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ME 280 Materials > Final > Flashcards

Final Flashcards

1
Q

What are the different types of cast iron

A 
Cast White, 
Gray, 
Compacted Graphite(CG), 
Ductile
(ductility increases from top-bottom)
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2
Q

What is the eutectic form of Cast White

A

Fe3C

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3
Q

What is the eutectic form of Gray Iron

A

Graphite Flakes

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4
Q

What is the eutectic form of Compacted Graphite

A

Graphite Balls & Blunt Flakes

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5
Q

What is the eutectic form of Ductile Iron

A

Graphite Balls

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6
Q

What is the difference between steel and cast iron?

A

No eutectic solidification in steel

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7
Q

How does the eutectic form of carbon in cast irons affect ductility?

A

?

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8
Q

How can you tell the carbon level in steel from its four-digit designation? Last 2 or 3 digits divided by 100. So for example

A

?

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9
Q

What is steel?

A

a hard, strong, gray or bluish-gray alloy of iron with carbon and usually other elements, used extensively as a structural and fabricating material.

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10
Q

What is rust? How can it be minimized in steel alloys?

A

a reddish- or yellowish-brown flaky coating of iron oxide that is formed on iron or steel by oxidation(Fe2O3+nH2O), keep away from moisture

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11
Q

What is a low alloy steel

A

type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel

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12
Q

How are gray and ductile irons classified by manufacturers?

A

Gray- by tensile strength (ex.Class 40)

Ductile- by Tensile/yield/elongation (ex.60/55/12)

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13
Q

Would you expect a gray or a ductile iron to be easier to machine? Why?

A

Gray Iron, Graphite flakes lead to more brittleness and poor ductility.

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14
Q

What are the two basic versions of aluminum alloys?

A

Wrought and Cast

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15
Q

Which has a higher melting point, aluminum or steel?

A

Steel

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16
Q

Which has a higher density, aluminum or steel?

A

Steel (has higher modulus)

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17
Q

Do aluminum alloys have good corrosion resistance?

A

yes

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18
Q

List some typical properties for copper alloys? Why are they chosen for electrical applications?

A

Pretty, and good conductor

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19
Q

What is a brass? What is a bronze?

A

Brass- Cu+Zn

Bronze - Cu+otherstuff

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20
Q

What are some typical applications for titanium alloys? Why are they used?

A

Expensive, aerospace(lighter than steel), Biomedical( good compatibility)

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21
Q

What is a superalloy?

A

Alloys can work at high temperature, high stress, and high oxidizing atmospheres.

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22
Q

The majority of metals processing starts with what type of processing technique?

A

Casting

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23
Q

What is the difference between a wrought and a cast product?

A

Wrought- deformed to shape

Cast- not deformed to shape

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24
Q

What are some solid forming techniques?

A

Rolling, extrusion, pressing, machining

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25
Q

Describe how powder processing of a metal and a ceramic is done. What is the advantage of this process?

A

Power -> pressuring, slip casting + heat ->
powders change to solid(melting not required).
-Reduces machining for complicated shapes.

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26
Q

What is the most common machining technique? What is difficult about this technique?

A

Drilling, causes heat in a hole

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27
Q

What is turning? What machine is it performed on?

A

Lathe (turning), machine tool that rotates the work piece on its axis to perform various operations,

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28
Q

What is milling?

A

Grinding or crushing material with use of a milling machine

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29
Q

What is the difference between welding, brazing and soldering?

A

Welding- high temp, partially melt materials
Brazing- melt a joining metal
Soldering- like brazing pipes & wires.

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30
Q

Let’s talk about porcelain

A

Ceramic- doesn’t melt
coated with glass (glass phase does melt, fills holes)
smooth surface

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31
Q

What is cement and how is it processed?

A

mixed with water and castable

forms solid by chemical reaction. ( takes times)

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32
Q

How is the fracture toughness increased in transformation toughened zirconia

A

Heat treat to stabilize phase, when crack appears transforms to equilibrium phase and changes volume.

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33
Q

What is the most common oxide glass?

A

Silica (SiO2)

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34
Q

How is glass tempered and what is the advantage of tempered glass?

