Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biomaterials > Exam 1 (Ch. 5-6) > Flashcards

Exam 1 (Ch. 5-6) Flashcards

1
Q

(metals/ceramics) are more susceptible to degradation in vivo?

A

metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

___________ is characterized by the leaching of ions from a metallic surface into the surrounding environment

A

corrosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

corrosion occurs through the coupling of ___________ and _____________ reactions

A

oxidation (generates electrons) and reduction (consumes electrons)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

oxidation occurs at the (anode/cathode)

A

anode (vowels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

in a galvanic cell (or battery), electrons flow from….

A

the anode (more negative standard reduction potential) to the cathode (alphabetical)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

in galvanic corrosion, what acts as the salt bridge? which metal dissolves faster?

A

physiological fluid, and the more active metal (anodic) dissolves faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does a Pourbaix diagram show?

A

for a given metal, a Pourbaix diagram shows regions of corrosion and non-corrosion as a function of cell potential and pH. diagonal dashed lines represent the stability of water - aqueous corrosion occurs between them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the three main regions on the Pourbaix diagram? order them top to bottom

A

passivation, corrosion, immunity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

in the immune region of a Pourbaix diagram, it is not energetically favorable for corrosion to occur. what is this also called?

A

cathodic protection (the metal cannot act as an anode)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

define passivation

A

oxidation on the surface leads to the formation of a stable solid film that coats the metal and prevents electrons from flowing in or out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

_______ corrosion occurs when oxygen is depleted within a narrow, deep crack, creating an anode and decreasing local pH

A

crevice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

________ corrosion occurs when the passivation film on the surface is disrupted (think a car’s paint job)

A

pitting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

__________ corrosion occurs at the grain boundaries, which tend to be anodic because they are higher energy

A

intergranular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

stress corrosion cracking leads to ___________ in metals

A

brittle fracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

_________ corrosion occurs due to continued bending, loading, or motion

A

fatigue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

________ corrosion is unique in that it is not related to loading, and involves removal of the passivating layer by mechanical means

A

fretting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

______ _________ involves breaking primary bonds and can occur via hydrolysis or oxidation reactions

A

chain scission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how can the presence of metals near polymeric components increase their degradation?

A

metal-catalyzed oxidation occurs, which forms strong oxidizing agents that attack the polymer coating, leading to brittle fracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are other ways polymers can degrade?

A

enzyme-catalyzed degradation, environmental stress cracking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

degradation is ________, while erosion is ________

A

the breaking of chemical bonds within a material, any change in the size or shape of a material (broader)

21
Q

ceramic bioerosion occurs mainly due to…

A

interactions with water

22
Q

(hydrated/nonhydrated) ceramics degrade faster

A

hydrated

23
Q

polycrystalline materials are _________ but ____________ than single-crystal

A

stronger but degrade faster

24
Q

synthetic polymers can degrade via _________ or __________, while natural polymers can only degrade via _________

A

hydrolysis or enzyme interaction, enzyme interaction

25
Q

degradation via enzymatic interaction is good for….

A

localized targeted drug delivery

26
Q

describe bulk degradation

A

rate of water inflow > rate of degradation, shape remains the same, material weakens over time

27
Q

describe surface degradation

A

rate of degradation > rate of water inflow, layers removed over time, material maintains its mechanical integrity

28
Q

metals are strengthened by…

A

alloying (adding point defects), cold working (adding line defects), or precipitation hardening (adding volume defects)

29
Q

metals are weakened by…

A

annealing (increases ductility), hot working, porosity from casting and powder processing

30
Q

the phenomenon in which a metal becomes stronger (but less ductile) as it is plastically deformed is known as…

A

strain hardening or cold working

31
Q

controlled cooling as part of annealing is called…

A

quenching

32
Q

order oil, water, and air by cooling rate

A

water&raquo_space; oil&raquo_space; air

33
Q

forging, rolling, extrusion and drawing are all common forming techniques for…

A

metals

34
Q

hot working occurs at or above…

A

0.3Tm

35
Q

investment casting is done with what material

A

wax (removed by melting)

36
Q

the process by which metal powders become densified by removing small voids through powder pressing is…

A

sintering

37
Q

glasses are shaped between what two temperatures?

A

working and softening

38
Q

pressing and blowing are methods of forming…

A

glasses

39
Q

describe thermoplasts

A

thermoplastic polymers soften when heated and harden when cooled

40
Q

describe thermosets

A

thermosetting polymers become permanently hardened when heated because covalent crosslinks are formed

41
Q

thermosets are formed via…

A

casting, especially compression molding

42
Q

a unique kind of forming for polymers is ______________, where a molten polymer is pumped through a plate with many small holes

A

fiber spinning

43
Q

similar to fiber spinning is _____________, where a molten polymer is extruded into a strong electrostatic field

A

electrospinning

44
Q

compression, injection, and blow molding are forming methods for…

A

polymers

45
Q

rapid prototyping techniques for polymers include…

A

inkjet bioprinting, laser-assisted bioprinting, stereolithography

46
Q

biomedical implants must have an ______________________ of 10^-6, or 1 in 1 million devices showing contamination

A

sterility assurance level (SAL)

47
Q

steaming (autoclaving) is good for…

A

metals

48
Q

ethylene oxide sterilization is good for many materials, but…

A

it is toxic

49
Q

what is the downside of radiation sterilization?

A

expensive, and only thin devices can be sterilized this way

Biomaterials (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions