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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. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.
True Stress
Extrinsic Semiconductors
M is known as what?
Insulators
2. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.
Superconductivity
Meissner Effect
True Stress
Why materials fail in service
3. Another optical property - Depends on the wavelength of the visible spectrum.
Opacifiers
Large Hardness
Dependence of Heat Capacity on Temperature
Color
4. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress
Ductile Materials
Etching
Opacity
Thermal Stresses
5. There is always some statistical distribution of flaws or defects.
There is no perfect material?
True Strain
Hard Magnetic Materials
True Stress
6. Typical loading conditions are _____ enough to break all inter-atomic bonds
Why do ceramics have larger bonding energy?
Not severe
Film Deposition
Internal magnetic moments
7. Wet: isotropic - under cut Dry: ansiotropic - directional
Plastic Deformation (Metals)
Thermal Conductivity
Etching
Thermal expansion
8. Becomes harder (more strain) to stretch (elongate)
Fourier's Law
Thermal Shock Resistance
Work Hardening
Griffith Crack Model
9. Cracks pass through grains - often along specific crystal planes.
Impact - Toughness
Transgranular Fracture
Large Hardness
Bending tests
10. Occur when lots of dislocations move.
The Transistor
Intrinsic Semiconductors
Diamagnetic Materials
Slip Bands
11. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.
Soft Magnetic Materials
What do magnetic moments arise from?
Metals: Resistivity vs. T - Impurities
IC Devices: P-N Rectifying Junction
12. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.
Liquid Crystal Displays (LCD's)
Reflectance of Non-Metals
Metallization
Ductile Materials
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)
Ductile Fracture
Valence band
Bending tests
Rockwell
14. 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
How an LCD works
Not severe
Opaque
Transgranular Fracture
15. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)
M is known as what?
Stages of Failure: Ductile Fracture
Luminescence
Engineering Fracture Performance
16. # of thermally generated electrons = # of holes (broken bonds)
Yield and Reliability
Thermal Expansion: Symmetric curve
Intrinsic Semiconductors
To improve fatigue life
17. 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
True Strain
Transgranular Fracture
4 Types of Magnetism
HB (Brinell Hardness)
18. 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.
Griffith Crack Model
Magnetic Storage
Holloman Equation
M is known as what?
19. 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
Iron-Silicon Alloy in Transformer Cores
Holloman Equation
Bending tests
Thermal Shock Resistance
20. Dimples on fracture surface correspond to microcavities that initiate crack formation.
Work Hardening
Brittle Fracture
Engineering Fracture Performance
Ductile Fracture
21. Diffuse image
Liquid Crystal Displays (LCD's)
Translucent
Specific Heat
Stress Intensity values
22. Ability to transmit a clear image - The image is clear.
Why do ceramics have larger bonding energy?
Coherent
Transparent
Transgranular Fracture
23. Metals are good conductors since their _______is only partially filled.
Valence band
4 Types of Magnetism
Stages of Failure: Ductile Fracture
Internal magnetic moments
24. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values
What do magnetic moments arise from?
Color
Thermal Conductivity
Thermal Stresses
25. The ability of a material to be rapidly cooled and not fracture
Charpy or Izod test
Thermal Conductivity
Thermal Shock Resistance
Bending tests
26. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.
Fatigue
Transparent
Electromigration
Heat Capacity from an Atomic Prospective
27. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.
Plastic Deformation (Metals)
Opacifiers
Insulators
Why materials fail in service
28. 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.
Iron-Silicon Alloy in Transformer Cores
Griffith Crack Model
Elastic Deformation
Shear and Tensile Stress
29. 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
To improve fatigue life
Reflection of Light for Metals
Why do ceramics have larger bonding energy?
30. For a metal - there is no ______ - only reflection
Refraction
Coefficient of Thermal Expansion
Elastic Deformation
Meissner Effect
31. The size of the material changes with a change in temperature - polymers have the largest values
Generation of a Magnetic Field - Vacuum
Luminescence
Coefficient of Thermal Expansion
Stress Intensity values
32. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)
M is known as what?
Rockwell
Two kinds of Reflection
Luminescence examples
33. Resistance to plastic deformation of cracking in compression - and better wear properties.
Response to a Magnetic Field
IC Devices: P-N Rectifying Junction
Hysteresis and Permanent Magnetization
Large Hardness
34. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.
Insulators
Thermal Shock Resistance
Lithography
Relative Permeability
35. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.
Modulus of Rupture (MOR)
Impact energy
Why materials fail in service
Impact - Toughness
36. 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.
Hard Magnetic Materials
Plastic Deformation (Metals)
M is known as what?
Insulators
37. Light Amplification by Stimulated Emission of Radiation
LASER
Why do ceramics have larger bonding energy?
Ductile Materials
Critical Properties of Superconductive Materials
38. 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.
Heat Capacity
Opacity
Scattering
Force Decomposition
39. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is
Soft Magnetic Materials
Incident Light
Relative Permeability
Insulators
40. 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
Critical Properties of Superconductive Materials
Griffith Crack Model
Transgranular Fracture
Slip Bands
41. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.
Brittle Fracture
Thermal Expansion: Symmetric curve
Luminescence
Liquid Crystal Displays (LCD's)
42. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION
43. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe
Electrical Conduction
Soft Magnetic Materials
Generation of a Magnetic Field - Within a Solid Material
Reflectance of Non-Metals
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.
Large Hardness
Valence band
Luminescence examples
Refraction
45. Process by which metal atoms diffuse because of a potential.
Translucent
Sparkle of Diamonds
Electromigration
Elastic Deformation
46. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.
47. 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
High impact energy
Bending tests
Liquid Crystal Displays (LCD's)
The Transistor
48. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.
Stages of Failure: Ductile Fracture
Influence of Temperature on Magnetic Behavior
Liquid Crystal Displays (LCD's)
Specific Heat
49. 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.
Why materials fail in service
Coherent
Opaque
Fourier's Law
50. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)
Thermal Conductivity
Force Decomposition
Thermal expansion
Film Deposition