Introduction to Materials

Introduction to Materials

© 2012 Project Lead The Way, Inc.

Principles of Engineering

What Are Materials?

Currently the MatWeb Material Property
Data website lists over 76,000 individually
unique materials

Substances out of which all things are
made

http://www.matweb.com

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Open Ended

What materials are present in the classroom?

Material History

Throughout history cultures
have been defined by their
ability to select and modify
materials.

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Open Ended

Can you think of a time in America when material availability played a critical role in defining culture?

Open Ended

Is American culture currently being defined by availability and demand for materials?

MaterialComposition

Consist of only one type of particle or atom

Cannot be broken down

Criteria for element classification

Based on individual properties

Grouped according to shared properties

Amount of substance is irrelevant

What makes a material?

Elements

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MaterialComposition

Physical Properties – Boiling point, melting point,
density, color, hardness, and texture
Chemical Properties – Reactivity to acid, oxygen,
and flammability

Classification of Elements

Divided into three categories based on:

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Elements

Metals

Nonmetals

Metalloids

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Physical Properties

Multiple Choice

Density is a physical property that describes the relationship between the ________ of its _________.

• matter, volume

• mass, volume

• volume, matter

• none of the above

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Multiple Choice

The physical property melting point is the

• temperature at which a liquid changes to a solid

• temperature at which a liquid boils

• temperature at which a solid changes to a liquid

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Open Ended

Explain malleable and ductile metals. What can be done to them?

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Poll

How do you know a property is physical?

• You can observe the property without changing the material

Multiple Choice

Which chemical property has the ability to become poisonous?

• flammability

• combustibility

• toxicity

• pH

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Multiple Select

Check all the PHYSICAL CHANGES:

• Melting an ice cube

• Painting a wall green

• Baking a cake

• Burning a piece of paper

• Cutting cardboard

MaterialComposition

Metal Elements

Good conductors of heat and electricity,
hard, shiny, reflect light, malleable,
ductile, typically have one to three
valence electrons

Distinguishing Characteristics

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MaterialComposition

Nonmetal Elements

Most are gases at room temperature

Solids are dull, brittle, and powdery;
electrons are tightly attracted and
restricted to one atom; poor conductors
of heat and electricity

Distinguishing Characteristics

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MaterialComposition

Metalloids

Possess both metallic and nonmetallic
properties

Distinguishing Characteristics

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MaterialComposition

Compounds are created when two or more
elements are chemically combined

Compounds

Properties are different than the elements
from which the compound was created

Most substances are compounds

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MaterialComposition

Element combinations are not random but
based upon specific mass ratios, such as

H2O = 1 g of hydrogen to 8 g of oxygen

Compounds

Compounds can only be broken down
through chemical processes, not physical
processes

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MaterialComposition

Elements within the mixture retain their
identity

Mixtures

Non-chemical combination of any two or
more substances

Mixtures can be physically separated

Mixtures do not have a definite ratio

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Multiple Choice

Mixtures and compounds are both made up of multiple elements: Mixtures can be physically separated - can compounds be physically separated?

• Yes

• No

MaterialClassification

Metallic Materials
Ceramic Materials
Organic Materials
Polymeric Materials
Composite Materials

Based upon material composition and
distinguishable properties

Common material classification categories:

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MetallicMaterials

Pure metal elements
(Not commonly found or used)

Thermal and electrical conductors

Mechanical properties include
strength and plasticity

Metal element compounds (alloy)
(Commonly used due to the engineered
properties of the compound)

Distinguishing Characteristics

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Compounds consisting of metal
and nonmetal elements

Thermal and electrical insulators

Mechanical properties include
high strength at high
temperatures and brittleness

Ceramic Materials

Distinguishing Characteristics

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CeramicMaterials

Applications

Clay—Shaped, dried, and fired
inorganic material
Examples: Brick, tile, sewer pipe,
chimney flue, china, porcelain, etc.

Refractory—Designed to
provide acceptable
mechanical or chemical
properties while at high
temperatures
Example: Space shuttle
all-silica insulating tiles

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CeramicMaterials

Applications

Rectifiers—Allow current to
flow in one direction

Heating elements for furnaces

Electrical

Resistors—Create desired voltage
drops and limit current

Thermistors—Application of
heat regulates current flow

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Are or were once living organisms

Consist of mostly carbon and
hydrogen

Renewable

Genetically alterable

OrganicMaterials

Distinguishing Characteristics

Sustainable

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Compounds consist of mostly
organic elements

Low density

Mechanical properties include
flexibility and elasticity

PolymericMaterials

Distinguishing Characteristics

Polymeric Subgroups

Plastics

Elastomers

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Plastics

PolymericMaterials

Formed into a desired shape by
applying heat and pressure and
being cooled

Thermoplastic

May be heated and remolded

Thermosetting

Formed into a desired shape by
applying heat and pressure and
being cooled

May not be heated and remolded

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Open Ended

Do you think thermoset plastics are recyclable? Why/Why not?

Elastomers

PolymericMaterials

Can be stretched 200 percent of their
length at room temperature and can
return quickly to original length after
force is released

Natural or synthetic material

Vulcanization

Chemical process used to form strong
bonds between adjacent polymers to
produce a tough, strong, hard rubber
(automobile tires)

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CompositeMaterials

Composed of more than one material

Designed to obtain desirable properties
from each individual material

Distinguishing Characteristics

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CompositeMaterials

Layer Composites—Alternate

layers of materials bonded
together

Particulate

Composites—Discrete particles
of one material surrounded by a
matrix of another material

Fiber-Reinforced

Composites—Composed of
continuous or discontinuous
fibers embedded in a matrix of
another material

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MaterialSelection

Material selection is based upon application,
required material properties, and budget.

Initial material property considerations consist of
product function, environmental conditions, and
material degradation.

Applications can vary from electrical components
to construction of large-scale civil engineering
projects.

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Refined material selection based upon:

Technical and structural analysis

Examination of known and desired properties,
such as:

MaterialSelection

Mechanical
Thermal
Electromagnetic
Chemical

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Mechanical Properties

Deformation and fracture as a response to
applied mechanical forces

MaterialSelection

Strength

Hardness

Ductility

Stiffness

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Thermal Properties

Affected by heat fluxes and temperature
changes

MaterialSelection

Thermal Capacity—Heat storage capacity of
a material

Thermal Conductivity—Capacity of a material to
transport heat

Thermal Expansion—How a material expands
or contracts if the temperature is raised or
lowered

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Electrical Properties

Material response to electromagnetic fields

MaterialSelection

Electrical Conductivity—Insulators, dielectrics,
semiconductors, semimetals, conductors,
superconductors

Thermoelectric—Electrical stimuli provoke
thermo responses; thermo stimuli provoke
electrical responses

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Chemical Properties

Response and impact of environment on
material structures

MaterialSelection

Oxidation and Reduction—Occur in
corrosion and combustion

Toxicity—The damaging effect a material
has on other materials

Flammability—The ability of a material to
ignite and combust

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