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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. Width of smallest feature obtainable on Si surface






2. 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






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






4. 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)






5. 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






6. Emitted light is in phase






7. High toughness; material resists crack propagation.






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






9. 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.






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






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






12. 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






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






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






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






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






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






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






19. 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






20. 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.






21. Light Amplification by Stimulated Emission of Radiation






22. 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.






23. 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.






24. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)






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






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






27. Second phase particles with n > glass.






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






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






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






31. 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






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






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






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. Diffuse image






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






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






38. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






39. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.






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






41. 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






42. Because of ionic & covalent-type bonding.






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






44. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






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






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






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






48. Stress concentration at a crack tips






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






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







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