Galvanic Corrosion in Metals Electrochemical Series Quiz

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What type of corrosion can occur when dissimilar metal skins are riveted together?

Surface corrosion

Galvanic corrosion (correct)

Stress corrosion

Intergranular corrosion

Where can galvanic corrosion take place?

Where metal is exposed to battery fumes

Where dissimilar metal skins are riveted together (correct)

Where cracks form along the sides of a structure

Where stress is applied to a structure

How does stress corrosion differ from intergranular corrosion?

Stress corrosion causes rapid crack growth at the end of a crack (correct)

Intergranular corrosion dulls the surface of the structure

Stress corrosion attacks the sides of a crack uniformly

Intergranular corrosion is caused by battery fumes

What causes the dulling of the surface in surface corrosion?

Conversion of microscopic metal into corrosion salts Signup and view all the answers

In which type of corrosion will there be a rather uniform attack over the entire surface area?

Surface corrosion Signup and view all the answers

What happens if the deposits from surface corrosion are not removed and the surface remains unprotected?

Corrosion pits will form Signup and view all the answers

What is the main purpose of using cadmium as a coating on steel hardware?

To improve resistance to corrosion fatigue Signup and view all the answers

How can you identify corrosion on a cadmium-plated surface?

By observing white-to-brown-to-black mottling of the surface Signup and view all the answers

Why is chromium used as a protective plating on parts?

To protect against wear and reclaim worn parts Signup and view all the answers

In what way does cadmium protect steel when they are coupled together?

By forming a continuous oxide coating Signup and view all the answers

What could be a consequence if a chromium-plated part shows cracks in the coating?

Origination of corrosion at the base metal below the separations Signup and view all the answers

Which material is anodic when coupled with steel, providing protection through galvanic action?

Cadmium Signup and view all the answers

What is the reason behind the dull grey-green discoloration seen on copper or copper alloy surfaces?

Formation of a fine-grained, airtight copper oxide crust Signup and view all the answers

In what applications does silver tarnish, producing a brown-to-black film of silver sulphide?

Waveguides, miniature circuits, and RF shielding Signup and view all the answers

Which metal is traditionally regarded as the best coating for corrosion resistance and solderability?

Gold Signup and view all the answers

What accelerates the corrosion of copper when silver is plated over it?

Galvanic action at pinholes in silver plating Signup and view all the answers

What happens when silver is plated over copper in the presence of pinholes or breaks in the plating?

Accelerated corrosion of copper Signup and view all the answers

What is the cause of the tarnish seen on silver surfaces in the presence of sulphur?

Tarnishing by silver sulphide Signup and view all the answers

What is the primary reason for scum formation along the edge of a seal in an integral fuel tank?

To cause a leak Signup and view all the answers

Why are aluminium and its alloys widely used in aircraft construction?

Because they are highly anodic and can resist mild corrosive conditions Signup and view all the answers

What is a common issue faced by aluminium alloys when exposed to certain conditions?

Pitting, intergranular corrosion, and stress corrosion cracking Signup and view all the answers

Why does galvanic corrosion occur when aluminium comes into contact with other metals?

Because aluminium is highly anodic to most other metals Signup and view all the answers

What is the role of the oxide film formed on aluminium under mild corrosive conditions?

To offer increased resistance to corrosion Signup and view all the answers

In what way does fungus growth in a fuel tank relate to the corrosion characteristics of aircraft metals?

Fungus growth can impact the sealant of the tank leading to leaks Signup and view all the answers

Why is tarnish removal critical on gold components?

To avoid darkening of reflecting surfaces Signup and view all the answers

What effect does gold plating over silver or copper have on the less noble metals?

Promotes corrosion by accelerating it Signup and view all the answers

What is the 'purple plague' mentioned in the text?

A brittle compound formed when bonding gold to aluminium Signup and view all the answers

Why is tin commonly used in solder applications?

Due to its solderability and corrosion resistance Signup and view all the answers

What issue arises from the growth of 'whiskers' on tin-plated wire?

Potential short-circuits or electrical failures Signup and view all the answers

What is the main advantage of tin plating on avionic RF shields and filters?

Enhanced corrosion resistance Signup and view all the answers