Material Science Flashcards
it involves investigating the
relationships that exist between the structures and
properties of materials
Materials Science
it involves the basis of
structure-property correlations, designing or
engineering the structure of a material to produce
a predetermined set of properties.
Materials Engineering
illustrative to represent
the four bonding types, a three-dimensional
tetrahedron with one of these “extreme” types
located at each vertex
Bonding Tetrahedron
some ionic character to
most covalent bonds and some covalent character
to ionic ones. It is represented between the ionic
and covalent bonding vertices.
Covalent-ionic Bonds
there is a gradual
transition from covalent to metallic bonding as one
move vertically down this column.
Covalent-Metallic Bonds
their properties
are
intermediate between the metals and
nonmetals
Metalloids or Semi-Metals
observed for compounds
composed of two metals when there is a significant
difference between their electronegativities
Metallic-ionic Bonds
The solid materials may be classified
according to the regularity with which
atoms or ions are arranged with respect to
one another
Crystalline
A ____ material is one in which the
atoms are situated in a repeating or
periodic array over large atomic distances
crystalline
In _____, atoms are
thought of as being solid spheres having
well-defined diameters
crystalline structures
This is termed the atomic hard sphere
model in which spheres representing
nearest-neighbor atoms touch one another
Crystalline
The atomic order in crystalline solids
indicates that small groups of atoms form
a ______.
repetitive pattern
_____ subdivide the structure into
small repeated entities.
Unit cells
A unit cell is chosen to represent the
_____ of the crystal structure.
symmetry
Thus, the _____ is the basic structural
unit or building block of the crystal
structure.
unit cell
cubic unit cell with atoms located at all eight
corners and a single atom at the cube center.
The Body-Centered Cubic Crystal Structure
a unit cell with atoms located at each of the
corners and the centers of all the cube faces
The Face-Centered Cubic Crystal Structure
(FCC)
The _____ is the sum of the sphere volumes of all
atoms within a unit cell (assuming the atomic
hard-sphere model) divided by the unit cell
volume-
Atomic Packing Factor
For the FCC structure, the atomic packing factor is
_____, which is the maximum packing possible for
spheres all having the same diameter.
0.74,
Imperfection of Solid
Grain
Nucleon
Anisotropy
Isotropic
is mainly a crystal without smooth
faces because in its growth was impelled by
contact with another gram or a boundary
surface. The interface found between
grains is called grain boundary surface.
Grain
the moment of crystal begins to
grow is called nucleation and the points
where it occurs is the nucleation point.
Nucleon
when properties of a materials vary with different crystallographic orientation.
Anisotropy
when properties of materials
are the same in all deviation.
Isotropic
unit cell geometry is
completely defined in terms of six parameters: the
three edge lengths a, b, and c, and the three
interaxial angles α, β, and y.
Lattice Parameters
Basic Classes of Crystal Defects
Point Defects
Linear Defects
Planar Defects
which are places where
an atom is missing or irregularly placed in
lattice structure; include vacancies, self-
inters
Point Defects
which we groups of
atoms in irregular positions. Sometimes
called dislocations.
Linear Defects
which are interfaces
between homogeneous region of the
material grain boundaries, stacking faults
and extend surfaces.
Planar Defects
Mechanical Properties of Metals
Plastic Deformation
Yielding
Proportional Limit
Yield Strength
Tensile Strength (TS)
Brittle
it occurs as the
material is deformed beyond this point;
the stress is no longer proportional to
strain.
Plastic Deformation
a structure or component that
has plastically deformed or experienced a
permanent change in shape-may not be
capable of functioning as intended.
Yielding -
for metals that
experience this gradual elastic-plastic
transition, the point of yielding may be
determined as the initial departure from
linearity of the stress-strain curve.
Proportional Limit (P) -
The stress (σ)
corresponding to the intersection of this
line and the stress-strain curve as it bends
over in the plastic region.
Yield Strength
is the stress at
the maximum on the engineering stress
strain curve (MPa or psi).
Tensile Strength (TS)
a metal that experiences very
little or no plastic deformation upon
fracture.
