Final Flashcards
What are the different types of cast iron
Cast White, Gray, Compacted Graphite(CG), Ductile (ductility increases from top-bottom)
What is the eutectic form of Cast White
Fe3C
What is the eutectic form of Gray Iron
Graphite Flakes
What is the eutectic form of Compacted Graphite
Graphite Balls & Blunt Flakes
What is the eutectic form of Ductile Iron
Graphite Balls
What is the difference between steel and cast iron?
No eutectic solidification in steel
How does the eutectic form of carbon in cast irons affect ductility?
?
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
?
What is steel?
a hard, strong, gray or bluish-gray alloy of iron with carbon and usually other elements, used extensively as a structural and fabricating material.
What is rust? How can it be minimized in steel alloys?
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
What is a low alloy steel
type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel
How are gray and ductile irons classified by manufacturers?
Gray- by tensile strength (ex.Class 40)
Ductile- by Tensile/yield/elongation (ex.60/55/12)
Would you expect a gray or a ductile iron to be easier to machine? Why?
Gray Iron, Graphite flakes lead to more brittleness and poor ductility.
What are the two basic versions of aluminum alloys?
Wrought and Cast
Which has a higher melting point, aluminum or steel?
Steel
Which has a higher density, aluminum or steel?
Steel (has higher modulus)
Do aluminum alloys have good corrosion resistance?
yes
List some typical properties for copper alloys? Why are they chosen for electrical applications?
Pretty, and good conductor
What is a brass? What is a bronze?
Brass- Cu+Zn
Bronze - Cu+otherstuff
What are some typical applications for titanium alloys? Why are they used?
Expensive, aerospace(lighter than steel), Biomedical( good compatibility)
What is a superalloy?
Alloys can work at high temperature, high stress, and high oxidizing atmospheres.
The majority of metals processing starts with what type of processing technique?
Casting
What is the difference between a wrought and a cast product?
Wrought- deformed to shape
Cast- not deformed to shape
What are some solid forming techniques?
Rolling, extrusion, pressing, machining
Describe how powder processing of a metal and a ceramic is done. What is the advantage of this process?
Power -> pressuring, slip casting + heat ->
powders change to solid(melting not required).
-Reduces machining for complicated shapes.
What is the most common machining technique? What is difficult about this technique?
Drilling, causes heat in a hole
What is turning? What machine is it performed on?
Lathe (turning), machine tool that rotates the work piece on its axis to perform various operations,
What is milling?
Grinding or crushing material with use of a milling machine
What is the difference between welding, brazing and soldering?
Welding- high temp, partially melt materials
Brazing- melt a joining metal
Soldering- like brazing pipes & wires.
Let’s talk about porcelain
Ceramic- doesn’t melt
coated with glass (glass phase does melt, fills holes)
smooth surface
What is cement and how is it processed?
mixed with water and castable
forms solid by chemical reaction. ( takes times)
How is the fracture toughness increased in transformation toughened zirconia
Heat treat to stabilize phase, when crack appears transforms to equilibrium phase and changes volume.
What is the most common oxide glass?
Silica (SiO2)
How is glass tempered and what is the advantage of tempered glass?
Heat treated for thicker glass to add compressive stress to surface (stronger).
more durable, smoother and sharper
How is glass made bullet proof? How about soundproof?
Bulletproof- composite, layer of glass and polymer.
sound proof- more glass layers
What is the difference between a thermoplastic and a thermoset?
Thermoplastic- secondary bonding between chains
Thermoset- primary bonding throughout
Would you expect a linear or a branched thermoplastic to be stronger? Why?
Branched, because it gets tangled between other connection (ex. sliding to tree branches together wont go smoothly)
What effect does average chain length have on the mechanical properties of a thermoplastic polymer?
chain length increases and gets stiffer & stronger.
What effect does larger side groups have on a thermoplastic polymer
Makes them stronger
What effect does increased crystallinity have on a thermoplastic polymer?
stronger and more secondary bonding
What is a copolymer?
mixed polymers
Are thermosets crystalline?
No
What are typical properties for an elastomer (rubber)?
Low stiffness, strength, and High ductility
Describe how thermoset and thermoplastic elastomers are structured and how this affects their deformation?
Thermosets have higher strength and lower ductility.
What is the difference between a composite and a metal or ceramic alloy?
composite is a mechanical mix of different materials. and metal or ceramics are not.
What is the definition of a dispersion strengthened composite and when and why are they used?
Dispersion strength- metal with ceramic particles,(tiny)
add strength good with high temps
What is the definition of a particulate composite? Give typical examples. When and why are they used?
big particles in matrix
What is the definition of a fiber-reinforced composite? When and why are they used?
Polymer matrix with fibers for strengthening.
What is the effect of fiber orientation on the strength of a fiber-reinforced composite
strength highest along length of fiber. and lowest perpendicular to length.
