Tuesday 6 March 2012
How do you measure hardness of polymers ?
Durometer:
Durometer:
For Elastomers and polymers, hardness is defined as the resistance of elastic deformation of the surface. To measure hardness of polymers most commonly using tool is Duro meter the test careered out on Duro meter is known as Durometer hardness test. The duro meter pushed over the polymer surfaces to be tested until it reaches a stop. It consist of different type of indenter ( differ type A, D, M) is then forced into the polymer, and the depth of the indentation is read of on an arbitrary scale 0f 0 - 100
Rockwell hardness test:
Generally used to measure hardness of harder plastics such as Nylon, Polycarbonate, Polystyrene and acetal where the resiliency or creep of the polymer is lesslikely to affectes the result
Generally Rockwell scales used for plastics are Rockwell E , Rockwell M , Rockwell R as well as minimum thickness of specimen should be ¼ inch (6.4mm)
rockwell hardness tester
Durometer:
For Elastomers and polymers, hardness is defined as the resistance of elastic deformation of the surface. To measure hardness of polymers most commonly using tool is Duro meter the test careered out on Duro meter is known as Durometer hardness test. The duro meter pushed over the polymer surfaces to be tested until it reaches a stop. It consist of different type of indenter ( differ type A, D, M) is then forced into the polymer, and the depth of the indentation is read of on an arbitrary scale 0f 0 - 100
Rockwell hardness test:
Generally used to measure hardness of harder plastics such as Nylon, Polycarbonate, Polystyrene and acetal where the resiliency or creep of the polymer is lesslikely to affectes the result
Generally Rockwell scales used for plastics are Rockwell E , Rockwell M , Rockwell R as well as minimum thickness of specimen should be ¼ inch (6.4mm)
rockwell hardness tester
Monday 5 March 2012
Material Science and Engineering Question (Summer 2011)
Group A
1 a) Draw schematic to show different types of Bravis lattices in crystalline material. calculate the atomic packing factor (APF)of FCC and BCC crystal structure.
b) Explain the types of defects in crystalline material in brief .
c) Differentiate between the edge and screw dislocation in term of burger’s vector .
d) Find the equilibrium concentration of vacancies in aluminium at 0k and 900 k . Enthalpy of formation of vacancies in aluminium , ∆Hf=68kj mol-1;R=8.314 jmol-1
2. a)Mention and explain Nernst-Einstein relation in diffusion.
b) Describe Fick’s second law of diffusion.the diffusion coefficient for copper in aluminium at 500 0 C and 600 0 C are 4.8*10-4 m2/s and 5.3x10-13 m2/s respectively . calculate the time required at 500 0 C to produce diffusion depth equal to that at 6000 C for 10 hr.
c) Explain Gibb’s phase rule . Find the degrees of freedom when FCC and BCC iron co exist in equilibrium.
d) Draw an eutectic phase diagram and explain it.
3. a) Draw and Explain Fe-Fe3C phase diagram. Indicate the carbon percentage range of steel.
b) Define peritectic reaction. Explain with a suitable phase diagram .
c) Explain the mechanism of working of zone refining process with the help of a diagram.
4. a) Differentiate between true and engineering stress – strain curve. Indicate the elastic zone ,plastic zone and yield point in stress strain curve of mild steel.
b) Describe viscoelastic behaviour of materials.Explain Maxwell element and voigt- Kelvin model
c) Explain Griffiths theory of brittle fracture ? why has silicate glass a relativelylow fracture strength.?
GROUP-B
5. a) Discuss different method of carburising ,nitriding and carbo-nitriding .
b) Define harden ability of metals . Describe jominy’s harden ability test in brief.
c) Discuss different mechanism of hardening in metals and allys
6. a) Explain the working principle of bimetallic thermo stat in regulating temperature.
b) Define thermal stress . Discuss stresses due to restrained thermal expansion and contraction ?
c) Define high temperature materials. Name some of the high temperature material .
d) What are ceramics? What is the range of thermal expansion coefficient in ceramics? Explain why ceramics have low coefficient of thermal expansion . 5
7 a) what are polymers? Describe briefly in terms ‘saturated polymer’ and ‘un saturated polymer’.
b) Differentiate between thermoplastic and thermosetting polymers .
c) Define the terms ‘composites’ . Describe the briefly about different types of composites and their application.
8. a) What are nano materials ? mention important application of nano materials .
b) Define curie temperature .what is spontaneous magnetisation ? write about characteristics of ferromagnetism material .
c) Discuss band theory of solids . Differentiate between metals semiconductor andinsulator on the basis of band theory.
