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Flashcards in Corrosion Deck (23):
0

Pitting

most common on stainless steels but common on aluminum and magnesium alloys, white or grey powdery deposits, similar to dust which botch the surface, tiny pits or holes can be seen on the surface

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1

Corrosion that occurs when different metals are in contact with each other and an electrolyte. Recognizable by the presence of a buildup of corrosion deposits at the joints between metals

Galvanic

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2

Intergranular

grain boundaries of the metals(cross sections), high strength aluminum alloys are most susceptible

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3

Exfoliation

An advanced form of intergranular, surface grains of the metal are lifted up by the force of expanding corrosion, lifting up or swelling is visible evidence of exfoliation corrosion

NAVAIR 01-1A-509-1 3-7

4

Crevice

electrolyte inside crevice contains less O2 and more metal ions than electrolyte just outside the crevice(stagnant solution has pooled). This is common around gasket surfaces, lap joints, and under bolt or rivet heads

NAVAIR 01-1A-509-1 3-7

5

Stress corrosion cracking

Intergranular or transgranular cracking of a metal caused by the combined effects of constant tensile stress and corrosion.

NAVAIR 01-1A-509-1 3-10

6

Fillform

O2 concentration cell corrosion or crevice corrosion occurs on metal surfaces having a thin organic coating system, wormlike trace of corrosion beneath the paint film. Starts at breaks in the coasting system such as scratches and cracks around fasteners and seams, Affected by humidity, keep aircraft below 65%

NAVAIR 01-1A-509-1 3-9,10

7

What are the two most important factors of preventing corrosion and the only which can be controlled by field personnel

1. the removal of the electrolyte
2. application of protective coatings

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8

Iron in the presence of moisture and air will return to its natural state which is what

iron oxide rust

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9

Aluminum and magnesium form corrosion products that are what

White oxides or hydroxides

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10

What is the most common type of corrosion and is also can be the most effectively treated by maintenance personal is what

Electrochemical corrosion

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11

What type of corrosion commonly occurs at the edge of aircraft skin sections or next to countersunk fasteners

Exfoliation

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12

What type of corrosion happens with a flashlight battery

Galvanic

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13

What metal has the highest potential to corrode

Lithium

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14

The most common type of corrosion, resulting from direct chemical attack on a metal surface that proceeds uniformly over the entire exposed surface. May show up as general dulling, etching, rough, frosted.

Uniform surface corrosion

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15

This type of corrosion most often occurs on extruded sections of metal and is found primarily in aluminum sheet around steel fasteners.

Exfoliation

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16

This corrosion is characterized by grooves, gullies, waves, rounded holes and/or valleys in the metal surface.

Erosion

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17

What can cause stress corrosion

Welding, cold working, forming, and heat treatment operations

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18

Corrosion occurs at contact areas between materials under load subject to repeated vibration, has a general appearance of galling, in which chunks of metal are torn from the surface. Occurs commonly in landing gear component attachment areas or engine blade roots

Fretting

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19

Also called high temperature oxidation, absence of water can occur at high temperatures such as those found in turbine engine combusters, turbine sections, and afterburners

Hot Corrosion

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20

What type of corrosion attacks aluminum alloy

surface pitting, intergranular, exfoliation, stress, and fretting- white to gray powder

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21

What type of corrosion attacks magnesium alloy

Pitting- white powdery, snowlike mounds, and white spots on surface

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22

How does corrosion usually present

Chalky white powder or green discoloration

CGTO PG-85-00-310-A 7-91