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

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






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






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






5. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






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






7. 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






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






9. Is analogous to toughness.






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






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






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






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






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






15. - 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






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






17. 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.






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






19. 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






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






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






22. 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.






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






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






25. 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.






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






27. 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.






28. 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)






29. Undergo extensive plastic deformation prior to failure.






30. 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.






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






32. - 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






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






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






35. Different orientation of cleavage planes in grains.






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






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






38. 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






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






40. 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.






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






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






43. Cracks propagate along grain boundaries.






44. Materials change size when temperature is changed






45. 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






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






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






48. These materials are relatively unaffected by magnetic fields.






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






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