[email protected] engr-45_lec-01_intro.ppt 1 bruce mayer, pe engineering-45: materials of...

[email protected] • ENGR-45_Lec-01_Intro.ppt1

Bruce Mayer, PE Engineering-45: Materials of Engineering

Bruce Mayer, PELicensed Electrical & Mechanical Engineer

[email protected]

Engineering 45

Materials of Materials of EngineeringEngineering

- Introduction - Introduction --



Course Goals SummarizedCourse Goals Summarized

Use the right material for the job• i.e.; Materials Application

Understand the relation between PROPERTIES, STRUCTURE, and PROCESSING• i.e.; Materials Science & Engineering

Recognize new design opportunities offered by materials selection• i.e.; Physical-Design Innovation



Class Q: Materials Engineering Class Q: Materials Engineering & Technology → What is it?& Technology → What is it?

Investigating the Structures & Properties of Materials and Correlating these with the Design or Engineering or Technology Objectives



The Evolution of MaterialsThe Evolution of Materials



Materials Science & EngineeringMaterials Science & Engineering

Materials are ENGINEERED Structures• Not Black Boxes

Basic Material Structure Has Many Dimensions

Structural Feature Dimension (m)Atomic Bonding <10-10

Missing/Extra Atoms 10-10

Crystals (Ordered Atoms) 10-10 - 10-1

Second Phase Particles 10-8 - 10-4

Crystal Texturing >10-6



Structure, Processing, & PropertiesStructure, Processing, & Properties PROPERTIES depend on STRUCTURE

• e.g.; The HARDNESS vs STRUCTURE of Steel

Cooling Rate (C/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(a)

30m

(b)

30m

(d)

30m(c)

4m

Har

dnes

s (B

HN

)

PROCESSING can change STRUCTURE• e.g., STRUCTURE vs

Cooling-Rate for Steel

TemperedMartensite

UNtemperedMartensite

Ferrite +Cementite

G10380 +w/ Pearlite



Classes of MaterialsClasses of Materials From Chem1A Recall The Periodic Table of Elements

Metals

CeramicsPolymers

SemiConductors



MetalsMetals

May be Pure or Compounds (Alloys)• Along with Polymers The Most Common

Everyday Material

• Typically from the 1st Row of Transition Metals in Periodic Table (Fe, Cu, Ni, etc.)

• Have LARGE Numbers of NonBound Electrons – Makes them Good Electrical & Thermal

CONDUCTORS

• Strong but Deformable (Ductile)



CeramicsCeramics

Basic Composition is the MINERAL Form of a Metal• Very Few Metals Exist in

PURE Form in Nature– Most That Do are Very Rare, e.g., Gold

Ceramics are Compounds of Metals and• Oxygen → Oxides (most Ceramics)

• Carbon → Carbides

• Nitrogen → Nitrides



Ceramics cont.Ceramics cont.

Some Typical Properties• HARD & BRITTLE

• HIGHEST Temperature Resistance– Thoria (Thorium Oxide) Max Temp 3000 K

• Llttle Temperature-SHOCK Resistance

• Corrosion Resistant

• Electrically Resistive (Insulative)

• Difficult to Join– Do Not Weld



PolymersPolymers

Many ChemUnits• MER A Basic Chemical Unit

• POLY Many

Chemical Compounds composed of, in VAST Majority, CARBON & HYDROGEN• Modified by the Presence of Other Elements

– O, Si, F, Cl, N, many others

Commonly Referred to as PLASTIC and/or (synthetic) RUBBER



Polymers cont.Polymers cont.

Some Typical Properties• Very LightWeight

• Very Corrosion Resistant– Best of ANY Class of Material

• Little, if any, Hi/Lo Temperature Resistance

• Little Structural Strength

• Very Deformable (ductile/flexible)

• Lowest $-Cost:Volume Ratio for Any Class of Material



SemiConductorsSemiConductors

May be made CONDUCTIVE or INSULATIVE (or Something in-between) by the Addition of Miniscule Amounts of IMPURITIES• Current Techniques Allow Precise Control

over the AMOUNT and LOCATION of the Impurities

Semiconductors are Very Important Electronic Device Materials



Semiconductors cont.Semiconductors cont.

