Biomedical Engineering Reference
In-Depth Information
Table 5.8
Corrosion current
I
c
and corrosion potential
E
c
for the lat not
etched Ti, porous electrochemically etched Ti, and Ti both lat
and porous, with deposited calcium-phosphate (data taken
from Figs. 5.26 and 5.27) [17]
Sample
I
c
(A/cm
2
)
E
c
(V)
Figure
Ti — not etched
3.90 × 10
-8
-0.46 5.26, 5.27 (a)
Ti — not etched with deposited Ca-P
(0.1M HCl + 0.005M HA)
1.57 × 10
-8
-0.66 5.26 (c)
Ti — not etched with deposited Ca-P
(0.042M Ca(NO
3
)
2
+ 0.025M
(NH
4
)
2
HPO
4
+ 0.1M HCl)
3.92 × 10
-8
-0.77 5.27 (c)
Ti — etched
2.52 × 10
-8
-0.90 5.26, 5.27 (b)
Ti — etched with deposited Ca-P
(0.1M HCl + 0.005M HA)
1.47 × 10
-8
-0.86 5.26 (d)
Ti — etched with deposited Ca-P
(0.042M Ca(NO
3
)
2
+ 0.025M
(NH
4
)
2
HPO
4
+ 0.1M HCl)
1.073 × 10
-8
-0.25 5.27 (d)
Corrosion current
I
c
for lat and porous Ti is 3.9 × 10
-8
A
⋅
cm
-2
and 2.52 × 10
-8
A
.
cm
-2
, respectively. The anodization (pores
formation) results in better corrosion resistance, due to the
formed thick surface oxide. After HA deposition, the polarization
curves signiicantly changes. The lowest corrosion current density
1.073 × 10
-8
A
⋅
cm
-2
(best corrosion resistance) has material
anodically etched (porous) with deposited Ca-P using 0.042M
Ca(NO
3
)
2
+ 0.025M (NH
4
)
2
HPO
4
+ 0.1M HCl electrolyte. The
anodically etched as well as anodically etched and HA deposited
materials shows high resistance to pitting corrosion, too. These
surfaces exhibit good passivation with extended passive range and
lowest current in the passive range. Generally, the calcium-phosphate
deposits enhance corrosion resistance, due to insulating behavior,
with respect to surface without the Ca-P layer.
In the work [19] Jakubowicz
et al
. investigated the corrosion
resistance of the lat, porous, and with Ca-P deposited [17-19]
Ti-45S5 nanocomposites in Ringer's solution, and the results are
shown in Fig. 5.28, Fig. 5.29 and Table 5.9.
