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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. The size of the material changes with a change in temperature - polymers have the largest values






2. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






3. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






4. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






5. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






6. -> fluorescent light - electron transitions occur randomly - light waves are out of phase with each other.






7. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






8. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






9. The ability of a material to absorb heat - Quantitatively: The energy required to produce a unit rise in temperature for one mole of a material.






10. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






11. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






12. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.






13. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






14. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






15. Wet: isotropic - under cut Dry: ansiotropic - directional






16. Cracks propagate along grain boundaries.






17. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






18. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






19. ...occurs in bcc metals but not in fcc metals.






20. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






21. Ability to transmit a clear image - The image is clear.






22. Light Amplification by Stimulated Emission of Radiation






23. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)






24. Diffuse image






25. Not ALL the light is refracted - SOME is reflected. Materials with a high index of refraction also have high reflectance - High R is bad for lens applications - since this leads to undesirable light losses or interference.






26. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.






27. # of thermally generated electrons = # of holes (broken bonds)






28. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






29. Increase temperature - increase in interatomic separation - thermal expansion






30. Ohms Law: voltage drop = current * resistance






31. Metals are good conductors since their _______is only partially filled.






32. Width of smallest feature obtainable on Si surface






33. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






34. Second phase particles with n > glass.






35. 1. Tc= critical temperature- if T>Tc not superconducting 2. Jc= critical current density - if J>Jc not superconducting 3. Hc= critical magnetic field - if H > Hc not superconducting






36. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






37. These materials are relatively unaffected by magnetic fields.






38. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






39. A high index of refraction (n value) allows for multiple internal reactions.






40. Typical loading conditions are _____ enough to break all inter-atomic bonds






41. A measure of the ease with which a B field can be induced inside a material.






42. Stress concentration at a crack tips






43. High toughness; material resists crack propagation.






44. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






45. Because of ionic & covalent-type bonding.






46. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R






47. Undergo little or no plastic deformation.






48. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






49. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






50. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.







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