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Corrosion Engineering > Corrosionof Non-Metals > Flashcards

Corrosionof Non-Metals Flashcards

1
Q

Corrosion is when a refined metal
is naturally converted to a more
stable form such as its

A

oxide,
hydroxide, or sulphide state

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2
Q

do not generally corrode in the same
manner as metals and alloys, but the term corrosion can also
be applied to these non-metals.

A

Non metals

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3
Q

TYPES OF NON-METALLIC CORROSION

A

CHEMICAL REACTION CORROSION
PHYSICAL INTERACTION CORROSION

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4
Q

occur when polymers are exposed to heat
above a specified temperature limit, which is unique for each
type of polymer.

A

Chain scission

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5
Q

Chemical reaction corrosion

A

Polymers effect of heat
Polymers effect of UV rad
Polymers effect of h2o
Polymers effect of o3

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6
Q

In the presence of oxygen, _____________ can cause a breakdown of the polymer chains

A

UV-radiation

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7
Q

________ t elevated temperatures causes
hydrolysis of certain groups in a polymer chain such as __________

A

absorption of water; urethane, ester groups

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8
Q

Attacks from ozone on ______________ (e.g. natural
rubber) under stress, causes characteristic cracks.

A

unsaturated polymers

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9
Q

____________ of nonmetallic materials are
caused by their interaction with the environment

A

Physical interaction corrosion

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10
Q

Types of Physical interaction corrosion

A

Degradation
Dissolving or Leakage of Additives
Deterioration/Swelling

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11
Q

Types of Degradation

A

Thermal
Photo
Oxidative
Hydrolytic
Bio
Oxidative Photodegradation (Light + oxygen)
Thermoxidative
Photohydrolytic

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12
Q

are materials
made of long, repeating
chains of molecules. These
materials have unique
properties, depending on
the type of molecules
being bonded and how
they are bonded.

A

Polymers

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13
Q

do not experience a
specific corrosion rate

A

Plastic

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14
Q

They are usually
completely resistant to chemical attack, or
they deteriorate rapidly

A

Plastic

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15
Q

Plastics are attacked either by

A

chemical reaction or by solvation

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16
Q

is the
penetration of the
plastic by a corrodent,
which causes
softening, swelling, and
ultimate failure

A

Solvation

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17
Q

Corrosion of plastics can be classified in the following
ways as to the attack mechanism

A

Disintegration or degradation
Oxidation
Hydrolysis
Radiation
Thermal degradation
Dehydration

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18
Q

Polymeric materials in outdoor applications are exposed to weather
extremes that can be extremely deleterious to the material, the
most harmful of which is exposure to

A

UV radiation

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19
Q

Type of UV rad which causes polymer damage

A

UVA

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20
Q

Type of UVrad that causes severe polymer damage

A

UV-B

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21
Q

is a molecular migration through microvoids
either in the polymer (if the polymer is more or less
porous) or between polymer molecules. In neither case is
there any attack on the polymer

A

Permeation

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22
Q

detrimental when a polymer is used to line piping or
equipment

A

Permeation

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23
Q

In lined equipment, permeation can result in:

A
  1. Failure of the substrate
  2. Bond failure and blistering
  3. Loss of contents through substrate and liner
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24
Q

Permeration is a function of two variable:

A
  1. Relating to diffusion between molecular chains
  2. Relating to the solubility of the permeant in
    the polymer
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25
Q

s the partial
pressure of gases and the concentration
gradient of liquids.

A

Driving force of diffusion

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26
Q

function of the affinity of the
permeant for the polymer

A

Solubility

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27
Q

Factors of permeation

A

Temperature
Pressure
Permeant concentration
Thickness of the polymer

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28
Q

the thickness will
generally __________ permeation by the
________ of the thickness

A

decrease; square

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29
Q

__________ of many
gases increases linearly with the partial
pressure gradient

A

permeation rate

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30
Q

_______________ the temperature
will increase the permeation rate because
the ____________ of the permeant in the polymer
will increase

A

increasing; solubility

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31
Q

can cause softening of the
polymer, introduce high stresses, and
cause failure of the bond on lined
components

A

Swelling

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32
Q

Polymers have the potential to absorb
varying amounts of corrodents with
which they come into contact,
particularly organic liquids

A

Absorption

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33
Q

s its ability to
withstand exposure to corrosive products without
reacting.

