EXAM Flashcards
(91 cards)
1
Q
Mer
A
repeatable unit in a polymer
2
Q
material suitable for cladding a building
A
Aluminium
3
Q
vinyl flooring in a building is ….
A
Thermoplastic
4
Q
BCC
A
6 planes x 2 directions = 12 systems
5
Q
FCC
A
4 planes x 3 directions = 12 systems
6
Q
HCP
A
1 plane x 3 directions = 3 systems
7
Q
Manufacturing Polymeric Materials
A
Ultrasonic Welding
Thermoforming
Injection Moulding
Extrusion
8
Q
Metal Defects
A
Dislocation
Interstitial
Substitutional
Grain Boundary
9
Q
Cold rolling increases number of …. in a crystalline structure.
A
Dislocations
10
Q
Suitable method for manufacture of a Steel Beam
A
Rolling of a Billet
11
Q
Hydration of dicalcium silicate is…
A
Exothermic
12
Q
Teflon is a …
A
Polymer
13
Q
Bohr Model of the atom
A
electrons in discrete orbitals
energies of electrons quantised
14
Q
Wave-Mechanical atomic model
A
wave and particle like properties
position of electron as a probability
15
Q
Dislocation effects on... Yield strength ductility hardness elastic modulus toughness
A
increases decreases increases same decreases
16
Q
Ferrite
A
BCC, alpha iron
17
Q
Austenite
A
FCC, gamma iron
18
Q
Cementite
A
Iron Carbide, Fe3C
19
Q
Pearlite
A
laminated structure of Ferrite and Cementite formed during cooling by the diffusion of Carbon
20
Q
Hardenability
A
ease of martensite formation
21
Q
Martensite
A
non-equilibrium phase formed during rapid cooling when diffusion is too slow to allow Pearlite formation
very hard and brittle
22
Q
APFS: FCC BCC HCP SC
A
- 74
- 68
- 74
- 52
23
Q
Defects found in crystalline solids
A
Point (atoms)
Line (dislocations)
Area (grains)
Volume (precipitates)
24
Q
Eutectic
A
Liquid
25
Eutectoid
Solid
26
Glass
Crystalline
27
Engineered Ceramic
Non-crystalline
28
how does impure limestone produce cement?
heated to around 1450 ºC
29
Clinker phases formed during manufacture of cement
Tricalcium Silicate (Alite) initial strength
Dicalcium Silicate (Belite) late strength
Tricalcium Aluminate
Calcium alumni ferrite
30
Gypsum
added to cement to stop flash set from the trillium aluminate phase. forms ettrengite.
31
Metal properties
strong, ductile
high thermal and electrical conductivity
opaque, reflective
32
Ceramic properties
compounds (metallic and non-metallic)
brittle, glassy, elastic
non conducting
33
Polymer properties
Covalent bonding
soft, ductile, low strength and density
translucent / transparent
34
Atomic Mass Unit
1/12 th mass of Carbon-12 atom
35
Relative Atomic Mass
mass of one mol
36
Electropositive (left)
| Electronegative (right)
give up electrons to become +ve ions
| acquire electrons to become -ve ions
37
Ionic Bonding
| ceramics
```
large bond energy
metallic and non-metallic
non-directional bonding
relatively strong
brittle
```
38
Covalent Bonding
| polymers, glasses and ceramics
```
variable bond energy
sharing electrons (non-metal compounds)
directional bonding
very strong
brittle
```
39
Metallic Bonding
| metals
```
variable bond energy
valence electrons become delocalised (metals and alloys)
non-directional bonding
intermediate strength
ductile
```
40
Van Der Waals
| polymers
weak secondary bond
directional
very ductile
41
Hydrogen Bonding
weak secondary bond
| interaction and delocalisation of hydrogen electrons
42
Crystalline
atoms situated in a periodic array over large atomic distances
(dense, regular packing) --> lower energy
43
Amorphous
no long range order, non-crystalline
| non-dense, random packing
44
Unit Cell
basic building block unit that repeats in space to create crystal structure
45
Ductility
ease of plastic deformation
46
Anisotropic
properties vary with direction
47
Poisson's Ratios:
metals
