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MME 2001 MATERIALS SCIENCE 1 yücel birol

Prof. Dr. Yücel BİROL Metallurgical & Materials Engineering

3rd floor / room # 324

Tel: 232 301 74 57

e-mail: [email protected]

lecturer

Fundamentals of Materials Science and Engineering:

An Integrated Approach

3rd Edition

W.D. Callister, Jr. and D. G.

Rethwisch

John Wiley and Sons, Inc.

(2007).

Both book and accompanying

CD-ROM are useful.

textbook

syllabus Come to class! Attendance is encouraged!

if late, don’t panic! Sneak in!

Cell phones silent/off in the classroom!

Be involved in discussions; questions are

welcome! There are no stupid questions,

only stupid people who refuse to ask

them!

Don’t be a stranger; No office hours: drop

by anytime!

grading

Quizzes 10% (2x%5)

Mid-term exam 40% (2x%20)

Final exam 50%

Grade 100%

Tentative program week # activity

1 / 15.9 What is Materials Science and Engineering?

2 / 22.9 Official holiday

3 / 29.9 Atomic structure of materials

4 / 6.10 Atomic structure of materials; cont’d

5 / 13.10 Crystal structure of materials

6 / 20.10 Crystal structure of materials; cont’d

7 / 27.10 imperfections in solids

Tentative program

week # activity

8 / 3.11 Mid-term

9 / 10.11 diffusion

10 / 17.11 Mechanical properties of materials

11 / 24.11 Mechanical properties; cont’d.

12 / 1.12 Strengthening mechanisms

13 / 8.12 Strengthening mechanisms; cont’d.

14 / 15.12 final

learning objectives

To learn about the microstructural features of

materials and to identify different material groups

based on their microstructural features (week # 1)

To understand the arrangement of atoms in

crystalline structures and to identify the most

closely packed/dense crystal directions and planes

(week # 2-6)

To understand the imperfections in materials and

the role of these imperfections on the deformation

and diffusion processes (week # 7-8)

learning objectives

To learn the transfer and transport mechanisms of

atoms across the materials (week # 9)

To learn about the mechanical properties of

materials and the testing methods employed to

measure these properties (week # 10-11)

To understand the stress-strain curves and to learn

how to estimate the mechanical properties of

materials from these curves (week # 10-11)

learning objectives

To learn the macroscopic and microscopic

characterization techniques employed to identify

material properties (week # ?)

To learn about the basic principals of different

strengthening mechanisms used to improve the

strength of materials (week # 12-13)

To learn about the change in mechanical

properties of materials subjected to deformation

hardening (week # 12-13)

Are you ready?

What is materials science? ● study of materials from the macro to the atomic

scale

● with a focus on the effect of structure and

chemistry on material properties!

● from COLA CAN to materials used in AEROSPACE.

Deep drawing beverage cans

● Materials Engineering

(ME) forms a bridge

between the Science

and the Engineering

of materials.

● ME puts theory into

practice in ways that

benefit everybody,

since everything we do

every day involves

materials.

What is materials engineering?

materials science & engineering

● characterize physical and chemical properties of

solid materials so as to enhance inherent

properties, to create or improve end products.

● examine the microstructure to improve the

strength, electrical conductivity, optical or

magnetic properties of a material.

● multidisciplinary, encompassing mechanical,

chemical, biomedical, civil, electrical and

aerospace engineering; physics; and chemistry.

● Materials have historically been important!

different eras of civilization were named after

materials!

● the Stone Age, the Bronze Age, and the Iron Age.

● The development of the semiconductor spawned

the modern era of information technology often

called the Silicon Age.

● Advances in materials science might make this

new millennium biomaterials / nanomaterials /

optical materials age.

Historical perspective

Stone age; The beginning of Material Science!

(2 million years ago!)

People began to make

tools from stone,

Natural materials: stone, wood, clay,

animal skins

The Stone Age ended

about 5000 years ago

with the introduction

of Bronze.

Historical perspective

Paleolithic axe: possibly

>100,000 years old.

Historical perspective

Bronze age ( 3000 BC)

a metal made up of Cu + <

25% of Sn + others.

can be hammered or cast into

a variety of shapes, can be

made harder by alloying,

corrodes slowly after a

surface oxide film forms.

Historical perspective

Iron Age began about 3000 years ago (1000 BC)

and continues

today.

