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






2. Materials change size when temperature is changed






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






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






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






6. 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






7. Stress concentration at a crack tips






8. 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






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






10. 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






11. Cracks propagate along grain boundaries.






12. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






13. Is analogous to toughness.






14. 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






15. 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.






16. 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






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






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






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

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20. 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.






21. Width of smallest feature obtainable on Si surface






22. Undergo little or no plastic deformation.






23. Undergo extensive plastic deformation prior to failure.






24. 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






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






26. Occur when lots of dislocations move.






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






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






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






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






31. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






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






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






34. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






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






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






37. 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






38. 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.






39. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






40. 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.






41. 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)






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






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






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






45. - 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






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






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






48. Sigma=ln(li/lo)






49. 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.






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