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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. 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.






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






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






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






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






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






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






8. 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






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






10. Undergo little or no plastic deformation.






11. 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






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






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






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






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






16. 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






17. 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






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






19. Typical loading conditions are _____ enough to break all inter-atomic bonds






20. 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)






21. These materials are relatively unaffected by magnetic fields.






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






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






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






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






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






27. 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






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






29. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






30. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






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






32. 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.






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. Ohms Law: voltage drop = current * resistance






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






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






37. 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.






38. 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






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






40. 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.






41. Different orientation of cleavage planes in grains.






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






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






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






45. 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






46. 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






47. Light Amplification by Stimulated Emission of Radiation






48. Width of smallest feature obtainable on Si surface






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






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