Rr220805-material-science-for-chemical-engineering

Set No. 1

Code No: RR220805

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 MATERIAL SCIENCE FOR CHEMICAL ENGINEERING (Chemical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Sketch the five, two dimensional (plane) lattices. (b) Explain why each is a distinct distribution of points in two dimension. (c) Why is “entered square” not a separate plane lattice. 2. Write about closed packed structures.

[10+3+3] [16]

3. State the difference between high angle and low angle boundary and their relative effects on materials. [16] 4. Discuss : (a) How solute atoms affect dislocation motion? (b) How precipitate particles affect dislocation motion?

[8+8]

5. (a) What is the difference between slip in single crystals and slip in polycrystalline metals? (b) Explain with neat sketches the mechanism for dislocation in plastic deformation. [6+10] 6. What is understood by viscoelastic deformation? State the mechanical models to demonstrate viscoelastic behavior of materials? Name the materials which exhibit viscoelastic behavior? [16] 7. What is fracture? State the causes of fracture in a material?

[16]

8. Calculate the present ferrite, carbide, and pearlite, at room temperature, in iron carbon alloy contains (a) 0.5% carbon (b) 0.8% carbon and (c) 1.5% carbon.

[16] ⋆⋆⋆⋆⋆

1 of 1

Set No. 2

Code No: RR220805

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 MATERIAL SCIENCE FOR CHEMICAL ENGINEERING (Chemical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Draw a two dimensational pentagonal lattice. (b) Draw a Fcc lattice unit cell. Connect the face centered lattice points (at opposite ends of a cube body diagonal) and show that the result is a primitive cell. [6+10] 2. The Brag angle corresponding to reflection for which (h2 +k 2 +l2 )=8 is found be 14.350 . Determine the lattice parameter of the crystal. X-rays of wave length 0.71A0 are used. If there are two other reflections with smaller Brag angles, what is the crystal structure? [16] 3. State the difference between high angle and low angle boundary and their relative effects on materials. [16] 4. (a) Briefly discuss about the interactions of dislocations? (b) Give simple rules for interaction between two edge dislocations?

[8+8]

5. What is engineering stress and strain? What is meant by true stress and true strain? State where each of them are particularly used and suitable? In mathematical terms, which of these is the independent variable? [16] 6. What happens at the lattice structure with in individual grains when a piece of polycrystalline material is deformed with in its elastic limit? [16] 7. The fracture strength of a sample of glass is 40 MN/m2 . Estimate the Griffith’s crack length in this sample assuming E=60,000MN/m2 .and γ = 0.2 J/m2 . [16] 8. A liquid containing 90% Ni and 10% Cu is cooled relatively quickly the bottom of the container upward. Describe the compositional differences in the final solid casting. [16] ⋆⋆⋆⋆⋆

1 of 1

Set No. 3

Code No: RR220805

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 MATERIAL SCIENCE FOR CHEMICAL ENGINEERING (Chemical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. A cube metal has atoms only at 14 , 14 , 14 , and 43 , 34 , 34 ,

3 4

(a) Sketch such a unit cell (b) What is the common name for this lattice? (c) Sketch the bcc unit cell of vanadium, with an atom placed at 0, 12 , 0. [6+2+8] 2. Give important names of: (a) Ionic crystals. (b) Covalent crystals. (c) Metallic crystals. And describe at least one structural arrangement of each type.

[6+5+5]

3. At 800 C, 1 out of 1010 atoms, and at 900 C, 1 out of 109 atoms has appropriate energy for movements within a solid. (a) What is the activation energy in calories per mole? (b) At what temperature will 1 out of 108 atoms have the required amount of energy? [8+8] 4. Derive an expression for the energy per unit length of an edge dislocation?

[16]

5. (a) What is meant by mechanical properties of materials? State their importance in the design of a machine or structure elements. (b) What do you meant by isotropy and anisotropy?

[10+6]

6. If a bar of metal is quenched from a high temperature, the surface layers are found to contain compressive stresses and the center portion tensile stresses. Explain the phenomena? [16] 7. What is meant by ductile-brittle transition temperature? Name a few materials which are susceptible to brittle transition? State some of the factors responsible for brittle transition? [16] 8. Define grain boundary and account for its character. ⋆⋆⋆⋆⋆

1 of 1

[16]

Set No. 4

Code No: RR220805

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 MATERIAL SCIENCE FOR CHEMICAL ENGINEERING (Chemical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. What are the factors that determine the density of a crystal? Which of these factors is dominant in determining the decreasing order of density with increasing atomic number in the following elements. Cu (z=29) 8960; Ge (z = 32) 5320 ; Se (z=34) 4790 Kg/m3 . [16] 2. What is the relation of the packing of crystal with coordination number and what conclusion can be derived from that relation? [16] 3. What is meant by crystal imperfections? Classify them in order of their geometry. [16] 4. (a) What is dislocation climb? (b) Explain jogs in dislocation. (c) Explain Frank-Read source of dislocation.

[5+5+6]

5. Explain the differences between: (a) Hardness and brittleness (b) Strength and stiffness (c) Ductility and malleability (d) Elasticity and plasticity.

[4×4=16]

6. What is preferred orientation? What are the principal effects?

[16]

7. How fractures are classified? State and explain different types of fracture giving appearance of the fracture in each case? [16] 8. Explain why the rate of transformation of austenite to pearlite goes through a maximum (the nose of the TTT as the reaction temperature is lowered below A1) (Supply TTT diagram in the examination). [16] ⋆⋆⋆⋆⋆

1 of 1