Title: Materials Science (C)
1Materials Science (C)
- By
- Linda (Lin) Wozniewski
- lwoz_at_iun.edu
- and
- Mat Chalker
- chalker7_at_gmail.com
2Disclaimer
- This presentation was prepared using draft
rules. There may be some changes in the final
copy of the rules. The rules which will be in
your Coaches Manual and Student Manuals will be
the official rules
3Safety
- Students must wear
- Closed shoes
- Slacks or skirts that come to the ankles
- Lab coat or lab apron
- Indirect vent or unvented chemical splash proof
goggles. No impact glasses or visorgogs are
permitted - Sleeved Shirt (if wearing a lab apron)
4What Students May Bring
- Calculator
- Any size 3 ring notebook
- A writing instrument
5What Supervisors Will Supply
- Everything the student will need
- This may include
- Glassware
- Reagents
- Balances
- Hot plates
- Thermometers
- Probes
- Magnets
- Stirrers
- Models
- Toothpicks and marshmellows
6What is Material Science?
- Take the paperclip we have given you
- Bend it so that the inner part is 180º from the
outer part - Does it break?
- Bend it back.
- Does it break?
- How many times does it take till it breaks?
- You have just done Material Science
7Properties
- Why did the paper clip break?
- Why didnt all of the paper clips break on the
same number of bends? - What is the difference between how these
materials behave? - What about these?
- What are properties of materials?
- Density
- Deformation under load
- Stiffness
- Fatigue
- Surface area to volume
- Crystal structure
- Thermodynamics
8Material Science
- Material Science is a relatively new
interdisciplinary field - It merges Metallurgy, Ceramics, and Polymers
- It merges Chemistry, Physics, and Geology
- Material Science takes advantage of the fact that
we can not make pure crystals of anything the
interesting effects of the impurities. - Material Science is a field where many of our
students will find lucrative employment in the
future. - Material Science also incorporates the
fascinating area of nano-technology
9Main Focus
- Material Performance and Atomic Structure 50
- Intermolecular Forces and Surface Chemistry 50
- How to prepare Students
- Experiment ideas
- Resources
10Classification of Pure Substances
11Types of Solids
12Materials Characteristics
13Materials Characteristics
? Density
14Metals
- Metals low electronegativity metal cationic
atoms in a sea of delocalized electrons.
Metallic bonds from electrostatic interaction -
different from ionic bonds. - Conducts electrons on the delocalaized valence
level sea of electrons - malleable/ductile, hard, tough, can be brittle.
Iron
15Ceramics
- Covalent and ionic bonding of inorganic
non-metals. electrons are localized in bonds -
poor conductors, brittle and very thermally
stable. - The crystal structure of bulk ceramic compounds
is determined by the amount and type of bonds.
The percentage of ionic bonds can be estimated by
using electronegativity determinations.
Resistance to shear and high-energy slip is
extremely high. - Atoms are bonded more strongly than metals fewer
ways for atoms to move or slip in relation to
each other. Ductility of ceramic compounds is
very low and are brittle. Fracture stresses that
initiate a crack build up before there is any
plastic deformation and, once started, a crack
will grow spontaneously.
Alumina Al2O3
http//mst-online.nsu.edu/mst/ceramics/ceramics3.h
tm
16Semiconductors
- Metalloid in composition (w/ exception).
Covalently bonded. More elastic than ceramics.
- Characterized by the presence of a band gap where
electrons can become delocalized within the
framework.
Germanium
17Polymers
- Macromolecules containing carbon covalently
bonded with itself and with elements of low
atomic number - Molecular chains have long linear structures and
are held together through (weak) intermolecular
(van der Waals) bonds. Low melting temp.
18Materials Properties
- Optical properties (Quantum Dots, LEDs)
- Magnetic properties (ferrofluids)
- Electronic Properties ( semiconductors)
- Thermal and Mechanical Properities (plastics,
metals, ceramics)
19Materials Performance
- Stress Vs. Strain relationship
20Linear DeformationStress Strain
Stress - force applied over a given area. Units
of lbs/in2 or Gigapascals
Strain - Deformation of material as a change in
dimension from initial. Unitless
21Stress, Strain, Youngs Modulus
- Youngs Modulus
- - a measure of material stiffness
- - E s/e
- F/A
- l/L
Hookes Law F k?x spring constant k F/?x
22Youngs Modulus
- E s/e (F/Ao)/(?L/Lo)
- Where
- E Youngs Modulus
- s Stress
- e Strain
- F Force
- Ao Initial cross section of material
- ?L Change in length of material
- Lo Initial length of material
23Yield Strength
Rubber
Glass
Polymers
True Elastic Behavior vs. Elastic Region
Vable, M. Mechanics of Materials Mechanical
properties of Materials. Sept. 2011
24Nano World
The size regime of the nano world is 1 million
times smaller than a millimeter.
