Test your basic knowledge |

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






2. 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.






3. 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






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






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






6. 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)






7. 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






8. 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.






9. 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.






10. - 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






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






12. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






13. Occur when lots of dislocations move.






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






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






16. Cracks propagate along grain boundaries.






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






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






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






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






21. Metals are good conductors since their _______is only partially filled.






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






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






24. High toughness; material resists crack propagation.






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






26. 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






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






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






29. Emitted light is in phase






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






31. 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






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






33. Sigma=ln(li/lo)






34. Is analogous to toughness.






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






36. 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






37. Undergo little or no plastic deformation.






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






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






40. Materials change size when temperature is changed






41. Width of smallest feature obtainable on Si surface






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






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






44. 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.






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






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






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






48. Different orientation of cleavage planes in grains.






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






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