Biomedical Engineering Reference
In-Depth Information
Narayanan and Seshadri [32] investigated corrosion resistance of
the Ti-6Al-4V alloy with additionally oxidized surface produced by
anodization in 1M H
3
PO
4
and 1M H
3
PO
4
with dissolved calcium and
phosphorus additions. The as prepared porous oxide coating have
90-280 nm thickness and is thicker for 1M H
3
PO
4
electrolyte than
those produced from electrolyte containing dissolved calcium and
phosphorus. The corrosion resistance of as prepared surfaces was
investigated in simulated body luid (8.74 g/L NaCl, 0.35 g/L NaHCO
3
,
0.06 g/L Na
2
HPO
4
0.06 g/L NaH
2
PO
4
). The coatings produced using
1M H
3
PO
4
have lower corrosion rate (because is thicker and less
defective) than the coatings produced from electrolyte containing
dissolved calcium and phosphorus (Fig. 5.7) [32].
•
I
corr
for samples etched in Ca+P containing solution A1, A3, and A7 is 0.29, 0.42, and 3.68
μA/cm
2
, respectively.
•
I
corr
for samples etched only in H
3
PO
4
solution P1, P3, and P7 is 0.014, 0.016, and 0.250
μA/cm
2
, respectively.
Figure 5.7
Potentiodynamic polarization curves of coatings on Ti-6Al-4V
produced from electrolyte containing Ca and P; A1 (sample
etched through 15 min) and A3 (sample etched through
3 h) show passivation, while A7 (sample etched through 24 h)
shows continuous dissolution [32]; (P1, P3, P7 samples etched
in H
3
PO
4
for 15 min, 3 h, 24 h, not shown here). See also Color
Insert.
The V-free alloys were investigated by Okazaki
et al
. [36] too.
They prepared a new Ti-15Zr-4Nb-4Ta-0.2Pd-0.2O-0.05N (Ti-Zr-
type) and Ti-15Sn-4Nb-2Ta-0.2Pd-0.2O-0.005N (Ti-Sn-type) complex
alloys and investigated theirs corrosion resistance, corrosion