A

Plastic’s chemical resistance

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34
Q

The more a plastic reacts to corrosive
agents, the __ its chemical resistance will be.

A

weaker

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35
Q

Ideally, we need to choose a
plastic that reacts well to
chemicals and other corrosive
agents.

A
  • Polypropylene
  • High Density Polyethylene
    (HDPE)
  • Polyvinylidene fluoride (PVDF)
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36
Q

material that is
neither metallic nor organic

A

ceramic

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37
Q

are typically hard and chemically
non-reactive and can be formed
or densified with heat

A

Ceramics

38
Q

offer superior corrosion resistance when compared to steel and plastic

A

technical ceramics

39
Q

will rarely breakdown due to corrosion and
they are resistant to acids and bases

A

ceramics

40
Q

Ceramic Materials with Exceptional
Chemical Resistance

A

Alumina
Silicates
Silicon carbide

41
Q

Uniform corrosion in a ceramic
takes place as a result of

A

chemical dissolution

42
Q

Factors affecting Ceramic Deterioration

A

Frost
Mold growth
Impact and abrasion
Water
Soluble salts

43
Q

Water can dissolve or
deform ceramics that have
been low fired, i.e., at
temperatures around

A

600C

44
Q

When the humidity is high
_________ can begin to form on
ceramic, particularly ones
in which there is no glaze

A

molds

45
Q

respond to changes in humidity both high and
low

A

Soluble salts

46
Q

Composites, also known as

A

Fiber-Reinforced Polymer (FRP) composites

47
Q

made from a
polymer matrix that is
reinforced with an engineered,
man-made or natural fiber (like
glass, carbon or aramid) or other
reinforcing material.

A

composites

48
Q

do not rust or corrode, which are
especially important characteristics in harsh
operating environments

A

Composites

49
Q

Applications of composites within the industries mentioned include

A
  • Pipes - Tanks
  • Fans - Hoods
  • Grating - Pumps
  • Cabinets
50
Q

is a vital procedure that
includes the examination and
measurement of the attributes
of polymers, engineering
plastics, composites, coatings,
and paints to ascertain the
reason for the failure

A

FAILURE ANALYSIS OF POLYMERIC MATERIALS

51
Q

This analysis is indispensable for comprehending the reasons
behind the failure of parts or components and pinpointing the
underlying cause of the issue

A

FAILURE ANALYSIS OF POLYMERIC MATERIALS

52
Q

Common modes of Failures of polymeric materials

A

Plastic deformation
Crazing
Fatigue
Thermal and residual stress
Physical aging
Moisture effect
Photodegradation
Chemical attack

53
Q

The deformation is irreversible
and it stays even after the
removal of the applied forces.

A

Plastic deformation

54
Q

Two prominent mechanisms of
plastic deformation in metals

A

Slip
Twinning

55
Q

are used to
shape objects into the desired form.

A

pressure and heat

56
Q

causes rapid material
changes, and at times, unable to conform to the
structural changes the material may break.

A

speed of stress

57
Q

employed in
the production of goods involves
subjecting the material to
controlled heat and pressure

A

plastic deformation

58
Q

Occurs in discrete multiples of atomic spacing

A

Slip plastic deformation

59
Q

Every atomic plane is involved

A

Twinning plastic deformation

60
Q

Occurs when shearing stress on the slip plane in the slip
direction strikes a threshold value known as the critical
resolved shear stress.

