Corrosion

Question 1

What component of the cell corrodes

Answer 1

The anode

Question 2

What are the 2 classifications of corrosion

Answer 2

Chemical and electrochemical

Question 3

What is electrochemical corrosion

Answer 3

Flow of electrons, needs water to be present

Question 4

What is aluminum more vulnerable to. Alkaline or acids

Answer 4

Alkaline

Question 5

What are salts

Answer 5

Metalic element combining with non-metal

Question 6

How does mercury affect aluminum

Answer 6

Mercury attacks aluminum by a chemical reaction known as amalgamation

Mercury attacks the grain boundary within the alloy and in a very short time period

Question 7

What is uniform etch

Answer 7

Area of unprotected metal is exposed to an atmosphere containing battery fumes, exhaust games, or industrial contaminants, a uniform attack over the entire surface

Question 8

How is uniform etch caused and identified

Answer 8

Caused by the reaction of metallic surfaces with atmospheric contaminants.

Determined by comparing the thickness of the corroded metal with undamaged metal

Question 9

What is pitting

Answer 9

Uniform surface corrosion left unattended.

Detected by the appearance of clumps of white powder on the surface.

All pits pentrate deep into the metal and cause damage out of proportion to amount of metal consumed

Question 10

What is intergranular

Answer 10

Corrosion attack along the grain boundaries of a material

Question 11

How is intergranular corrosion caused

Answer 11

Delay in quenching during heat treating process

Question 12

What is exfoliation

Answer 12

An extreme case of intergranular corrosion.

By the time it is evident of the surface, the metal has been damaged beyond salvage

Question 13

What is filaform corrosion

Answer 13

Filiform corrosion is a type of corrosion that looks like little worms or filaments spreading under the coating on a metal. It can only occur when there is a layer or coating (usually paint) over the top of the metal.

Question 14

What is galvanic corrosion

Answer 14

2 dissimilar metals in contact with each other with an electrolyte present

Question 15

What is fretting

Answer 15

When 2 surfaces are tightly fit together but can move relative to one another

This type of corrosion is abrasive wear caused by the 2 surfaces rubbing against each other

Fatigue failures often result from fretting at structural bolted joints

Question 16

What is stress corrosion

Answer 16

Occurs when metal is subjected to tensile stress in the presence of a corrosive environment

This can come from improper quenching or from interference fit of a fastener

Common locations are between rivets of stressed skin, around pressed in bushings and tapered pipe fittings

Question 17

What rule mandates the inspection of all aircraft

Answer 17

Part 43, general maintenance rules