25Units of length
26SEM, TEM, AFM Images of CdSe Quantum Dots
Picture C.P. Garcia, V. Pellegrini , NEST
(INFM), Pisa. Artwork Lucia Covi http//mrsec.wis
c.edu/Edetc/SlideShow/slides/quantum_dot/QDCdSe.ht
ml http//www.jpk.com/quantum-dots-manipulation.20
7.en.html?imageadf24cc03b304a4df5c2ff5b4f70f4e9
27Surface area to volume ratio
Surface Area
Volume
28Consequences of Large Surface Area to Volume ratio
Gas law P nRT
V
As volume decreases, SA increases as does
pressure
29Surface Tension
- Depends on attractive forces in fluids
- Examples
- How to Measure
- The force to break a known area free from the
liquid is measured
30Contact Angle
- The relationship between the surface tension of
the liquid and the attraction of the solid - Important if you want ink to stick to film or if
you dont want water to stick to car or skis - Measured by finding angle between surface and
tangential line drawn from drop contact
31Surface Tension
- Tension on thin glass or Pt plate measured
- Equation
- l is the wetted perimeter of the plate
- 2d 2w
- ? is the contact angle
- In practice ? is rarely measured.
- Either literature values are used or complete
wetting is assumed (? 0)
32Crystal Structure
33Space Lattice
- A lattice is an array of points repeated through
space - A translation from any point through a vector
Rlmnlambnc, where l, m, n are integers,
locates an exactly equivalent point. a, b, c
are known as lattice vectors.
34Cubic Crystal Lattices
90º
The size and shape of a unit cell is described,
in three dimensions, by the lengths of the three
edges (a, b, and c) and the angles between the
edges (a, ß, and ?). These quantities are
referred to as the lattice parameters of the unit
cell.
35Simple Cubic
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38Body Centered Cubic
39Body Centered Cubic
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41Face Centered Cubic
42Face Centered Cubic
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47Characterizing a Crystal
48Wave Particle Interaction
Interference in Scattered Waves
X-ray Diffraction in Crystalline Solids
49Braggs Law
50Diffraction Patterns
51Common X-Ray Wavelengths
52X-Ray Powder Diffraction Patterns
53Miller Indices
Understanding crystal orientation
54http//www.doitpoms.ac.uk/tlplib/miller_indices/pr
intall.php
55Viscosity
- A measure of resistance of a fluid to deformation
or flow. - Water has a low viscosity. It is thin and flows
easily - Honey has a high viscosity. It is thick and does
not flow easily - Viscosity is measured usually in one of two ways
- A given volume is timed to fall through a hole
- Balls are timed falling through a given length
56Creep Rate
- Creep is the movement of material under stress
over time usually at higher temperatures - Creep ends when the material breaks
57Fracture Toughness
K1 is the fracture toughness
s is the applied stress
a is the crack length
ß is a crack length and component geometry factor that is different for each specimen and is dimensionless.
58Fatigue Limit
- Maximum fluctuating stress a material can endure
for an infinite number of cycles - Determined from a stress/cycles curve
59Shear Modulus
60Poissons Ratio
- ? -etrans/eaxial
- Where
- ? Poissons Ratio
- etrans Transverse Strain
- eaxial Axial Strain
- e ?L/Lo
- ?L Change in length of material
- Lo Initial length of material
61Resources
- For Event Supervisors
- http//mypage.iu.edu/lwoz/socrime/index.htm
- For Lesson Plans for classroom use
- http//mypage.iu.edu/lwoz/socrime/index.htm
- Miller Indices
- http//www.doitpoms.ac.uk/tlplib/miller_indices/pr
intall.php - Stress, Strain, etc.