Iron and steel,

a stronger and

cheaper

material

made a drastic

impact on the

daily life of a

common person.

Historical perspective

● 2100 AC (throughout the Iron Age)

new materials have been introduced

(ceramic, semiconductors, polymers,

composites!

Historical perspective

Historical Perspective (Cont’d)

Modern Era

Intelligent design of new materials.

Bioinspired materials

Smart materials

Energy materials

Environmentally friendly materials

Why do we study materials?

design problems almost always involve materials

Transportation/aerospace/automotive;

construction/bridges; buildings

We must select the right material from the

thousands available.

understanding the relationship among

processing, structure, properties, and

performance of materials is crucial!

structure subatomic level

Electronic structure of individual

atoms that defines interaction

between atoms (interatomic

bonding)

atomic level

Arrangement of atoms in materials

(the same atoms can have different

properties, e.g. Two forms of

carbon: graphite and diamond)

structure

Micro level (microns)

Arrangement of small grains that

can be identifed with optical

microscopy

Macro level (>mm)

Structural elements that can be

viewed with the naked eye!

Composition

Type of bonding

crystal structure

Processing

define

microstructure

which in turn defines

materials

properties

material properties

ex: hardness vs structure of steel

• Properties depend on structure

ex: structure vs cooling rate of steel

• Processing can change structure

Structure, Processing & Properties H

ard

ne

ss (

BH

N)

Cooling Rate (ºC/s) 100

2 00

3 00

4 00

5 00

6 00

0.01 0.1 1 10 100 1000

(d)

30 mm (c)

4 mm

(b)

30 mm

(a)

30 mm

Property Example (Physics) Properties

Mechanical response to mechanical forces; Rate

of material deformation

Strength

Elastic modulus

Electrical Response of material to an applied

electrical field

Electrical

conductivity

Thermal expansion/contraction with change

in temperature; conduction of heat

and heat capacity

Heat capacity,

thermal

conductivity

Magnetic Response of a material to an applied

magnetic field

Magnetic

susceptibility

Optical absorption, transmission and

scattering of light

Refractive

index

Chemical

stability

Rate of decomposition of material

(often in presence of acid, etc.)

Corrosion rate

Material properties

electrical properties • Electrical Resistivity of Copper:

• Adding “impurity” atoms to Cu increases resistivity.

• Deforming Cu increases resistivity.

T (°C) -200 -100 0

1

2

3

4

5

6 R

esis

tivity,

r (

10

-8 O

hm

-m)

0

thermal properties Space Shuttle Tiles:

Silica fiber insulation

offers low heat conduction!

Composition (wt% Zinc)

Therm

al C

onductivity

(W/m

-K)

400

300

200

100

0 0 10 20 30 40 100 mm

Thermal Conductivity of Cu:

decreases when you add zinc!

magnetic properties

Magnetic Permeability

vs. Composition:

Adding 3% Si

makes Fe a better

recording medium!

Magnetic Storage

Recording medium

is magnetized by

recording head.

Magnetic Field M

ag

ne

tiza

tio

n

Fe+3%Si

Fe

Transmittance:

Aluminum oxide may be transparent, translucent, or

opaque depending on the material structure.

single crystal polycrystal:

low porosity

polycrystal:

high porosity

optical properties

corrosion resistance Stress & Saltwater...

causes cracks!

4 mm material:

7150-T651 Al

"alloy"

(Zn,Cu,Mg,Zr)

Heat treatment: Slows

crack speed in salt water!

held at 160 C

for 1 h

increasing load cra

ck s

peed (

m/s)

“as-is”

10 -10

10 -8

Alloy 7178

selection of materials

Different

materials

have

different

crystal

structures

and

different

properties

aluminium

magnesium

1. Pick Application Determine required Properties

2. Properties Identify candidate Material(s)

3. Material Identify required Processing

Processing: changes structure and overall shape

ex: casting, sintering, vapor deposition, doping

forming, joining, annealing.

Properties: mechanical, electrical, thermal,

magnetic, optical, corrosion.

Material: structure, composition.

Materials Selection Process

Material criteria

Selecting the right material for the job!

final decision has to consider:

In-service conditions that dictate the

material properties

Deterioration of material properties during

service operation.

Overriding criteria: Finished product COST!

