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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. Materials change size when temperature is changed






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






3. These materials are relatively unaffected by magnetic fields.






4. A high index of refraction (n value) allows for multiple internal reactions.






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






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






7. 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






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






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


10. Because of ionic & covalent-type bonding.






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






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






13. 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.






14. 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.






15. 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






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


17. 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






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






19. Light Amplification by Stimulated Emission of Radiation






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






21. 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






22. 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.






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






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






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






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






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






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. 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






30. 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






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






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






33. Ohms Law: voltage drop = current * resistance






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






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






36. 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.






37. Is analogous to toughness.






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






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






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






41. Cracks propagate along grain boundaries.






42. 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.






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






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






45. Undergo extensive plastic deformation prior to failure.






46. 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.






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






48. 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)






49. 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






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