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