In-service conditions

dictates the required

properties

Rarely a material possess

the maximum or ideal

combination of properties

Sacrificing one

characteristic for another

might be necessary

i.e., strength vs. ductility:

the stronger a material the

less ductile (malleable)

Deterioration

Can occur during service operation

Mechanical strength might be lowered by:

Exposure to elevated temperatures

Exposure to corrosive environments

Finished product cost

You could have perfect material, but too costly

Again, some compromise or sacrifice must be

made

Cost of finished piece includes fabrication cost

Metals

Ceramics

Polymers

Classifications are based on:

Chemistry

Atomic Structure

Additional Material Classes:

Composites

Advanced Materials

Material classes

Metals valence electrons detached from atoms – free e-’s!

Long range atomic order

high density

high mechanical strength

very stiff & strong

high ductility

high fracture toughness

high thermal conductivity

high electrical conductivity

typically magnetic

opaque, reflective

Ceramics either positive or negative ions; bound by Coulomb

forces: e-’s tied up! oxides, nitrides & carbides of metallic and

nonmetallic elements Hard & brittle (susceptible to fracture)

low electrical & thermal conductivity/insulators

optically variant

transparent,

translucent or

opaque

Examples:

glass, porcelain

Polymers covalently bonded + weak van der Waals forces

large molecular structures + hydrocarbon chains

decompose at moderate temperatures (100–400C)

lightweight

low strength, soft, ductile

chemical inertness

optically translucent or

transparent

low electrical and

thermal conductivity

examples: plastics,

rubber compounds

Composites composed of materials from two or more classes

Engineered to achieve a combination of properties

not present in one single material

Fiberglass a classic example of a composite

Glass fibers are embedded

within an epoxy or polyester

substrate

Glass fibers: strong & stiff Polymer: ductile & flexible

Composites

BOEING 787 dreamliner

%50 composites!

carbon-fiber composite Ford

Focus hood, weighing 50% less

than a standard steel version.

density

1-30g/cm3 1.5-10g/cm3

1.5-3g/cm3

0.3-3g/cm3

stifness

50-1000GPa

10-1100GPa

0.005-10GPa

7-750GPa

strength

700-1500MPa

50-1200MPa

10-100MPa

20-1300MPa

fracture toughness

electrical conductivity

Future of materials science

Miniaturization

“nanostructured” materials,

with microstructures that has length scales between

1-100 nanometers with unusual properties.

Electronic components, materials for quantum

computing.

Smart/Intelligent Materials

Airplane wings that adjust to the air flow

buildings that stabilize themselves in earthquakes!

Future of materials science

Environmentally friendly materials

Bio/photodegradable plastics

advances in nuclear waste processing

Learning from nature

Shells and biological hard tissue as strong as the

most advanced laboratory-produced ceramics

mollusces produce biocompatible adhesives.

Quantum dots nanocrystal semiconductor materials

small enough to exhibit quantum

mechanical properties.

The electronic properties are intermediate between those

of bulk semiconductors and of discrete molecules.

Applications in transistors, solar cells, LEDs, diode lasers,

medical imaging, quantum computing.

The first commercial release of a product utilizing

quantum dots was the Sony XBR X900A flat panel

television released in 2013.

Typically made of binary compounds such as lead sulfide,

lead selenide, cadmium selenide, cadmium sulfide.

Quantum dots

Colloidal quantum dots

irradiated with a UV light.

Different sized quantum dots

emit different color light due

to quantum confinement.

Sony XBR-55X900A

Ultra high definition TV

Quantum dots in cancer cure

Nanoparticles with intense stable fluoresence to detect tens

to hundreds of cancer biomarkers in blood assays on cancer

tissue biopsies or as contrast agents for medical imaging

Quantum dots in cancer cure

Quantum dots processed with different bio agents to to

detect different types of tumors viewed under UV light.

Quantum dots

are expected to make a very

big impact in cancer cure.

Quantum dots

"Kilosu 10 milyon dolar"

Dünyanın en pahalı yüksek teknoloji ürünü

kuantum dots Türkiye'de üretilecek.

14.9.2014 tarihli

gazete haberi

Carbon nanotubes

Carbon nanotubes are allotropes of carbon with

a cylindrical nanostructure. These

cylindrical carbon molecules have unusual properties, which are

valuable for nanotechnology electronics, optics and other fields

of materials science and technology.

Carbon nanotubes cylindrical structure with a diameter of several nms.

