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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. 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.






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






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






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






5. 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






6. 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






7. 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






8. 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.






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






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






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






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






13. Second phase particles with n > glass.






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






15. 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






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






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






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






19. Width of smallest feature obtainable on Si surface






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

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21. 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.






22. 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






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

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






25. Stress concentration at a crack tips






26. 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.






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






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






29. 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.






30. 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.






31. Cracks propagate along grain boundaries.






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






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






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






35. Sigma=ln(li/lo)






36. 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.






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






38. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






39. Light Amplification by Stimulated Emission of Radiation






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






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






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






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






44. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R






45. 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






46. Occur when lots of dislocations move.






47. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






48. Because of ionic & covalent-type bonding.






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






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