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Test your basic knowledge |
Engineering Materials
Start Test
Study First
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. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.
Thermal Conductivity
Large Hardness
The three modes of crack surface displacement
To improve fatigue life
2. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow
IC Devices: P-N Rectifying Junction
Generation of a Magnetic Field - Within a Solid Material
Opacity
Impact - Toughness
3. Sigma=ln(li/lo)
True Strain
Shear and Tensile Stress
Opacifiers
Electromigration
4. -> fluorescent light - electron transitions occur randomly - light waves are out of phase with each other.
Incoherent
Scattering
Oxidation
Influence of Temperature on Magnetic Behavior
5. Materials change size when temperature is changed
Hardness
Valence band
Elastic Deformation
Thermal expansion
6. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW
Metals: Resistivity vs. T - Impurities
High impact energy
Griffith Crack Model
True Stress
7. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.
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8. 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)
Reflection of Light for Metals
Generation of a Magnetic Field - Vacuum
Stress Intensity Factor
4 Types of Magnetism
9. Becomes harder (more strain) to stretch (elongate)
Coherent
Fourier's Law
Work Hardening
Liquid Crystal Displays (LCD's)
10. Metals are good conductors since their _______is only partially filled.
Not severe
The three modes of crack surface displacement
Valence band
Ductile Materials
11. 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.
Impact energy
Reflectance of Non-Metals
Heat Capacity
Hardness
12. Typical loading conditions are _____ enough to break all inter-atomic bonds
Metallization
Not severe
Valence band
Yield and Reliability
13. 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
Opacifiers
Impact energy
How an LCD works
Thermal Shock Resistance
14. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.
Electrical Conduction
Heat Capacity
Critical Properties of Superconductive Materials
Brittle Fracture
15. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.
Pure Semiconductors: Conductivity vs. T
Thermal Stresses
Specific Heat
What do magnetic moments arise from?
16. 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
Energy States: Insulators and Semiconductors
Why fracture surfaces have faceted texture
Color
Reflection of Light for Metals
17. Undergo little or no plastic deformation.
Brittle Materials
IC Devices: P-N Rectifying Junction
Energy States: Insulators and Semiconductors
Refraction
18. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.
Scattering
Conduction & Electron Transport
What do magnetic moments arise from?
Why fracture surfaces have faceted texture
19. 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
Brittle Fracture
How to gage the extent of plastic deformation
Stages of Failure: Ductile Fracture
Meissner Effect
20. - 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
Luminescence
Paramagnetic Materials
Etching
Critical Properties of Superconductive Materials
21. Another optical property - Depends on the wavelength of the visible spectrum.
Color
Yield and Reliability
Engineering Fracture Performance
Not severe
22. Process by which metal atoms diffuse because of a potential.
Electromigration
Diamagnetic Materials
Refraction
Energy States: Insulators and Semiconductors
23. 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."
Brittle Materials
True Stress
Relative Permeability
Charpy or Izod test
24. 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
Internal magnetic moments
Yield and Reliability
Slip Bands
Etching
25. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB
Thermal Expansion: Symmetric curve
HB (Brinell Hardness)
Influence of Temperature on Magnetic Behavior
Brittle Materials
26. Cracks pass through grains - often along specific crystal planes.
Thermal Stresses
Transgranular Fracture
Stages of Failure: Ductile Fracture
Shear and Tensile Stress
27. 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.
Generation of a Magnetic Field - Vacuum
Shear and Tensile Stress
Intrinsic Semiconductors
Two kinds of Reflection
28. These materials are relatively unaffected by magnetic fields.
To improve fatigue life
Scattering
Soft Magnetic Materials
Diamagnetic Materials
29. Second phase particles with n > glass.
Opacifiers
Two ways to measure heat capacity
Internal magnetic moments
Thermal Conductivity
30. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.
Linewidth
Ductile-to-Brittle Transition
Hardness
Meissner Effect
31. 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.
Plastic Deformation (Metals)
Opacifiers
Film Deposition
Metallization
32. Because of ionic & covalent-type bonding.
Opacity
Why do ceramics have larger bonding energy?
The three modes of crack surface displacement
Reflection of Light for Metals
33. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.
Meissner Effect
Luminescence
High impact energy
Force Decomposition
34. 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
Magnetic Storage
Fatigue
Transgranular Fracture
Critical Properties of Superconductive Materials
35. 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)
Translucent
Rockwell
How an LCD works
Thermal Expansion: Asymmetric curve
36. 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
Thermal Expansion: Symmetric curve
Oxidation
Ductile Materials
Griffith Crack Model
37. Specific heat = energy input/(mass*temperature change)
Force Decomposition
Soft Magnetic Materials
Generation of a Magnetic Field - Within a Solid Material
Specific Heat
38. Ability to transmit a clear image - The image is clear.
Linewidth
Incident Light
Griffith Crack Model
Transparent
39. Elastic means reversible! This is not a permanent deformation.
Elastic Deformation
Intrinsic Semiconductors
Ductile Fracture
Linewidth
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
Superconductivity
Incoherent
Refraction
Hysteresis and Permanent Magnetization
41. 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
Critical Properties of Superconductive Materials
Extrinsic Semiconductors
Opaque
Iron-Silicon Alloy in Transformer Cores
42. For a metal - there is no ______ - only reflection
Yield and Reliability
Opacity
Where does DBTT occur?
Refraction
43. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.
Iron-Silicon Alloy in Transformer Cores
Ductile Fracture
Two ways to measure heat capacity
Charpy or Izod test
44. Increase temperature - no increase in interatomic separation - no thermal expansion
Thermal Expansion: Symmetric curve
Why materials fail in service
Electromigration
Diamagnetic Materials
45. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION
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46. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)
Film Deposition
Liquid Crystal Displays (LCD's)
Sparkle of Diamonds
Reflection of Light for Metals
47. 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.
HB (Brinell Hardness)
Magnetic Storage Media Types
Luminescence examples
Dependence of Heat Capacity on Temperature
48. Diffuse image
Metals: Resistivity vs. T - Impurities
Why fracture surfaces have faceted texture
Translucent
Brittle Ceramics
49. Undergo extensive plastic deformation prior to failure.
Refraction
Ductile Materials
True Strain
Incoherent
50. 1. Tensile (opening) 2. Sliding 3. Tearing
Color
Intrinsic Semiconductors
Scattering
The three modes of crack surface displacement