Carbon nanotubes are the strongest and stiffest

materials. This strength results from the covalent

sp2 bonds formed between the individual carbon

atoms. Owing to special

thermal conductivity

and mechanical and

electrical properties,

carbon nanotubes are

additives to various

structural materials in

electronics, optics.

owing to their extraordinary thermal conductivity and mechanical and electrical properties, carbon nanotubes find applications as additives to various structural materials. For instance, nanotubes form a tiny portion of the material(s) in some (primarily carbon fiber) baseball bats, golf clubs, car parts or damascus steel.[2][3]

Carbon nanotubes

owing to their extraordinary thermal

conductivity and mechanical

and electrical properties, carbon nanotubes find

applications as additives to various structural

materials.

nanotubes form a tiny portion of the material(s) in

some (primarily carbon fiber)

baseball bats,

golf clubs,

car parts or

damascus steel.

Carbon nanotubes

graphene pure carbon in the form of a one atom thick, nearly

transparent sheet.

a crystalline allotrope of carbon with 2-dimensional

properties.

100 times stronger

than steel!

very low weight

a good conducter

of heat and

electricity.

It was first

produced in the lab in 2004.

graphene Andre Geim and Konstantin Novoselov at the

University of Manchester won the Nobel Prize in

Physics in 2010 "for groundbreaking experiments

regarding the

two-dimensional

material

graphene"

graphene

the main impediment to everyday graphene is the

difficulty and cost associated with manufacturing

the material.

Flexible

computers

could one

day be

made with

graphene

Graphene aerogel

Density: 0.16 mg/cm3.

a lower density than

helium and only twice as

much as hydrogen.

Regular air has a density

of about 1.2 mg/cm3

(7.5 times heavier than

graphene aerogel)

it’s less dense than air,

but this near-magical

substance is still a solid.

Graphene in health care elastic bands with graphene:

a flexible sensor for medical use at reasonable cost.

the highly pliable rubber bands fused with graphene

imparts an electromechanical response on

movement – the material

can be used as a sensor to

measure a patient's

breathing, heart

rate or movement,

alerting doctors to

any irregularities.

Graphene solar panels graphene combined with the transition metal,

dichalcogenides:

so thin and flexible, it can absorb sunlight to

produce electricity at the same rates of solar panels.

the ability to power

homes,

incorporated in

smartphones and

tablets.

Graphene plastic composites as a very stiff, light material, Graphene can be

mixed with epoxy to replace metals within the

automotive and aerospace industry. lightweight cars

and planes?

more fuel

efficient!

for aerospace,

the conductivity

of graphene-

plastic composites

would also help in

electrical storms or interference.

Graphene filters Drinkable Clean Water

researchers have developed a graphene filter.

with tiny holes, this filter keeps salt out, making

saltwater drinkable.

Graphene applications

● gas sensors that can sense down to very low

concentrations—at the parts per trillion level.

● coatings that would make any metal rust-free,

● windows that would darken themselves when the

sun is at its strongest

● anodes for lithium-ion batteries

● Flexible solar cells

● membranes for fuel cells

Nanoengineered textiles

Nanosilver ions are integrated

into the polymer matrix or

coated onto the surface of the

fibres, they offer possibilities

such as improved durability,

self cleaning, and water- or

dirt repellent features.

They protect the wearer

from pathogens, toxic gases,

benefiting the medical and rescue services and

allow the constant monitoring of body functions

Smart Materials Materials science is no longer what it used to be!

We were speaking about passive stuff to be cut,

shaped and formed into components for structures

and machines. We wanted materials that would

survive/degrade as little as possible: that wouldn't

swell, or corrode, or bend, or vibrate.

Now things are different. Many of the advanced

materials at the forefront of materials science are

functional: they are required to do things, to

undergo purposeful change. They play an active

part in the way the structure or device works.

Smart Materials state-of-the-art materials for

new technologies.

these materials are able to

sense changes in their

environments and then

respond to these changes in

predetermined manners.

Components include a type of

sensor and an actuator (that

performs a response).

Smart materials have one or more properties that can be significantly

altered in a controlled fashion by external stimuli,

such as stress, temperature, moisture, pH, electric

or magnetic fields.

Piezoelectric /magnetostrictive materials

Shape memory alloys

PH sensitive polymers

electro/magnetorheological fluids

Halochromic materials

Chromogenic systems

Piezoelectric/magnetostrictive materials Piezoelectric materials are materials that

produce an electric field when stress is applied.

this effect applies also in the reverse manner!

a voltage across the sample will produce stress

and strain within the sample.

