Material Science Flashcards by EGAÑA, SHEA P.

it involves investigating the
relationships that exist between the structures and
properties of materials

Materials Science

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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

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illustrative to represent the four bonding types, a three-dimensional tetrahedron with one of these “extreme” types located at each vertex

Bonding Tetrahedron

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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

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there is a gradual
transition from covalent to metallic bonding as one
move vertically down this column.

Covalent-Metallic Bonds

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their properties
are
intermediate between the metals and
nonmetals

Metalloids or Semi-Metals

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observed for compounds composed of two metals when there is a significant difference between their electronegativities

Metallic-ionic Bonds

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The solid materials may be classified according to the regularity with which atoms or ions are arranged with respect to one another

Crystalline

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A ____ material is one in which the
atoms are situated in a repeating or
periodic array over large atomic distances

crystalline

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In crystalline structures, ____ are thought of as being solid spheres having well-defined diameters

atoms

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This is termed the atomic hard sphere
model in which spheres representing
nearest-neighbor atoms touch one another

Crystalline

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The atomic order in crystalline solids
indicates that small groups of atoms form
a ______.

repetitive pattern

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_____ subdivide the structure into
small repeated entities.

Unit cells

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A unit cell is chosen to represent the
_____ of the crystal structure.

symmetry

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Thus, the _____ is the basic structural
unit or building block of the crystal
structure.

unit cell

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cubic unit cell with atoms located at all eight
corners and a single atom at the cube center.

The Body-Centered Cubic Crystal Structure

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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)

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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

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For the FCC structure, the atomic packing factor is
_____, which is the maximum packing possible for
spheres all having the same diameter.

0.74,

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Imperfection of Solid

Grain
Nucleon
Anisotropy
Isotropic

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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

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the moment of crystal begins to
grow is called nucleation and the points
where it occurs is the nucleation point.

Nucleon

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when properties of a materials vary with different crystallographic orientation.

Anisotropy

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when properties of materials
are the same in all deviation.

Isotropic

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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

1. Earthen Wares 2. Stone Wares 3. 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

1. Rotary tube furnaces 2. Pusher furnaces 3. Belt conveyor furnaces 4. Vertical conveyor furnace 5. 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:

1. Natural 2. Synthetic

most common polymer in the world built from a monomer called ethylene

Polyethylene

Properties of Polymers:

1. Nearly all polymers are solids 2. Many of them don't have definite MP 3. Responds in interesting way when squeezed or stretched which are called mechanical properties hence Chemical Engineers can control their physical properties 4. Considered important engineering material (strength and elasticity)

Categories of Polymers:

1. Thermoplastic 2. 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:

1. Addition - Polymers or Chain growth polymers 2. 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

1. ribonucleic acid (RNA) 2. 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)

Material Science Flashcards

(101 cards)