Mat33 Test 1 (Callister)

Front 1

Crystalline

Back 1

atoms arranged in a regular periodic manner
- most metals, some ceramics

Front 2

Non-Crystalline (glassy)

Back 2

- no long range order
- atoms are randomly oriented (some ceramics

Front 3

ceramics

Back 3

compound between metal and non metal

Front 4

composites

Back 4

combination of different groups of materials where the properties are better than the individual material

Front 5

Polymers structure

Back 5

- consist of macro-moleculues with repeat unit

Front 6

Properties: Metals

Back 6

- excellent electrical conductor
- good thermal conductor
- ductile (will bend before breaking)
- relatively high strength
Moderate:
melting temp
elastic modulus
thermal expansion

Front 7

Properties: ceramics

Back 7

- Electrical insulator
- thermal insulator
- brittle (not ductile)
- High compression, weak tension
Large:
- melting temp
- elastic modulus
-Small thermal expansion

Front 8

Properties: Polymers

Back 8

- electrical insulator
- thermal insulator
- strong variable depending on chain
- light weight
-small melting temp
- small elastic modulus
- large thermal expansion

Front 9

electropositive / electronegative

Back 9

(+)
- atoms have a greater tendancy to lose electrons
(-)
- atoms have a greater tendancy to form a negative ion (anion)

Front 10

covalent bonding

Back 10

-: atoms achieve a filled outer orbital by sharing of electrons
Properties:
- strong bond
- high melting point
- electrons localized, cannot move freely through material = electric insulator
- bonding is direction, resists deformation

Front 11

ionic bonding

Back 11

- filled outer shells achieved by transfer of electrons
properties:
- strong bond
- no free electrons = electric insulator
- non-directional = electrostatic attraction

Front 12

the more electronegative the non-metal...

Back 12

the more electropositive the metal, the more ionic the bonding
(LiF totaly ionic)

Front 13

metallic bonding

Back 13

- outer electrons are only loosely bound due to sea of electrons
Properties:
- electrons are delocalized and can move freely = electron conductor
- planes of atoms can slide over each other = metals are easily deformed
- high electrical and thermal conductivity

Front 14

vander waals bonding

Back 14

In covalent moleculues, electrons not shared evenly between different atoms. Electric dipole causes vander waals attractions

Front 15

fully close-packed

Back 15

bonding is non-directional, atoms are the same size, there are no charge constraints, the densest possible structure (FCC, HCP, BCC)

Front 16

atomic packing factor

Back 16

Volume of atoms in a unit cell / total unit cell volume
FCC = .74
BCC = .68
HCP = .74

Front 17

Theortical Density

Back 17

p = (n*A)/(Vc*Na)

n = number of atoms associated with each unit cell
Vc = volume of uni cell
Na = avagadro's number
A = atomic weight

Front 18

FCC (a?) cord#

Back 18

face centered cubic

a = 2*R*sqrt(2)

cord # = 12

Front 19

BCC (a?) cord#

Back 19

body centered cubic

a = (4*R)/(sqrt(3))

cord# = 8

Front 20

Planar Atomic Density

Back 20

#atoms in plane / area of plane

Front 21

Lattice parameter (a)

Back 21

the length of unit cell
- : the equilibrium spacing of atoms, how close together the atoms want to come, if they go any closer they will repel, any further they will attract

Front 22

SiO2, B2O3 are types of network

Back 22

formers

Front 23

Na2O, K2O, CaO are network...

Back 23

modifiers

Front 24

Tg

Back 24

glass transition temp. glass does not melt but becomes softer and network is weaker

Front 25

Intermediate Oxide

Back 25

PbO

- : does not form glass alone, but sits in or between the network

Front 26

Theoretical Density for ceramics (two diff atoms)

Back 26

P = (Na*Aa + nb*Ab ) / (Vc * Na)

Front 27

xrtl Structure NaCl

Back 27

cord# = 6
rc/ra + .414 to .732

2 FCC structures

Front 28

xrtl structure CsCl

Back 28

cord# = 8
rc/ra = .732 to 1

BCC? no, two atoms in the center

Front 29

ZnS xrtl structure

Back 29

cord# = 4
rc/ra = .225 to .414
- all ions are tetrahedrally coordinated

Front 30

Point Defects ( 0 dimensions)
- vacancy

Back 30

- : abscence of an atom or ion

props:
- thermodynamically stable defects
- equilibrium defects
- as temp increases, concentration of vacancies increases

Front 31

concentration of vacancy

Nv = Nexp(-Qv / kT)

Back 31

Nv = # of vacant sites
N = # of total sites
Qv = energy requiered to create vacancy
K = boltzman's constant
T = absolute temp

- vacancy increase = density decrease

Front 32

interstitial defect

Back 32

extra ion or atom present

- conc. interstitial < conc. of vacancies

Front 33

Frenkel defect (ceramic)

Back 33

cation vacancy
- moves from vacancy to interstitial spot

Front 34

Schottky defect

Back 34

charge neutrality maintained by having one cation vacancy for every one anion vacancy

Front 35

Substitiational (metal)

Back 35

An atom replaces that of the regular metal that is about the same size, same xtal struc., higher valancy

Front 36

Interstitial (metal)