Suitably designed structures made from these

materials can therefore be made that bend,

expand or contract when a voltage is applied.

Buzzers are piezoelectric.

Piezoelectric actuators and sensors

Piezoelectric effect (sensor)

An electric field is generated

due to a change in dimensions

of a material

+

-

-

+

Converse Piezoelectric effect (actuator)

A change in

dimensions of

a material due to

an electric field

Piezoelectric materials

ink-jet printers where fine movement control is

necessary.

Piezoelectric materials sensors which deploy car airbags.

The material changes in shape with the impact thus

generating a field which deploys the airbag.

Piezoelectric materials

Car electric lighters use

piezoelectric materials:

A spark is created by

pressing a button that

compresses a

piezoelectric crystal

(piezo ignition),

generating an electric

arc.

Use of piezo-electric

ceramics in active

damping mechanisms

to reduce vibrations

application of a

current / voltage

results in mechanical

deflection … or vice

versa

Piezoelectric ceramics

magnetostrictive materials

similar to piezoelectric except for magnetic fields.

Magnetostrictive materials can convert magnetic

energy into kinetic energy, or the reverse, and are

used to build actuators and sensors.

Automotive suspensions

Automotive steering

Automotive tank levels

magnetostrictive materials in suspension systems

magnetostrictive materials a linear electromagnetic motor at each wheel.

There are magnets and coils of wire inside the

motor. When electrical power is applied to the

coils, the motor retracts and extends, creating

motion between the wheel and car body.

shape memory alloys (SMA)

Shape memory alloys are thermoresponsive

materials – after being deformed, revert back to

their original shape with a temperature change.

One of the most common alloys is a combination

of nickel and titanium.

This shape memory alloy can be treated so that

when it reaches a set temperature it contracts.

When it cools it then returns to its original

shape.

Application of SMA Nitinol is used in medicine for stents:

A collapsed stent can be inserted into a vein and

heated (returning to its original expanded shape)

helping to improve blood flow.

Also, as a replacement

for sutures where nitinol

wire can be weaved through

two structures then allowed

to transform into it's

pre-formed shape which

should hold the structures

in place.

Coroner angiography NiTi stents

Shape memory alloy wire remembers its shape.

When a small electrical

current passes through

the wire, it changes

shape.

The wire becomes shorter.

This shortening can be

used to control a robotic

hand.

Shape memory alloys

In the future, this may help to produce artificial

motion that similar to the human movement.

Shape memory alloys

NiTi eyeglass frame

Superelastic effect

Shape memory alloys are alternatives to conventional

steel and concrete in bridges.

They endure heavy strain and still return to their

original state, either through heating or

superelasticity. SMAs demonstrate an ability to re-

center bridge columns,

which minimizes the

permanent tilt columns

can experience after an

earthquake.

Shape memory alloys in civil engineering

PH sensitive polymers pH-sensitive polymers are materials which

swell/collapse when the pH of the surrounding

media changes.

The sensor is prepared by entrapping within a

polymer matrix a pH sensitive dye that responds,

through visible colour changes

two kinds of pH sensitive materials: one which

have acidic group and swell in basic pH, and others

which have basic groups and swell in acidic pH.

Polyacrylic acid is an example of the former and

Chitosan is an example of the latter.

Drug release systems

Controlled release of insulin

Hydrogel works as insulin containing reservoir

within copolymer in which glucose oxidase is

immobilized.

molecular entraces for delivery of insulin

protons are released causing the gates to be

opened for transportation of insulin.

electrorheological fluids

The particles are randomly

distributed in a low strength

field. They align with an

increase in the viscosity of

the fluid when a higher field

strength is applied.

The viscosity changes

X 100,000 in response to an electric field.

suspensions of extremely fine

non-conducting particles in an

electrically insulating fluid.

A simple ER fluid can be made by

mixing cornflour in a light

vegetable oil or silicone oil/cross

linked polyurethane particles in

silicone oil.

The particles are 5 microns in

diameter and contain dissolved

metal ions for fast polarisation and

the electro rheological effect.

Electrorheological fluids

Electrorheological fluids valves and clutches: when the

electric field is applied, an ER

hydraulic valve is shut or the

plates of a

clutch are

locked

together, when

the electric

field is removed

the ER hydraulic

valve is open or

the clutch plates are disengaged.

