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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.
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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. 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)






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






4. Ohms Law: voltage drop = current * resistance






5. Emitted light is in phase






6. 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.






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






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






9. Undergo little or no plastic deformation.






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






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






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






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






14. Width of smallest feature obtainable on Si surface






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






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






17. 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






18. Diffuse image






19. 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






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






21. Stress concentration at a crack tips






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






23. 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.






24. 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






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






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






28. 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.






29. 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






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






31. 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."






32. 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.






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






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






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






36. Light Amplification by Stimulated Emission of Radiation






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






38. These materials are relatively unaffected by magnetic fields.






39. 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.






40. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






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






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






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






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






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

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46. Materials change size when temperature is changed






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






48. 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)






49. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






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