MCQOPTIONS
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MCQOPTIONS
This section includes 11 Mcqs, each offering curated multiple-choice questions to sharpen your Powder Metallurgy knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Coble developed rate equations for three stage sintering assuming the compact to be made of packed spheres and in the final stage form interlocking ___________ |
| A. | Tetrakaioctahedrons |
| B. | Tetrakaidecahedrons |
| C. | Tetracontagons |
| D. | Tetrakaitetrahedrons |
| Answer» C. Tetracontagons | |
| 2. |
The equilibrium pore pressure is given by Pp= ________ |
| A. | P<sub>atm</sub>-2 <sub>sv</sub>/r |
| B. | P<sub>atm</sub>+2 <sub>sv</sub>/r |
| C. | P<sub>atm</sub>+2 <sub>ss</sub>/r |
| D. | P<sub>atm</sub>+2 <sub>sv</sub>/x |
| Answer» C. P<sub>atm</sub>+2 <sub>ss</sub>/r | |
| 3. |
Entrapment of gas within the pores is an important reason for not achieving theoretical density in practice during sintering. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4. |
At equilibrium, the relation between dihedral angle and surface energy is represented by the equation ______ |
| A. | cos ( frac{ theta}{2}=- frac{ gamma_{sv}}{ gamma_{ss}} ) |
| B. | cos ( frac{ theta}{2}= frac{ gamma_{sv}}{ gamma_{ss}} ) |
| C. | cos ( frac{ theta}{2}= frac{ gamma_{ss}}{ gamma_{sv}} ) |
| D. | cos ( frac{ theta}{2}=- frac{ gamma_{ss}}{ gamma_{sv}} ) |
| Answer» D. cos ( frac{ theta}{2}=- frac{ gamma_{ss}}{ gamma_{sv}} ) | |
| 5. |
Which of the following is the expression for plastic flow as the driving force for sintering? |
| A. | ( frac{ds}{dt}=A sigma^{3n}e^{ frac{Q_c}{RT}} ) |
| B. | ( frac{ds}{dt}=A sigma^{2n}e^{ frac{Q_c}{RT}} ) |
| C. | ( frac{ds}{dt}=A sigma^{n}e^{ frac{Q_cR}{T}} ) |
| D. | ( frac{ds}{dt}=A sigma^{n}e^{ frac{Q_c}{RT}} ) |
| Answer» E. | |
| 6. |
Bulk flow of material by movement of dislocations is a possible mechanism for densification during sintering only if the two conditions are met. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7. |
The equation for coefficient of viscosity as proposed by Frenkel, is given by ________ |
| A. | = ( frac{k^2T}{D Omega} ) |
| B. | = ( frac{kT}{D Omega} ) |
| C. | = ( frac{kT}{Dx} ) |
| D. | = ( frac{kT}{Da} ) |
| Answer» C. = ( frac{kT}{Dx} ) | |
| 8. |
Which of the following mechanisms operate during sintering, according to Bal shin theory? |
| A. | Particle re-arrangement, particle shape change, and grain shrinkage |
| B. | Particle shape change, particle size change, and grain growth |
| C. | Particle re-arrangement, particle shape change, and grain growth |
| D. | Particle re-arrangement and grain growth |
| Answer» D. Particle re-arrangement and grain growth | |
| 9. |
The expression for viscous flow mechanism proposed by Frenkel is given by ________ |
| A. | ( frac{x^2}{a}= frac{3 gamma eta}{2t} ) |
| B. | ( frac{x^3}{a}= frac{3 gamma t}{2 eta} ) |
| C. | ( frac{x^2}{a}= frac{3 gamma}{2 eta} ) |
| D. | ( frac{x^2}{a}= frac{3 gamma t}{2 eta} ) |
| Answer» E. | |
| 10. |
___________ are structural arrangement of dislocations and are not perfect sinks. |
| A. | Pores |
| B. | Grain boundaries |
| C. | Vacancies |
| D. | Necks |
| Answer» C. Vacancies | |
| 11. |
Nabarro and Herring supported ________ as the dominant mechanism in sintering. |
| A. | Evaporation-condensation |
| B. | Viscous flow |
| C. | Diffusion |
| D. | Recrystallization |
| Answer» D. Recrystallization | |