Used in hydraulic

Electrorheological fluids

Used in the automotive and aerospace industries in

vibration damping and variable torque transmission.

smooth ride and steering

Magnetorheological materials

Magnetorheological fluid is a type of smart

material that has the ability to change state when

placed in a magnetic field.

These fluids are composed of iron-

like particles.

In their normal state they are fluid.

When placed in a magnetic field

the particles are attracted to each

other and join up to form a solid.

MR dampers are used to control the suspension in

cars to allow the feel of the ride to be varied.

Mercedes cars: electronic air suspension!!

Magnetorheological materials

Dampers are also

used in prosthetic

limbs to allow the

patient to adapt to

various

movements for

example the

change from

running to

walking.

Magnetorheological materials

Halochromic Materials

Halochromic materials are

materials that change

their colour as a

result of changing

acidity.

One suggested

application is for paints

that can change colour to

indicate corrosion in the

metal underneath them.

Chromogenic systems

change colour in response to electrical,

thermal or optical changes.

electrochromic materials

thermochromic materials

photochromic materials

Chromogenic materials

Electrochromic materials

Flip a switch and an electrochromic

window can change from clear to

fully darkened or any level of tint

in-between.

The windows operate on a very low

voltage and only use energy to

change their condition, not to

maintain any particular state.

Thermochromic materials Thermochromic materials react to changes in

temperature: temporarily change colour when they

are exposed to heat.

● Tiny capsules in thermochromic

ink contain liquid crystals.

● As the temperature changes

these crystals move.

● The reorientation of the

crystals changes how the

material reflects light,

with a change in colour!

Thermochromic materials Kettles that change colour and signs that

glow-in-the-dark.

thermochromic pigments are now routinely

made as inks for paper and fabrics – and

incorporated into injection moulded plastics.

Warm Cool

Thermochromic materials

The pigments can be incorporated in to dyes for

fabric to produce clothing

which changes colour

with temperature.

Thermochromic inks can

also be used for printing

on to clothing and food

packaging.

‘Smart’ clothing for heat release / retention

Photochromic materials Photochromic materials are sensitive to light:

undergo a reversible change of colour when exposed

to a certain amount of light.

Photochromic lenses become

dark when they are exposed

to UV radiation.

Once the UV radiation is

removed, the lenses gradually

return to their normal state.

They can be made

of either glass or plastic.

Biologically inspired materials Animals show an impressive

performance in classifying, localizing and tracking odor trails.

Dogs can track scent trails of a particular person and identify buried land mines.

Moths can use single-molecule hits of scent to locate the female.

Simple insects use wind sensors and chemical sensors.

Biologically inspired materials

Bioinspired materials are synthetic materials whose

structure, properties mimic those of natural

materials or organisms. Examples of bioinspired

materials are light-harvesting photonic materials

that mimic

Photosynthesis!

Hair bundles in the

inner ear that transduce

mechanical motion into

electrical signals

Polymer E-nose Technology Polymer doped with conducting particles.

polymer swells upon exposure to odor.

longer path for current, hence higher resistance.

Conduction mechanism primarily electron tunneling.

Resis

tan

ce

e- e-

A

B On Off

Time

insulating polymer matrix

conducting element

Polymer E-nose Technology

capable of detecting most

Toxic Industrial Chemicals

(TICS) and Chemical

Warfare Agents (CWA) -

such as Sarin, at levels

below IDLH (Imminent

danger to life and health).

Nanoengineered Materials atoms are arranged bottom up to develop

mechanical, electrical, magnetic, and other

properties into materials that are otherwise not

possible.

‘Nano’: on the order of a nanometer, or 10-9 m.

Self cleaning paints car that can clean itself instantly using a special

kind of paint.

The ultra resistant paint uses nanotechnology

to create a thin air shield

above the surface of the

car that makes rain, road

spray, frost, sleet and

standing water roll off

the car without tainting

its surface at all.

Repels water and oils,

as well as dirt, dust, mud and grit

multiferroics Certain metal oxides, can

exhibit both magnetism

and ferroelectricity. An

electric field will alter the

magnetic state, and a

magnetic field can alter

the electrical polarization.

This allows us to store

data using an electric

field, which is much easier

to generate than a

magnetic field.

Advanced materials

Newly developed, high

performance materials

high-tech applications

semiconductors,

biomaterials, materials in

lasers, integrated circuits,

magnetic storage, LCD’s, and

fiber optics.

