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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. 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






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






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

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4. - 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






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






6. Becomes harder (more strain) to stretch (elongate)






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






8. 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






9. Light Amplification by Stimulated Emission of Radiation






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






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






12. These materials are relatively unaffected by magnetic fields.






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






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






15. Width of smallest feature obtainable on Si surface






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

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






18. 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






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






20. Different orientation of cleavage planes in grains.






21. Ohms Law: voltage drop = current * resistance






22. 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.






23. 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






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






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






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






27. 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)






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






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






30. Diffuse image






31. 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.






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






33. 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






34. Sigma=ln(li/lo)






35. Stress concentration at a crack tips






36. 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






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






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






39. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






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






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






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






43. Materials change size when temperature is changed






44. Because of ionic & covalent-type bonding.






45. Undergo extensive plastic deformation prior to failure.






46. 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)






47. 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.






48. 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.






49. Occur when lots of dislocations move.






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