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WorksheetsMETALS CORROSION
Total questions: 15
Worksheet time: 8mins
What is the fundamental definition of 'metals corrosion'?
The degradation of a metal due to electrochemical reactions with its environment.
The strengthening of a metal by alloying it with other elements.
The simple dissolving of a metal in a strong acid, like sugar in water.
The process of melting and reshaping a metal.
In an electrochemical corrosion cell, what happens at the anode?
The metal gains electrons (reduction).
A protective, passive layer is formed.
The surrounding environment (e.g., oxygen) is consumed.
The metal loses electrons (oxidation) and dissolves.
Which of the following is NOT one of the four essential components of an electrochemical corrosion cell?
Anode
Cathode
Electrolyte (e.g., water)
A passive film
What is 'passivity' in the context of corrosion?
When a metal is non-reactive because it is noble, like gold.
A form of corrosion where the metal becomes chemically 'passive' or inert.
The formation of a thin, protective oxide film that stops further corrosion.
The process of coating a metal with paint to make it passive.
Which form of corrosion is characterized by a relatively even loss of metal over the entire exposed surface?
Pitting corrosion
Galvanic corrosion
Uniform corrosion
Crevice corrosion
Galvanic corrosion occurs when:
A metal corrodes preferentially along its grain boundaries.
A metal is exposed to high levels of stress in a corrosive liquid.
A small, stagnant pool of liquid causes localized attack.
Two different metals are in electrical contact in the presence of an electrolyte.
Which form of corrosion is a localized attack in a small, confined space (like under a bolt head or gasket) due to a stagnant solution?
Intergranular corrosion
Pitting corrosion
Crevice corrosion
Uniform corrosion
Why is 'pitting corrosion' considered particularly dangerous?
It affects the entire surface, causing a large loss of metal.
It can cause structural failure from deep, localized holes with minimal visible surface damage.
It is a form of corrosion that is bright blue, making it highly visible.
It only occurs in very expensive, noble metals.
Intergranular corrosion is a selective attack that occurs:
Along the grain boundaries of the metal's microstructure.
On the surface of the grains, eating them away evenly.
In a straight line, following mechanical scratches on the surface.
Only when two different grains of metal touch.
Stress Corrosion Cracking (SCC) requires the simultaneous presence of which two factors?
A small crevice and a stagnant solution.
High temperatures and a pure oxygen atmosphere.
A tensile (pulling) stress and a specific corrosive environment.
Two dissimilar metals and an electrolyte.
What is the primary mechanism of corrosion 'inhibitors'?
They reverse the electrochemical cell, making the metal the cathode.
They remove the electrolyte by drying out the metal surface.
They are chemicals added to the environment that slow the anodic or cathodic reactions.
They add a thick, physical layer of rubber or plastic to the metal.
How do most protective coatings, like paint or powder coating, prevent corrosion?
By making the metal super-heated so moisture evaporates.
By acting as a physical barrier to separate the metal from the electrolyte (e.g., moisture and oxygen).
By attracting a passive layer from the atmosphere.
By chemically neutralizing the metal surface.
Which of the following is an example of a 'design change' to prevent corrosion?
Using an inhibitor in the fluid that will flow through a pipe.
Painting the metal after it has been assembled.
Attaching a block of zinc to a steel boat hull.
Designing a tank with a sloped bottom and drain hole to prevent stagnant water.
What is the main principle of 'cathodic protection'?
Applying a 'cathodic paint' that is resistant to electricity.
Forcing the metal to be protected to act as the cathode in the corrosion cell.
Using a strong acid to clean the cathode surface.
Removing the cathode from the environment so the cell stops.
A steel pipeline is buried underground. To protect it, blocks of zinc are buried alongside it and connected with a wire. This is an example of:
A passive coating
Sacrificial anode (a form of cathodic protection)
Crevice corrosion
An inhibitor