A

Slip

61
Q

Twin lines occur in

A

pair

62
Q

Slip lines are present in

A

even or odd numbers

63
Q

Occurs in high-impact
plastics due to the combined
effect of stress and
aggressive environment

A

crazing

64
Q

Since Crazing is a series of cracks in your
glaze, they are the perfect hideaways for

A

food particles, bacteria, and fungi like mold

65
Q

simply one failure mechanism, in
which prolonged cyclical stresses cause
undue or unexpected wear on a part until it
ultimately fails

A

fatigue

66
Q

Repeated support of
extreme weights can cause fibers to tear

A

Fatigue in composites

67
Q

prolonged or cyclical
exposure to weight or pressure can cause
cracks that eventually lead to failure

A

Fatigue in polymers

68
Q

Results in change in dimensions of the
material or a residual stress fixture
and hence a loss in its function.

A

Thermal and residual stress

69
Q

Occurs below glass transition
temperature (Tg) and material
becomes brittle

A

Physical aging

70
Q

It is a significant phenomenon
characterized by changes in material
properties over time due to molecular
relaxations

A

Physical aging

71
Q

Lowering of Tg , increase in ductility,
loss of creep resistance.
In non-metal materials, humidity can
cause swelling and shrinking.

A

Moisture effect

72
Q

absorb water and
expand, while certain types of
plastic can shrink

A

Wood

73
Q

The process by which the absorption
of photons— particularly those with
wavelengths in the UV–visible
spectrum—causes a molecule to
degrade

A

Photodegradation

74
Q

Materials that are usually ductile
become prone to brittle
intergranular failure after exposure
to certain liquid metals.

A

Chemical attack

75
Q

is a common feature in failure
of ceramic components. Cracks branch at a
critical velocity, which is of the order of half the
speed of sound in the specific glass under
study

A

Crack branching

76
Q

The acceleration of crack initiation to the
critical velocity depends on the e________ from the release of stored
energy

A

energy
dissipation available

77
Q

possess excellent corrosion and high-temperature
resistance, with the main disadvantages being brittleness and
lower tensile strength.

A

Ceramics

78
Q

show good corrosion resistance, electric and
heat conductivity, but they are fragile

A

Carbon

79
Q

attacked by aggressive environments

A

Wood

80
Q

Typical changes in the medium that are often employed are

A

.
Changing Mediums
Lowering temperatures
Lowering pressure
Changing permeant concentration
Increasing permeant thickness and density
Decreasing velocity
Removing oxygen/oxidizers

81
Q

IncreasingThicknessandDensity

A

Thickness^2 ∝ 1/Permeation
Density ∝ 1/ Permeation

82
Q

____________ velocities should be always avoided where
possible, because of erosion-corrosion effects

A

very high

83
Q

A chemical oxygen scavenger such as ________ is still
required to completely remove dissolved oxygen from
the feedwater, but pairing a deaerator with an
oxygen scavenger will greatly reduce the amount of
chemical used.

A

sulfite

84
Q

As thickness increases, the thermal stresses on the boundary increase,
which can result in

A

bond failure

85
Q

are the most common causes of bond failure

A

Temperature changes and large differences in coefficients of thermal expansion

86
Q

two of the factors that
influence these stresses.

A

Thickness and modulus of elasticity

87
Q

Relationship between absorption and corrosion rate

A

Absorption ∝ Corrosion Rate

88
Q

will reduce the temperature
gradient across the vessel. This also reduces the rate and magnitude
of temperature changes, keeping blisters to a minimum

A

Thermal insulation

89
Q

A general rule as to the differences in the corrosion resistance of
the t__________ can be derived from the periodic table

A

thermoplasts

90
Q

plays an important part in the chemical resistance
of the thermoset

A

curing the resin

91
Q

The presence of contaminants in the fluid may act as an

A

accelerator

92
Q

It is important to remember that __________ are specific in
terms of metal, environment, temperature, and concentration
range

A

inhibitors

Corrosion Engineering (6 decks)

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