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






2. 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.






3. Emitted light is in phase






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






5. Ohms Law: voltage drop = current * resistance






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






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






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






9. Second phase particles with n > glass.






10. Cracks propagate along grain boundaries.






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






12. Undergo extensive plastic deformation prior to failure.






13. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






14. 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






15. 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.






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






17. Light Amplification by Stimulated Emission of Radiation






18. 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






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






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






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






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






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






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

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






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






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






28. 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.






29. 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






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






31. Is analogous to toughness.






32. Stress concentration at a crack tips






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






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






35. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






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






37. 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






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






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






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






41. 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






42. 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






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






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






46. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






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






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






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






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