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Friday, 26 June 2015

Material science and engineering-Model question paper for B.E/B.Tech Engineering

1(a) How are materials classified? (4 Marks)
(b) Give the construction and working of Bragg’s X-ray spectrometer. (8 Marks)
(c) Discuss briefly the general usefulness of the periodic table in reference to atomic structure. (4 Marks)
(d) The workfunction of sodium is 2.3 eV. Calculate the threshold frequency and its corresponding wavelength. (4 Marks)
2(a) Give the composition, properties and uses of the following alloying steels: High speed steel, Silicon steel, Stainless steel and Tungsten steel. (8 Marks)
(b) Name the important mechanical tests which give valuable information about metals and alloys. (4 Marks)
(c) State ‘Gibb’s phase rule’. What is its importance? (4 Marks)
(d) The crack length of a sample of certain material is 4.4 μm, and the Young’s modulus of the material is 60 GN/m2. The surface energy is 1.32 J/m2. Calculate the fracture strength and compare it with the Young’s modulus. (4 Marks)
3(a) Explain the basic mechanism involved in solid solution hardening and give examples of alloys strengthened by this process. (6 Marks)
(b) What is a retained austenite? Why is it not desirable? How can it be eliminated? (4 Marks)
(c) Enumerate various types of Portland cement. (5 Marks)
(d) Determine the temperature co-efficient of resistance of material used in a resistor if the resistance at 250C is 50 Ω and at 700C is 57.2 Ω. (5 Marks)
4(a) Describe the domain theory of magnetic materials. Explain also the experimental verification for the existence of domains in magnetic materials. (8 Marks)
(b) Discuss briefly about the characteristics of permalloys and soft magnetic ferrites. What is meant by cyclic magnetization and spontaneous magnetization? (8 Marks)
(c) In a certain transformer, the hysteresis loss is 0.9 Wb/m2 and the frequency 50 Hz. What would be the hysteresis loss if the maximum flux density were increased to 1.1 Wb/m2 and the frequency reduced to 40 Hz. Assume the hysteresis loss over this range  to be proportional to B1.7max . (4 Marks)
5(a) What do you understand by polymerization? What is the difference between addition-polymerisation and condensation-polymerisation? (6 Marks)
(b) What is the degree of polymerization of a polymer molecule? Give three examples of linear polymers. (5 Marks)
(c) What is a hybrid composite? Give important advantages of hybrid composites over normal fiber composites. (5 Marks)
(d) An applied strain of 0.4 produces an immediate stress of 10 MPa in a piece of rubber. Calculate the relaxation time for this process. What will be the stress after 90 days? (4 marks)
6(a) What is water-cement ratio? How does it affect the strength of concrete? (4 Marks)
(b) Explain the significance of testing the initial and final setting time of cement and how is it done? What is the effect of addition of gypsum on setting time? (6 Marks)
(c) What are the functions of springs? On which factors does the choice of material for springs depend? List various materials which are employed for producing springs. (7 Marks)
(d) The fineness modulus of coarse and fine aggregates are 6.0 and 3.0 respectively. If the mixture has a fineness modulus of 5.0, find the percentage of fine aggregate to be mixed with coarse aggregate. (3 Marks)
7(a) Explain the terms ‘thermal shock’ and ‘thermal shock resistance’. (4 Marks)
(b) What are the different types of coatings applied to prevent corrosion? Compare their advantages and disadvantages. (6 Marks)
(c) Explain the zone theory of solids. Discuss characteristics of conductors, semiconductors and insulating materials. (6 Marks)
(d) Calculate the diffusion coefficient for magnesium in aluminium at 5700C, given that D0 and Q are 1.2 × 104 m2/s and 131 kJ/mole respectively. (4 Marks)
8(a) State briefly the process of making a powder metallurgy product having improved properties. Discuss the advantages of powder metallurgy. (8 Marks)
(b) What effect will preheating have on the microstructure of the weld area in high carbon steel? (4 Marks)
(c) Explain with neat sketches thermit welding and metallic arc welding. (8 Marks)

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