Transcript Lesson 3-10 An Introduction to Materials Technology

An Introduction
to Materials
Technology
Foundations of Technology
Unit 3.10
Objectives
 To
familiarize students with the connection
between materials science and
engineering materials and how
researchers have consistently improved
materials that, in turn, enhance the
performance of the technologies that use
them.
What are materials?
 The
tangible substances that go into the
makeup of a physical object. One of the
basic resources used in a technological
system.
Basic Concepts
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The physical properties of the material are
generally a basic reason for selecting the material
for the needed product performance.
The performance of a product frequently requires
various behaviors and thus types of properties.
It is frequently found that a compromise among
the needed properties must be made to be
consistent with the processing selected and the
structural state desired.
Most of the useful properties are related to the
structural state of the material.
Descriptions of Materials
 Metals:
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Materials are normally combinations of
“metallic elements”.
These elements, when combined, usually
have electrons that are non-localized and
have generic types of properties.
Metals are usually good conductors of heat
and electricity.
They are quite strong, but malleable, and
tend to have a lustrous look when polished.
Descriptions of Materials
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Ceramics:
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Ceramics are generally compounds between
metallic and nonmetallic elements.
Typically, they are insulating and resistant to
high temperatures and harsh environments.
Plastics:
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Plastics (or polymers) are generally organic
compounds based upon carbon and
hydrogen.
They have very large molecular structures.
Usually they have low density and are unstable
at high temperatures
Descriptions of Materials
 Semiconductors:
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have electrical properties intermediate
between metallic conductors and ceramic
insulators.
The electrical properties are strongly
dependant upon small amounts of
impurities.
 Composites:
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consist of more than one material type.
Examples include plywood and fiberglass.
Properties
 Mechanical:
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tensile strength, fracture toughness, fatigue
strength, creep, hardness
 Electrical:
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conductivity or resistivity, ionic conductivity,
semi-conductivity
 Magnetic:
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magnetic susceptibility, Curie Temperature,
Neel Temperature
Properties Continued
 Optical
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and Dielectric:
polarization, capacitance, refractive index,
absorption
 Thermal:
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coefficient of thermal expansion, heat
capacity, thermal conductivity
 Environmental-related:
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corrosion behavior, wear behavior