Biju Patnaik University of Technology 2008-4th Sem B.Tech (B Tech) , material science (chemical) . - Question Paper

BPUT(B Tech) , fourth semester material science (chemical) ques. paper.

Total number of printed pages -6 B. Tech

BSCC 2202

Fourth Semester Examination - 2008 MATERIAL SCIENCE (Chemical)

Full Marks-70

Total number of printed pages -6 B. Tech

BSCC 2202

Time : 3 Hours    j

Answer Question No. 1 which is compulsory and any five from the rest.

The figures in the right-hand margin indicate marks.

1. Answer the following in brief and to the point.

2x10

(a) What do you mean by weighted index in material selection methods ?

(b)    Calculate the critical current density at Ok for a wire of lead which has a circular cross section of radius 5mm. The critical magnetic field for Pb at OK is 803 *10^_4T.

(c)    What is the value of Lorentz number in SI system according to quantum theory of free electrons in metals ?

(d)    Distinguish between dielectric strength and dielectric constant.

(e)    What are the different processes that may occur when visible radiation is incident on a material ?

(f)    What is the difference between thermosetting and thermoplastic polymers ?

(g)    Why does thermal spalling occur in ceramics during service ?

(h)    What are ceramics ?

(i) Why is stainless steel corrosion resistance ?

(j) Why are aluminum alloys used for construction of aircrafts but not steel ?

2.    (a) Calculate the density of energy states per

unit volume with energies between OeV to 1,5eV.    3

(b)    Explain with necessary theory how you can design a device to measure power in a plane polarized electromagnetic wave by using the concepts of Hall effect. 4

(c)    Distinguish between ferromagnetic, ferri-magnetic and antiferromagnetic materials.

3

3.    (a) Write the mechanism of polymerization

of styrene using potassium amide as initiator. What is Ziegler-Natta catalyst ? Mention its importance in polymerization.

4+1+1

(b) Discuss injection moulding for fabrication of plastics. Mention two important uses of butyl rubber.    4

4.    (a) Calculate the saturation magnetization for

nickel which has a density of 8.90 cm^-3. Given Bohr magneton = 9.27x1 Qr^2AA.m² and Avogadros number = 6.023 xio²³ atoms / mole.    3

(b)    The band gap energies of silicon and germanium are 1.11eV and 0.67ev respectively. Over what range of wavelengths of electromagnetic spectrum they are opaque ?    4

(c)    Explain why magnesium is a conductor even though the outer most valence shell of Mg is completely filled.    3

5.    (a) Explain briefly pitting corrosion and stress

corrosion.    2+3

(b) How is corrosion prevented by cathodic protection ? Explain how rusting of iron is prevented by galvanization.    2+3

6.    (a) Briefly explain the BCS theory of super

conductivity.    4

(b)    Ammonium chloride gas has dielectric constant 1.0083 at 0C and dielectric constant 1.0049 at 100C. The concentration of Ammonium chloride molecule at

0 C is 2.7x1 o25 rrr3. Calculate the permanent dipole moment of ammonium chloride.    4

(c)    What are the advantages of photonic communication over electronic communication ?    2

7.    (a) What are different classes ofcomposites ?

What is Whisker ?    3+2

(b) Discuss about R.C.C. with regard to composition, strength and its protection. 5

8. (a) What are different types of composites ? What are the factors that control the strength of ceramics ?    3+2

(b) Mention the composition of clay. What are fire clay and china clay ? Give important applications of ceramics.

1+2+2

BSCC 2202    6    -C

Attachment: biju-patnaik-university-of-technology-2008-b-tech-36036-1.pdf

Earning:   Approval pending.