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Atmospheric coatings > chapter 14 coatings failurs > Flashcards

chapter 14 coatings failurs Flashcards

1
Q

the mechanism of chalking is essentially one in which the coating _______ tends to gradually _______, leaving the surface covered with pigments that had been held on the surface by the ________.

A

binder
disintegrate
binder

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2
Q

______ or ______ of a coating is due to the exposure of a coating to the ________ rays of the sun and the action of the __________ on the organic binder.

A

powdering
chalking
actinic
radiation

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3
Q

_______ have a positive influence on chalking, as they tend to reduce the chalking by _______ the resin from the sun’s rays

A

pigments

shielding

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4
Q

Identify an ASTM standard that provides a method of determining the degree of chalking

A

ASTM standard D4214

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5
Q

_______ is essentially a wearing away of the coating surface in a _______ manner similar to the chalking mechanism.

A

Erosion

gradual

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6
Q

_______ is small breaks in a coating surface that forms as a coating ages and does not ______ the full depth of the coating.

A

Checking

penetrate

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7
Q

_______ is the shrinkage of the surface while at the same time the _____ of the coating does not change in the same way.

A

Alligatoring

body

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8
Q

___________ results from stresses on the _______, while cracking is caused by stresses ______ the film and ______ the film and the substrate.

A

checking
surface
throughtou
between

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9
Q

Cracking occurs as a coating ages: as it is subject to _____ and _____, ____ and _____, _____, and _____ of moisture, etc.

A

expansion and contraction
wetting and drying
absorption and desorption

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10
Q

Reinforcing pigments, which are _____ or _______, aid materially in reinforcing the coating against cracking action.

A

Fibrous or acicular

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11
Q

ASTM Standard _______ can be used to evaluate extent of cracking.

A

D661-81

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12
Q

___ ______ occurs when highly filled coatings area applied rather heavily.

A

Mud cracking

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13
Q

______ is the result of the ______ of a coating where the _____ of the coating expands more rapidly during the drying period than the ______ of the coating.

A

Wrinkling
swelling
surface
body

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14
Q

Some driers are used to speed the _____ cure and others are used as ______-______ materials

A

Surface

through- drying

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15
Q

_____ materials are examples of surface driers; _____ and _____ compounds are classified as through driers.

A

Cobalt

zinc and lead

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16
Q

Poly-amide curing agents are susceptible to biological failure, while _____ ____ curing agents have excellent resistance to sewage conditions.

A

Amine type

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17
Q

Fungus growth can be largely eliminated by the use of _____ _____ as part of the pigmentation, along with the addition of _____ , _____ or a combination of all three.

A

Zinc Oxide
Fungicides
Bactericides

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18
Q

Inorganic zinc coatings are highly filled with metallic zinc, and the _____ to binder ration is very high, so when drying is ____, fine surface ____ can occur.

A

pigment
rapid
checking

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19
Q

Chalking remedy

A

coating formulated with radiation resistant resins (acrylic) and non catalytic, non chalking pigments.

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20
Q

Alligatoring remedy

A

Apply thin coats, dry thoruoughly before additional coats, never apply hard top coats (epoxy) over soft under coat (asphalt).

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21
Q

Mud Cracking remedy

A

use coatings with strong adhesions, apply under proper drying conditions, prevent sags, puddles, or areas of excess thickness.

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22
Q

Biological failure remedy

A

select oil-based coating which contain fungicides or bactericides.

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23
Q

Wrinkling

A

choose coatings with even, thorough drying, charctristics

apply evenly avoid excess thickness.

24
Q

pinpoint rusting remedy

A

apply maintenance coat at first sign of failure.

remove coating and reapply more satisfactory zinc coating.

25
Q

erosion remedy

A

select chalk resistant coating with good flow out to a smooth film

26
Q

three types of contaminants in steel after blasting

A

rusting
chlorides
sulfides

27
Q

previously used steel failure

A

retention of minute amounts of corrosion product or contaminant along grain boundaries of the steel.

28
Q

galvanized steel failure

A

formation of zinc salts (oxides, sulfide, zinc soap)

29
Q

copper failure

A

smooth copper oxide surface. No physical adhesions

30
Q

wood failure

A

expansion and contraction due to humidity soft porous grain

31
Q

concrete failure

A

chemical reactivity and moisture content

32
Q

coating failures are more probable when _____ are used than when the same coating is applied over a _____ abrasive blasted surface.

A

inhibitors

dry

33
Q

retained solvents may cause ______ and ___ adhesion to the substrate because the underlying coating is ____ and the ___ ___ are close to the substrate.

A

blistering and low
porous
retained solvents

34
Q

regardless of their size and description, _____ are essentially discontinuity in a coating.

A

Holidays

35
Q

______ is generally the result of poor gun adjustment, or application of the coating at too ____ a distnce from the surface, and not applying an even _____ film to the surface.

A

over-spray
great
wet

36
Q

For the most part, ______ result from ______ application of a coating, with ____ being blown into the surface during the application.

A

pinholes
heavy
air

37
Q

cratering (or ________ or ______) may be either an ______ problem, a _____ problem, or _______.

A

bug-eying or crawling
application
material
or both

38
Q

Much catering is due to _______ on the surface or that falls into the wet coating.

A

contamination

39
Q

runs, sags, and curtains failures

A

lack of care in application

40
Q

Brush mark failure

A

pooor workmanship

41
Q

overspray failure

A

uneven spray passes with gun too far from the surface

42
Q

pinhole failures

A

spray gun to close to surface with air bubbles being forced into coating

43
Q

holidays failure

A

poor, inconsistent application

44
Q

cratering failure

A

improper solvent mixture

45
Q

two types of blisters

A

coating separating from substrate or

between coats

46
Q

Where there is solvent retention and the coated surface _____ in temperature, the solvent itself may create a sufficient _____ pressure to cause blisters to form in the coating.

A

changes

vapor

47
Q

cathodic protection blisters in coatings are caused by _____ gas being formed on the metal underneath the coating is sufficient volume so the the _____ ____ pressure pushes the coating off the surface.

A

hydrogen

hydrogen vapor

48
Q

peeling can be caused by _____ surface preparation, _____ between coats, or when the coating thickness is too _______.

A

poor
contamination
great

49
Q

_______ is much like peeling except that the flaked coating is usually _____ and _____ and tends to pull itself away from the substrate.

A

Flaking

hard and brittle

50
Q

Inter-coat _________ occurs most often where repair or maintenance coatings are being applied over existing coatings that are _____, have ______ embedded in the surface, or have oxidized or cured to the point of complete _______ and ________.

A

delamination
chalky
dirt
insolubility and impenetrability

51
Q

When coal tar epoxy coatings are exposed to ______, that will catylyze the curing of the surface to the point where additional coats will not ______ ______.

A

sunlight

adhere properly

52
Q

__________ of a coating is the action of rust under the coating, usually forming around a small _____ in the coating.

A

undercutting

break

53
Q

A coating applied over ____ ____ is susceptible to undercutting, since once a break in the coating occurs: corrosion can begin between the ____-____ _____ and the steel

A

Mil scale

mil scale surface

54
Q

Reverse impact is ____ ____ difficult for a coating to resist than _____ _____ .

A

much more

direct impact

55
Q

Most coatings are _____ for faying surfaces because of the fact that the coefficient of friction is not _____ for the bonding of the joint.

A

unsuitable

sufficient

Atmospheric coatings (12 decks)

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