Semiconductors Semiconductors have electrical properties that are

intermediate between the electrical conductors

(metals and alloys) and insulators (ceramics and

polymers).

electrical properties

depend strongly on

minute proportions of

contaminants.

Examples: Si, Ge, GaAs.

Semiconductors Semiconductors have made possible the advent of

integrated circuitry that has revolutionized electronics and the computer industry.

Light emitting diodes

LED is a special semiconductor that illuminates

When an electrical charge passes through it. LEDs

Are commonly green, amber or red; however can be

An assortment of other

colors.

amoled AMOLED (active-matrix organic

light-emitting diode) is a display

technology for use in mobile

devices and televisions.

OLED describes a specific type of thin

film-display technology in which

organic compounds form the

Electroluminescent material, and

active matrix refers to the

Technology behind the addressing of

pixels.

AMOLED technology is used in mobile

phones, media players and digital cameras.

Biomaterials implanted into the human body for replacement

of diseased/damaged body parts

must not produce toxic substances and must be

compatible with body tissues.

Metals, ceramics,

polymers,

composites,

semiconductors

may all be used as

biomaterials.

Hip Implant

Requirements

mechanical strength (many cycles)

good lubricity

biocompatibility

With age or certain illnesses joints deteriorate.

Particularly those with large loads (such as hip).

Optical lenses Silicone & Hydrogel Contact Lenses

difference between silicone hydrogel lenses and

conventional hydrogel lenses is the high oxygen

transmissibility of silicone hydrogel lenses.

Conventional hydrogel lenses are classified

according to the water content. Low hydrogels

range between 12-30%

water; high hydrogels

range from 90-99.5%

water content.

Ceramic cement for bone repair

Frontal views 6 months after reconstruction of

full-thickness defect with hydroxyapatite bone

paste (Bone Source)

Advanced materials in sports change in racket frames

from wood to aluminium

then to fibre reinforced

composites has resulted in

larger racket heads. An

increase in the sweet-spot

area on the racket face

means the ‘power’ of the

racket has increased, which

has increased the speed of

the game.

The serve speed has increased

to 155 mph.

Spectators have complained

about the lack of rallies and

excitement in the game.

To slow the game down on fast

surfaces new balls are being

introduced. One new ball type

is 6% larger giving a 12%

increase in drag and hence 10%

increase in response time for

the receiver.

Advanced materials in sports

Solar Cells/photovoltaics ● Photons in sunlight hit the solar panel and

are absorbed by semiconducting materials,

such as silicon.

● Electrons (negatively charged)

are knocked loose from their

atoms, allowing them to flow

through the material to

produce electricity.

● An array of solar cells

converts solar energy

into DC electricity.

Waldpolenz Solar Park

Nellis AFB Solar panels

Future of photovoltaics Convergence of PV and nanotechnology to capture

and convert solar energy more efficiently

Inexpensive plastic solar cells or panels that are

mounted on curved surfaces

nanotubes, flexible plastic organic transparent

cells, ultra-thin silicon wafers

Fuel Cells ● Fuel cells are like batteries

● We feed hydrogen gas into one side.

● hydrogen is split into hydrogen ions and

electrons.

● Only H+ can transfer through the cell through

the electrolyte.

● Electron transfer produces electricity!

● H+ ions and electrons combine with oxygen from

the air and make water at the other electrode.

Fuel Cells

H2

H2

H2

O2

O2

O2

H+

H+

H+

H+

H+

e-

e-

e-

e-

e- e-

e-

e-

e-

e-

H2 2H+ + 2e- ½ O2 + 2e- + 2H+ H2O

hydrogen to fuel a car?

Unlike batteries, fuel cells don’t need to be

replaced. We just

have to refill

the tank with H2!

aerogels

porous, solid materials that exhibit extreme

materials properties.

known for their extreme low densities (0.0011 to

~0.5 g cm-3).

a silica aerogel is only three times heavier than

air.

Typically aerogels are 95-99% air (or other gas) in

volume, with the lowest-density aerogel ever

produced being 99.98% air in volume.

●

●

●

●

aerogels – frozen smoke made of Silica with the sol-

gel process.

a gel is created in solution

and then the liquid is

removed.

