Text Book

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Text Book
The Science and Engineering of Materials (Fifth
Edition) by Donald R. Askeland and Pradeep P
Phule is the course text book
Assignments
There will be three assignments, one in May (3
marks), one in June (3 marks) and one in July (4
marks). (10 marks total)
Tests
There will be two mid-terms (15 marks each), one
in late May or early June, another in June or
early July. The final will be in August (40
marks).
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Laboratories
There are 5 labs conducted in room ELW B231.
Their manuals are obtained by the MECH 285 web
site. (20 marks total) 1) The Use of Phase
Diagrams (5 marks) TAs Amine Yildiz (Mondays)
Robert McLeod (Tuesdays) 2) Introduction to
Practical Metallography (5 marks) TAs Amine
Yildiz (Mondays) Robert McLeod (Tuesdays) 3)
Solification of Pb-Sn Alloys (5 marks) TAs
Julio Rodriguez (Mondays) Neil Armour
(Tuesdays) 4) Measurement of Thermal Conductivity
(2.5 marks) TAs Julio Rodriguez (Mondays)
Neil Armour (Tuesdays) 5) Dislocations (2.5
marks) TAs Julio Rodriguez (Mondays) Neil
Armour (Tuesdays)
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Lectures
There will be 16 lectures, which can be found on
the MECH 285 web site. The lectures are in
PowerPoint and pdf format, which can be
downloaded to your computer. The source of the
lectures are derived from 1) the text book,
Science and Engineering of Materials (Fifth
Edition) by Donald R. Askeland and Pradeep P
Phule 2) personally generated information 3)
published literature
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Lecture 1 - Objectives

• At the end of this lecture you should be able to
• Describe the course organization, name the
  required text book, be aware of the class
  expectations and know how your performance will
  be evaluated.
• Know the various classification of materials and
  some examples of each
• Describe a typical new product design process
• Discuss the role of materials in the design
  process

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Materials Science and Engineering (MSE)

• MSE is an interdisciplinary field concerned with
  inventing new materials and improving existing
  materials by developing a deep understanding of
  the microstructure-composition-processing
  relationships.
• Vocabulary is important and the following 4 terms
  will be used over and over.
• Composition means the chemical make-up of a
  material.
• Structure means a description of the arrangement
  of atoms.
• Synthesis refers to how materials are made from
  naturally occurring or man-made chemicals.
• Processing means how materials are shaped into
  useful components to cause changes in the
  properties of different materials.

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Materials Science and Engineering (MSE)

• In materials science the emphasis is on
  understanding the underlying relationships
  between synthesis and processing, structure and
  properties of materials.
• In materials engineering, the focus is on how to
  translate or transform or apply materials into a
  useful device or structure.

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Types of Engineering Materials

• There are four common states of matter, which are
  the most basic forms of materials. These are
• 1) Plasma
• Combustion internal combustion engine
• Florescent lights, Neon signs
• Welding arc
• Fusion energy, the Sun
• 2) Gases
• Compression/expansion heat pumps, refrigerators
• Heat exchange in many systems
• Vacuum pumping
• Fuel in internal combustion engine

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What is a Plasma?
Sun
Fusion
Neon-Lights
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Types of Engineering Materials

• 3) Liquids
• Fluid dynamics
• Hydraulics
• Cryogenics, eg., Liquid Petroleum, Liquid
  Nitrogen, Liquid Hydrogen (Fuel Cells)
• 4) Solids
• Metals and alloys
• Semiconductors
• Ceramics
• Glasses
• Polymers (plastics)
• Composites
• Of these states, in this course we will primarily
  focus on the solid materials.

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Functional Classification of Materials

• Aerospace Materials strong, light weight,
  resistance to radiation damage
• Biomedical materials materials that replace
  bones, organs, teeth, etc.
• Electronic materials semiconductors used in
  computers, ceramics used as sensors, metals used
  as conductors, superconductors for powerful
  magnets.
• Energy and Environmental materials The nuclear
  industry use uranium for fuel, zirconium to hold
  the uranium and high-strength, low-corrosion
  steel in the nuclear reactors. The fuel cell
  industry uses many types of materials such as
  zeolites, alumina, etc as catalysts. Solar
  panels use materials such as amorphous silicon.
• Magnetic materials computer hard disks and
  audio and video cassettes use many types of
  ceramics, metals, and polymers

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Functional Classification of Materials

• Photonic or Optical materials silica is used
  for fiber optics. Communication industry uses
  optical materials for semiconductor detectors
  watand Lasers. Polymers are used to make Liquid
  Crystal Displays used in the projector used for
  this lecture.
• Smart materials can sense and respond to an
  external stimulus such as temperature, stress,
  humidity or chemical environment consisting of a
  sensors and actuators and read change and
  initiate an action such as Lead Zirconium Niobate
  (PZT).
• Structural materials are designed for carrying
  some kind of stress such as in buildings, bridges
  and automobiles and they usually consist of
  steels, aluminum, concrete and composites. Often
  in these applications, combinations of strength,
  stiffnes and toughness are needed under different
  conditions of temperature and loading. These are
  still the most common use of materials.

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Functional classification of materials with some
examples.
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Classification of Materials Based on Structure

• Crystalline materials atoms are arranged in a
  periodic fashion.
• Single crystals are entirely consisting of only
  one crystal such as silicon used in the
  electronics industry
• Polycrystalline material consists of many
  crystals or grains with a certain size, shape,
  composition, etc. The grains are separated from
  each other by grain boundaries.
• Amorphous materials atoms do not have a long
  range order.
• The newest material being developed is amorphous
  metals, which have a super-large elastic modulus
  enabling extremely high stiffness and elasticity.

