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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • 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. Specific heat = energy input/(mass*temperature change)






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






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






4. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






5. 1. Tensile (opening) 2. Sliding 3. Tearing






6. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






7. Stress concentration at a crack tips






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






9. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.






10. These materials are "attracted" to magnetic fields.






11. Plastic means permanent! When a small load is applied - bonds stretch & planes shear. Then when the load is no longer applied - the planes are still sheared.






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






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






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






15. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






16. Materials change size when temperature is changed






17. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






18. 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.






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






20. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






21. Resistance to plastic deformation of cracking in compression - and better wear properties.






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






23. Is analogous to toughness.






24. 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)






25. 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






26. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.






27. Dimples on fracture surface correspond to microcavities that initiate crack formation.






28. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






29. 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






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






31. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






32. Cracks pass through grains - often along specific crystal planes.






33. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






34. Width of smallest feature obtainable on Si surface






35. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






36. 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.






37. If a material has ________ - then the field generated by those moments must be added to the induced field.






38. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






39. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






40. High toughness; material resists crack propagation.






41. Without passing a current a continually varying magnetic field will cause a current to flow






42. Becomes harder (more strain) to stretch (elongate)






43. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






44. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.






45. 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






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






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






48. The size of the material changes with a change in temperature - polymers have the largest values






49. The ability of a material to be rapidly cooled and not fracture






50. Occur when lots of dislocations move.