Corrosion Engineering written test Questions & Answers on “Environments – Liquid Metals and Fused Salts”.
1.The liquid-metal corrosion is usually a physical effect rather than an electrochemical attack.
a) True
b) False
Answer: a
Clarification: Liquid metal corrosion is usually a physical effect rather than an electrochemical attack. Electrochemical attack includes reduction and oxidation of hydrogen ions and metallic atoms respectively.
2. Which of the following is/are the types of liquid-metal corrosion?
a) Solution of structural metal
b) Diffusion of liquid into solid metal
c) Intermetallic compound formation
d) Solution of structural metal, diffusion of liquid into solid metal and intermetallic compound formation
Answer: d
Clarification: Types of liquid-metal corrosion are:
i. Solution of structural metal
ii. Diffusion of liquid into solid metal
iii. Intermetallic compound formation
iv. Mass transfer.
3. Which of the following is/are undesirable in heat-exchange systems handling liquid metals?
a) Deposition of impurities in cool areas
b) Resistance to heat transfer
c) Formation of brittle intermetallic compounds, resistance to heat transfer and deposition of impurities in cool areas
d) Formation of brittle intermetallic compounds
Answer: c
Clarification: Conditions that are undesirable in heat-exchange systems handling liquid metals:
i. Deposition of impurities in cool areas
ii. Resistance to heat transfer
iii. Formation of brittle intermetallic compounds.
4. Which of the following parameter has a direct relation with the corrosion rate in liquid metals?
a) Percentage of alloying elements
b) Solubility of the metallic structure in liquid metal
c) Solubility of alloying elements in metallic matrix
d) Percentage of oxygen
Answer: b
Clarification: Solubility of alloying elements in metallic matrix has direct relation with corrosion rate in liquid metals. Whereas liquid-metal corrosion is a physical effect rather than a chemical effect.
5. Which of the following parameter is taken as Xin the given graph regarding corrosion of various metals in liquid-metal corrosion?
a) Atomic weight
b) Weight loss
c) Solubility percentage
d) Atomic number
Answer: c
Clarification: The given graph shows the direct relation of corrosion rate with solubility of metallic structures in liquid mercury for various metals. And solubility of the metallic component in liquid mercury is taken as x.
6. Which of the following materials shows good resistance to both liquid-metals and high-temperature oxidation?
a) High alloy stainless steels
b) Monel
c) Hastelloy
d) Hastelloy, high alloy stainless steels and monel
Answer: d
Clarification: Materials that show good resistance to both liquid-metals and high-temperature oxidation are 18Cr-8Ni stainless steel, high alloy stainless steel, monel, and Hastelloy.
7. Which of the following type of stainless steels are attacked by magnesium at its melting point?
a) Duplex stainless steels
b) Austenitic stainless steels
c) Martensitic stainless steels
d) Ferritic stainless steels
Answer: b
Clarification: Austenitic stainless steels are the types of stainless steels that are attacked by magnesium at its melting. Liquid magnesium preferentially leaches out nickel from this alloy from the iron matrix.
8. The presence of traces of titanium and magnesium in mercury can inhibit the corrosion of iron in ferrous-based alloys.
a) True
b) False