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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. 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






2. 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






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






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






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






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






7. These materials are relatively unaffected by magnetic fields.






8. Undergo extensive plastic deformation prior to failure.






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. Diffuse image






11. Different orientation of cleavage planes in grains.






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






13. Wet: isotropic - under cut Dry: ansiotropic - directional






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






15. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






16. Sigma=ln(li/lo)






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






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






19. 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






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






21. 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






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






23. Occur when lots of dislocations move.






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






25. 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






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






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






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






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






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






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






32. 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.






33. 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






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






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






36. Process by which metal atoms diffuse because of a potential.






37. 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.






38. 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.






39. 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.






40. 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






41. For a metal - there is no ______ - only reflection






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






43. 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.






44. 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."






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






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






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






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






49. 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)






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