Back 36

an atom with a smaller atomic diameter fills the voids among host atoms

Front 37

diffusion

Back 37

material transport by atomic motion

Front 38

interdiffusion

Back 38

atoms of one metal diffuse into another

Front 39

self-diffusion

Back 39

atoms exchanged positions are the same type

Front 40

conditions for diffusion

Back 40

must be an empty (vacant) adjacent site
- atom must have sufficient energy to break bonds with neighbor atoms and cause slight lattice distortion

Front 41

vacancy diffusion

Back 41

atoms adjacent to vacant site jumps into it and so on

Front 42

Interstitial diffusion

Back 42

jump from interstitial site to another rapidly
- fast than vacancy diffusion

Front 43

Ficks first law of diffusion

J = -D (dC/dX)

Back 43

- diffusion is driven by a concentration gradient of diffusing species

J = flux of atoms
dC = concentration change
dX = change of position
D = diffusion coefficient
- conc. gradient does not change with time

Front 44

ficks second law of diffusion

Cs-Cx / Cs-Co = erf( x/ (2sqrt(Dt))

Back 44

Cx = conc at depth
Co = initial conc
Cs = const surface conc., set by atmosphere
D = diffusion coeff
x = depth
t = time
erf(z)

Front 45

temp diffusion

D = Do*exp(-Qd / RT)

Back 45

Do = temp independent (m^2 / s)
Qd = activation energy
R = gas constant (units pending)
T = abs temp

Front 46

carburization (ficks second law)

Back 46

increase the carbon content at the surface of a steel component by heat treating the component, more carbon at the surface. obtains a harder, more wear resistant surface

Front 47

Hooke's Law ...

Back 47

stress strain behavior

Front 48

elastic deformation

Back 48

deformation where stress and strain are proportional. plot is linear
E = dStress / dStrain

Front 49

plastic deformation

Back 49

perminant, non-recoverable deformation

Front 50

yielding

Back 50

when elastic deformation becomes plastic deformation

Front 51

proportional limit (P)

Back 51

represents the on set of plastic deformation on a microscopic level

Front 52

yield strength (omega y)

Back 52

the stress value corresponding to the strain offset
- magnitude is a measure of a metals resistance to plastic deformation

Front 53

tensile strength

Back 53

the stress value at the maximum on the stress-strain curve, represents the maximum stress that can be sustained by a structure in tension
- maintaining this stress fractures the material

Front 54

ductility

Back 54

a measure of the degree of plastic deformation that has been sustained at a fracture

Front 55

brittle

Back 55

low ductility = little or no plastic deformation

Front 56

hardness

Back 56

a measure of a materials resistance to localized plastic deformation

Front 57

scratch test

Back 57

if substance A can scratch B, A is considered harder
- scratchability

Front 58

hardness test

Back 58

uses indentor
- harder the material, deeper the indentor goes, the larger the indentation.
- measure width of indent to determine hardness

Front 59

slip

Back 59

permanant deformation, planes of atoms slide across one another, plastic deformation produced bu dislocation mothion

Front 60

slip system

Back 60

slip plane and slip direction

{ plane } <direction>

Front 61

Burgess vector : characteristics of dislocation

Back 61

vector that completes the circuit

Front 62

b(FCC)
b(BCC)
b(HCP)

Back 62

- a/2 <110>
- a/2 <111>
- a/3 <11 2bar 0>

Front 63

resolved shear stress

tR = Ocos(phi)cos(lambda)

Back 63

shear components that exist at all but parallel or perpendicularr alignment to the stress direction

phi - angle between the normal to the slip plane and the applied stress direction
lambda - angle between slip direction and
O(omega) - applied tress

Front 64

yield strength

Back 64

d = grain diamter
ky , omegao = constants for particular material
omega y = yield strength

Front 65

glass: melting point - viscocity = 100P

Back 65

glass is fluid enough to be considered liquid

Front 66

glass: working point 10^4 P

Back 66

glass is easily deformed

Front 67

glass: softening point 4*10^7 P

Back 67

max temp that a glass piece can be handled without alterations

Front 68

glass : annealing point 10^13 P

Back 68

atomic diffusion is sfficiently rapid that any stress maybe removed within 15 minutes

Front 69

strain point 3*10^14 P

Back 69

any temp below this point, fracture will occer before plastic deformation

Tg > strain point temp

Front 70

float glass method

Back 70

makes sheet glass

Front 71

press and blows method

Back 71

makes bottle shapes, put glob of molten glass in shape mod, press into mod, control temp, blow compressed air in so it takes shape of container

Front 72

glass fibecs

Back 72

spin molten glass and pull out small fibers

Front 73

tempered glass

Back 73

start with glass at high temp around softening point, blow with cold air so glass tries to contract, surface layer in compression, inside in tension

Front 74

slip casting

Back 74

- forming ceramic
- suspend clay and/or other non plastic materials in water and pour into a porous mold. the mold will absorb the water and leave behin the solid clay

Front 75

solid casting

Back 75

solid clay piece

Front 76

drain slip casting

Back 76

just the outline of the mold (pot)

Front 77

uniaxial pressing

Back 77

powder compacted in a metal die by pressure applied in a single direction, simple

Front 78

isotatic pressing

Back 78

powder material contained in a number envelope and the pressure is applied by a fluid with some magnitude in all directions

Front 79

hot pressing

Back 79

powder pressing and heat treatment performed simultaneously, used for materials that do not form liquid except at very high temp