MCQOPTIONS
Saved Bookmarks
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. |
What is the empirical relationship for the rate of neck growth when two spheres are in contact with one another? |
| A. | ( frac{x^7}{a^4}= frac{40 gamma Omega D.t}{RT} ) |
| B. | ( frac{a^2}{x^5}= frac{400 gamma Omega D.t}{RT} ) |
| C. | ( frac{x^5}{a^2}= frac{40 gamma Omega D.t}{RT} ) |
| D. | ( frac{x^5}{a^3}= frac{40 gamma Omega D.t}{RT} ) |
| Answer» D. ( frac{x^5}{a^3}= frac{40 gamma Omega D.t}{RT} ) | |
| 2. |
What is the empirical relationship for the rate of neck growth when a sphere is in contact with a flat surface? |
| A. | Rate of neck growth (t^{ frac{1}{6}} ) |
| B. | Rate of neck growth (t^{ frac{1}{7}} ) |
| C. | Rate of neck growth (t^{ frac{2}{7}} ) |
| D. | Rate of neck growth (t^{ frac{1}{8}} ) |
| Answer» C. Rate of neck growth (t^{ frac{2}{7}} ) | |
| 3. |
The vacancy concentration is given by Dvac= ______ |
| A. | D.C<sub>0</sub> |
| B. | D.C |
| C. | d.C |
| D. | D.c |
| Answer» B. D.C | |
| 4. |
Vacancy concentration causes _______ |
| A. | The outflow of vacancies from the curved surface towards the flat region |
| B. | The outflow of vacancies from the flat surface towards the curved region |
| C. | The outflow of atoms from the curved surface towards the flat region |
| D. | The influx of vacancies from the curved surface towards the flat region |
| Answer» B. The outflow of vacancies from the flat surface towards the curved region | |
| 5. |
Diffusion occurs as a result of _______ gradient. |
| A. | Velocity |
| B. | Vacancy concentration |
| C. | Pressure |
| D. | Momentum |
| Answer» C. Pressure | |
| 6. |
The equilibrium vapor pressure over the neck _____ particle surface. |
| A. | < |
| B. | > |
| C. | = |
| D. | >> |
| Answer» B. > | |
| 7. |
The mass transport during evaporation-condensation mechanism occurs from _______ particle surface to the ______ necks. |
| A. | Concave, convex |
| B. | Convex, bi-concave |
| C. | Convex, concave |
| D. | Bi-convex, concave |
| Answer» D. Bi-convex, concave | |
| 8. |
The driving force for evaporation-condensation mechanism is given by ________ |
| A. | - <sub>0</sub>=( &ohm;)/r<sub>1</sub>=RT ln ( frac{p_0}{p} ) |
| B. | - <sub>0</sub>=(- &ohm;)/r<sub>1</sub>=RT ln ( frac{p}{p_0} ) |
| C. | <sub>0</sub>- =(- &ohm;)/r<sub>1</sub>=RT ln ( frac{p}{p_0} ) |
| D. | - <sub>0</sub>=( &ohm;)/r<sub>1</sub>=RT ln ( frac{p}{p_0} ) |
| Answer» C. <sub>0</sub>- =(- &ohm;)/r<sub>1</sub>=RT ln ( frac{p}{p_0} ) | |
| 9. |
________ mechanism operates in a system having materials with a high vapor pressure at sintering temperature. |
| A. | Viscous flow |
| B. | Volume diffusion |
| C. | Evaporation and condensation |
| D. | Plastic flow |
| Answer» D. Plastic flow | |
| 10. |
_______ is the liquid-like movement of individual atoms under stress while _______ is the slip of entire planes of atoms. |
| A. | Plastic flow, viscous flow |
| B. | Volume diffusion, plastic flow |
| C. | Viscous flow, volume diffusion |
| D. | Viscous flow, plastic flow |
| Answer» E. | |
| 11. |
Which of the following are the main types of material transport mechanisms proposed to be operating during sintering? |
| A. | Evaporation |
| B. | Dislocation movement |
| C. | Evaporation-condensation, viscous flow, plastic flow and diffusion |
| D. | Viscous flow, metal flow |
| Answer» D. Viscous flow, metal flow | |