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






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






3. 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.






4. 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






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






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






7. 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






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






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






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






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






12. 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






13. # of thermally generated electrons = # of holes (broken bonds)






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






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






16. Sigma=ln(li/lo)






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






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






19. 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






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






21. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






22. Stress concentration at a crack tips






23. 1. Tc= critical temperature- if T>Tc not superconducting 2. Jc= critical current density - if J>Jc not superconducting 3. Hc= critical magnetic field - if H > Hc not superconducting






24. 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.






25. Undergo little or no plastic deformation.






26. 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."






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






28. Ohms Law: voltage drop = current * resistance






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






30. 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






31. 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.






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






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






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






35. 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.






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






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






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






39. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






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






41. Materials change size when temperature is changed






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






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






44. Undergo extensive plastic deformation prior to failure.






45. Cracks propagate along grain boundaries.






46. Different orientation of cleavage planes in grains.






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






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






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






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