ME Corrosion and Degradation

Question 1

In electrochemical corrosion, the metal that undergoes oxidation (loses electrons) is called the:

Accepted Answer

Anode

Answer

Cathode

Answer

Electrolyte

Answer

Reference electrode

Question 2

Galvanic corrosion occurs when two dissimilar metals are in electrical contact in an electrolyte. The more active (less noble) metal will:

Accepted Answer

Corrode preferentially as the anode

Answer

Be protected and act as the cathode

Answer

Remain unaffected

Answer

Form a protective oxide layer

Question 3

Passivation in metals like stainless steel involves the formation of:

Accepted Answer

A thin, adherent, self-healing chromium oxide film

Answer

A thick iron oxide scale

Answer

A zinc-rich primer coat

Answer

A galvanic protection layer

Question 4

Pitting corrosion is a particularly dangerous form of localized corrosion because:

Accepted Answer

It creates deep, narrow pits that are hard to detect and can initiate stress corrosion cracking

Answer

It removes material uniformly across the surface

Answer

It only occurs on austenitic alloys

Answer

It requires strongly acidic environments

Question 5

The corrosion protection mechanism of a zinc coating on steel (galvanizing) is primarily:

Accepted Answer

Cathodic (sacrificial) protection

Answer

Barrier protection only

Answer

Anodic protection

Answer

Passivation by a zinc oxide film

Question 6

Intergranular corrosion in sensitized austenitic stainless steel is caused by:

Accepted Answer

Chromium depletion at grain boundaries due to chromium carbide precipitation

Answer

Uniform dissolution of grain boundaries

Answer

Hydrogen embrittlement of grain boundaries

Answer

Pitting at grain boundary intersections