chapter 2 continued 1 Flashcards

1
Q

Metals that are ______ negative in the electromotive force series will corrode in comparison to the other metal which is less negative

A

More

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2
Q

The farther apart the two metals are int eh electromotive force series, the ______ the potential difference between the two, and the greater the ______will take place on the more _______ surface.

A

greater
corrosion
negative

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3
Q

The rate of galvanic corrosion is not only determined by the _______ position of the metals in the EMF series, but also by the ______ area of the metal.

A

relative

exposed

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4
Q

_____ the use of combinations of metals that have potentials that are _______ separated in the galvanic series.

A

avoid

widely

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5
Q

______ joints of _______ metals when possible.

A

insulate

dissimilar

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6
Q

paint or coat all ______ when possible. Avoid painting the _____ metal only.

A

surfaces

anodic

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7
Q

Seal _______ (close-fit) surfaces

A

Faying

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8
Q

Apply _____ coatings to _____ the potential difference between dissimilar metals.

A

metallic

reduce

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9
Q

_____ threaded connections when dissimilar metals are used.

A

avoid

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10
Q

An ______ concentration cell commonly develops where two steel plates overlap. The also develop under _____rivets, under loose ____, and under ____paint films

A

Oxygen
cocked
washers
loose

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11
Q

A pile of sand on a metal surface can also create an ________ concentration cell because the available oxygen in the solution surrounding the pile of sand is _______ than under the sand.

A

Oxygen

greater

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12
Q

In a metal ion concentration cell, the corrosion reaction is similar to the oxygen concentration cell, the difference being that the concentration of ______ _____ in one place is ______than at another.

A

metal ions

greater

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13
Q

to prevent crevice corrosion
use _____ joints in preference to _____ or _____ joints

_____ OR ______ unavoidable crevices, using noncorrosive materials

minimize the ____ between metal, and ______ plastic debris

A

welded bolted or riveted

caulk or seal

contact plastic

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14
Q

to prevent crevice corrosion
avoid contact with materials that are known to contain ________ ______ because they ______ the cell effect.

avoid sharp corners, ______, and ______ where debris can accumulate.
where a crevice is inevitable coat thoroughly both surfaces before the are ________

A

corrosive elements accelerate

ledges and pockets

joined

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15
Q

pH is the ______ logarithm of the hydrogen ion concentration in a solution .
water is equal pH of _______
acids pH is less than ____
alkalies range from ___ to ____

A

NEGATIVE
7
7
7 TO 14

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16
Q

The most common oxidizing salt is ______ _______

A

sodium hypochlorite (NaOCl)

17
Q

common sulfides include

A

ammonia
calcium
sodium

18
Q

Hydrogen sulfides reacts ______ with metal and does not require an electrolyte for the corrosion reaction to take place .

A

directly

19
Q

Moist concrete can develop a pH of up to ____. In sewers the reaction of _______ acid develops ant and above the mean water line. It has been measured at concentrations as high as 10% and can disintegrate concrete at the rate of up to 2 inches per year.

A

13

sulfuric

20
Q

Mill scale is _____: it is always strongly _______ to bare steel.

A

magnetic

cathodic

21
Q

filiform corrosion is generally thought to be caused by ____ surface contamination caused by _____ particles deposited from the atmosphere or particles that ______ after the metal has been processed.

A

mild
solid
remain

22
Q

pitting corrosion is a ______ of corrosion in one particular area so that the metal goes into solution more _____ at that spot that ant any other adjacent area.

A

concentration

rapidly

23
Q

graphitic is the _________ dissolution of iron leaving a soft _____ residue.

A

preferential

graphite