JNTU
JNTU B.Tech III ENVIRONMENTAL DEGRADATION OF MATERIALS Previous Question Paper (January/February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What is meant by fast corrosion?
Answer
Fast corrosion, often referred to as rapid or accelerated corrosion, occurs when a metal is exposed to highly aggressive environments, such as strong acids or high-temperature oxidizing atmospheres, leading to a quick and significant loss of material thickness or structural integrity.
What is Dry corrosion?
Answer
Dry corrosion, also known as chemical corrosion, is the direct attack of a metal by atmospheric gases (such as O₂, H₂S, SO₂, or Cl₂) in the absence of any liquid electrolyte. It typically occurs at high temperatures and results in the formation of a solid corrosion product layer on the metal surface.
Write an expression to find corrosion rate.
Answer
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What is passivation?
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Write two preventive measures to minimize fretting corrosion.
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Define galvanic corrosion.
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Elaborate corrosion inhibition.
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What is the role of anodic protectors?
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Define polymer.
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Write the important properties of composites.
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Part B
Define Corrosion. Explain the thermodynamic aspects of corrosion.
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Describe the various forms of environmental degradation with the help of suitable examples.
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Briefly explain about Pourbaix diagrams with the help of examples of equilibria.
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Explain the EMF series and its applications.
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Write about Nernst Equation and write its applications.
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Briefly explain various experimental methods to identify corrosion susceptibility.
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Write about Autocatalytic Nature of Pitting. Explain the concept using the help of neat sketch.
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How can Tafel’s extrapolation method assess the corrosion rate and describe the role of coatings and inhibitors for corrosion control?
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Explain DC and AC methods of testing.
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What causes polymer degradation and how to control it?
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Differentiate polymer and composite and explain three main categories of composite materials.
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