MATERIALS

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MATERIALS
ME 102 Lecture
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Core elements of Materials Science and Engineering
Source Materials Science and Engineering for the
1990s, NRC, 1989
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Metals and alloys

• Ferrous metals and alloys
• Nonferrous metalls and alloys
• Refractory metals and alloys
• Superalloys
• Metallic glasses
• Intermetallics
• Nuclear materials
• Precious metals and alloys

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Mechanical properties of metals and alloys
Toughness Brittleness Ductility Malleability Corrosion resistance
Cu Ni Fe Mg Zn Al Pb Sn Co Bi White cast iron Gray cast iron Steel Bi Mg Bronzes Al Zn Sn Cu Fe Au Ag Pt Fe Ni Cu Al W Zn Sn Pb Au Ag Al Cu Sn Pb Zn Fe Au Pt Ag Hg Cu Pb Sn Ni Fe Zn Mg Al
High
Low
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Ferrous alloys Fe-base alloys

• Steels Fe-C alloys, C lt 2.06 wt
• ferritic (low carbon sheet steel)
• austenitic, martensitic
• stainless, magnetic, high-strength
• refractory, cryogenic, tool, etc.
• Cast iron Fe-C alloys, C gt 2.06 wt
• white (dissolved)
• gray (plates)
• ductile (spheres)
• malleable (popcorn-shaped)
• compacted (rods)

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Nonferrous alloys

• Al-base alloys
• Cu-base alloys
• Mg-, Ni-, Ti-, Zn-, Pb-, Sn-base alloys

• Classification
• Heavy alloys - ? gt 4 g/cm3 (Cu, Ni, Zn, St, Pb)
• Light alloys - ? lt 4 g/cm3 (Al, Mg)
• Ti alloys medium
• ? 4.5 g/cm3

Applications Aerospace 80 of an airplan is
Al-alloy standard Boeing 747 75000kg Al-alloys
Automotive - engine blocks, cylinder heads, heat
exchangers, transmission housings, engine parts,
wheels Transportation rapid trains, boates,
ferries Food industry Al-foil, cans,
cooking Building construction windows, doors,
frames Electrical - electric lines, motors,
appliances
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Refractory metals and alloys

• Applications
• filaments
• heating elements
• thermocouples
• integrated circuits
• chemical industry
• defense industry
• alloying elements for special steels

• Mo, W, Nb, Ta
• High melting points gt 2500C
• High densities 8.5-19.3 g/cm3
• Fast oxidation at high T

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Superalloys

• Ni-, Fe-Ni and Co-base alloys
• High strength and corrosion resistance at high T
  gt 540C
• Main alloying elemnts Cr, Mo, Nb, Ti, Al
• provide resistance to oxidation and hot
  corrosion
• give strength at elevated temperatures
• Small amounts of C, W, Hf, Re, Zr, Ta, Si, B

• Applications
• Gas turbine and aerospace industries - high
  stress and temperature for long time
• Chemical-plant and petrochemical equipment
• Oil equipment
• Biomedical implants

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Intermetallics

• Intermetallic compounds
• Ni3Al, Fe3Al, FeAl, TiAl
• MoSi2, Ni3Si, Nb3Si, Ti5Si3
• Fe-Co-V alloys
• High melting point
• Low density
• High strength
• Good oxidation and creep resistance
• Sperconductibility
• H2 storage capability
• Magnetic properties
• Low costs

• Applications
• Aircraft, automotive, metallurgic, chemical
  industry turbine blades, divergent flaps,
  nozzle, exhaust valve, reaction vessels, boilers,
  heat exchangers, heating elements, protective
  coatings, porous gas filters, etc.
• Food industry parts (no hazardous elements - Ni,
  Cr)
• Biomedical knee and hip implants, heart valves

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Nuclear materials

1. Fuel materials
2. Structural materials
3. Moderator, reflector and blanket material
4. Coolant material
5. Control, shielding and safety system materials

• Properties
• General properties
• Mechanical strength
• Ductility
• Toughness
• Fabricability
• Special properties
• Neutronic properties
• Induced radioactivity
• Irradiation stability
• Spent fuel processing, etc

• UO2, (U,Pu)O2, Th-U and Th-Pu alloys (1)
• Be and BeO, Mg-, Al-, and Zr- alloys, austenitic
  steels (2,3)
• Light and heavy water, molten metals (Na, Li),
  He, CO2 (4)
• B, B4C, Cd, Ag-Cd-In, Hf, Ag-Hf, Ag-Ir-Hf, Eu2O3,
  Gd2O3 (5)

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Ceramics and glasses

• Inorganic materials - as old as human
  civilization
• tools, bricks, porcelain, body paints,
  insulators, abrasives, modern high-tech
  ceramics
• Crystalline or amorphous (non-crystalline)
• Metal oxides, nitrides, carbides, borides,
  sulfides, silicides, phosphides, carbonates

• High-tech ceramics
• synthetic powders
• special manufacturing methods
• certain applications
• Functional electrical, magnetic, optical,
  chemical
• Structural wear and erosion resistance, high
  temperature strength, chemical inertness,
  high-temperature stability

• Keramos (Greek) burned earth
• Types
• Traditional ? technical
• Oxide ? nonoxide
• Structural ? functional

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Composites

• Complex material composed of two or more
  constituents
• Constituents - physical combining, do not lose
  their identity

• Matrix material
• Metal matrix composites MMC
• Ceramic matrix composites CMC
• Polymer matrix composites PMC

• Reinforcing material
• Fibers (carbon, asbestos, B, SiO2)
• Wiskers (graphite, carbon)
• Particles (SiO2, SiC, Al2O3)