A

Heat treated for thicker glass to add compressive stress to surface (stronger).
more durable, smoother and sharper

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35
Q

How is glass made bullet proof? How about soundproof?

A

Bulletproof- composite, layer of glass and polymer.

sound proof- more glass layers

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36
Q

What is the difference between a thermoplastic and a thermoset?

A

Thermoplastic- secondary bonding between chains

Thermoset- primary bonding throughout

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37
Q

Would you expect a linear or a branched thermoplastic to be stronger? Why?

A

Branched, because it gets tangled between other connection (ex. sliding to tree branches together wont go smoothly)

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38
Q

What effect does average chain length have on the mechanical properties of a thermoplastic polymer?

A

chain length increases and gets stiffer & stronger.

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39
Q

What effect does larger side groups have on a thermoplastic polymer

A

Makes them stronger

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40
Q

What effect does increased crystallinity have on a thermoplastic polymer?

A

stronger and more secondary bonding

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41
Q

What is a copolymer?

A

mixed polymers

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42
Q

Are thermosets crystalline?

A

No

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43
Q

What are typical properties for an elastomer (rubber)?

A

Low stiffness, strength, and High ductility

44
Q

Describe how thermoset and thermoplastic elastomers are structured and how this affects their deformation?

A

Thermosets have higher strength and lower ductility.

45
Q

What is the difference between a composite and a metal or ceramic alloy?

A

composite is a mechanical mix of different materials. and metal or ceramics are not.

46
Q

What is the definition of a dispersion strengthened composite and when and why are they used?

A

Dispersion strength- metal with ceramic particles,(tiny)

add strength good with high temps

47
Q

What is the definition of a particulate composite? Give typical examples. When and why are they used?

A

big particles in matrix

48
Q

What is the definition of a fiber-reinforced composite? When and why are they used?

A

Polymer matrix with fibers for strengthening.

49
Q

What is the effect of fiber orientation on the strength of a fiber-reinforced composite

A

strength highest along length of fiber. and lowest perpendicular to length.

50
Q

What is the effect of fiber aspect ratio on a fiber-reinforced composite?

A

longer skinny fibers makes better strength

51
Q

Why do most fiber-reinforced composites have a thermoset matrix? Why is there a push to move to thermoplastic matrices?

A

easier to process not as viscous, recycling.

52
Q

What is a laminant? Give a typical example.

A

layer composites

53
Q

What is a bimetallic? Give a typical example?

A

2 metals joined together but not melted together.

54
Q

What is a sandwich composite? When are they used?

A

outer layers rigid inner layers light weight.

55
Q

How are glass products produced

A

blow - roll - plate glass - float on molten tin

56
Q

How are polymer fibers produced?

A

liquid - die with small holes

57
Q

How are carbon and graphite fibers produced?

A

burn polymers fibers

58
Q

What is injection molding?

A

push molten metal into die metal polymer into die and let it harden

59
Q

Describe the slip casting process, what is it used for

A

Ceramics - take ceramic powder add to water - pour into porous plaster of mold - water sucked into mold leaves ceramic shell.

60
Q

What is an interesting property of Teflon

A

Slippery!

61
Q

What are typical additives for plastics and why are they added?

A

dye for color, filler retardant, and plasti sizer for more ductility.

62
Q

Would you expect he corrosion rate to increase or decrease with a) increased temperature, b) increased stress on the material and c) increased liquid motion

A

all increases

63
Q

What is uniform corrosion? How is it avoided?

A

corrosion uniform (avoided by coating and keeping dry)

64
Q

What is galvanic corrosion? How is it avoided?

A

2 different metals (avoided by using metals with similar activity, add sacrificial metal.)

65
Q

What is crevice corrosion? How is it avoided?

A

corrode areas where liquid is stagnant( avoided by design- no crevices, and flush)

66
Q

What is pitting corrosion? How is it avoided?

A

protective coating (avoid by not breaking coating)

67
Q

What is intergranular corrosion? How is it caused?

A

corrosion around grain boundaries

68
Q

What is selective leaching

A

one phase dissolves in a 2 metal phase

69
Q

What is hydrogen embrittlement? How is it avoided?

