‘’INTRODUCTION’’

IE-114 Materials Science and General Chemistry

Lecture-1

Our history has been defined by the materials we use

The stone age

The copper age

The bronze age

The iron age

History of Materials

Stone Age

– naturally occurring material (Special rocks, skins, wood)

The pottery appeared during the Neolithic ("The last stone age"). Till then, the

pots were made of stone and wood.

Ceramic appeared 8,000 years ago in the Middle East, from Macedonia to Iran

How was it done?

Mixing of clay with water, shaping and firing at high temperature(1000-1200oC) to gain strength

Pottery in stone age

IRON AGE TOOLS

Metal (Copper, Bronze&Iron) Age

COPPER AND BRONZE (Cu +Sn) PARTS

Mining IRON MAKING in high temperature furnaces

(Casting and forging)

Gold occurs in high purity elemental state

As a result of this, it has high ductility & can be shaped easily

Gold (Au)

500 BC

Ore (e.g. iron)

Open Pit mining or underground mining

Crushing, Grinding, Screening

MINING

MINERAL DRESSING

METAL EXTRACTION

PYROMETALLURGY (High T) e.g. Iron, steel, Pb, Sn,Cu

HYDROMETALLURGY (Taking into solution) e.g. Au, Ag, V, Al

ELECTROMETALLURGY (Electric current) e.g. Pb, Cu, Ni

Metal Extraction

Earth’s

Crust

Concentrated

here

IN THE FORM OF MINERALS

Fe2O3 (Hematite)

Fe3O4 (Magnetite)

CuFeS2 (Chalcopyrite)

Al2O3.H2O (Boehmite) ..........

Extracting of metal from its ore and purifying it

16 km’s thick

Iron&steel plant

Ao Ad

force

die

blank

force

• Forging

(wrenches, crankshafts)

FORMING

• Drawing (rods, wire, tubing)

often at

elev. T

• Rolling (I-beams, rails)

• Extrusion

(rods, tubing)

tensile force

Ao

Addie

die

Metal Fabrication Methods

CASTING

• Sand Casting

(large parts, e.g.,auto engine blocks)

• Investment Casting

(low volume, complex shapes

e.g., jewelry, turbine blades)

• Die Casting

(high volume, low T alloys)

• Continuous Casting (simple slab shapes)

Metal Fabrication Methods

plaster

die formed

around wax

prototype

Materials Science&Engineering

Materials Engineering

-Is, on the basis of these structure-property correlations, designing or

engineering the structure of a material to produce a pre-determined set of

properties

Materials Science&Engineering

Materials Science

-Investigating relationships that exist between the structure and

properties of materials

1) Sub atomic – electrons and nuclei (protons and neutrons)

2) Atomic – organization of atoms or molecules

3) Microscopic – groups of atoms that are normally

agglomerated together 4) Macroscopic – viewable with the un-aided eye

1 Ao = 10

-10 m

1 nm = 10-9 m

1 m = 10-6 m

1 mm = 10-3 m

1 cm = 10-2 m

Structure

Property

- A material trait expressed in terms of the measured response

to a specific imposed stimulus

- Hardness

- Strength

- Ductility, etc.

- Resistivity

- Conductivity

- Mag. permeability

- Index of refraction

- Reflectivity

- Ther. conductivity

- Heat capacity

+ Deteriorative Properties: Relate to the chemical reactivity of materials

Structure&Property Relationship

- Properties (mechanical, electrical&magnetic, optical, thermal) of materials

depends on internal structure (in microscopic and atomic level ; bonding,

crystal structure and composition)

Mechanical property(hardness) vs. Internal (micro) structure

affected from processing type

- Different hardness values are obtained due to

difference in microstructure

Optical property (light transmittance) vs. Internal structure

- Three different Al2O3 specimens

Transparent

- Single crystal

Translucent

- Composed of many single

crystals (polycrystalline)

Opaque

- Polycrystalline +

contains micro pores

- Structure of a material will depend on how it is processed

Processing&Structure Relationship

- Thermal processing, mechanical processing, etc,.

