Anna University Chennai 2005 B.E Chemical Engineering PH232 – MATERIAL SCIENCE - Question Paper

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2005.

Third Semester

Chemical Engineering

PH232 – MATERIAL SCIENCE

(Common to Leather and Textile Technology)

Time: 3 hours Maximum : 100 MARKS

ans ALL ques.

PART A – [10 X two = 20 MARKS]

1. At atmospheric pressure a material of unknown composition indicates 4 phase in equilibrium at
927K. What is the minimum number of components in the system?

2. Why is the phase diagram for Fe-Fe3C a metastable diagram?


3. What is fracture toughness?

4. Why are cold-worked materials avoided for high temperature applications?

5. Distinguish ranging from kind I and kind II superconductors.

6. A conducting wire has a resistivity of 2.0 X 10-8 O-m. An electric field of 150V/m is applied
parallel to the wire. If the density of conduction electrons is six X 1028, compute the drift velocity.

7. Define dielectric constant and electric polarization.

8. Write any 2 applications of ferroelectric materials.

9. Why is the electronic and lattice specific heat value of a conductor different?

10. How is step index fibre various from graded index fibre?


PART B – [5 X 16 = 80 MARKS]

11. (i) State and discuss Gibbs phase rule. How is it used for studying the phase relationship for 2
components system? [8 MARKS]

(ii) explain the transformation of austenite when cooled at different cooling rates based on TTT
diagram. [8 MARKS]


12. (a) (i) define Griffiths crack model for purely brittle materials. [8 MARKS]

(ii) Draw the creep curve and discuss different stages of creep. [8 MARKS]

[OR]

(b) (i) discuss viscoelastic properties of rubber. [8 MARKS]

(ii) discuss in detail the ductile-brittle transition. [8 MARKS]

13. (a) (i) discuss the domain theory of ferromagnetic materials. [8 MARKS]

(ii) explain the fabrication, properties and uses of metallic glasses. [8 MARKS]

[OR]

(b) (i) Derive an expression relating electrical conductivity and relaxation time. [8 MARKS]

(ii) define the properties and uses of soft and hard magnetic materials. [8 MARKS]

14. (a) (i) define various kinds of electric breakdown. [8 MARKS]

(ii) State the legal regulations of mass action for semiconductor and find an expression for it. [8 MARKS]

[OR]

(b) (i) Derive an expression for the Hall coefficient and discuss an experiment to determine the
identical. [8 MARKS]

(ii) explain in detail the various kinds of polarization mechanism in dielectric materials.
[8 MARKS]

15. (a) (i) Derive Einstein's formula for the lattice specific heat of a solid and explain its variation with
temperature. [8 MARKS]

(ii) discuss the principle and working of an nematic LCD. [8 MARKS]

[OR]

(b) (i) discuss how light is propagated through optical fibres. [8 MARKS]

(ii) How is compound semiconductor various from elemental semiconductor? elaborate its uses?
discuss the working of a LED. [8 MARKS]

Earning:   Approval pending.