What is the effect of fiber aspect ratio on a fiber-reinforced composite?
longer skinny fibers makes better strength
Why do most fiber-reinforced composites have a thermoset matrix? Why is there a push to move to thermoplastic matrices?
easier to process not as viscous, recycling.
What is a laminant? Give a typical example.
layer composites
What is a bimetallic? Give a typical example?
2 metals joined together but not melted together.
What is a sandwich composite? When are they used?
outer layers rigid inner layers light weight.
How are glass products produced
blow - roll - plate glass - float on molten tin
How are polymer fibers produced?
liquid - die with small holes
How are carbon and graphite fibers produced?
burn polymers fibers
What is injection molding?
push molten metal into die metal polymer into die and let it harden
Describe the slip casting process, what is it used for
Ceramics - take ceramic powder add to water - pour into porous plaster of mold - water sucked into mold leaves ceramic shell.
What is an interesting property of Teflon
Slippery!
What are typical additives for plastics and why are they added?
dye for color, filler retardant, and plasti sizer for more ductility.
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
all increases
What is uniform corrosion? How is it avoided?
corrosion uniform (avoided by coating and keeping dry)
What is galvanic corrosion? How is it avoided?
2 different metals (avoided by using metals with similar activity, add sacrificial metal.)
What is crevice corrosion? How is it avoided?
corrode areas where liquid is stagnant( avoided by design- no crevices, and flush)
What is pitting corrosion? How is it avoided?
protective coating (avoid by not breaking coating)
What is intergranular corrosion? How is it caused?
corrosion around grain boundaries
What is selective leaching
one phase dissolves in a 2 metal phase
What is hydrogen embrittlement? How is it avoided?
makes metal brittle (avoided by baking)
What is microbial corrosion in metals?
microbiabls (poop acid)
What happens to the rate of dry corrosion with temperature?
increases
Does dry corrosion require two balanced reactions like wet corrosion?
NO
What type of oxide scale is protective?
Adherent without cracks
What acid will dissolve all ceramics?
Hydroflouric acid
Is corrosion generally a big problem in ceramics? Why not?
Not like in metals, pretty stable
What is swelling and dissolution in a polymer and why is it a problem.
liquid migrates into polymer -gets bigger and weaker
Describe what happens when radiation damage occurs to a polymer
polymers - uv redirection
cross linking - additional primary bonds(brittle)
shorter chains - lower strength
What is microbial degradation in a polymer?
microbials eating polymers
What is a metal made up of?
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
What are typical mechanical properties for a metal?
Some of the important mechanical properties of a metals are Brittleness, Creep, Ductility, Elasticity,Hardness, Malleability,Plasticity,Toughness,
Are metals typically amorphous or crystalline?
Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms.
Are metals typically single crystal or multi-grained?
multicrystaline grain structure
Do metals have high or low electrical and thermal conductivity?
good electrical and thermal conductors
What is a ceramic?
Compounds of metallic
and non-metallic elements can be Crystalline and amorphous
What are typical mechanical properties for a ceramic?
low electric and thermal conductors
hard but brittle
can stand high temps
lower density than metals
Are ceramics typically amorphous or crystalline?
both
Are crystalline ceramics typically single crystal or multi-grained
multi grained
Do ceramics have high or low electrical and thermal conductivity
low
What is a polymer?
Thermoplastics
Thermosets
Elastomers
What are typical mechanical properties for a polymer?
can be tranparent or opaque low electrical and thermal conductors bad in high temps low density uv degradation and swell in liquids
Are polymers typically amorphous or crystalline
-Thermoplastics and
elastomers are amorphous or partially crystalline
-Thermosets are
amorphous
Do polymers have high or low electrical and thermal conductivity?
low
What is a composite material?
Materials formed – mechanically – from two or
more materials, producing unique properties that are not attainable from one group alone.
What is a semiconductor?
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
How can the electrical properties of a semiconductor be altered?
Electrical properties can be tailored by altering the
concentration of minute amounts of impurity atoms
Are semiconductors typically amorphous or crystalline?
single crystal
What is a mechanical property
-Describe how a material responds to an applied force
-Affects both how the material can be used and
produced
Grain structure
A grain structure is found in many
crystalline materials
What is viscoelasticity?
the property of a substance of exhibiting both elastic and viscous behavior
Do all metals have the same tendency to corrode? Does this tendency stay the same in all conditions?
No, NO
Which is more likely to corrode? A more noble or a more active metal?
More active
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?
worse to have less noble metal with smaller surface area because 2 reactions balance
What is passivity? How does it occur? Does it exist in all conditions?
protective oxide film that stops corrosion.
-does not exist in all conditions.
done by Al, Cr, Ni, Ti
stiffness
elastic(modulus)
strength
plastic or plastic/elastic interference
ductility
energy required for failure
