Introduction to Materials Science and Engineering

IntroductionMaterial Science

Involves determining the relationship between the structures and properties of materials

A material scientist tries to determine the relationship of material properties to the response of the material

For example, what is the relationship between the pressure and temperature of a material?

Materials EngineeringStudy on the process of creating or designing a

new material based on an existing material with similar properties

Materials EngineerTries to create a new material with the desired

properties based on an existing material with similar properties

For example, car window glasses previously breaks into splinters causing severe injury. To make the glass safer, the glass is tempered by increasing its internal stress such that when broken, will crumble into granular chunks

Microscopic vs. MacroscopicMicroscopic structure is defined as the

material structure that can be seen with microscopes such as Optical microscope Scanning electron microscope Atomic force microscope

Macroscopic structure is defined as structures that can be seen by unaided eye

Structure of a MaterialThe structure of a material usually relates to

the arrangement of its internal components.For example, materials are composed of

atoms that may have specific atomic configuration (e.g. crystalline or noncrystalline)

Properties of a MaterialDefined as the characteristic of a material that

differentiate it from other materials. It is independent on its size and shape

Material properties are grouped into six: Mechanical Electrical Thermal Optical Magnetic Deteriorative

Mechanical properties relate deformation to an applied load or force

Electrical properties, such as electrical conductivity and dielectric constant, the stimulus is an electric field

Thermal behavior of solids can be represented in terms of heat capacity and thermal conductivity

Magnetic properties demonstrate the response of a material to the application of a magnetic field.

Optical properties, the stimulus is electromagnetic or light radiation

Deteriorative characteristics relate to the chemical reactivity of materials.

Four Components of MaterialsThe structure of a material depends on how it

is made or processed while the performance of the material depends on its properties. The four components of a material are interrelated:

For example, even though graphite and diamond are made up of carbon atoms, they are processed differently to produce a different material

Why Study Materials?For the engineer and scientist, it is necessary to

study materials to enable to select the necessary material for a specific purpose

Usually there is a tradeoff between one characteristic to another

For example, a ductile material have limited strength and vice versa. Therefore, as an engineer, it is necessary not only to know the right specifications but also the limitation induced by the increased performance of the material

Deterioration of material property is also important. For example, if you have a beach house, you need to determine if the roof of the house is highly resistant to corrosive attack. Note that salt is corrosive that can shorten the lifetime of your roof

You need to have basic knowledge about the economic consideration of creating or replacing traditional materials

For example, solar panels are very effective in replacing electrical sources but they are very expensive. Return of investment will usuall be around 15 years.

Buying expensive leather shoes might be cheaper in the long run compared with buying cheaper synthetic leather shoes

The more familiar you are with the various characteristics and structure–property relationships, as well as processing techniques of materials, the more proficient and confident you will be to make judicious materials choices based on these criteria.

Classification of MaterialsBasic Classification

MetalsPolymersCeramics

Advance MaterialsCompositesSemiconductorsBiomaterials

MetalsMetals includes Cu, Fe, Al, ZnMetallic alloys includes small amounts of

nonmetalllic materials such as carbon, nitrogen and oxygen

In terms of density, metals are denser than ceramics and polymers.

Bar-chart of room temperature density values for various metals, ceramics, polymers, and composite materials

Bar-chart of room temperature stiffness

Bar-chart of room temperaturestrength

Bar-chart of room-temperature resistance to fracture

Bar-chart of room temperatureelectrical conductivity ranges

CeramicsCeramics are compounds between metallic

and nonmetallic elementsThey are most frequently oxides, nitrides,

and carbidesExamples includes:

PorcelainGlassTilesAluminaSilica

Ceramics are relatively stiff , strong and hard

However, they are brittle and easy to fractureInsulators and more resistant to heat and

harsh environment compared with metals and polymers

PolymersPolymers include the familiar plastic and rubber

materialsChemically based on carbon, hydrogen and other

nonmetallic elements like oxygen, nitrogen and silicon

Examples arePolyethyleneNylonPolyvinyl chloride (PVC)Polystyrene (styrofoam)Rubber

Polymers usually have low densitiesNot stiff nor as strong as ceramics and

metalsDuctile and pliableInert and unreactive to most harsh

environmentOne major drawback of polymers is its low

melting temperature

Knowledge ApplicationWhat are the Pros and Cons in the container

of most carbonated drinks?There are 3 kinds of containers used in most

carbonated drinks:Glass bottles (Ceramics)Plastic bottles (Polymer)Aluminum cans (Metal)

Glass bottles have the following advantages:Can able to store the carbon dioxide in the

beverage for longer timesCheaper than Aluminum cans

The disadvantage is it can easily breaks and heavier than the other containers

Aluminum cans are lighter and quickly cools. It can easily be recycled and can paint the surface. However, it is more expensive

Plastic containers are relatively cheaper than aluminum cans but can only store the carbon dioxide at shorter times

CompositesComposite is composed of two (or more)

individual materials, which come from either metals, ceramics, and polymers

Examples are:Fiberglass or Glass fiber reinforced polymer

(GFRP) Composed of glass fibers in epoxy or polyester

Carbon fiber reinforced polymer (CFRP) Carbon fiber in epoxy or polyester . Better than

fiberglass but more expensive