Most SOLID STATE (no moving parts) Electronic Devices are Semiconductors

Major applications for Semi Transistors• Voltage Amplifiers

• On/Off switches

Additional Advantage: Semiconductor Electronic Devices can be constructed at Extremely SMALL Scales

SILICON is the Most Widely Used



CompositesComposites

Materials that Consist of More than One Material Type• Goal is to Combine the Best

Features of Multiple Materials

Some Examples• FiberGlass = Glass (ceramic) + Polymer

– Strength + Flexibilty

• ReInforced Concrete = Steel + Concrete– Tension-Strength + Compression-Strength



BioMaterialsBioMaterials

Defined as Those Materials Which Are compatible with Human Tissue• Classic Example = Stainless Steels

used For Bone repair (Screws, Staples, Plates, Hip-Joints)

At least a few of ALL other Classes of Materials are BioCompatible• Including Silicon



Smart MaterialsSmart Materials

Smart Materials Materials That Can Sense Changes in the Environment and Respond with a Material Shape/Property Change• Example: "smart" materials that can be

attached to, or embedded in, structural systems – enable the structure to sense disturbances,

process the information and through commands to actuators, to accomplish some beneficial reaction



Smart Materials, cont.Smart Materials, cont. Potential Applications – Structural Systems

• Machine Tools - Improve precision and increase productivity by controlling chatter

• Flexible robotics - enable faster motion with greater accuracy

• Photo-lithography - Enable the manufacture of smaller micro-electronic circuits by controlling vibration in the photo-lithography circuit printing process

• Biomechanical & Biomedical - artificial muscles, drug delivery systems and other assistive technologies

• Process Control - e. g., on/off shape control of solar reflectors or aerodynamic surfaces



NanoTechnologyNanoTechnology

Most Materials are Statistical Devices• i.e., Their Properties are the Average of a

LARGE Number of Atoms or Molecules– A change in a Single NanoScale Particle does

NOT affect Material Characteristics

NanoScale Materials, on the Other hand, are built ONE NanoParticle at a time• Properties Can be PRECISELY Tailored



MaterialsMaterialsApplicationApplicationChainChain

Processing

Structure

Properties

Performance

Selection

Field Application SELECTION is the Critical Step

for Physical-Design Engineers



Materials SelectionMaterials Selection

1. Pick APPLICATION → Determine Required PROPERTIES

• Properties• Mechanical• Electrical• Thermal• Magnetic• Optical• Deteriorative

• Corrosion• Wear• Ageing• UV exposure, etc.



Materials Selection cont.Materials Selection cont.

2. PROPERTIES → Identify candidate Material(s)

• Properties Follow• COMPOSITION as Identified by

CHEMICAL CONTENT• STRUCTURE as Determined by

Material-Formation Processing; e.g.:• Amorphous vs PolyCrystalline vs FullyCrystalline• Second (and perhaps Tertiary) Phases

• Type• Quantity• Size• Distribution



Materials Selection cont.2Materials Selection cont.2

3. MATERIAL → Identify PROCESSING to Obtain Required Structure, and Hence Properties

• Processing Changes STRUCTURE or SHAPE, but NOT Composition• e.g.:

• Casting • Sintering• Thin Film Deposition (CVD, Sputtering, Evap, etc.)• Forming or other Cold-Working• Joining• Annealing, Tempering, or other Heat Treatment• Etc.



Material PropertiesMaterial Properties

Mechanical load deformation, stress, strain

“structural matls” modulus/stiffness, strength, toughness

Envt./Chemical chemicals, temp (aqueous solution)

corrosion passivity, pollution

Electrical electrical field conductivity “electronic matl.s” semiconductors, resistivity, dielectric

Magnetic magnetic field magnetism magnets, hysteresis, moments

Thermal heat conductivity heat capacity, thermal expansion

Optical radiation (em, light)

color, transparency

index of refraction, reflectivity

Property Stimulus Result Terms

Material performance depends on material properties



Basic Material PropertiesBasic Material Properties

General

Weight: Density , kg/m3

Expense: Cost/kg Cm, $/kg

Mechanical

Stiffness: Young’s modulus E, GPa

Strength: Elastic limit y , MPa

Fracture strength: Tensile strength ts , MPa

Brittleness: Fracture toughness KIc , MPa·m1/2

Thermal

Expansion: Expansion coeff. , 1/K

Conduction: Thermal conductivity , W/m·K

Specific Heat (Capacity), cp or cv, J/kg·K

Electrical

Conductor? Insulator? Conductivity σ, S/m

Dielectric Capacity, F/m

Young’s modulus, E

Elastic limit, y

Strain

Str

ess

Ductile materials

Brittle materials

Young’s modulus, E

Tensile (fracture) strength, ts

Strain

Str

ess

Thermal expansion

o

Expansion coefficient,

Temperature, T

Th

erm

al s

tra

in

x

T1 To

Q joules/secArea A

Thermal conduction

Mechanical properties

Thermal conductivity,

(T1 -T0)/x

He

at

flux,

Q/A



Mechanical Properties ExampleMechanical Properties ExampleStiffStrongToughLight

Not stiff enough (need bigger E) modulus of elasticity

Not strong enough (need bigger y ) yield strength

Not tough enough (need bigger KIc)fracture toughness

Too heavy (need lower ) density

All OK !



