engineering materials 01 introduction

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METB113ENGINEERING MATERIALS

INTRODUCTION
http://www.bing.com/images/search?q=logo+uniVERSITI+TENAGA+NASIONAL&view=detail&id=85D01D8CAADD822204841FDA6F3BCB3C14748406&first=0&FORM=IDFRIR


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What it is?

Definition

Standard Methods

Applications


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The Mars Rovers - Spirit and

Opportunity

Spirit and Opportunity are made up of materials such as

* Metals * Ceramics * Composites * Polymers * Semiconductors

www.nasa.gov


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What are Materials? Materials may be defined as substance of which

something is composed or made.

We obtain materials from earth crust and atmosphere.

Examples :-

Siliconand Ironconstitute 27.72 and 5.00

percentage of weight of earths crust

respectively.

Nitrogenand Oxygenconstitute 78.08 and20.95 percentage of dry air by volume

respectively.

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Why the Study of Materials isImportant?

Production and processingof materials constitute a large part of oureconomy.

Engineers choose materials to suite design. New materials might be needed for some new applications.

Example:- High temperature resistant materials.

Space station and Mars Roversshould sustain conditionsin space.

* High speed, low temperature, strong but light.

Modification of properties might be needed for some applications.

Example :- Heat treatment to modify properties.

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Materials Science and Engineering Materials science deals with basic knowledgeabout the internal

structure, properties and processing of materials.

Materials engineering deals with the application of knowledge

gained by materials science to convert materials to products.

Resultant

Knowledgeof Structure and

Properties

Applied

Knowledge

of Materials

Materials ScienceMaterials Science and

Engineering Materials Engineering

Basic

Knowledgeof

Materials

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Types of Materials Metallic Materials

Composed of one or more metallic elements.

Example:-I ron, Copper, Aluminum.

Metallic element may combine with nonmetallic elements.Example:-Sil icon Carbide, I ron Oxide.

Inorganic and have crystallinestructure.

Good thermal and electric conductors.

Metals and Alloys

Ferrous

Eg: Steel,

Cast Iron

Nonferrous

Eg:Copper

Aluminum

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Types of Materials

Polymeric (Plastic) Materials Organic giant molecules and mostly

noncrystalline. Some are mixtures of crystalline and

noncrystalline regions.

Poor conductors of electricity and hence used asinsulators.

Strength and ductility vary greatly.

Low densities and decomposition temperatures.

Examples :-Poly vinyl Chloride (PVC), Polyester .

Applications:-Appliances, DVDs, Fabrics etc.

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Types of Materials Ceramic Materials

Metallic and nonmetallic elements are chemically bonded

together.

Inorganic but can be either crystalline, noncrystalline or

mixture of both.

High hardness, strength and wear resistance.

Very good insulator. Hence used for furnace lining for heat

treating and melting metals.

Also used in space shuttle to insulate it during exit andreentry into atmosphere.

Other applications: Abrasives, construction materials,

utensils etc.

Example:-Porcelain, Glass, Sili con ni tr ide.

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Types of Materials Composite Materials

Mixture of two or more materials.

Consists of a filler material and a binding material.

Materials only bond, will not dissolve in each other. Mainly two types :-

o Fibrous: Fibers in a matrix

o Particulate: Particles in a matrix

o Matrix can be metals, ceramic or polymer

Examples:-Fiber Glass ( Reinforcing material in a polyester or

epoxy matrix)

Concrete ( Gravels or steel rods reinforced in cement andsand)

Applications:-Aircraft wings and engine, construction.

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Types of Materials

Electronic Materials

Not Major by volume but very important.

Silicon is a common electronic material.

Its electrical characteristics are changedby adding impurities.

Examples:- Silicon chips, transistors

Applications :-Computers, IntegratedCircuits, Sattelites etc.

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Competition Among Materials Materials compete with each

other to exist in new market

Over a period of time usage of

different materials changes

depending on cost and

performance.

New, cheaper or better materials

replace the old materials when

there is a breakthrough in

technology

Example:-

0

200

400

600

800

1000

1200

1400

1600

lb/Car

1985 1992 1997

Model Year

Aluminum

Iron

Plastic

Steel

Predictions and use of

materials in US automobiles.

Figure 1.14

After J.G. Simon, Adv. Mat. & Proc., 133:63(1988) and new data1-10

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Future Trends

Metallic MaterialsProduction follows US economy closely.

Alloys may be improved by better chemistry andprocess control.

New aerospace alloys being constantly researched.

o Aim:To improve temperature and corrosion resistance.

o Example:Nickel based high temperature super alloys.

New processing techniques are investigated.

o Aim:To improve product life and fatigue properties.

o Example:Isothermal forging, Powder metallurgy.

Metals for biomedicalapplications

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Future Trends

Polymeric (Plastic Materials)

Fastest growing basic material (9% peryear).

After 1995 growth rate decreased due to

saturation.

Different polymeric materials can beblend together to produce new plastic

alloys.

Search for new plastic continues.

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Future Trends

Ceramic Materials

New family of engineering ceramicsare produced last

decade

New materials and applications are constantly found.

Now used in Auto and Biomedicalapplications.

Processing of ceramics is expensive.

Easily damaged as they are highly brittle.

Better processing techniques and high-impact

ceramics are to be found.

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Future Trends

Composite Materials

Fiber reinforced plasticsare primary

products.

On an average 3% annual growth from 1981

to 1987.

Annual growth rate of 5% is predicted for

new composites such as Fiberglass-EpoxyandGraphite-Epoxycombinations.

Commercial aircrafts are expected to use

more and more composite materials.

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Future Trends Electronic Materials

Use of electronic materials such as silicon

increased rapidly from 1970.Electronic materials are expected to play vital

role in Factories of Future.

Use of computers and robots will increase

resulting in extensive growth in use of electronic

materials.

Aluminum for interconnections in integrated

circuits might be replaced by copper resulting in

better conductivity.

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Future Trends

Smart Materials :Change their properties bysensing external stimulus.

Shape memory alloys: Strained material reverts

back to its original shape above a critical

temperature.

Used in heart valves and to expand arteries.

Piezoelectric materials: Produce electric field

when exposed to force and vice versa.

Used in actuators and vibration reducers.

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MEMS and Nanomaterials MEMS: Microelectromechanical systems.

Miniature devices

Micro-pumps, sensors

Nanomaterials:Characteristic length < 100 nmExamples: ceramics powder and grain size < 100 nm

Nanomaterials are harder and stronger than bulk

materials. Have biocompatiblecharacteristics ( as in Zirconia)

Transistors and diodes are developed on a nanowire.

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Case Study

Material Selection Problem:Select suitable material for bicycle

frame and fork.

Low cost but

Heavy. Less

Corrosion

resistance

Light and

strong. But

Cannot be

shaped

Very light and

strong. No

corrosion.

Very expensive

Light, moderately

Strong. Corrosion

Resistance.

expensive

Slightly better

Than Al

alloys. But much

expensive

Cost important? Select steel

Properties important? Select CFRP

Ti and Mg

alloys

Aluminum

alloys

Carbon fiberReinforced

plastic

WoodSteel and

alloys

engineering materials 01 introduction

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