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. |
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.C0 |
| 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. | μ-μ0=(γΩ)/r1=RT ln\(\frac{p_0}{p}\) |
| B. | μ-μ0=(-γΩ)/r1=RT ln\(\frac{p}{p_0}\) |
| C. | μ0-μ=(-γΩ)/r1=RT ln\(\frac{p}{p_0}\) |
| D. | μ-μ0=(γΩ)/r1=RT ln\(\frac{p}{p_0}\) |
| Answer» C. μ0-μ=(-γΩ)/r1=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 | |