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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • 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. 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






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






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






5. 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






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






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






8. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






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






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


12. 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






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






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






15. Undergo little or no plastic deformation.






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






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






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






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






20. 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






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






22. Process by which metal atoms diffuse because of a potential.






23. Stress concentration at a crack tips






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






25. 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






26. 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.






27. Emitted light is in phase






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






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






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






31. 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.






32. Is analogous to toughness.






33. 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."






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






35. 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.






36. 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






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






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






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






40. Undergo extensive plastic deformation prior to failure.






41. Occur when lots of dislocations move.






42. Light Amplification by Stimulated Emission of Radiation






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






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






45. 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






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






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






48. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






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






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