What is Materials Science and Engineering and material science and technology ppt
MaterialsWhat is Materials Science and
PropertiesThe goal of materials science is to empower
scientists and engineers to make informed
decisions about the design, selection and
use of materials for specific applications.
Photograph: Nils Jorgensen/REX
Under Armour piezoelectric ad
https://www.youtube.com/watch?v=MK7gYP9HWpYFour Fundamental Tenets Guide Materials Science
1. The principles governing the behavior of materials are grounded in science and
2. The properties of a given material are determined by its structure. Processing
can alter the structure in specific and predictable ways
3. Properties of all materials change over time with use and exposure to
4. When selecting a material for a specific application, sufficient and appropriate
testing must be performed to ensure that the material will remain suitable for its
intended application throughout the intended life of the productA materials scientist or engineer must be able to:
1. Understand the properties associated with various classes of materials
2. Know why these properties exist and how they can be altered to make a material
more suitable for a given application
3. Be able to measure important properties of materials and how those properties
will impact performance
4. Evaluate the economic considerations that ultimately govern most material
5. Consider the long-term effects of using a material on the environmentFundamental types of materials important to
1. Crystals - Engineering metals and alloys
Systemic, regular pattern, minimize volume
2. Engineering Ceramics (including glass)
High viscosity at liquid-solid point prevents crystallization. These materials
are usually amorphous
Long chains of simple, molecular structures. Plastics and living things
Long chain polymers which fold or coil. Natural and artificial rubber.
Enormous extensions associated with folding and unfolding of chains.Semiconductors
Steel reinforced concrete
http://www.buzzfeed.com/scott/nerd-venn-diagramThe Fundamental Material - Atom
1. What are the atomic building blocks?
a) Nucleus – Protons (+) and Neutrons (0)
b) Electrons (-)
c) Atoms have a neutral charge (protons =electrons)
2. How are electrons distributed through an atom?
a) Electrons in organized shells in an electron cloud
b) electrons/shell = 2N (N = the shell number)
3. What are valence electrons? Why are they important?
a) Valence electrons are in the outermost shell
b) Reactivity of atom depends upon valence electrons
4. Why are noble gases inert?
a) The noble gases have full shells of electrons
Atom = stadium
Nucleus = housefly in the center of the field
M%26T_Bank_Stadium_DoD.jpgAtoms – Can we see them?
Electron Microscopy and Scanning Probe Microscopy
Xe on Ni Au
resolution_Au100.JPG/200px-Atomic_resolution_Au100.JPGThe Fundamental Material - Atom
1. All atoms of a given element are ______________
2. Atoms of different elements have different ________________
3. A compound is a specific combination of atoms of more than one
4. In a chemical reaction, atoms are neither created nor destroyed – only
change partners to produce new substances
HCl + NH NH Cl
drochloric_acid_ammonia.jpgWhat holds the atoms in metals/crystals, ceramics,
polymers and elastomers together?
• Two or more atoms share electrons
• Strong and rigid
Shared electron from Shared electron
• Found in organics and sometimes ceramics
hydrogen from carbon
• Strongly directional
• Methane CH
Carbon has ___ valence electrons
Hydrogen has ___ valence electrons
• Elemental solids – diamond
• Can be stronger – diamond
• Can be weaker - Bi
• Bonding between a metal and a non-metal
• Metal gives up valence electron(s) to non-metal
• Results in all atoms having stable electron configuration
• Na Cl
• Metal becomes +ly charged (cation); non-metal becomes –ly
• Coulombic attraction
Example: Na (+) (small) and Cl (-)(large)
Packing: as close as possible.
• Hold metals and alloys together
• Allows for dense packing of atoms (why metals are heavy)
• Valence electrons are not bound to a particular atom and
are free to drift through the entire material = “sea of
• Nonvalence electrons + atomic nuclei = ion core (with a net
• Good electrical conductivity
• Good heat conductivityIntermolecular Forces
Bonds holding molecules together
• Intermolecular attraction in which a H atom bonded to a small,
electronegative atom (N, O or F) is attracted to a lone pair of
electrons on another N, O or F atom.
• Weak interactions
• Due to the charge distribution on molecule
• Often seen in organic compounds
Example: H O
• 5 to 30 kJ/mole (as compared to about 100kJ/mole for chemical bond)
-O-H O=Intermolecular Forces
Bonds holding molecules together
Van der Waal forces:
• Short-time interactions
• Arise from surface differences across
• Weaker forces (10 kJ/mole)
• Gecko feet: Microscopic branched
elastic hairs on toes which take
advantage of these atomic scale
attractive forces to grip and support
http://upload.wikimedia.org/wikipedia/en/0/03/Micro_and_nano_view_of_gecko's_toe.jpgConsequences of Structure
• Structure is related to the arrangement of the
components of a material
• This could be on any length scale – atomic,
nano-, micro-, macro-
• All length scales matter
• Types of carbon (literally just carbon)
d) Buckminster Fullerene C60
g) Amorphous carbon
h) Carbon Nanotube
Take a 10 minute break
During the break take time to think about spaghetti
How does it break?
How many ways can it break?
How can it be made stronger?Material Properties
How easy does spaghetti break in tension (by pulling)?
Is thicker spaghetti easier or harder to break in tension?
Theory says that force needed to break in tension increases with cross-sectional area.
How easily does spaghetti buckle in compression?
Depends on force, material strength, length and thickness of spaghetti
A longer piece buckles easier than a shorter piece
A thinner piece buckles easier than a thicker piece
How easily does spaghetti bend if you push on it perpendicularly?
Is it in tension or compression?
Deflection depends on force, material strength, span length and cross-sectional area.
A larger force yields a larger deflection
For a given force, longer pieces bend easier
For a given force, thin pieces bend easier