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BioMaterials > 2- Metallic Biomaterials > Flashcards

2- Metallic Biomaterials Flashcards

1
Q

Biomaterials are used for what two functions?

A

functional performance, biocompatibility

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2
Q

Biomaterials can be divided into 4 materials? Name them.

A

metals, ceramics (including glasses), composites, polymers

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3
Q

What properties of meals make them widely used?

A

there strength and toughness

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4
Q

Name 3 implant metals that are generally biocompatible.

A

SS Steel, Titanium, Cobalt alloys

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5
Q

Name Problems with current metal implants (3)

A

some people may be allergic to the ions released, the wear particle can cause inflammation, and imlplant loosing.

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6
Q

Name where metals are used?

A

bone and joint replacement, dental implants, cardiovascular devices, surgical instruments

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7
Q

Packing- state how order packing relates to energies

A

dense, ordered packed structures tend to have lower energies

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8
Q

unit cell

A

smallest repetitive volume which contains the complete lattice pattern of a crystal

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9
Q

Metallic crystal structures…. 1. how are they packed. why? is bond energy low or high? why?1

A

they are densely packed. THis is because only one element is usually present, so all radii are the same, metallic bonding is not directional, it is low in energy because the nearest neighbor distances tend to be small

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10
Q

define solidification and the 2 steps

A

the result of casting of molten material.

  1. nuclei form
  2. nuclei grow to form crystals- grain structure
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11
Q

Name two categories for types of imperfections in metal crystaline structure

A

point defects; line defects

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12
Q

name 2 types of point defects

A

vacancy atoms (missing atoms), interstitial atoms(extra atoms), substitutional atoms

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13
Q

name types of line defects

A

dislocations

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14
Q

When metals mix they form in what two ways?

A

substitution(replace atoms), intersitial(just adds between atoms)

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15
Q

name types of metal fabrication (forming)

A

forging(hammering; stamping), rolling (hot or cold rolling), drawing (rods, wire, tubing), extrusion (rods, tubing)

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16
Q

name types of metal fabrication (casting)

A

casting-mold is filled with metal. metal melted in furnace, may alloy added. then cast in mold

17
Q

Name types of metal fabrication (misc)

A

powder metallurgy, welding

18
Q

name components of 316 SSL

A

–Fe 60-65 wt%
–Cr 17-19 wt %
–Ni 12-14 wt%
–C max 0.03%

19
Q

SSL why add chromium?

A

corrosion resistance by formation of surface oxide

20
Q

SSL why add nickel

A

improve strength by increase face center cubic phase

21
Q

SSL why reduce carbon content…?????

A

well it is reduce to .03%. when this is reduce it has better resistance to in vivo corrosion….. by reducing carbide Crv23Cv6 formation at grain boundry…. carbide impairs formation of surface oxide

22
Q

what may SSL316 release?

A

NI^+2, Cr^+3, Cr^+6

23
Q

name a colbalt alloy used for implants

A

ASTM F799

24
Q

What is added to colbalt alloys?

A

W(tungsten) and NI (nickel)

25
Q

Titanium: how much in TI, grade for?

name components in Ti-6Al-4V ELI (ASTM F136)

A

Ti 89%
Al 6%
V 4%

26
Q

where is Ti-6Al-4V ELI (ASTM F136) used?

A

hip and knee implants, screws and fittings, dental implants, pacemaker housing

27
Q

what is special about Ti-6Al-4V ELI (ASTM F136)?

A

IT PERMITS BONE GROWTH AT THE INTERFACE

28
Q

Comparison SSL to others

A 
cheap
high strength, ductility, and toughness
corrosion can be a problem
less bone bonding then others
may produce nickel ion sensitiviy
29
Q

Comparison Co/Cr/Mo alloys to others

A

hardest to fabricate
cast forms-lower cost, higher modulus
wrought or forged forms- highest cost, highest strenth/wear resistance
may produce colbalt or chromium ion sensitivity/toxitcity

30
Q

Comparison Titanium Alloy (Ti-6Al-4v) vs (Titanium metal

A

Ti alloy is stronger than Ti metal
both have relatively low moduli
neither is as wear resistant as SS or Co/Cr/Mo alloys
both have best corrosion resistance of all metals, expecially pure Ti
both have excellent bone bonding, best of all metals

31
Q

name some dental metals

A

amalgam, gold, nitiol

32
Q

what is uniquie about nitiol

A

dental metal, it shape memory alloy… remember stiches

BioMaterials (17 decks)

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