Group-C
9 Answer the following in brief:
i) At high temperature,the mechanical strength is high or low ? Give answer with proper reasoning .
ii) Draw the binary phase diagramof Al2O3-Cr2O3. Clearly showing the tie line
iii) Why thoria dispersed nickel retains very good mechanical strength up to 0.9Tm , where Tm is its melting point ?
iv) Mention relative magnitudes of enthalpy of motion for the atoms moving on the surface along the boundary and within the lattice .
v) Explain how surface cracks can be made ineffective.
vi) Find the fractional amount of ferrite (α) and cementite (Fe3C)using lever’s rule and placing the fulcrum at 0.8% Carbon in iron-iron carbide phase diagram
vii) What is glass ? mention its important characteristics .
viii) Explain the degree of polymerisation.
ix) Draw the schematics of a) linear b) branched c) cross linked d)networked polymer structures
x) Define a) susceptibility b)permeability c)magnetisation of magnetic material
1 a) Draw schematic to show different types of Bravis lattices in crystalline material. calculate the atomic packing factor (APF)of FCC and BCC crystal structure.
b) Explain the types of defects in crystalline material in brief .
c) Differentiate between the edge and screw dislocation in term of burger’s vector .
d) Find the equilibrium concentration of vacancies in aluminium at 0k and 900 k . Enthalpy of formation of vacancies in aluminium , ∆Hf=68kj mol-1;R=8.314 jmol-1
2. a)Mention and explain Nernst-Einstein relation in diffusion.
b) Describe Fick’s second law of diffusion.the diffusion coefficient for copper in aluminium at 500 0 C and 600 0 C are 4.8*10-4 m2/s and 5.3x10-13 m2/s respectively . calculate the time required at 500 0 C to produce diffusion depth equal to that at 6000 C for 10 hr.
c) Explain Gibb’s phase rule . Find the degrees of freedom when FCC and BCC iron co exist in equilibrium.
d) Draw an eutectic phase diagram and explain it.
3. a) Draw and Explain Fe-Fe3C phase diagram. Indicate the carbon percentage range of steel.
b) Define peritectic reaction. Explain with a suitable phase diagram .
c) Explain the mechanism of working of zone refining process with the help of a diagram.
4. a) Differentiate between true and engineering stress – strain curve. Indicate the elastic zone ,plastic zone and yield point in stress strain curve of mild steel.
b) Describe viscoelastic behaviour of materials.Explain Maxwell element and voigt- Kelvin model
c) Explain Griffiths theory of brittle fracture ? why has silicate glass a relativelylow fracture strength.?
GROUP-B
5. a) Discuss different method of carburising ,nitriding and carbo-nitriding .
b) Define harden ability of metals . Describe jominy’s harden ability test in brief.
c) Discuss different mechanism of hardening in metals and allys
6. a) Explain the working principle of bimetallic thermo stat in regulating temperature.
b) Define thermal stress . Discuss stresses due to restrained thermal expansion and contraction ?
c) Define high temperature materials. Name some of the high temperature material .
d) What are ceramics? What is the range of thermal expansion coefficient in ceramics? Explain why ceramics have low coefficient of thermal expansion . 5
7 a) what are polymers? Describe briefly in terms ‘saturated polymer’ and ‘un saturated polymer’.
b) Differentiate between thermoplastic and thermosetting polymers .
c) Define the terms ‘composites’ . Describe the briefly about different types of composites and their application.
8. a) What are nano materials ? mention important application of nano materials .
b) Define curie temperature .what is spontaneous magnetisation ? write about characteristics of ferromagnetism material .
c) Discuss band theory of solids . Differentiate between metals semiconductor andinsulator on the basis of band theory.
Group-C
9 Answer the following in brief:
i) At high temperature,the mechanical strength is high or low ? Give answer with proper reasoning .
ii) Draw the binary phase diagramof Al2O3-Cr2O3. Clearly showing the tie line
iii) Why thoria dispersed nickel retains very good mechanical strength up to 0.9Tm , where Tm is its melting point ?
iv) Mention relative magnitudes of enthalpy of motion for the atoms moving on the surface along the boundary and within the lattice .
v) Explain how surface cracks can be made ineffective.
vi) Find the fractional amount of ferrite (α) and cementite (Fe3C)using lever’s rule and placing the fulcrum at 0.8% Carbon in iron-iron carbide phase diagram
vii) What is glass ? mention its important characteristics .
viii) Explain the degree of polymerisation.
ix) Draw the schematics of a) linear b) branched c) cross linked d)networked polymer structures
x) Define a) susceptibility b)permeability c)magnetisation of magnetic material
Material Science and Engineering Question (Winter 2010)
group A
1
a) What are Bravais lattices? Explain in brief the differences in stacking
sequence of FCC and HCP crystal structure.
b) Caculate the atomic packing factor (APF) for the FCC crystal structure.
c) What are point defects and how are they created? Discuss different types
point defects in brief .
d) Discuss major differences between edge and srew dislocation.
