensive and are characterized by ease of formation and adequate structural properties

Periodic table with the elements associated with commercial polymers in color

Üç farklı malzeme türünden imal

edilen ve günlük hayatta sıkça

karşılaştığımız ürünlerden biri, gazlı içecek kaplarıdır. Gazlı içecekler

alüminyum (metal) kutularda (üstte), cam (seramik)(ortada) ve

plastik (polimer) şişelerde (altta) satışa sunulmaktadır.

And Formula One – the future of automotive is …

http://www.autofieldguide.com/articles/050701.html

Figure 1. A small sample of Aerospace grade Carbon-fibre/Epoxy laminate. This is a photo of a small piece of laminated uni-directional Carbon Fibre

Figure 2. Airbus A350, 53% compositematerials

Figure 3. Tail of a radio-controlled helicopter, made of CFRP (carbon fibrereinforcement polymer)

Composite Materials – oh so many combinations

Fiber Glass Composite:

Properties depend on Structure (strength or hardness)

Hard

ness (

BH

N)

Cooling Rate (ºC/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(d)

30mm(c)

4mm

(b)

30mm

(a)

30mm

And: Processing can change structure! (see above structure vs Cooling Rate)

Another Example: Rolling of Steel

At h1, L1

low UTS

low YS

high ductility

round grains

At h2, L2

high UTS

high YS

low ductility

elongated grains

Structure determines Properties but Processing determines Structure!

Electrical Properties (of Copper):

Adapted from Fig. 18.8, Callister 7e.

(Fig. 18.8 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,r

(10

-8O

hm

-m)

0

Electrical Resistivity of Copper is affected by:

• Contaminate level

• Degree of deformation

• Operating temperature

DETERIORATIVE Properties

• Stress & Saltwater...--causes cracks!

Adapted from chapter-opening photograph,

Chapter 17, Callister 7e.

(from Marine Corrosion, Causes, and

Prevention, John Wiley and Sons, Inc., 1975.)

4mm--material:7150-T651 Al

"alloy"

(Zn,Cu,Mg,Zr)Adapted from Fig. 11.26,

Callister 7e. (Fig. 11.26 provided courtesy of G.H.

Narayanan and A.G. Miller, Boeing Commercial

Airplane Company.)

• Heat treatment: slows

crack 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 160ºC for 1 hr before testing”

increasing loadcra

ck s

pe

ed (

m/s

)

“as-is”

10-10

10-8

Alloy 7178 tested in saturated aqueous NaCl solution at 23ºC

Example of Materials Engineering Work – Hip Implant

With age or certain illnesses joints deteriorate. Particularly those with large loads (such as

hip).

Adapted from Fig. 22.25, Callister 7e.

Example – Hip Implant

Requirements

mechanical strength (many cycles)

good lubricity

biocompatibility

Adapted from Fig. 22.24, Callister 7e.

Example – Hip Implant

Adapted from Fig. 22.24, Callister 7e.

Solution – 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

Must hold up in body chemistry

Must be strong yet flexible

Acetabular

Cup and

Liner

Ball

Femoral Stem

• Using the right material for the job.one that is most economical and “Greenest” when life cycle usage is considered

• Understanding the relation between properties, structure, and processing.

• Recognizing new design opportunities offeredby materials selection.

Course Goal is to make you aware of the importance of Material Selection by:

High temperature, high pressure, fatigue

Advanced Materials

Adva

nce

d M

ate

rials

-better structuralproperties-Strength-Thermal resistance-Wear resistance

-Forming-better machiningproperties

-Light-Functional Designs-Small

Advanced Materials

Technical Ceramics: High hardnessvalue, good wearresistance, hightemperatureoperating possibility

High PerformancePlastics: lightweight, goodformability, temperaturestability and highmechanicalproperties

Composite materials: offer manyalternatives in termsofmaterial properties

Smart Alloys: A shape-memory alloy (SMA, smart metal, memory metal, memory alloy, muscle wire, smart alloy) is an alloy that "remembers" its original shape and that when deformed returns to its pre-deformed shape when heated. automotive, aerospace, biomedical and robotics. Akıllı alaşımlar, hatırlatma yetenekleri sayesinde bağlama ve tahrik fonksiyonlarında alışılmamış yeni çözümlere imkan tanımaktadır.

Metal Foams: lightweightconstructions, filter, thermalconductivity, impact absorbing