Brainscape's Knowledge GenomeTM

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


See full index

DM > MEtals and Alloys > Flashcards

MEtals and Alloys Flashcards

1
Q

what metals make up the “royal family”?

A

Rhodium, paladium, silver (not in mouth), osmium, iridium, platinum, and gold

are the “royal” faily as they do not corrode

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

what make up the new rich elements?

A

titanium, chromium, cobalt and nickel – not royal bc they corrode, but corrode only once and are stable

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

what make up the elements that work for the ryoal family?

A

copper and zinc– clean and strengthen

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

define alloy

A

a substance made by combining two or more metallic elements, esp to give greater strength or resistance to corrosion;

an alloy is produced by fusion of elements above their melting point

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

define precious metal

A

containing metals of high economic value;

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

define noble metal

A

precious metal that is resistant to tarnish

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

define high gold alloys

A

greater than 75% gold or other noble metals (type I-IV)

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

define medium gold alloys

A

25-75% gold or other noble metals; which means gold represent less than every other atom

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

define low gold alloys

A

less than 25% gold or any other noble metal

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

define gold substitute alloys

A

precious metal alloys that don’t contain gold

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

define base metal alloys

A

alloys not containing any precious metals for corrosion resistance, but generate a protective oxide film on their surface which prevents continuing corrosion

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

define carat

A

part of pure gold in the alloy out of 24; e.g. if gold is 24 caraat gold it is pure gold; if 18 carat, it is 75% pure gold

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

define fineness

A

parts per 1000 of gold; pure gold is 1000 fine, 75% gold is 750

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

define pennyweight

A

weight measuring 24 g; 1 pennyweight -= 1.555 g = 24 grains

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

why would gold be put in an alloy?

A

to offer corrosion resistance and increase ductility and malleability

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

why would copper be added to an alloy?

A

to increase hardness

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

why would silver be added to an alloy?

A

to counteract the orang ecolour of copper and also to reduce the melting temp; as well, it increases ductility and malleability

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

why would palladium be added into an alloy?

A

increase melting point, hardness, absorb H2 gas that can cause porosity in casting, reduce corrosion, as whitens gold

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

why would platinum be added to an alloy?

A

increase melting point, hardness, tensile strength, decrease coeff. of thermal expansion, and reduce corrosion

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

why would zinc be added to an alloy?

A

prevents oxidation by forming ZnO film during melting, increases fluidity; decreases surface tension (improves castability)

21
Q

what are some high noble alloys?

A

noble metal not less than 60% wt an gold not less than 40%

  • Au-Pt-Pd
  • Au-Pd-Ag
  • Au-Pd
22
Q

what are some noble alloys?

A

min 25% noble metal

  • Pd-Ag
  • Pd-Cu-Gallium
  • Pd-Ga
23
Q

whata are some predominantly base ?

A

noble metal less than 25% wt

  • Ni-Cr
24
Q

what are some properites of high gold casting alloys?

A

from type I-IV: hardness, strength, ductility, and corrosion resistance

25
Q

what influences the relewase of toxic element s from alloys?

A
  • corrosion resistant ability

- alloy microstructure

26
Q

what are some required characteristics of dental laloys?

A
  • physical properties must meet a moinimum standard for the type of resto it’s being used for
  • must have resisliency
  • should be tarnish resistant
  • should be tough
  • should have good fatigue resistance
27
Q

what are the typical properites of alloys?

A
  1. crystalline structures
  2. increased hardness (but not Hg)
  3. increase ultimate tensile strength
  4. increased ductility
  5. increased burnishability
  6. a melting RANGE
  7. good conduction (heat, electricity)
28
Q

what is a unit cell?

A

the basic component of the crystalline structure of metals; attoms are arranged in either a simple cubic structure (unstable), FCC, BCC, or hexagonal close packed in PURE metals

29
Q

FCC has HIGHER DUCTILITY whereas HCP has LOWER ductility

A

ye

30
Q

which metals have an FCC config?

A

Au, Pd, Ag, Cu, Ni, Al

31
Q

which metals have a BCC config?

A

Cr, Fe

32
Q

which metals ahve anHCP config?

A

Ti, Co,Zn

33
Q

what are the three possible outcomes when an alloy cools?

A
  1. solid sol’n –> metal are soluble with each other and cool to a homogenous structure; can have two types: substitutional (atoms replace one another in lattice) or interstital where one atom is smaller and fills the gaps between the larger atoms)
  2. compound (intermetallic) : when metals are sol as liquid but not as solids; heterogenous
  3. eutectic : unique atomic percentage ratio between the components– as each pure has its own distinct bilk lattice arrangement
34
Q

elements of similar diameter mix well with each other as they can replace each other in their lattice structures; form a solid so;’n and exhibit solid solubility

A

ye

35
Q

what is a multiphase alloy?

A

alloy formed of two or more elements which are present in amounts which exeed their solubility limit in one another; one or more phase will ppt out

36
Q

what is a slip plane?

A

the plane along which the dislocation moves – move through lattice to form a new shape

37
Q

what is elastic limit?

A

the stress required to initiate the movement of atoms within the lattice to new positions

38
Q

define plastic defomation

A

application streess is greater than the elastic limit and causes material to be deformed permanently as a result of the dislocation movement

39
Q

what are extra half planes?

A

dislocations – defects responsible for deformation

somehow connected to ductility idk

40
Q

the amount of energy relquired to move dislocations through the crystal structure is related to the strength of the material

A

force required depends on:

  • type of space lattice: cubic type is easiest to move
  • grain size: small fine particles slip more easily)
  • pure metals have fairly low strength hardness and proportional limit–easier to move
  • alloys have high strength so dislocation is more difficult
41
Q

what are CoCr alloys used for?

A

partial dentures and frameworks

42
Q

what are NiCr alloys used for?

A

inlays, crowns, and bridges

43
Q

what are Ag alloyds used for?

A

surgical splint

44
Q

what are Ti and Ti alloys used for?

A

partial denture frameworks, crowns and bridges, inlays

45
Q

the solid solution of an alloy depends on the alloy size, crystal structure, etc – e.g. metaals with a similar atomic diameter can replace each other in the lattice structure

A

ye

46
Q

what are the different forms an alloy may take?

A
  • pure metal phase
  • solid solution
  • intermetallic compound
47
Q

the resistance to elastric strain is indicated by the high elastic modulus of metals

A

ye

48
Q

define elastric strain in terms of lattice structure

A

elastic stretching of lattice–ALL atoms are shifted from their equilibrium positon by a FRACTION of their atomic spacing

49
Q

study slide 21 and 22

A

ye

DM (18 decks)

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