• Toughness (impact strength)
• Chemical, wear and corrosion resistance
• Electrical properties
• Dimensional stability
• Reduce costs and weight
• Increase secondary uses and recyclability
• Reduce negative impact on the environment
• Improve design flexibility

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Cemented carbide cutting tools
Personal protection
Military
Anti-ballistic panels
Composites with lubricating reinforcements
(graphite)
Aircraft cabin parts
Sports
High-performance brake disks strong, light, good
heat conductors
Aircraft structure
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Polymers and plastics
Polymeric Polumeres (Greek) having many parts
Repeated chemical units (MONOMER) ? POLYMER
(large molecules)
5 - 500 atoms
gt50 monomers

• Ethylene ? Polyethylene (PE) - plastic bags
• Styrene ? Polystyrene (PS) - plastic cups
• Acrylamide ? Polyacrylamide - plastic compact
  discs
• Phenol ? Bakelite tools, machines

PLASTICS

• Carbon atom ? tetrahedron (pyramid)
• Many carbon atoms ? polymers
• gt 60 000 different plastics

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Polyamides (nylons) - substitute for silk
Neoprene - the first synthetic rubber
Building and construction materials Containers Toy
s Sporting goods Electronic appliances Textiles Ca
rpets Medical products
Polyethylene and polypropylene
biodegradable polymer wafers - implanted in human
organs to deliver drugs at a controlled rate
Cells growing on polymer fibers ? artificial
tissues
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Fibers

• Glass fibers telecomunication, composites
• Carbon fibers - reinforcement
• Metallic fibers
• Polymer fibers composites, textiles
• Natural fibers

• Applications
• Fabrics, ropes, cords, etc.
• Aircraft, airspace, defence
• Marine and civil construction
• Sporting equipment

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Carbon
Graphite

• Applications
• Baterry electrodes
• Sports equipment
• Steel, aluminium industry
• Nuclear power plants moderator
• Purification, filtration
• Aircraft brakes, ballistic missiles, aerospace
  vehicles, turbine and rocket components
• Pencils
• Printing ink

• Carbon blacks
• Carbon fibers
• Carbon-carbon composites
• Carbon electrodes
• Carbon films
• Carbon foams
• Metallurgical coke

Diamond
Fullerenes
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Biomaterials

• Examples
• Hip, knee, other implants polyethylene, Ti-,
  Co-Cr alloys, alumina ceramics, hydroxyapatite,
  acrylic cement
• Heart valve Ti-alloys, pyrolytic carbon
• Breast implant silicone
• Intraocular lens acrylic, polypropylene
• Dental restoration amalgam, Au-alloys,
  Ti-alloys, acrylics, porcelain, composite
• Bones replacement PTFE, bioglass

• Materials used in medicine and dentistry
• Materials in permanent contact with the tissues
  or fluids of the body - implants
• Materials for sutures, clips, adhrsives, staples
• Materials for tools in surgery or dentistry
• Materials for medical devices perfusion,
  dialysis, breathing, etc.
• Materials for drugs delivery

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Role of Materials Science Engineering in
Industry

• Materials Selection/Product Design What do you
  make your product from?
• Metals
• Plastics
• Ceramics
• Composites

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• Materials Development/Process Design.
• Production of Raw Materials
• Optimization of Properties
• Fabrication of Components
• Materials Testing and Characterization.
• Properites of Materials?
• Strength, Hardness, Conductivity, Corrosion, etc.
• Structure of the Materials?
• Microstructure, Crystal Structure, Interfaces,
  Defects

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Design limiting material properties

• Economic Cost Recyclability
• General Density
• Mechanical Elastic moduli Strength Hardness
  Fracture toughness / Fatigue Damping
  capacity
• THERMAL Melting point / glass transition
  Temp Thermal conductivity / diffusivity /
  expansion / Specific heat / shock
  resistance
• Electrical Conducting / non conducting
• Environmental Corrosion / oxidation / wear

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Industrial ceramic parts Materials alumina,
silicon nitride, zirconia, silicon carbide, boron
carbide and boron nitride
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• Failure Analysis and Prevention
• Why did it break?
• How do you Prevent Future Failures?
• Liability?

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PRODUCT DESIGN

• Materials Selection
• Meeting customers objectives
• Engineering materials
• Geometrical shape
• Required precision
• Environmental application
• Companys objective
• Cost
• Manufacturability

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IN the old days

• Few choices for material selections
• Metals
• Ceramics
• Glass
• Plastics

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New materials to choose from

• New metal alloys
• Powder metallurgy
• Stronger plastics
• Composites

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Materials selection vs. manufacturing

• Material must match a manufacturing process
• Or
• A manufacturing process must be developed

MATERIAL
PROCESS
Warning !! Less costly material may lead to
costly manufacturing
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Designing a part

• 3 distinct stages
• Conceptual-design
• Functional-design
• Prototype
• Production-design

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Sequence of activities

• 1. Design
• 2. Material Selection
• Shape or geometry
• Property requirements
• Mechanical properties
• Physical properties
• Service environment
• Manufacturing concerns

(contd)
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Sequence of activities

• 3. Process Selection
• Type of manufacturing process
• Considerations
• 4. Production
• 5. Evaluation
• 6. Redesign/Modification

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The Design Process

• Ashby
• Market need
• Concept
• Embodiment
• Detail
• Product

• Norton
• Identify need
• Background research
• Goal statement
• Task specifics
• Synthesis
• Analysis
• Selection
• Detailed design
• Prototyping and testing
• Production

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