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






2. Sigma=ln(li/lo)






3. Undergo little or no plastic deformation.






4. Cracks propagate along grain boundaries.






5. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






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






7. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)






8. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






9. High toughness; material resists crack propagation.






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






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






12. Liquid polymer at room T - sandwiched between two sheets of glass - coated with transparent - electrically conductive film. - Character forming letters/ numbers etched on the face - Voltage applied disrupts the orientation of the rod- shaped molecule






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






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






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






16. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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






18. 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






19. Ohms Law: voltage drop = current * resistance






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






21. 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






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






23. Emitted light is in phase






24. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






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






26. 1. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






27. For a metal - there is no ______ - only reflection






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






29. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






30. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






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






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






35. They are used to assess properties of ceramics & glasses.






36. Width of smallest feature obtainable on Si surface






37. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






38. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in






39. 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






40. 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)






41. Process by which metal atoms diffuse because of a potential.






42. 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






43. 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.






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






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






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






47. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






48. Second phase particles with n > glass.






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






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.