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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. Occur when lots of dislocations move.
Engineering Fracture Performance
Slip Bands
Ductile Fracture
Critical Properties of Superconductive Materials
2. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.
Why fracture surfaces have faceted texture
Superconductivity
Brittle Fracture
Pure Semiconductors: Conductivity vs. T
3. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals
Generation of a Magnetic Field - Vacuum
Shear and Tensile Stress
Impact - Toughness
Pure Semiconductors: Conductivity vs. T
4. 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.
There is no perfect material?
Opacity
Superconductivity
True Stress
5. 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
M is known as what?
Reflection of Light for Metals
Intrinsic Semiconductors
Specific Heat
6. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.
Coherent
Why fracture surfaces have faceted texture
Thermal Shock Resistance
Domains in Ferromagnetic & Ferrimagnetic Materials
7. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in
Impact - Toughness
Transparent
Critical Properties of Superconductive Materials
Thermal Expansion: Asymmetric curve
8. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.
Plastic Deformation (Metals)
Not severe
Heat Capacity from an Atomic Prospective
Superconductivity
9. Materials change size when temperature is changed
Hysteresis and Permanent Magnetization
Critical Properties of Superconductive Materials
Thermal expansion
Diamagnetic Materials
10. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)
Yield and Reliability
HB (Brinell Hardness)
Hysteresis and Permanent Magnetization
Film Deposition
11. 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
4 Types of Magnetism
Opaque
What do magnetic moments arise from?
Stress Intensity values
12. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.
Liquid Crystal Displays (LCD's)
Why materials fail in service
Brittle Fracture
Etching
13. 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.
Thermal Conductivity
Magnetic Storage
Shear and Tensile Stress
Stress Intensity values
14. 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.
Insulators
Internal magnetic moments
Thermal expansion
How to gage the extent of plastic deformation
15. Stress concentration at a crack tips
High impact energy
Work Hardening
Coefficient of Thermal Expansion
Griffith Crack Model
16. Is analogous to toughness.
Relative Permeability
Ductile Fracture
Impact energy
Incident Light
17. 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.
Iron-Silicon Alloy in Transformer Cores
Opaque
Ductile-to-Brittle Transition
Linewidth
18. 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.
Brittle Ceramics
Diamagnetic Materials
Scattering
How an LCD works
19. If a material has ________ - then the field generated by those moments must be added to the induced field.
Internal magnetic moments
Impact - Toughness
Hysteresis and Permanent Magnetization
Domains in Ferromagnetic & Ferrimagnetic Materials
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)
Rockwell
Magnetic Storage
Fourier's Law
Response to a Magnetic Field
21. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.
What do magnetic moments arise from?
Opaque
Why do ceramics have larger bonding energy?
Pure Semiconductors: Conductivity vs. T
22. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.
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23. These materials are relatively unaffected by magnetic fields.
Diamagnetic Materials
Influence of Temperature on Magnetic Behavior
Where does DBTT occur?
Reflectance of Non-Metals
24. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow
Thermal Expansion: Symmetric curve
IC Devices: P-N Rectifying Junction
Stages of Failure: Ductile Fracture
Generation of a Magnetic Field - Vacuum
25. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel
Reflection of Light for Metals
Two kinds of Reflection
Hard Magnetic Materials
Opaque
26. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.
Valence band
Fatigue
Stress Intensity values
Oxidation
27. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress
Large Hardness
Stages of Failure: Ductile Fracture
Thermal Stresses
Generation of a Magnetic Field - Vacuum
28. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)
Coherent
Force Decomposition
Response to a Magnetic Field
Transgranular Fracture
29. 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
Yield and Reliability
How to gage the extent of plastic deformation
HB (Brinell Hardness)
Critical Properties of Superconductive Materials
30. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))
How to gage the extent of plastic deformation
True Stress
Modulus of Rupture (MOR)
Coefficient of Thermal Expansion
31. 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.
How an LCD works
IC Devices: P-N Rectifying Junction
Heat Capacity
Ductile Materials
32. 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."
Thermal Expansion: Symmetric curve
Charpy or Izod test
Elastic Deformation
Response to a Magnetic Field
33. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture
Pure Semiconductors: Conductivity vs. T
Not severe
Stages of Failure: Ductile Fracture
Lithography
34. Process by which metal atoms diffuse because of a potential.
Electromigration
Holloman Equation
Refraction
LASER
35. Wet: isotropic - under cut Dry: ansiotropic - directional
Luminescence
Why fracture surfaces have faceted texture
Thermal Conductivity
Etching
36. Second phase particles with n > glass.
Engineering Fracture Performance
Opacifiers
Lithography
Charpy or Izod test
37. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB
HB (Brinell Hardness)
Conduction & Electron Transport
4 Types of Magnetism
Linewidth
38. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)
Specific Heat
Heat Capacity from an Atomic Prospective
Two kinds of Reflection
Response to a Magnetic Field
39. 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
Ductile-to-Brittle Transition
Hardness
The Transistor
There is no perfect material?
40. 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
Modulus of Rupture (MOR)
Reflectance of Non-Metals
How an LCD works
Transgranular Fracture
41. Sigma=ln(li/lo)
Lithography
Oxidation
Impact - Toughness
True Strain
42. Another optical property - Depends on the wavelength of the visible spectrum.
Insulators
Brittle Fracture
Color
Internal magnetic moments
43. 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
IC Devices: P-N Rectifying Junction
Refraction
Pure Semiconductors: Conductivity vs. T
Rockwell
44. Elastic means reversible! This is not a permanent deformation.
Linewidth
Thermal Shock Resistance
Elastic Deformation
Meissner Effect
45. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.
To improve fatigue life
Why materials fail in service
What do magnetic moments arise from?
Modulus of Rupture (MOR)
46. Ability to transmit a clear image - The image is clear.
Internal magnetic moments
Oxidation
Film Deposition
Transparent
47. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)
Meissner Effect
Yield and Reliability
Magnetic Storage Media Types
Impact - Toughness
48. 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
Thermal Expansion: Symmetric curve
Iron-Silicon Alloy in Transformer Cores
Work Hardening
Two ways to measure heat capacity
49. There is always some statistical distribution of flaws or defects.
Specific Heat
There is no perfect material?
Brittle Materials
Thermal Shock Resistance
50. Increase temperature - no increase in interatomic separation - no thermal expansion
Metals: Resistivity vs. T - Impurities
Coefficient of Thermal Expansion
Thermal Expansion: Symmetric curve
Heat Capacity