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






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






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






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






5. High toughness; material resists crack propagation.






6. Emitted light is in phase






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






8. 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)






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






10. 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.






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






12. Diffuse image






13. 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






14. 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






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






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






17. 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






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






19. These materials are relatively unaffected by magnetic fields.






20. - 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






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






22. Sigma=ln(li/lo)






23. 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






24. 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.






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






26. 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






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






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






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






30. Second phase particles with n > glass.






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






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






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






34. Cracks propagate along grain boundaries.






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






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






37. 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.






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






39. 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.






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






41. Because of ionic & covalent-type bonding.






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






43. 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






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






45. Different orientation of cleavage planes in grains.






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






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






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






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






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