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






2. Second phase particles with n > glass.






3. Sigma=ln(li/lo)






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






5. 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.






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






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. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






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






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. Materials change size when temperature is changed






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






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






14. 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






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






16. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






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






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






19. 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






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






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






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






24. 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.






25. 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.






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






27. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






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






29. Undergo little or no plastic deformation.






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






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






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






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






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






35. 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






36. Occur when lots of dislocations move.






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






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






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






40. They are used to assess properties of ceramics & glasses.






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






42. 1. Tensile (opening) 2. Sliding 3. Tearing






43. Ohms Law: voltage drop = current * resistance






44. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






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






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






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






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






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






50. 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.