Course: B.Tech (Chemical / Mechanical / Metallurgical Engineering)Subject Code: CH404Subject Title: Material Science Exam Type: Theory (Semester IV, 2016–17)Duration: 3 HoursMaximum Marks: 100
SECTION – A (10 × 2 = 20 Marks) Short and fundamental questions — tests definitions, atomic concepts, and material behavior.
No. Question Concept Summary (a) What is a Solid Solution? Homogeneous mixture of two or more elements in a single crystal lattice (e.g., brass = Cu + Zn). Types: substitutional and interstitial. (b) Define Unit Cell and Space Lattice. Unit cell → smallest repeating structure; Space lattice → 3D arrangement of atoms representing crystal geometry. (c) Applications of Aluminum and Its Alloys. Used in aircraft, packaging, heat exchangers, and lightweight structures due to low density and corrosion resistance. (d) Concept of Magnetism. Property by which materials exert attractive or repulsive forces; classified as diamagnetic, paramagnetic, ferromagnetic, and antiferromagnetic. (e) Superconductivity. Phenomenon of zero electrical resistance below a critical temperature (e.g., NbTi, Hg). Used in MRI, maglev trains. (f) Different Types of Lattices. 7 crystal systems, 14 Bravais lattices (Cubic, Tetragonal, Orthorhombic, etc.). (g) Atomic Mass and Atomic Number. Atomic mass = total mass of protons + neutrons; Atomic number = number of protons (defines element). (h) Phase in Metals. A region of material with uniform composition and structure (e.g., α, β phases in alloys). (i) Importance of Alloys. Enhance mechanical, thermal, and corrosion resistance properties. (j) Atomic Model. Describes atom’s structure — Thomson, Rutherford, Bohr, and Quantum models.
SECTION – B (5 × 10 = 50 Marks) Detailed conceptual questions on metallurgy, defects, and material processing.
(a) Polymerization Techniques Methods: Addition (chain-growth) and condensation (step-growth).
Techniques:
Bulk Polymerization – pure monomer, no solvent; produces clear polymer but risk of overheating.
Solution Polymerization – monomer dissolved in solvent; better heat control.
Suspension Polymerization – monomer droplets in water; forms beads.
Interfacial Polymerization – polymer forms at boundary between two immiscible liquids; used in thin-film membranes.
(b) Terms Explanation Quenching: Rapid cooling from high temperature to increase hardness.
Poisson’s Ratio: ν=−lateral strainlongitudinal strain\nu = -\frac{lateral \ strain}{longitudinal \ strain}ν=−longitudinal strainlateral strain (typical metals ≈ 0.3).
Plastic Deformation: Permanent deformation beyond elastic limit due to dislocation motion.
(c) Carbon Steels Type Carbon % Example Properties Low Carbon < 0.25% Mild steel Ductile, malleable Medium Carbon 0.25–0.6% Structural steel Good strength High Carbon 0.6–1.5% Tool steel Hard, brittle, high wear resistance
(d) Investment Casting Process: Wax pattern → ceramic coating → molten metal poured → shell broken → casting obtained.
Advantages: High precision, smooth finish.
Limitations: Costly, small part size.
(e) Hot & Cold Working Aspect Hot Working Cold Working Temperature Above recrystallization Below recrystallization Strength Lower Higher Ductility High Reduced Surface Finish Poor Good Example Forging Rolling, drawing
(f) Defects in Solids Point Defects: Vacancies, interstitials, substitutionals.
Line Defects: Dislocations (edge, screw).
Surface Defects: Grain boundaries, twin boundaries.
Volume Defects: Voids, cracks, inclusions.
(g) Fracture in Metals Types: Ductile (cup-and-cone) & Brittle (cleavage).
Causes: Overload, stress concentration, temperature drop, impurities.
(h) Crystalline vs Glass Ceramics Property Crystalline Glass-Ceramic Structure Ordered Partially crystalline Strength Moderate High Thermal Shock Resistance Low Excellent Applications Tiles, bricks Cookware, insulators
SECTION – C (2 × 15 = 30 Marks) Analytical and application-based questions on advanced materials and processes.
Q3. Smart Materials & Optical Fiber Smart Materials: Materials that respond to external stimuli (stress, temperature, field).
Optical Fiber Principle: Total internal reflection — transmits light signals through a core surrounded by cladding.
Applications: Telecommunications, medical endoscopy, sensors, data transfer.
Q4. Cupola Furnace Used for melting cast iron in foundries.
Zones: Crucible → Melting → Combustion → Preheating.
Operation: Coke burns to melt metal; flux removes impurities as slag.
Limitations: Cannot melt high-melting metals; pollution issues.
Q5. Patterns & Pattern Allowances Pattern: Replica of casting used to prepare mould cavity.
Allowances:
Shrinkage – compensates contraction during cooling.
Machining – extra material for finishing.
Draft – taper for pattern removal.
Rapping – for easy withdrawal.
Distortion – for warping correction.
Summary The Material Science (CH404) paper comprehensively tests:
Atomic structure and bonding
Crystal geometry and defects
Mechanical properties (stress, strain, fracture)
Metal processing (casting, working, heat treatment)
Modern materials (polymers, ceramics, smart materials)
