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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. 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.






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






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






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






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






6. 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.






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






8. 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.






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






10. Second phase particles with n > glass.






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






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






13. 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.






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






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






16. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.






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






18. 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.






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






20. Diffuse image






21. 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






22. - 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






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






24. Ability to transmit a clear image - The image is clear.






25. Different orientation of cleavage planes in grains.






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






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






28. 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






29. 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






30. Materials change size when temperature is changed






31. 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






32. Undergo extensive plastic deformation prior to failure.






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






34. 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






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






36. 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.






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






38. 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






39. Occur when lots of dislocations move.






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






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






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






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






44. Light Amplification by Stimulated Emission of Radiation






45. Sigma=ln(li/lo)






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






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






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






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 metal atoms diffuse because of a potential.