Electrical Structure/PropertiesElectrical Structure/Properties Electrical Resistivity of Copper

Adding “impurity” atoms to Cu increases resistivity Deforming Cu increases resistivity

T (°C)-200 -100 0

Cu + 3.32 at%Ni

Cu + 2.16 at%Ni

deformed Cu + 1.12 at%Ni

1

2

3

4

5

6

Resi

stiv

ity,

(1

0-8 O

hm

-m)

0

Cu + 1.12 at%Ni

“Pure” Cu

Note: Resistivity, = 1/Conductivity• Resistivity → ρ

(Ω-m)

• Conductivity → σ (S/m)



Thermal Structure/PropertiesThermal Structure/Properties THERMAL Conductivity of Copper

Adding “impurity” atoms to Cu (zinc to make a BRASS) Decreases Thermal conductivity

Composition (wt%Zinc)Therm

al C

onduct

ivit

y

(W/m

-K)

400

300

200

100

00 10 20 30 40



Magnetic Structure/PropertiesMagnetic Structure/Properties Magnetic Permeability vs. Composition for Iron

Adding 3 atomic % Si makes Fe a Much BETTER magnetic recording medium

Magnetic FieldMagneti

zati

onFe+3%Si

Fe



Optical Structure/PropertiesOptical Structure/Properties Aluminum Oxide Light Transmittance

may be transparent, translucent, or opaque depending on the material structure

single crystalpolycrystal:low porosity

polycrystal:high porosity



Deteriorative Structure/PropertiesDeteriorative Structure/Properties SaltWater and

STRESS can Cause Cracks in Metals

Heat treatment: slows crack formation speed in salt-water exposed metal

“held at 160C for 1hr before testing”

increasing loadcrack

sp

eed

(m

/s)

“as-is”

10-10

10-8

Alloy 7178 tested in saturated aqueous NaCl solution at 23C



Materials Information for DesignMaterials Information for DesignThe goal of design:“To create products that perform their function effectively, safely, at acceptable cost”

What do we need to know about materials to do this? More than just test data.

Test Test data

Data capture

Stat/Mathanalysis

Design data Successful applications

$

Economic analysisand business case

Selection ofmaterial and process

Potential applications

Mechanical Properties

Bulk Modulus 4.1 - 4.6 GPaCompressive Strength 55 - 60 MPaDuctility 0.06 - 0.07Elastic Limit 40 - 45 MPaEndurance Limit 24 - 27 MPaFracture Toughness 2.3 - 2.6 MPa.m1/2

Hardness 100 - 140 MPaLoss Coefficient 0.009- 0.026Modulus of Rupture 50 - 55 MPaPoisson's Ratio 0.38 - 0.42Shear Modulus 0.85 - 0.95 GPaTensile Strength 45 - 48 MPaYoung's Modulus 2.5 - 2.8 GPa

Characterization Selection and implementation

© 2002, M.F. Ashby and D. Cebon



Goals of Matls Engineering & TechnologyGoals of Matls Engineering & Technology

Select the Best Material for the Job

If something goes wrong (“failure”)• Understand Why

• Fix & Prevent

Understand Inter-Relationships of• processing

• structure

• properties

• performance

Structure

Processing

Properties

Performance

Open new design opportunities with new materials



WhiteBoard WorkWhiteBoard Work

Problem Summary Here• List problem

– Features

– Constraints

– Criteria

– Goals



IBM-Almaden InternshipIBM-Almaden Internship Target Audience

• Projects and the program are designed for sophomores and juniors with majors in chemistry, physics, chemical engineering and related sciences

Program Details Duration: 10 weeks, beginning June 7 or June 21, 2004. Stipend: Students $4500 for 10 weeks (not bad...). Eligibility: Undergraduate (pre-graduate school) standing,

with preferably two years of chemistry. Requirements vary by project, but outstanding candidates at any level and technical major in science or engineering are encouraged to apply. Preference is given to chemistry, chemical engineering, and materials science majors. Participants must be citizens or permanent legal residents of the US.



IBM-Almaden InternshipIBM-Almaden Internship

The BAD News → A Pretty Nasty Set of Application Documents• Two App Forms

• Two Letters of Req– I can Help

• Personal Essay

For the Forms see• http://www.almaden.ibm.com/st/info/

studentopps/nsfstudent/NSFapplic.html