JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II METALLURGICAL THERMODYNAMICS Previous Question Paper (April - 2018 - R15)
Note: This question paper contains two parts A and B. 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
Give any two applications of Fick’s laws?
Answer
Two primary applications of Fick’s laws are the calculation of diffusion rates during homogenization of alloys and the determination of carburization or decarburization depths in surface hardening processes.
Define and explain Kirkendal effect?
Answer
The Kirkendall effect is the observation that in a diffusion couple of two different metals, the interface between them shifts over time. This occurs because the two species diffuse at different rates (intrinsic diffusivities), leading to a net flux of vacancies toward the faster-diffusing species, which results in the formation of pores on the side of the faster-diffusing metal.
Define intrinsic diffusivity?
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Give the limitations of Ellingham diagrams?
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Define partial molal property?
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Give the applications of Sievert’s law?
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Give the applications of phase diagrams?
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Explain the determination of liquidus line for eutectic system?
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Define oxidation potential and reduction potential?
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What is electro chemical cell? Give an example.
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Part B
In Alcad, 20mm thick duralumin sheets are covered on either side with 0.2mm thick pure aluminum sheets. For retaining the corrosion resistance, the copper concentration at a depth of 0.1mm from the outer surface should not exceed 0.4%. How long can the material be kept at 550°C, without damaging the corrosion resistance? Given that D0 = 0.25 × 10⁻⁴ m² S⁻¹.
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Briefly describe self-diffusion in pure metals.
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Derive Boltzman-Matano equation for the determination of interdiffusion coefficient.
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Explain the mechanism of grain boundary diffusion.
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Explain the uses of oxygen nomographic scale in Richardsons diagrams?
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Calculate the equilibrium constant for the reaction ZrO₂ = Zr + O₂ ΔG⁰ = 259,940 + 4.33 T logT – 59.12 T Cal at 1727°C.
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Explain the usefulness of Ellingham diagrams in metal extraction.
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Calculate the equilibrium constant for the reaction at 750°C from the following data. <NiO> + (H₂) = <Ni> + (H₂O) Given data: <Ni> + ½(O₂) = <NiO>; ΔG⁰ = -58450 + 23.55 T Cal; (H₂) + ½(O₂) = (H₂O); ΔG⁰ = -58900 + 13.1 T Cal
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Derive Gibbs-Duhem equation and give its importance.
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Differentiate between ideal and non-ideal solutions.
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Define and explain Roult’s law? Give its applications.
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What is Excess thermodynamic property? Explain its determination.
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Explain the determination of solidus and liquidus lines for an ideal solution.
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Explain the importance of phase diagrams in metal extraction.
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What is equality of chemical potentials in equilibrated phases? Explain.
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The phase diagrams are useful in metal extraction and heat-treatment. Justify?
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Define electrode potential and derive an equation to determine the electrode potential of a cell.
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Explain the working principle of Galvanic cell.
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What is Gibbs-Helmholtz equation? Give its applications to Galvanic cells.
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Differentiate between Galvanic cells and concentration cells.
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