Brittle
may be expressed quantitatively as either
percent elongation or percent reduction in area.
Ductility
is the percentage of
plastic strain at fracture.
Percent Elongation
The motion of
dislocations in response to an externally
applied shear stress is termed slip.
Slip Systems
is that plane that has the
densest atomic packing, and the slip
direction is the direction within this plane
that is most closely packed with atoms.
Slip Plane
The three usual causes of failure are:
Improper materials selection and
processing
Inadequate component design
Component misuse
the separation of a
body into two or more pieces in response
to an imposed stress that is static (i.e.,
constant or slowly changing with time) and
at temperatures that are low relative to the
melting temperature of the material.
Simple Fracture
For ductile metals,
two tensile fracture profiles are possible:
Necking down to a point fracture when
ductility is high. Only moderate necking
with a cup-and-cone fracture profile when
the material is less ductile
Ductile Fracture
For brittle fracture,
the fracture surface is relatively flat and
perpendicular to the direction of the
applied tensile load.
Brittle Fracture -
____ crack propagation paths are
possible for polycrystalline brittle materials.
Trans granular (through-grain) and intergranular
(between-grain)
is an inorganic non-metallic solid or
metalloid atom made up of either metal or
nonmetal
compound that have been
shaped/hardened through heating to an elevated
temperature
CERAMIC
Types of Ceramics
- Earthen Wares
- Stone Wares
- Porcelain
- clay fired at relatively low temperature of
between 1000 to 1050°C - hardened but brittle material which is slightly
porous- can’t be perfect to use as water container
Earthen Wares
- made from a particular clay which is fired at a
much higher temperature of about 1200° - more durable material, with a denser, stone-like
quality. - finished product need not be glazed unlike the
earthenware but still waterproof.
Stone Wares
- made from a refined clay which is fired at a very
high temperature of approximately 1200-1450°C - extremely hard, shining material, often white
and translucent in appearance.
Porcelain
Properties of Ceramics
-high melting point therefore heat resistant
-great hardness and strength
-considerable durability therefore long lasting
-low electrical and thermal conductivity hence, proven to be
good insulators
-chemical inertness hence very unreactive with other chemicals
-most of them are non-magnetic
chemicals except ferrites
Uses of Ceramics
-used in quartz clock, tiled bathroom, cups, bowls, etc.
-used as microchips, capacitors or resistors
-used as catalytic converters in cars
-used as high temperature superconductors
-used as high-performance cutting tools like silicon nitrides, boron nitrides and tungsten carbides
-used in making integrated circuits (microchips) - Aluminum oxide, Silicon dioxide
-used as heat protective nose cover in space rockets- Lithium Silicon oxide
new product
design using furnace and Kiln Technologies that
incorporate improved flexibility, operating
efficiencies and equipment control to help scale
up production rates temperature ranging from
300 to 3000 degrees Celsius.
Thermal processing solutions
white lives do calcine powders
end components such as stormy stars, very stars
comma and monolithic and multi-layer
capacitors.
Harper Kilns
Technology Solutions for Ceramics
- Rotary tube furnaces
- Pusher furnaces
- Belt conveyor furnaces
- Vertical conveyor furnace
- Microwave furnaces
- exceptional versatility reliability and energy
efficiency and enable better mixing resulting in
improved heat transfer and mass transfer for
technical ceramics; \ - Used for processing granular, powder, or
particulate aggregate
Rotary Tube Furnaces
- ideal for processing requiring precise control of
temperature and atmosphere - acquire longer residents time and those with a
lower gas/solid reaction - evacuation of volatile
Pusher Furnaces
- designed for continuous processing of parts and
advanced materials - like granular, powder or particulate aggregates
in high purity and specialty atmosphere - environment at temperatures Up to 2000
degrees Celsius.
Belt Conveyor Furnace
- used particularly for materials requiring high
temperature solid to solid and solid to gas
reaction such as carbide, nitride, borides, and
refractory metal powders.
