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






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






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






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






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






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






7. 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






8. Cracks propagate along grain boundaries.






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






10. These materials are relatively unaffected by magnetic fields.






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






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






13. Ability to transmit a clear image - The image is clear.






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






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






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






17. - 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






18. Stress concentration at a crack tips






19. 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)






20. Occur when lots of dislocations move.






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






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






23. 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






24. 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)






25. 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






26. Materials change size when temperature is changed






27. Metals are good conductors since their _______is only partially filled.






28. Specific heat = energy input/(mass*temperature change)






29. 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.






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






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






32. 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






33. 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






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






35. 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.






36. Is analogous to toughness.






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






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






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






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






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






42. - 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






43. Diffuse image






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






45. 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.






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






47. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






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






49. Width of smallest feature obtainable on Si surface






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