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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. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.
Opaque
Why materials fail in service
Reflectance of Non-Metals
Brittle Materials
2. Ohms Law: voltage drop = current * resistance
Electrical Conduction
Opacity
There is no perfect material?
Sparkle of Diamonds
3. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.
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4. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.
Sparkle of Diamonds
True Strain
Etching
Fatigue
5. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.
What do magnetic moments arise from?
Why materials fail in service
Engineering Fracture Performance
Thermal expansion
6. These materials are relatively unaffected by magnetic fields.
Thermal expansion
IC Devices: P-N Rectifying Junction
M is known as what?
Diamagnetic Materials
7. Elastic means reversible! This is not a permanent deformation.
Brittle Materials
Transparent
Elastic Deformation
Why materials fail in service
8. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.
Holloman Equation
Metallization
Generation of a Magnetic Field - Within a Solid Material
To improve fatigue life
9. Without passing a current a continually varying magnetic field will cause a current to flow
Elastic Deformation
Magnetic Storage Media Types
Stress Intensity values
Response to a Magnetic Field
10. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.
Work Hardening
Electromigration
Fatigue
Metallization
11. 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.
Shear and Tensile Stress
Not severe
Ductile-to-Brittle Transition
True Strain
12. The ability of a material to be rapidly cooled and not fracture
Coherent
Linewidth
Thermal Shock Resistance
Brittle Ceramics
13. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by
Generation of a Magnetic Field - Vacuum
Magnetic Storage
Pure Semiconductors: Conductivity vs. T
How an LCD works
14. Another optical property - Depends on the wavelength of the visible spectrum.
Color
Extrinsic Semiconductors
High impact energy
Translucent
15. 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
Metallization
Extrinsic Semiconductors
Sparkle of Diamonds
Critical Properties of Superconductive Materials
16. 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.
Critical Properties of Superconductive Materials
Soft Magnetic Materials
Rockwell
Scattering
17. Resistance to plastic deformation of cracking in compression - and better wear properties.
Response to a Magnetic Field
What do magnetic moments arise from?
Insulators
Large Hardness
18. 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.
To improve fatigue life
Hysteresis and Permanent Magnetization
Reflectance of Non-Metals
True Strain
19. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.
Thermal Expansion: Asymmetric curve
Bending tests
Stress Intensity values
Influence of Temperature on Magnetic Behavior
20. 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."
Insulators
Charpy or Izod test
Linewidth
Heat Capacity from an Atomic Prospective
21. Becomes harder (more strain) to stretch (elongate)
Metals: Resistivity vs. T - Impurities
Domains in Ferromagnetic & Ferrimagnetic Materials
Work Hardening
Thermal Expansion: Symmetric curve
22. A high index of refraction (n value) allows for multiple internal reactions.
Sparkle of Diamonds
Reflection of Light for Metals
HB (Brinell Hardness)
Incident Light
23. Light Amplification by Stimulated Emission of Radiation
LASER
Linewidth
Relative Permeability
Transgranular Fracture
24. 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
Luminescence
Impact energy
Oxidation
Color
25. 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
Thermal Expansion: Asymmetric curve
Coefficient of Thermal Expansion
Domains in Ferromagnetic & Ferrimagnetic Materials
26. High toughness; material resists crack propagation.
Thermal Stresses
Stages of Failure: Ductile Fracture
Hysteresis and Permanent Magnetization
High impact energy
27. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.
Ductile-to-Brittle Transition
Pure Semiconductors: Conductivity vs. T
Thermal Shock Resistance
Transgranular Fracture
28. 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
True Strain
Generation of a Magnetic Field - Vacuum
Thermal Conductivity
Refraction
29. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals
Pure Semiconductors: Conductivity vs. T
Hardness
Specific Heat
Heat Capacity
30. 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.
Metallization
Transparent
Insulators
Domains in Ferromagnetic & Ferrimagnetic Materials
31. 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
How to gage the extent of plastic deformation
Two ways to measure heat capacity
Magnetic Storage
Holloman Equation
32. 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
Transgranular Fracture
The three modes of crack surface displacement
Thermal Stresses
How an LCD works
33. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.
There is no perfect material?
Refraction
Conduction & Electron Transport
Response to a Magnetic Field
34. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)
Film Deposition
Heat Capacity
Color
Ductile-to-Brittle Transition
35. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.
Extrinsic Semiconductors
Iron-Silicon Alloy in Transformer Cores
Hysteresis and Permanent Magnetization
Coefficient of Thermal Expansion
36. 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
Translucent
Opacifiers
Electrical Conduction
Stress Intensity Factor
37. 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.
Slip Bands
Opacity
LASER
Energy States: Insulators and Semiconductors
38. 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
To improve fatigue life
There is no perfect material?
Reflection of Light for Metals
Incoherent
39. 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
Color
Intergranular Fracture
Oxidation
Impact - Toughness
40. 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
Lithography
Holloman Equation
The Transistor
Thermal Conductivity
41. Occur when lots of dislocations move.
Slip Bands
Why do ceramics have larger bonding energy?
Film Deposition
Where does DBTT occur?
42. Process by which metal atoms diffuse because of a potential.
Ductile Materials
Color
Electromigration
Transparent
43. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION
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44. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is
LASER
Impact - Toughness
Incident Light
Plastic Deformation (Metals)
45. 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
Insulators
Iron-Silicon Alloy in Transformer Cores
Yield and Reliability
Brittle Fracture
46. 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.
Opaque
Paramagnetic Materials
Film Deposition
To improve fatigue life
47. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid
Why do ceramics have larger bonding energy?
Incoherent
Response to a Magnetic Field
Generation of a Magnetic Field - Within a Solid Material
48. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB
Metallization
Insulators
HB (Brinell Hardness)
Magnetic Storage
49. Increase temperature - increase in interatomic separation - thermal expansion
Thermal Expansion: Asymmetric curve
Sparkle of Diamonds
Dependence of Heat Capacity on Temperature
Holloman Equation
50. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.
How an LCD works
Heat Capacity from an Atomic Prospective
IC Devices: P-N Rectifying Junction
Refraction