2
a) What is Gibbs phase rule ?Explain its application with reference to
binary phase digram s.
b) Write the eutectoid reaction in Fe-Fe3C system and find thr amount of different phases at the eutectoid point .
c) What is true stress ? Deduce the relationship between engineering and true stress ?
d) What is meant by the toughness of material ?How is it measured and assessed?
3 a) Differentiate between ductile fracture and brittle fracture ?
b) Explain the S-N curve with respect to ferrous and non ferrous material?
c) Explain how deformation takes place by twinning .
d) Differentiate between cold working and hot working.
4 Write notes on any four of the following:
a) Fick’s law of diffusion
b) Creep behaviour in metals
c) Hume Rothery’s rules
d) Deformation in polycrystalline materials
e) Solid solution strengthening
f) Recovery ,recrystallization and grain growth.
GROUP-B
5 a) Draw the iron-iron carbide phase diagram. Clearly indicating the phase present at different temperatures and carbon content.
b) Explain in brief the time-temperature-transformation(T-T-T) diagrams.
6 a) Distinguish between thermal heat capacity and thermal heat content .
b) Explain the types of magnetism in brief .
c) Differentiate between the instrinsic and extrinsic type semiconductor.
d) Discuss the mechanism of sintering of ceramic materials .
7 a) Discuss different mechanism of polymerization .
b) What are the factors affecting mechanical properties of polymers ?
Discuss
c) What are composite materials ? Briefly classify the composite materials.
8 A)Write short notes on any four of the following
a) Annealing and normalising
b) Thermoplastic and thermosets
c) Surface hardening
d) Basic refractories
e) Continuous cooling transformation(CCT)digrams
f) Zone theory of solids
GROUP-C
9 Give brief and precise answer to the following
i) Define hardenibility
ii) What is isomorphous system ?
iii) State the Hall-Petch equation ,explaining the meaning of each symbol.
iv) What is pertectic reaction?
v) What is Bauschinger effect ?
vi) What is critical cooling rate ?
vii) What are the main material for cryogenic application ?
viii) What is glass transition temperature(Tg)?
ix) Define fracture toughness of a material .
x) What is superconductivity?
1
a) What are Bravais lattices? Explain in brief the differences in stacking
sequence of FCC and HCP crystal structure.
b) Caculate the atomic packing factor (APF) for the FCC crystal structure.
c) What are point defects and how are they created? Discuss different types
point defects in brief .
d) Discuss major differences between edge and srew dislocation.
2
a) What is Gibbs phase rule ?Explain its application with reference to
binary phase digram s.
b) Write the eutectoid reaction in Fe-Fe3C system and find thr amount of different phases at the eutectoid point .
c) What is true stress ? Deduce the relationship between engineering and true stress ?
d) What is meant by the toughness of material ?How is it measured and assessed?
3 a) Differentiate between ductile fracture and brittle fracture ?
b) Explain the S-N curve with respect to ferrous and non ferrous material?
c) Explain how deformation takes place by twinning .
d) Differentiate between cold working and hot working.
4 Write notes on any four of the following:
a) Fick’s law of diffusion
b) Creep behaviour in metals
c) Hume Rothery’s rules
d) Deformation in polycrystalline materials
e) Solid solution strengthening
f) Recovery ,recrystallization and grain growth.
GROUP-B
5 a) Draw the iron-iron carbide phase diagram. Clearly indicating the phase present at different temperatures and carbon content.
b) Explain in brief the time-temperature-transformation(T-T-T) diagrams.
6 a) Distinguish between thermal heat capacity and thermal heat content .
b) Explain the types of magnetism in brief .
c) Differentiate between the instrinsic and extrinsic type semiconductor.
d) Discuss the mechanism of sintering of ceramic materials .
7 a) Discuss different mechanism of polymerization .
b) What are the factors affecting mechanical properties of polymers ?
Discuss
c) What are composite materials ? Briefly classify the composite materials.
8 A)Write short notes on any four of the following
a) Annealing and normalising
b) Thermoplastic and thermosets
c) Surface hardening
d) Basic refractories
e) Continuous cooling transformation(CCT)digrams
f) Zone theory of solids
GROUP-C
9 Give brief and precise answer to the following
i) Define hardenibility
ii) What is isomorphous system ?
iii) State the Hall-Petch equation ,explaining the meaning of each symbol.
iv) What is pertectic reaction?
v) What is Bauschinger effect ?
vi) What is critical cooling rate ?
vii) What are the main material for cryogenic application ?
viii) What is glass transition temperature(Tg)?
ix) Define fracture toughness of a material .
x) What is superconductivity?
Subscribe to:
Posts (Atom)