Test your basic knowledge |

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






2. 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)






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






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






5. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






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






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






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






9. 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.






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






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






12. 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






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






14. Occur when lots of dislocations move.






15. 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.






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






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






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






19. 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






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






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






22. Undergo extensive plastic deformation prior to failure.






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






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






25. 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.






26. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






27. 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.






28. Materials change size when temperature is changed






29. 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)






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






31. 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.






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






33. Second phase particles with n > glass.






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






35. 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






36. These materials are relatively unaffected by magnetic fields.






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






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






39. Width of smallest feature obtainable on Si surface






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






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






42. Cracks propagate along grain boundaries.






43. - 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






44. 1. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






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






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






47. 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






48. 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






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






50. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)