Corrosion Engineering Questions and Answers for Campus interviews on “Cathodic and Anodic Protection – 2”.
1. Which of the corrosion prevention method is used for reducing the maintenance cost of highway and bridges?
a) Sacrificial anode
b) Impressed current supply
c) Anodic protection
d) Use of inhibitors
Answer: b
Clarification: Impressed current supply is used as the corrosion prevention for reducing maintenance costs of big metallic structures such as highways and bridges. It also used to reduce the corrosion of reinforced steel.
2. Which of the following is depicted in the given figure?
a) Anodic protection
b) Impressed current supply
c) Stray current effect
d) Sacrificial anode
Answer: c
Clarification: The given figure depicts the stray current effect that usually caused to the dense pipelines in the vicinity of a tank or pipeline protected by the impressed current system.
3. Anodic protection is based on the formation of a protective film on metals by external applied anodic currents.
a) True
b) False
Answer: a
Clarification: Anodic protection is one of the corrosion prevention methods that is based on the formation of a protective film on metals by external applied anodic currents.
4. Which of the following metals can be protected using anodic protection?
a) Nickel and iron
b) Nickel, iron, and titanium
c) Titanium only
d) Nickel, iron, titanium, and magnesium
Answer: b
Clarification: Anodic protection can be used only for active-passive transition metals as it provides external current for the formation of a passive oxide layer. Active-passive transition metals include nickel, iron, aluminum, titanium, and its alloys.
5. A potentiostat is an electronic device that maintains a metal at a constant potential to a reference electrode.
a) True
b) False
Answer: a
Clarification: A potentiostat is an electronic device that maintains a metal at a constant potential to a reference electrode. It is required to protect a metal anodically by a passivating metal surface.
6. Which of the following corrosion prevention method is depicted in the given figure?
a) Sacrificial anode
b) Impressed current supply method
c) Use of inhibitors
d) Anodic protection
Answer: d
Clarification: Anodic protection of a storage tank is depicted in the given figure. A potentiostat is used to maintain the constant potential for a metallic structure against the reference electrode that results in passivity.
7. Which of the following auxiliary cathode is used for anodic protection?
a) Graphite
b) Platinized titanium
c) Platinum-clad electrode
d) Aluminum electrode
Answer: c
Clarification: It is necessary to have an inert auxiliary cathode such as a platinum-clad electrode as the anode provides external electric current to passivates the metallic structure.
8. Which of the following reference electrode is used in anodic protection?
a) Standard hydrogen electrode
b) Copper/copper sulfate reference electrode
c) Standard hydrogen electrode and calomel electrode
d) Calomel electrode
Answer: d
Clarification: The Calomel electrode is used to measure the potential maintained during the operation. It is connected to the third terminal of potentiostat whereas metal and auxiliary cathode are connected to first and second terminals respectively.
9. Which of the following is/are the advantages of anodic protection than cathodic protection?
a) Availability in extremely corrosive conditions
b) Low current requirement
c) Availability in extremely corrosive conditions and low current requirement
d) Very low installation cost
Answer: c
Clarification: Advantages of anodic protection than cathodic protection is:
i. Availability in extremely corrosive conditions
ii. Low current requirement.
10. Which of the following is/are the unique advantages of anodic protection?
a) To monitor instantaneous corrosion rate
b) Operating conditions can be established in the lab
c) It is applicable for all type of metals
d) To monitor instantaneous corrosion rate and operating conditions can be established in the lab
Answer: d
Clarification: Unique advantages of anodic protection are:
i. To monitor the instantaneous corrosion rate of a metal
ii. Operating condition of anodic protection can be precisely established in the lab.
Corrosion Engineering for Campus Interviews,