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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. 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






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






3. 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.






4. 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.






5. - 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






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






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






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






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






10. Second phase particles with n > glass.






11. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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12. Elastic means reversible! This is not a permanent deformation.






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






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






15. Width of smallest feature obtainable on Si surface






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






17. Sigma=ln(li/lo)






18. Undergo little or no plastic deformation.






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






20. Emitted light is in phase






21. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB






22. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






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






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






25. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






26. 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






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






28. Diffuse image






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






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






31. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






32. 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






33. Occur when lots of dislocations move.






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






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






36. 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






37. 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."






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






39. 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.






40. 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.






41. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






42. 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






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






44. 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






45. 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.






46. Light Amplification by Stimulated Emission of Radiation






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






48. Different orientation of cleavage planes in grains.






49. There is always some statistical distribution of flaws or defects.






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