- http//www.ndt-ed.org/EducationResources/Community
College/Materials/Mechanical/Mechanical.htm
62Resources Continued
- YouTube.
- LOTS of nice videos on stress, strain, Youngs
Modulus, etc. - Contact Angles
- http//www.csu.edu/chemistryandphysics/csuphysvan/
participantactivities/Kondratko.FengertHS.ContactA
ngleIFTWetting.pdf
63Workshop Test
- Unwrap a Hersheys Kiss without hurting the
wrapper. - Flatten the wrapper out completely
- Draw a circle around the widest part of the kiss
- Put the Kiss, on the wrapper out in the sun or in
front of a heat lamp, noting the time - After doing each of the next events (10 min), go
out, note the time, and draw a circle around the
kiss.
64Youngs Modulus
- Form some Play dough into a cylinder
- Determine the height and radius
- Attach a dual force sensor with a round tip to
the calculator. - Determine the force of the cylinder resting in an
empty petri dish balanced on top of the sensor - Push down, noting the force
- Determine the new height
65Youngs Modulus Continued
- Stress Force/Area0
- Determine difference in Force
- Determine the initial area of the cylinder
- Divide
- Strain ?L/L0
- Determine the difference in the heights
- Divide the difference by the original height
- Youngs Modulus
- Divide Stress by Strain
66Surface Tension
- Fill petri dish with water.
- Use Pasteur pipette to drops of water to slide
until large enough drop to measure contact angle. - Measure width of slide
- Attach dual force sensor with hook end to
calculator - Attach slide suspended from clamp to hook
- Determine Force
- Determine Force when slide just touches water
- Determine how far up water moves on slide
67Surface Tension
- Determine perimeter of water on slide
- Determine force difference
- Surface tension is
- l is the perimeter
- ? is the contact angle
- F is the difference in the forces
68Thickness of a Molecule
- Fill the pie plate with water
- Sprinkle chalk dust on top
- Determine how many drops from the Pasteur pipette
are required to make 1 ml. - Add one drop of soap to the center of the pie
plate. - Determine the radius of the circle of soap
- Since the soap has a hydrophobic part, it will
spread out 1 molecule thick on top of the water. - Divide the volume of the drop by the area
69Face Centered Cube
- Put 4 toothpicks at right angles to each other
around the middle of one marshmallow. - Repeat for 5 more marshmallows
- Pick 2 of your toothpicked marshmallows add
marshmallows to the 8 toothpicks - These are now 2 of the sides of the cube.
- The other 4 toothpicked marshmallows are the
insides of the cube. - Put the toothpicks into the edge marshmallows to
form cube
70Questions Continued
n? 2d(sin?)
- Using CuKa radiation (?.154 nm), the 1st order
reflection for the spacing between the 200
planes of gold occurs at a 2? angle of 44.5º - What is the spacing between the 200 planes?
- What is the value of a?
- What is the radius of gold?
a.406 nm
r.203 nm
71Surface Area/Volume Relationship
- Using your play dough, make a 1 cm cube, 2 cm
cube, and 3 cm cube. - Determine the surface area of each
- Determine the volume of each
- Divide the surface area by the volume
- What trend do you see?
72Creep Rate
- Retrieve the kiss
- Note the time and draw the last circle around the
bottom - Without removing the circle lines, remove the
kiss. - Measure all of the diameters and match them to
their times - Using your calculator, make a spreadsheet of the
times vs. the diameters. - Subtract the original diameter from each diameter
73Creep Rate
- Divide the differences in the diameters by the
original diameter and multiply by 100 to get the
percent stress - Plot the time on the x axis vs. the stress on the
y axis. - Determine the slope of the middle range by
defining the area of interest and then finding
the tangent. - The creep rate is the slope
74Deflection
- Measure the length and diameter of a straightened
paperclip. - Suspend the paperclip across two tall containers
so the paperclip is resting at its two ends.
Place a ruler across the containers too. - Attach a dual range force sensor with a hook to
the calculator - Pull down in the center of the paperclip until
the clip is deflected down a measureable amount. - Note the deflection and the Force difference.
75Deflection
- The formula for deflection is
- d (Wl3)/(12pr4Y)
- Solving for Youngs Modulus (Y) we get
- Y (WI3)/12pr4d)
- W force added
- I length of paperclip
- d deflection
- r radius of paperclip diameter/2