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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. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.
Oxidation
Two ways to measure heat capacity
Linewidth
Generation of a Magnetic Field - Within a Solid Material
2. Typical loading conditions are _____ enough to break all inter-atomic bonds
Critical Properties of Superconductive Materials
Not severe
Brittle Fracture
Magnetic Storage
3. These materials are relatively unaffected by magnetic fields.
Insulators
Diamagnetic Materials
Thermal Shock Resistance
To improve fatigue life
4. High toughness; material resists crack propagation.
Superconductivity
High impact energy
Thermal expansion
Translucent
5. 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.
Thermal Expansion: Asymmetric curve
Thermal Stresses
Opaque
Metallization
6. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress
To improve fatigue life
Thermal Stresses
Intrinsic Semiconductors
Insulators
7. 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
Hysteresis and Permanent Magnetization
IC Devices: P-N Rectifying Junction
Impact energy
Fatigue
8. 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.
Luminescence
Incoherent
Hardness
LASER
9. Process by which metal atoms diffuse because of a potential.
Engineering Fracture Performance
To improve fatigue life
Electromigration
Incoherent
10. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.
Meissner Effect
True Strain
IC Devices: P-N Rectifying Junction
To improve fatigue life
11. A measure of the ease with which a B field can be induced inside a material.
Rockwell
Engineering Fracture Performance
Relative Permeability
Coefficient of Thermal Expansion
12. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)
Translucent
Critical Properties of Superconductive Materials
Incident Light
Two kinds of Reflection
13. 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)
Where does DBTT occur?
IC Devices: P-N Rectifying Junction
Rockwell
Why fracture surfaces have faceted texture
14. 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.
Paramagnetic Materials
Insulators
Plastic Deformation (Metals)
Thermal Expansion: Symmetric curve
15. Metals are good conductors since their _______is only partially filled.
Insulators
Intrinsic Semiconductors
Etching
Valence band
16. 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
Generation of a Magnetic Field - Vacuum
Fourier's Law
Sparkle of Diamonds
How an LCD works
17. Dimples on fracture surface correspond to microcavities that initiate crack formation.
Ductile Fracture
Translucent
Metallization
IC Devices: P-N Rectifying Junction
18. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.
Incoherent
Fatigue
Conduction & Electron Transport
The Transistor
19. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)
Stress Intensity Factor
Translucent
Film Deposition
Generation of a Magnetic Field - Within a Solid Material
20. The ability of a material to be rapidly cooled and not fracture
Linewidth
Thermal Shock Resistance
Brittle Materials
Response to a Magnetic Field
21. Stress concentration at a crack tips
Griffith Crack Model
Response to a Magnetic Field
Holloman Equation
Not severe
22. 1. Tensile (opening) 2. Sliding 3. Tearing
The three modes of crack surface displacement
Stress Intensity values
Hysteresis and Permanent Magnetization
To improve fatigue life
23. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.
Work Hardening
Superconductivity
Generation of a Magnetic Field - Within a Solid Material
Why fracture surfaces have faceted texture
24. If a material has ________ - then the field generated by those moments must be added to the induced field.
Luminescence
Internal magnetic moments
What do magnetic moments arise from?
Rockwell
25. Undergo little or no plastic deformation.
Extrinsic Semiconductors
Valence band
Brittle Materials
Opacity
26. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB
HB (Brinell Hardness)
Fatigue
Plastic Deformation (Metals)
Intergranular Fracture
27. Increase temperature - increase in interatomic separation - thermal expansion
Thermal Expansion: Asymmetric curve
Critical Properties of Superconductive Materials
Engineering Fracture Performance
Force Decomposition
28. 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
Critical Properties of Superconductive Materials
Two kinds of Reflection
Reflection of Light for Metals
Pure Semiconductors: Conductivity vs. T
29. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals
Pure Semiconductors: Conductivity vs. T
Iron-Silicon Alloy in Transformer Cores
Intrinsic Semiconductors
Specific Heat
30. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.
Coefficient of Thermal Expansion
Fatigue
Work Hardening
Film Deposition
31. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.
Refraction
Thermal Stresses
Holloman Equation
High impact energy
32. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.
Heat Capacity from an Atomic Prospective
Scattering
Large Hardness
Generation of a Magnetic Field - Vacuum
33. Cracks pass through grains - often along specific crystal planes.
Transgranular Fracture
Generation of a Magnetic Field - Within a Solid Material
Sparkle of Diamonds
Electromigration
34. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.
Influence of Temperature on Magnetic Behavior
Two ways to measure heat capacity
Brittle Ceramics
M is known as what?
35. 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
Incoherent
Why materials fail in service
Energy States: Insulators and Semiconductors
36. Cracks propagate along grain boundaries.
Intergranular Fracture
Heat Capacity
Etching
Work Hardening
37. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)
Engineering Fracture Performance
Opacifiers
Brittle Materials
Fatigue
38. 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.
Brittle Ceramics
Opacity
There is no perfect material?
Critical Properties of Superconductive Materials
39. 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."
Charpy or Izod test
Two kinds of Reflection
Bending tests
Rockwell
40. 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.
Stages of Failure: Ductile Fracture
Specific Heat
Reflectance of Non-Metals
Valence band
41. 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
Large Hardness
Two kinds of Reflection
Stress Intensity Factor
Shear and Tensile Stress
42. Specific heat = energy input/(mass*temperature change)
Generation of a Magnetic Field - Within a Solid Material
Specific Heat
Linewidth
LASER
43. Occur when lots of dislocations move.
Fourier's Law
Slip Bands
Intrinsic Semiconductors
Ductile Materials
44. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.
Why materials fail in service
Conduction & Electron Transport
Slip Bands
Ductile-to-Brittle Transition
45. 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.
Opacity
What do magnetic moments arise from?
Energy States: Insulators and Semiconductors
Luminescence examples
46. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.
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47. 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.
Incoherent
Thermal Expansion: Symmetric curve
Shear and Tensile Stress
Slip Bands
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.
Reflection of Light for Metals
Impact energy
Modulus of Rupture (MOR)
Sparkle of Diamonds
49. - 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
The three modes of crack surface displacement
Relative Permeability
Why fracture surfaces have faceted texture
50. 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
Color
The Transistor
Transparent
Influence of Temperature on Magnetic Behavior