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






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






3. Light Amplification by Stimulated Emission of Radiation






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






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






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






7. 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.






8. 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.






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






10. 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.






11. 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.






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






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






14. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






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. 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






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






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






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






20. 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






21. 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.






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






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






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






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






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






27. 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






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






29. 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






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






31. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






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






33. 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






34. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






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






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






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






38. Different orientation of cleavage planes in grains.






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






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






41. 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.






42. Cracks propagate along grain boundaries.






43. 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.






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






45. 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






46. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






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






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






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






50. These materials are relatively unaffected by magnetic fields.