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






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






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






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






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






6. 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.






7. 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






8. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






9. Occur when lots of dislocations move.






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






11. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






12. Increase temperature - no increase in interatomic separation - no thermal expansion






13. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






14. 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.






15. Is analogous to toughness.






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






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






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






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






20. 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






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






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






23. 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.






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






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






26. Another optical property - Depends on the wavelength of the visible spectrum.






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






28. Undergo little or no plastic deformation.






29. 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)






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






31. Ohms Law: voltage drop = current * resistance






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






33. Undergo extensive plastic deformation prior to failure.






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






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






36. These materials are relatively unaffected by magnetic fields.






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






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






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






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






41. 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






42. Different orientation of cleavage planes in grains.






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






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






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






46. 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.






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






48. 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






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






50. High toughness; material resists crack propagation.






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