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






2. - 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






3. 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






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






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






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






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






8. Different orientation of cleavage planes in grains.






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






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






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






12. 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.






13. 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






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






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






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

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






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






19. Light Amplification by Stimulated Emission of Radiation






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






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






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






23. 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






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






25. These materials are relatively unaffected by magnetic fields.






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






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






28. 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.






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






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






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






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






33. - 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






34. 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






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






36. 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






37. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






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






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






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






41. 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






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






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






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






45. Occur when lots of dislocations move.






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






47. 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.






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






49. 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






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