Cleaning And Corrosion

Question 1

When does corrosion happen

Answer 1

Corrosion happens when metals are exposed to water and air

Question 2

Why is aircraft cleaning important ?

Answer 2

Making sure the aircraft is clean is important because DIRT can cover up damaged components as well as trap moisture and solvents that lead to corrrosion

Question 3

What is hydrogen embrittlement?

Answer 3

When you use the nonapproved chemicals and cleaning compound, hydrogen embrittlement can occur , a chemical reaction occurs and hydrogen gas is absorbed into the metal, this reduces a metals ductility and allows the formation of cracks and stress correction

Question 4

What is used to remove oil , grease, or soft preservative compounds ?

Answer 4

Naphtha is used to remove oil , grease , and soft preservatives

Question 5

What are the two most common types of naphtha ?

Answer 5

The two most common are aliphatic and aromatic

Question 6

What is aliphatic naphtha ?

Answer 6

It’s a hydrocarbon solvent that dissolves grease and oil but does not harm rubber or acrylic components

Question 7

What is aromatic naphtha ?

Answer 7

Aromatic attacks rubber and acrylic, frequently used to wipe down cleaned surfaces before painting

Question 8

What are corrosive agents

Answer 8

Corrosive agents are substances that cause corrosion. Example water , salt and oxygen

Question 9

Types of corrosion looks explain

Answer 9

Aluminum and magnesium corrosion is grey or white powdery deposit

Copper and copper alloy is green

Steel is reddish brown

Question 10

Anodic reaction

Answer 10

Where the metal loses electrons and corrodes

Question 11

Cathodic reaction

Answer 11

Where electrons are gained

Question 12

Electrochemical series

Answer 12

A chart showing which metals give up electrons easier ( corrodes easier )

Question 13

Explain oxidation

Answer 13

Oxidation is known as dry corrosion and it happens when a metal is exposed to a gas containing oxygen

Question 14

Explain uniform surface corrosion

Answer 14

An unprotected metal is exposed to an atmosphere containing battery fumes , exhaust gases , or industrial contaminants

Question 15

Explain pitting corrosion

Answer 15

Pitting is a result of uniform surface corrosion left untreated, it looks like powdery salt on the surface

Question 16

Explain galvanic corrosion

Answer 16

When two not the same metals come in contact in the presence of an electrolyte. For example aluminum plates with steel screws.

Question 17

Explain concentration cell corrosion

Answer 17

The deterioration of parts of a metal surface at different rates

Question 18

When does oxygen concentration cell corrosion occur

Answer 18

When water covers the surface of an aluminum aircraft skin and seeps into the cracks

Question 19

Metallic ion concentration forms

Answer 19

In the closed areas between the faying surfaces

Question 20

Active passive cells happen on

Answer 20

Metals that use a passive film for corrosion protection

Question 21

Explain filiform corrosion

Answer 21

Occurs on an organic coating system , usually occurs when the wash primer has not been properly cured

Question 22

Intergranular corrosion

Answer 22

An attack along the grain boundaries

Question 23

Exfoliation corrosion

Answer 23

An extreme case of intergranular corrosion

Question 24

Stress corrosion

Answer 24

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

Question 25

Fretting corrosion

Answer 25

Occurs around rivets in a skin and is indicated by dark deposits around the rivet heads. (Rivet smoking )

Question 26

Types of corrosive agents

Answer 26

Salts, water , mercury , air

Question 27

What are the two types of ultrasonic indications or corrosion detection ?

Answer 27

The pulse echo and the resonance method

Question 28

What are some corrosion prone areas

Answer 28

Engine exhaust , battery compartments , food service areas , landing gear , fuel tanks , control cables

Question 29

Process of corrosion treatment

Answer 29

Remove as much corrosion as possible , neutralize any residual material, and restore the protective surface film

Question 30

What can be used as a protective coating for aluminum

Answer 30

Paint , cladding , and surface oxide film

Question 31

What do Primers like epoxy do

Answer 31

Used under paint to inhibit the formation of corrosion on aluminum aircraft

Question 32

How to remove corrosion from ferrous metals

Answer 32

Abrasive blasting

Question 33

Ferrous metals can be pretreated to protect them from corrosion

Answer 33

Using methods like nickel , chrome plating, cadmium plating , applying primers like zinc chromate