- Microstructure of steel after different thermal treatments

(heated to 900oC and cooled down to room temperature at different cooling rates)

Martensite microstructure

Pearlite+ferrite

microstructure

Metals:

Metallic bonding;

Cu, Al, Ni, Fe, Au, bronze (Cu-Sn), steel (Fe-C) etc.

Aluminum cup

They are groupped as ferrous (steels) and non-ferrous (copper, magnesium, titanium

and so on) metals

Properties: strong, ductile, high density, good conductors of heat and electricity

(free valance electrons)

Types of Materials

Copper electric wires

Car body panel: low carbon steel

Engine composed of steel and cast iron

parts

Drawback:

Corrosion of

some metals,

i.e. Steel,iron

Jet engine containing

mainly titanium alloys

METALS IN PERIODIC TABLE

Structural: bioceramics, cutting tools, engine components, armour.

Electrical: Capacitors, insulators, magnets and superconductors

2-ADVANCED CERAMICS

1-TRADITIONAL CERAMICS

Pottery, porcelain, brick, glass

Ceramics:

Combinations of metals or with oxygen, nitrogen, carbon and boron

(oxides, nitrides, carbides, borides) CaO, Al2O3, BN, SiC, TiB2

Properties: hard but very brittle, Insulators of heat and electricity, resistant to

high temperature and hars environments,

Brake disc SiC engine components SiC body armour Cutting tools

Whiteware

C N Metal + B O

CERAMIC (metal + commonly B, C, N or O)

CERAMICS IN PERIODIC TABLE

Polymers:

Organic compounds based on C, H and other nonmetallic elements.

Large molecular structures

(e.g. Epoxy, Nylon, PVC, Polystyrene, Plastics and rubber)

Properties: weak, low density, ductile, extremely flexible,insulators.

Natural Polymers

Rubber, cotton, wool, leather, silk

Synthetic Polymers

PP, PS, PVC, PE

1-THERMOPLASTIC Chains of molecules are not

connected to each other

Can be soften or molten and reformed

into new shape by reheating.

Property Type of Polymer

i.e.Polyethylene(PE), Poly vinly chloride

(PVC), polypropylene (PP)

Cannot be soften or molten and

reshaped 2-THERMOSETTING Heavily cross-linked to produce a

strong three dimensional network

structure

i.e.Polyester, epoxies, silicone

3-ELASTOMERS

Polymers that have an elastic

deformation >200%

Gains its original shape when

deformed and then released

Polyisoprene (vulcanized rubber)

Composites:

Engineered to consist of more than one type of material (metal+ceramic,

polymer+ceramic, etc), so that display a combination of best characteristics

Properties: strong, ductile, low density, conductors and insulators.

Matrix: metal,

ceramic or

polymer

Reinforcement: metal,

ceramic or polymer

Types of composites

Reinforcement particles used in composites

Examples

Concrete (CMC) Automobile tire (PMC) Matrix

Reinforcement

Boats (PMC)

Matrix: epoxy

Reinforcement: glass fiber

Cutting tools (MMC) Used for shaping of

hard materials

High strength to weight ratio

Structural Composites, i.e. Honeycomb structure

Cellulose fibers are surrounded by lignin

Structural Composites, i.e. Wood

Comparison of Properties of

Materials

Density Strength

Electrical

conductivity

Semiconductors

Electrical properties are intermediate between conductors and insulators

(e.g. Silicon)

(a) Micro-Electrical-Mechanical Systems (MEMS), (b) Si wafer

for computer chip devices.

Advanced Materials

(Semiconductors, Biomaterials, smart materials, Nanoengineered materials)

Biomaterials

(Co-Cr alloys, Stainless steels, Ti&Ti-alloys)

Nanomaterials

Nano-antenna Carbon nano tube