A

makes metal brittle (avoided by baking)

70
Q

What is microbial corrosion in metals?

A

microbiabls (poop acid)

71
Q

What happens to the rate of dry corrosion with temperature?

A

increases

72
Q

Does dry corrosion require two balanced reactions like wet corrosion?

A

NO

73
Q

What type of oxide scale is protective?

A

Adherent without cracks

74
Q

What acid will dissolve all ceramics?

A

Hydroflouric acid

75
Q

Is corrosion generally a big problem in ceramics? Why not?

A

Not like in metals, pretty stable

76
Q

What is swelling and dissolution in a polymer and why is it a problem.

A

liquid migrates into polymer -gets bigger and weaker

77
Q

Describe what happens when radiation damage occurs to a polymer

A

polymers - uv redirection
cross linking - additional primary bonds(brittle)
shorter chains - lower strength

78
Q

What is microbial degradation in a polymer?

A

microbials eating polymers

79
Q

What is a metal made up of?

A

Metals such as platinum, gold, copper and silver are found in pure forms, while alloys, such as bronze and brass are made by heating two different kinds of metal together and then allowing the mixture to cool

80
Q

What are typical mechanical properties for a metal?

A

Some of the important mechanical properties of a metals are Brittleness, Creep, Ductility, Elasticity,Hardness, Malleability,Plasticity,Toughness,

81
Q

Are metals typically amorphous or crystalline?

A

Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms.

82
Q

Are metals typically single crystal or multi-grained?

A

multicrystaline grain structure

83
Q

Do metals have high or low electrical and thermal conductivity?

A

good electrical and thermal conductors

84
Q

What is a ceramic?

A

Compounds of metallic

and non-metallic elements can be Crystalline and amorphous

85
Q

What are typical mechanical properties for a ceramic?

A

low electric and thermal conductors
hard but brittle
can stand high temps
lower density than metals

86
Q

Are ceramics typically amorphous or crystalline?

A

both

87
Q

Are crystalline ceramics typically single crystal or multi-grained

A

multi grained

88
Q

Do ceramics have high or low electrical and thermal conductivity

A

low

89
Q

What is a polymer?

A

Thermoplastics
Thermosets
Elastomers

90
Q

What are typical mechanical properties for a polymer?

A 
can be tranparent or opaque
low electrical and thermal conductors
bad in high temps
low density
uv degradation and swell in liquids
91
Q

Are polymers typically amorphous or crystalline

A

-Thermoplastics and
elastomers are amorphous or partially crystalline
-Thermosets are
amorphous

92
Q

Do polymers have high or low electrical and thermal conductivity?

A

low

93
Q

What is a composite material?

A

Materials formed – mechanically – from two or

more materials, producing unique properties that are not attainable from one group alone.

94
Q

What is a semiconductor?

A

a solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects

95
Q

How can the electrical properties of a semiconductor be altered?

A

Electrical properties can be tailored by altering the

concentration of minute amounts of impurity atoms

96
Q

Are semiconductors typically amorphous or crystalline?

A

single crystal

97
Q

What is a mechanical property

A

-Describe how a material responds to an applied force
-Affects both how the material can be used and
produced

98
Q

Grain structure

A

A grain structure is found in many

crystalline materials

99
Q

What is viscoelasticity?

A

the property of a substance of exhibiting both elastic and viscous behavior

100
Q

Do all metals have the same tendency to corrode? Does this tendency stay the same in all conditions?

A

No, NO

101
Q

Which is more likely to corrode? A more noble or a more active metal?

A

More active

102
Q

What’s worse, having a large surface area of a more noble material relative to a less noble material in a corrosion cell or vise versa? Why?

A

worse to have less noble metal with smaller surface area because 2 reactions balance

103
Q

What is passivity? How does it occur? Does it exist in all conditions?

A

protective oxide film that stops corrosion.
-does not exist in all conditions.
done by Al, Cr, Ni, Ti

104
Q

stiffness

A

elastic(modulus)

105
Q

strength

A

plastic or plastic/elastic interference

106
Q

ductility

A

energy required for failure

ME 280 Materials (3 decks)

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