ceramics
polymers
0. 33
0. 25
0. 40
48
Yield Strength
stress at which noticeable plastic deformation has occurred
49
Tensile Strength
max. stress that a structure can sustain
50
Toughness
energy to break a unit volume of material
51
Resilience
ability of a material to store energy
52
Hardness
resistance of materials to localised plastic deformation
53
Metal strengthening mechanisms
reduce grain size
solid-solution strengthening
precipitation strengthening
cold work
54
Alloy
metallic substance made up of more than one element
55
Low Carbon Steels
| car body components, reinforced concrete
carbon <0.25wt%
unresponsive to heat
soft and weak
excellent ductility
56
Medium Carbon Steels
| railway wheels, gears
carbon 0.25-0.6wt%
heat treatable only in thin sections
stronger, wear resistant
less ductile
57
High Carbon Steels
| cutting tools, blades
carbon 0.6-1.4wt%
heat treatable in thick sections
strong, hard, wear resistant
least ductile
58
Casting
sand casting
investment casting
die casting
59
Forming
forging
rolling
extrusion
drawing
60
Joining
powder processing
welding
heat affected zone
61
Glass properties
brittle
low toughness
amorphous
62
Glass Fabrication Techniques
pressing
blowing
drawing
fibre forming
63
Strengthening of Glass
tempering
chemical
reinforcement
64
Natural Ceramics
Sedimentary rocks
| Igneous rocks
65
Traditional Ceramics
local clays
66
Vitrification
formation of liquid glass which flows into pores and produces dense ceramic
67
Polymers
organic macromolecules made of repeating 'mer' units
68
Thermoplastic
soften on heated
linear chains
weak intermolecular bonding
ductile
69
Thermoset
degrade on heating
heavily cross linked
brittle
70
polymerisation
chemical process that causes a large number of monomers to combine to form the polymer
71
Elastomers
linear with some cross linking
| shape retention
72
Cold Drawing
molecules drawn out and aligned
elastic modulus increases
tensile strength increases
ductility decreases
73
Concrete
composite material, aggregates held together by a cementing medium
74
cement paste functions
1) fill voids between aggregates
| 2) provide strength to hardened concrete
75
aggregate functions
1) cheap fill for cementing material
2) provide a mass of particles which resist loads, abrasion...
3) reduce volume change
76
Portland Cement raw materials
Limeston, Clay and Gypsum
77
super-plasticisers
high range water reducing admixtures that don't affect setting
78
compressive strength
maximum stress that the concrete may carry
| related to water/cement ratio
79
tensile strength
roughly a 1/10th of compressive strength
80
Mortar
paste + fine aggregate
81
Portland Cement Production
1) grind raw materials
2) burn in large rotary kiln at 1450º to form balls known as Klinker
3) cool klinker and grind to fine powder
4) add gypsum
82
Hydration (2 methods)
1) In Solution
| 2) Solid State
83
Hydration Products
Calcium Silicate Hydrate
| Calcium Hydroxide
84
Tricalcium Aluminate Products
1) Ettringite (early stages of hydration)
| 2) Monosulfate (Later stages of hydration)
85
Cement Gel
rigid aggregation of very small particles
| porosity = 28%
86
Water within hardened cement paste
1) chemically combines in the hydrates
2) interlayer water
3) absorbed water
4) capillary water
87
Pozzolanic
material containing active Silica
88
accelerators / retarders
increase / decrease rate of hydration
| increase / decrease solubility of C3A
89
Aggregates
hard, strong, free from impurities
90
s, d, p and f block orbitals
1-2
3-12
13-18
lanthanides and actinides
91
valence electrons
single electron in the outer shell of an atom, can be gained or lost (incomplete outer shell)