Vertical Furnaces
- manufactured to meet the specific requirements
of customers - used for continuous processing of advanced
materials - used encoding of particles to attain production
with modified superficial properties and powerful
stream of fluid up through particles
Fluid Bed Furnaces
Types of polymers:
- Natural
- Synthetic
most common polymer in the
world built from a monomer called
ethylene
Polyethylene
Properties of Polymers:
- Nearly all polymers are solids
- Many of them don’t have definite MP
- Responds in interesting way when
squeezed or stretched which are called
mechanical properties hence Chemical
Engineers can control their physical
properties - Considered important engineering material
(strength and elasticity)
Categories of Polymers:
- Thermoplastic
- Thermosetting
long, linear polyethylene molecules
which are packed together very tightly producing
relatively dense plastic; strong hard materials
used in bottles, kitchenware and structured
plastic in children’s toys.
High Density Polyethylene (HDPE)
loose packed polyethylene molecules
with a much lower density commonly used in
plastic films, sandwich bags and squeeze bottles.
Low Density Polyethylene (LDPE)
hundreds of thousands molecules-
use
for
standard filling for bulletproof
vest/skating rinks
ultra high molecular weight
polyethylene
Types of Rxn in Polymers:
- Addition - Polymers or Chain growth
polymers - Condensation - Polymers or Step Growth
Polymers
Different
(Addition):
Structures of Monomers
1) Isotactic
2) Syndiotactic
3) Atactic
if the methyl groups all point
forward or backward.
Isotactic
if the position of the methyl
groups systematically alternates between
forward and backward
Syndiotactic
arrangement of the methyl groups
in random sticking “into” and “out of” the
page with no regular pattern.
Atactic
Are large molecules built up by repetitive
bonding together of many smaller units called
monomers.
POLYMERS
Occurs when two or more different monomers
are allowed to polymerize together
Copolymerization
mammoth polymers or
biopolymers or polymers found in biological
systems (carbohydrates, proteins, or nucleic
acids)
Biopolymers
are simple sugars ; are the
monomers from which more complex
carbohydrates are constructed.
Monosaccharides
contains either 5 or 6 carbon
atoms
Simple Sugar
are monosaccharides that contain
aldehyde
Aldoses
are those that contain ketone
Ketoses
blood sugar in most
common monosaccharide
Glucose or Dextrose
milk sugar (Disaccharide)
Lactose
- milk sugar (Monosaccharide)
Galactose
- beer sugar (Disaccharide)
Maltose
dextrose (Monosaccharide)
Glucose -
table sugar (Disaccharide)
Sucrose -
- fruit sugar (Monosaccharide)
Fructose
are compounds formed by the linking
of small numbers of amino acids
Peptides
amide bonds linking the amino
acids monomers
Peptide bond
common amino acids found in proteins (non polar)
a. nonpolar, R groups
alanine
glycine
isoleucine
leucine
methionine
phenylalanine
proline
Tryptophan
Valine
common amino acids found in proteins (polar)
b. polar, neutral groups
asparagine
glutamine
aspartic acid
cysteine
tyrosine
serine
threonine
arginine
histidine
lysine
common artificial sweetener =
dipeptide
Aspartame
- scavenging agent for harmful
oxidizing agents believed the cause cancer =
tripeptide
Glutathione
- Naturally occurring analgesic
(pain reliever) that occur in the brain =
pentapeptide
Enkephalins
- biopolymers; MW typically 5000
gram per mole or greater consisting of one or
more polypeptide chains
Proteins
- a protein that catalyzes biological
reactions
Enzyme
- are 3 very different types of
monomers: phosphate, group of one or 2 simple
carbohydrate units (deoxyribose or ribose) and
selected base.
Nucleic acids
2 types of nucleic acid
- ribonucleic acid (RNA)
- deoxyribonucleic acid (DNA)
is one of the largest molecular known;
Estimated to have up to 3 billionbase pairs
resulting in a MW in the tens of billions
DNA
is
smaller; MW - 20,000 to 40,000. There are 20
common amino acids found in proteins.
RNA
(PEEK)
Polyetheretherketone
is a semicrystalline thermoplastic with
excellent mechanical and chemical resistance
properties that are retained to high temperatures.
(PEEK)
