Material Science - Dec 2015

Mechanical Engg (Semester 3)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Solve any one question from Q1 and Q2

1 (a) Show that the atomic packing factor for BCC crystal is 0.68.(4 marks) 1 (b) Explain any two point defects with the help of diagram.(4 marks) 1 (c) A continuous and aligned glass fiber reinforced composite of 40 volume % of glass fibers having a modulus of elasticity of 69 Gpa and 60 volume % of a polyster resin that, when hardened, displays a modulus of 3.4 GPa. If the cross-sectional area is 250 mm² and a stress of 50 Mpa is applied in this longitudinal direction, compute the magnitude of the load carried by each of the fiber and matrix phases.(4 marks) 2 (a) Derive linear density expression of FCC [100] and [111] directions in terms of the atomic radius R.(4 marks) 2 (b) Explain the following processing methods of ceramics:
i) Cold isostatic pressing
ii) Slip casting.(6 marks) 2 (c) Explain work hardening on the basis of dislocations.(2 marks)

Solve any one question from Q3 and Q4

3 (a) A cylindrical specimen of steel having an original diameter 12.8 mm is tensile to fracture and found to have an engineering fracture strength of 460 Mpa if its cross-sectional diameter of fracture is 10.7 mm, determine:
i) Ductility in terms of percent reduction in area.
ii) True stress at fracture.(6 marks) 3 (b) What is fatigue? Draw S-N curve for Mild Steel and Aluminium and explain Endurance limit.(6 marks) 4 (a) Explain the methods of magnetization and demagnetization of component during magnetic particle inspection. Why the demagnetization is necessary after testing?(6 marks) 4 (b) Differentiate between dye penetrant inspection and fluorescent penetrant inspection.(4 marks) 4 (c) Explain Moh's hardness scale.(2 marks)

Solve any one question from Q5 and Q6

5 (a) Discuss about particle size, shape and size distribution and its effect on the properties of the final sintered compact.(6 marks) 5 (b) Using flow sheet explain manufacturing of cemented carbide tools by powder metallurgy.(7 marks) 6 (a) Discuss production of Iron powder by reduction process.(4 marks) 6 (b) What is compaction? List the defects of compact and their remedies.(5 marks) 6 (c) What is sintering? Explain the stages of sintering.(4 marks)

Solve any one question from Q7 and Q8

7 (a) Define nano-material and give application. Write a note on carbon nano-tubes.(6 marks) 7 (b) Give the classification of bio-material. Describe properties and application of Nickel alloy as bio-material.(7 marks) 8 (a) Explain the use of Ni base and Cobalt base alloy for high temperature application.(4 marks) 8 (b) Explain the properties of superconductors. Briefly explain any two applications of superconductors.(6 marks) 8 (c) Discuss the effect of Cryogenic heat treatment on steel alloy.(3 marks)