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Why Study Materials

• Engineers do many things besides design new
  products.
• One of the distinguishing characteristics about
  engineers is their ability to design.
• - To many, design is the essence of
  engineering!
• To design is to synthesize something new or
  collect/arrange existing items in a new way to
  satisfy a recognized need of society.
• Referred to as, Technology Push versus Market
  Pull.
• A good design demands both analysis and
  synthesis.
• Few products consist of only one
  component/material
• Systems to subsystems to assemblies to components
  to materials.
• A very simple definition of a material is, the
  substance of which something is made.
• The production and processing of materials into
  finished goods is a large part of our economy,
  creating many jobs. New products are primarily
  made by engineers.
• Because creating new and better products involves
  analysis and synthesis with the building blocks
  being materials. Engineers MUST know what
  materials exist and have a broad knowledge of
  material properties.

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Material Selection Process
The materials selection process changes as the
design process changes. The mechanical engineer
must recognize the different stages of the
design. One model is shown below.
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The MSE tetrahedron shows the heart and soul of
this field. The main objective is to develop
materials or devices that have the best
performance for a particular application where
the performance-to-cost ratio, as opposed to
performance alone, is of utmost importance. The
three corners of the tetrahedron are represented
by A the composition, B the microstructure,
C- the synthesis processing of materials, which
are all interconnected and ultimately affect the
cost-to-performance ratio.
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Application of the tetrahedron of MSE to ceramic
superconductors. Note that the
microstructure-synthesis and processing-compositio
n are all interconnected and affect the
performance-to-cost ratio.The performance-to-cost
ratio is high limiting these materials only to
specialty applications such as small magnets
having low-field strength.
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Application of the tetrahedron of MSE to sheet
steels for automobile chassis. Note that the
microstructure-synthesis and processing-compositio
n are all interconnected and affect the
performance-to-cost ratio.
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Application of the tetrahedron of MSE to
semiconducting polymers for microelectronics.
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Material Selection Process

• The interactions among the design function,
  material, shape, and process are at the heart of
  the materials selection process.
• Out of the 100,000 materials available for use by
  engineers, the down selection process starts by
  using design constraints to limit choices of
  materials. Thus the properties of the materials
  MUST be known.
• Data for materials properties are needed at every
  stage of the design process.

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Design Process

• The design process is changing due to global
  pressures and new technology.
• Global competitiveness is pushing
• Shorter lead times
• Shorter delivery times
• Flexibility in product variations
• Higher quality
• Environmental issues are becoming increasingly
  important.
• Energy and Materials optimization in a life-cycle
  design
• The manufacturer is responsible for
  environmentally safe disposal.
• Insurance companies demand proof.
• Green labels give competitive edge.
• Environmental and regulatory agencies demand life
  cycle design documentation.

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Design Process

• Technology of Materials Design and Applications
• Requires high-speed computer with large and fast
  memories
• Data base management programs
• Scanners/digitizers/numerical fitting software
• Simulations before prototype production.
• Simulations before design experimentation.

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Engineering Megatrends

• Megatrends are revolutioning new product design
• More powerful computer tools
• Design for export
• Design for manufacturing
• Outsourcing engineering design
• Quest for quality
• Smart machines
• Faster design cycles
• Taylor-made materials
• Life-cycle engineering
• Engineering without walls
• Micro and nanoscale designs

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Materials Properties for Design

• Physical Properties
• Crystal structure
• Density
• Melting point
• Viscosity
• Vapor pressure
• Porosity

• Mechanical Properties
• Hardness
• Modulus of elasticity
• Poissons ratio
• Yield strength
• Shear strength
• Fatigue
• Fracture stength
• Creep
• Wear
• Erosion

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Materials Properties for Design

• Electrical Properties
• Conductivity
• Mobility of carriers
• Carrier lifetime
• Charge density
• Dielectric constant

• Photonic Properties
• Transparency
• Reflectivity
• Refractive index
• Emissivity Absorptivity

• Thermal Properties
• Conductivity
• Specific heat
• Coefficient of expansion
• Emissivity
• Ablation rate

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Materials Properties for Design

• Chemical Properties
• Oxidation
• Hydration
• Corrosion
• Electronegativity
• Electropositivity
• Molecular weight
• Molecular number
• (periodic table)

• Magnetic Properties
• Permeability
• Hard versus soft
• Hysteresis

• Nuclear Properties
• Half life
• Absorption cross-section
• Stability

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Materials Properties for Design

• Fabrication Properties
• Formability
• Machinability
• Weldability
• Castability
• Hardenability
• Heat treatability

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Representative strengths of various categories of
materials.
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National Aerospace Plane (NASP) X-33 prototype,
which uses different materials for different
parts.
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Realization for the Need of Materials Design

• Major changes in F1 cars
• carbon composite brake pads
• ceramic capped cylinder heads
• electronic fuel injection system
• electronic brakes and accelerators

• Need for
• light weight, high strength materials
• high strength, high temperature materials

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Polymers being used to make an exact reproduction
of a face.
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Electronic materials being used as a blanket.
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Photonic materials being used in an advanced
camouflage device.
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Cost of Materials

• Materials typically are considered on the basis
  of performance, cost and processing ease.
• Cost of materials can significantly affect the
  final product cost with 50 being the rule
• Automobile materials typically are 70 of the
  manufacturing costs.
• Ship materials are nominally 45 of the
  manufacturing costs
• In electronic devices, such as computers,
  materials can be 75 of the manufacturing costs.

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