Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech IV ELECTROMETALLURGY AND CORROSION Previous Question Paper (May/June - 2019 - R15)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART- A
Define specific conductance and mention its unit.
Answer
Specific conductance (or conductivity) is the reciprocal of specific resistance (resistivity) of a material, representing its ability to conduct electric current. Its SI unit is Siemens per meter (S/m) or ohm⁻¹m⁻¹.
What is electrochemical cell?
Answer
An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. It consists of two electrodes (anode and cathode) immersed in an electrolyte, where oxidation occurs at the anode and reduction at the cathode.
What is Concentration Cell?
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Write the Nernst equation.
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Bolt and nut made of the same metal is preferred in practice. Why?
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What are the effects of pitting corrosion?
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What is the role of relative areas of anodic and cathodic parts in preventing the corrosion?
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Write down two pretreatments of surface for coating.
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What is High Temperature Corrosion?
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Explain the effect of oxidative environment to the rate of corrosion.
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PART-B
Give the basic principle of corrosion with the help of electrochemical corrosion.
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Describe the electroplating of Zn.
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Explain any two testing methods of electro deposits.
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Explain the Faraday’s law of electromagnetic induction.
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What is Polarization resistance? Explain with suitable examples.
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Explain the characteristics of Tafel and Nyquist Plots.
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Explain how the Pourbauix diagram is helpful to decide the corrosion characteristics of metals.
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What are Thermodynamic aspects of corrosion? Explain it with respect to electrochemical cell.
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What is galvanic corrosion? Explain beneficial applications of galvanic corrosion.
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Explain the terms: i) Effect of pH on rate of corrosion ii) Season’s cracking
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Explain the Erosion corrosion and its effects on metals.
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What is fretting corrosion? Explain with suitable examples.
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Write short note on: i) Types of electroplating ii) Role of pH in prevention of corrosion
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Write the functions and properties of anodic and cathodic inhibitors.
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Discuss the use of protective coatings such as organic and inorganic coatings.
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“Galvanizing is preferred over tinning”. Explain with justification.
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Explain the effect of oxidizers on the basis of modern theory.
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Discuss the high temperature oxidation with some practical examples.
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Explain the effects of velocity on active-passive metal and its significance.
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Give significance of Pilling Bed-worth ratio to the rate of corrosion.
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