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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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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. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.






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






3. Because of ionic & covalent-type bonding.






4. 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






5. Ohms Law: voltage drop = current * resistance






6. Undergo extensive plastic deformation prior to failure.






7. 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






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






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






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






11. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






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






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






14. 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)






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






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






17. 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






18. 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






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






20. 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.






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

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22. These materials are relatively unaffected by magnetic fields.






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






24. 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.






25. 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






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






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






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






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






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






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






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






33. 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.






34. Is analogous to toughness.






35. - 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






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






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






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






39. Diffuse image






40. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






41. 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.






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






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






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






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






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






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






48. 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






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






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