Upload
others
View
8
Download
0
Embed Size (px)
Citation preview
1
Tribological Property and Biocompatibility of Titanium Plate
Coated with Carbon Nanotubes
2
Boeing 787 Dreamliner
Background
• High strength• Good corrosion resistance• Good biocompatibility • Low density
Carbon nanotubeCarbon nanotube
• Superior self-lubrication• High yield stress• High Young’s modulus• High electrical & thermal
conductivity
Stent
Implant
d= ~20nmφL= 1~5μm
10μm
Naturally uniform as bundles due to van der
Waals forces
Poor Tribology property contacted with other
materials and Ti
TitaniumTitanium
3
2. Investigate the biocompatibility of pure Tiplate coated with CNTs.
① Network-structured MWCNTs coating on Ti plate.
② Analysis on interface between CNTs and Ti substrate.
③ Effect of annealing temperature on tribologicalbehavior of CNTs coating films.
Objectives
1. Investigate tribological property and wearbehavior of pure Ti plate coated with CNTsunder dry sliding condition.
4
CNT dispersions
CNTs bundle disassemble in zwitterionic surfactant solution
“Heads”; hydrophilic
“Tails”; hydrophobic
CNT
Headgroup
Tail
Bundled CNTs
Zwitterionic Surfactant
Un-bundled CNTs in
Zwitterionic surfactant
Self-assembly
Electrostatic force
5
CNTs distributed in water with surfactants
CNTs distributed in water after ultrasonic vibration
Segregation of bundled CNTsSegregation of bundled CNTs
CNT dispersions
6
Preparation of specimen
Dipped
Surfactant solution with un-bundled
CNTs
10μm
Coated with un-bundled CNTs
Annealed• Ball-on-disk
wear test• XRD & SEM-
EDS analysis
Pure Ti plate
6
7
Observed by SEM & AFM on CNTs coated on pure Ti plate annealed at 1123 K
SEM and AFM observation
1μm
8
30 35 40 45 50 55 60 65 70 75 80
Inte
nsity
/ a.
u.
Diffraction Angle, 2θ / °
XRD result
8
●TiC□α-Ti(hcp)
●
● ●□
□
□
□
□□
□
●
(a)
(b)
(c)
― with CNTs annealed at 1123 K (a) ― with CNTs annealed at 973 K (b)― as-received pure Ti Plate (c)
9
33 34 35 36 37 38 39 40 41 42 43Diffraction Angle 2Θ / degreeDiffraction Angle, 2θ / °
Inte
nsity
(a.u
.)
●□ □ ●□
(a)
(b)
(c)
Inte
nsity
(a.u
.)
Diffraction Angle, 2θ / ° 9
XRD result
●TiC□α-Ti(hcp)
― with CNTs annealed at 1123 K (a) ― with CNTs annealed at 973 K (b)― as-received pure Ti Plate (c)
10
XRD result
― with CNTs annealed at 1123 K (a) ― with CNTs annealed at 973 K (b)― as-received pure Ti Plate (c)
75.8 76 76.2 76.4 76.6
Inte
nsity
(a.u
.)
Diffraction Angle, 2θ / degree
Ti peak (1, 1, 2)
(a)
(b)
(c)
2
2
2
22
34
1
cl
ahkkh
d
h, k, l: Miller indicesa, c: Lattice constant
11
(a) with CNTs annealed at 1123 K (b) with CNTs annealed at 973 K (c) as-received pure Ti Plate
Latti
ce c
onst
ant,
a / Å
ExperimentalTheoretical
(a) (b) (c)2.94
2.95
2.96
2.97
2.98
2.99
3.00
a
c
Relationship between lattice constant
XRD result
Latti
ce c
onst
ant,
c / Å
4.66
4.67
4.68
4.69
4.70
4.71
4.72
4.73ExperimentalTheoretical
(a) (b) (c)
12
Cross-section of pure Ti plate coated with CNTs annealed at 1123 K
TiCarbon
1μm
SEM-EDS analysis result
TiC Layer
12
1μm
TiC Layer
CNTs Film
13 13
(a) with CNTs annealed at 1123 K (b) with CNTs annealed at 973 K (c) as-received pure Ti Plate
Vick
ers
mic
ro h
ardn
ess
(Hv)
0
100
200
300
400
500
600
(a) (b) (c)
1μm
Testing area
Hardness result
14
Total sliding distance, L =113m ( ←31.4 mm/s×3600s)
Load F=100gf
Ti Plate
SUS304 ball(φ; 4.7mm)
Test condition: Room Temperature, No lubricant (Dry condition)
SUS304ball
Attachment
RotatingRotating
Ball-on-disk wear test equipment
Ball-on-disk wear test
14
15
μ0 = 0.19(a) CNTs annealed at 1123K
Conditions • Counterpart Material ;SUS304 Ball• Load ;100gf•Rotating Speed;31.4mm/s
μ0 = 0.34(b) CNTs annealed at 973K
μ0 = 0.95
(c) as-received Ti Plate
Ball-on-disk wear test results
15
16
100μm
1μm
Slid
ing
dire
ctio
n
Wear track of Ti plate as received (with NO film) and SUS 304 ball
Wear debris
Abrasive wear area
Pure Ti Plate
500μm
500μm500μm
500μm
Ti
Fe Cr
Counterparts material (SUS 304 ball)
Ball-on-disk wear test results
17
1μm
100μmSlid
ing
dire
ctio
n
Wear track of Ti plate coated with CNTs annealed at 1123K and SUS 304 ball Ball-on-disk wear test results
Ti Plate coated with CNTs
10μm 10μm
10μm 10μm
10μm
C Ti
Fe Cr
Counterparts material (SUS 304 ball)
18
CNTs hold as a tissue engineering substrate ?
Biomedical application of Titanium
Surface modification of Titanium surface by CNTs
Facilitating tissue engineering
Examined
① Cell adhesion after 72 h
② Biocompatibility of rat
Object #2Investigate the biocompatibility of pure Ti plate coated with CNTs
5 weeks
19
Tissue engineering - Cell adhesion test result
100μm
100μm
Ti plate
Ti Plate coated with CNTs
Cell attachment and spreading out Ti plate coated with CNTs > Ti plate
Cell growing on CNT-net
3 μm
Well-demonstrated CNTsin the tissue engineering
20
Observations at 5 weeks after implantation into rat Inflammatory cell infiltration was rarely observed
good biocompatibility Promoting new bone formation by CNT-net
Tissue engineering - Study of bioactivity
Evaluate the biocompatibility of CNT-net nano morphologies
Plate
head
head
tissue
tissueNew bone
21
1. CNTs were successfully coated on Ti plate annealed at 973 Kand 1123 K.
2. Formation of network-structured CNT films was effective toreduce the friction coefficient of Ti plate due to their excellentself-lubricant effect.
3. Annealing at 1123 K caused TiC formation at interface betweenCNTs and Ti substrate, and then excellent metallurgical bondingwas obtained. As a result, CNT films were obviously remainedat wear track even after dry sliding when SUS304 stainless ballwas used as a counterpart material.
4. CNT-net nano modification provided the acceleration of newbone formation to the Ti plate surface.
Conclusions
21