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28 Cards in this Set
- Front
- Back
define corrosion
|
the chemical or
electrochemical deterioration of a material |
|
why does corrosion occur?
|
because
of the tendency of metals to return to their naturally occurring state |
|
can Corrosion
occur in the absence of water? |
yes, but only at high
temperatures, such as those found in gas turbine engines. |
|
what is the most common type of corrosion
|
electrochemical corrosion
|
|
what is The smallest unit of an element
|
an atom
|
|
__________ is A negatively charged subatomic
particle |
electron
|
|
_________ is An atom or group of atoms or molecules
which has acquired a net electric charge by gaining or losing electrons |
ION
|
|
_____ is A liquid (usually water) solution
containing ions |
ELECTROLYTE
|
|
the THEORY OF CORROSION is...
|
All metals will corrode
to some extent in a natural environment |
|
what Four conditions must
exist before metal corrosion can occur |
1. metal present
2. the cathode must be present 3. electrolyte must connect the anode and cathode 4. Electrical contact between the anode and cathode must exist |
|
what are The metals most commonly used in aircraft
construction |
aluminum, steel, titanium, and
magnesium |
|
_____ results from a direct chemical attack on a
metal surface that proceeds uniformly over the entire exposed surface |
UNIFORM SURFACE CORROSION
|
|
______ occurs when different metals are in contact with each
other and an electrolyte |
GALVANIC CORROSION
|
|
GALVANIC CORROSION is usually
recognizable by |
the presence of a buildup of corrosion
deposits at the joint between the metals |
|
____ is a form of
extremely localized attack that results in holes in the metal |
PITTING CORROSION
|
|
Pitting is usually first noticeable as...
|
a white or
gray powdery deposit, similar to dust, which blotches the surface |
|
______ is an attack on the grain
boundaries of the metal. |
INTERGRANULAR CORROSION
|
|
_____ is where the surface grains of a
metal are lifted up by the force of expanding corrosion products occurring at the grain boundaries |
EXFOLIATION CORROSION
|
|
what is visible evidence of exfoliation corrosion
|
lifting up or swelling
|
|
_____ is recognized by its characteristic wormlike
trace of corrosion products beneath the coating |
FILIFORM CORROSION
|
|
____ is
the increase in the rate of attack on a metal due to the action of a corrosive fluid against the metal surface |
Erosion corrosion
|
|
Erosion corrosion is
characterized by... |
grooves, gullies, waves, rounded holes
and/or valleys in the metal surface |
|
____is the intergranular or transgranular
cracking of a metal caused by the combined effects of constant tensile stress |
STRESS CORROSION
|
|
Stress corrosion appears in the form of...
|
cracks
|
|
____ is the cracking of metals caused by the combined effects of cyclic stress and corrosion
|
CORROSION FATIGUE
|
|
___occurs at contact areas between materials under load
subject to repeated vibration |
FRETTING CORROSION
|
|
Fretting has the general appearance of....
|
galling, in which chunks of metal are torn from the
surface with corrosion at the torn areas or ragged pits |
|
The corrosion
products of _____are white powdery snow-like mounds |
MAGNESIUM
|