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






2. Light Amplification by Stimulated Emission of Radiation






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






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






5. 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.






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






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






8. 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.






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






10. High toughness; material resists crack propagation.






11. 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.






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






13. Width of smallest feature obtainable on Si surface






14. 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.






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






16. Undergo little or no plastic deformation.






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






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






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






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






21. 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






22. 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.






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






24. Sigma=ln(li/lo)






25. 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.






26. 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






27. 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."






28. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






29. 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






30. Undergo extensive plastic deformation prior to failure.






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






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






33. 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






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






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






36. Second phase particles with n > glass.






37. 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.






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






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






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






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






42. - 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






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






44. 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






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






46. They are used to assess properties of ceramics & glasses.






47. 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






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






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






50. 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)