Aerogels are good thermal

insulators.

hydrogels for tissue engineering

Hydrogels are formed by

crosslinking polymer

chains, through physical,

ionic or covalent

interactions, and are

well known for their

ability to absorb water.

biological substitutes that

restore, maintain, or

improve tissue function

Materials in wind power Materials play a critical role in wind power.

wind turbines use blades made of polymer-matrix

composite materials reinforced with Fiber glass

or graphite fibers.

Compact electrical generators in the turbines

contain powerful magnets made from rare earth

materials.

The rotation of the turbine blades is used to drive

an electrical generator through a gearbox, which

uses special alloys in order to accommodate a wide

range of wind speeds.

Materials in wind power

Turbine sizes continue to increase.

The growth of off-shore installations means long-

time exposure to higher stresses and hostile

environments that can challenge the durability of

turbine materials.

The turbine blades must have adequate stiffness to

prevent failure due to deflection and buckling.

They also need adequate long term fatigue life in

harsh conditions, including variable winds, ice

loading and lightning strikes.

Materials in wind power

Smart blade materials that automatically

adjust pitch to accommodate wind speed

variations for the most efficient operation

will high strength materials that resist

corrosion and fatigue

Sensors included

in turbine blades to

continuously monitor

fatigue damage and

signal the need for repair

Transportation

● Continued reductions in vehicle mass can be

achieved through

● Advanced High Strength Sheet Steels (AHSS)

developed to enable low-cost crash-resistant

vehicle manufactured with reduced

● sheet thickness and vehicle weight

● light metal developments and application of

new aluminum, magnesium, titanium alloys.

Transportation ● Carbon fiber composites may also play an

increasing role, especially where the weight

savings can justify the much greater cost

● New materials developments to enhance energy

storage (advanced batteries) and conversion

● Advanced magnetic materials and electric

motors

● Membranes and catalysts for fuel cells

● Structural materials for high power-density

drive trains

Energy efficient buildings

● net-zero energy balance buildings:

● lower cost multifunctional materials

● more efficient solid state lighting materials

● more corrosion resistant metals

● improved manufacturing processes

Energy efficient buildings

● Materials have increased the energy efficiency

of today’s buildings

● Low emissivity glass, significantly lowering the

initial investment costs for heating and cooling

● Compact fluorescent lighting and light emitting

diodes (LEDs), reducing lighting costs and heat

loads

● Cool roofs, saving energy

● High efficiency fiber glass insulation

Energy efficient buildings ● Phase change materials to store or

release large amounts of energy in the

walls, floor and roof, thereby saving

energy

● inorganic nanomaterials to positively

influence the solar gain and provide

long term durability

● Electrochromic and liquid crystal

glasses responding to occupants and

external conditions to actively control

both light and solar gain

Phase change materials phase-change material is a substance with a high

heat of fusion which, melting and solidifying at a

certain temperature, is capable of storing and

releasing large amounts of energy. Heat is absorbed

or released when

the material

changes from solid

to liquid and vice

versa.

A sodium acetate heating pad.

When the sodium acetate solution

crystallises, it becomes warm.

Energy storage and transmission

● Energy storage solutions require short-term as

well as long-term high capacity storage methods

and materials

● Supercapacitors—carbon nanotube or other

electrode materials with high internal surface

area, high polar electrolytes

● Batteries—deep discharge and high cycle

materials (lithium-based batteries, lead acid

with new electrodes, flow batteries)

● Sunlight is an important carbon-neutral energy

source.

● More energy from sunlight strikes the Earth in one

hour (13 terawatts) than all the energy consumed

by humans in one year. (0.02% of the total

electrical power is from solar energy.)

● Materials scientists and engineers can provide

materials-based solutions to efficiently capture

the unlimited and free energy from sunlight to

address the world’s energy needs.

Future needs-energy issues

● light battery materials with storage capacity

● turbine blades that can operate at 2500 C

● room temperature super conductors,

● chemical sensors (artificial nose)

● Corrosion-resistant alloys for

high-temperature

power conversion

Future needs-energy issues

Hydrogen fuel cell very feasible and attractive

Holds promise in the car industry as a power source

For this to be efficient,

better materials must

be engineered

Future needs-energy issues

Many materials used are from non-renewable

sources

i.e. oil and some metals

Materials are being depleted steadily which is

cause for:

Need of discovery of additional reserves

Development of similar materials with less

adverse environmental impact

Increase recycling efforts

Future materials needs

see you next week!