Question Paper: Material Science Question Paper - Dec 17 - Mechanical Engineering (Semester 3) - Pune University (PU)
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Material Science - Dec 17

Mechanical Engineering (Semester 3)

Total marks: 80
Total time: 3 Hours
INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

1.a.
Calculate no. of atoms per Unit cell for BCC and FCC metal with proper formula.
(6 marks) 00

1.b. If a metal is forged what difference will be seen in its the following properties and explain why?

i)Surface finish

ii) Dislocation density

ii)Internal stresses

(6 marks) 00

OR

2.a. What is polymer and what are the polymeric arrangements in polymer? Which properties of ceramics makes them different than metal?
(4 marks) 00

2.b. Show the following planes on a cubic structures :

i) (111)

ii) (010)

(4 marks) 00

2.c. Explain work hardening with respect to dislocation theory in detail.
(4 marks) 00

3.a. Suggest the suitable hardness tester for the following applications (any three) and justify your answers.

i) Gray cast iron casting

ii)Hardened steel component.

iii) Porous powder metallurgical parts.

iv) Hardness of Cr which is plated

(8 marks) 00

3.b. If two metals should be joined together in assembly which joining method should be preferred to increase its corrosion resistance and explain why?
(5 marks) 00

OR

4.a. Suggest different techniques used to increase corrosion resistance of metals.
(7 marks) 00

4.b. Draw the self explanatory diagram for the following (any two) :

i) Stress-strain diagram for 0.4% carbon steel

ii) IZods test specimen

iii) X-ray tube used in X-ray radiography.

iv) Through transmission Ultrasonic test.

(6 marks) 00

5.a. In which surface improvement process it changes its chemical composition in surface? Explain the process in detail.
(6 marks) 00

5.b. Draw the self explanatory diagram for the following :

i) Electroplating

II) Powder coating

(6 marks) 00

OR

6 Suggest the suitable surface coating process for the following applications (and four) and give proper justification for the selection.

i) Cr is to coated on handles of door.

ii) Slides in park

iiI) Semiconductor

iv) Exterior roofs

v) Coating of Titanium nitride on carbide tool.\

vi) Corrosion protection of aircraft structural steel parts.

(12 marks) 00

7.a. Why is it necessary to control furnace atmosphere in sintering?
(4 marks) 00

7.b. Explain physical method for manufacturing of powders.
(5 marks) 00

7.c. Write down the common flow chart used in powder metallurgy.
(4 marks) 00

OR

8.a. Define the following:

i) Compatibility

ii) Flowability

(4 marks) 00

8.b. Is liquid phase and solid phase sintering is same?
(3 marks) 00

8.c. List important disadvantages and applications of powder metallurgy over other processes.
(6 marks) 00

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