Biomedical Engineering Reference
In-Depth Information
lowest corrosion resistance (slightly improved by anodic oxidation
with respect to the parent not etched nanocrystalline alloy).
HA deposition on nanocrystalline Ti-6Al-4V does not improve
corrosion resistance as was in the case of the rest materials [18].
Generally, worse corrosion resistance estimated by electrochemical
method, shows nanocrystalline materials, especially Ti-6Al-4V. This
behavior is related with large grain boundaries volume fraction. The
grains boundaries state an easy way for the electrolyte penetration,
which is useful during pores formation, but unfortunately highly
unexpected during corrosion tests. The HA deposition improve the
corrosion resistance for both types of electrolytes [18].
The corrosion resistance of the Ti-6Al-4V alloy after calcium
ion implantation was examined by Krupa
et al
. [26]. The anodic
polarization curves (in SBF) for the non-implanted and calcium ion
implanted Ti-6Al-4V alloys are shown in Fig. 5.31. The increase
of the anodic current density observed in the implanted samples
when the potential exceeds about 1900 mV, suggests the pitting
corrosion.
Figure 5.31
Anodic polarization curves for a non-implanted and calcium
implanted Ti-6Al-4V alloy after various times of exposure in
SBF: (1) non-implanted (13 h), (2) non-implanted (733 h), (3)
calcium-implanted (13 h), (4) calcium-implanted (181 h) and
(5) calcium-implanted (733 h) [26].
The results obtained for the Ti-6Al-4V alloy implanted to a
level of 10
17
Ca
+
/cm
2
indicate that the calcium ion implantation
affects the corrosion resistance of the alloy. The calcium ion
implantation increases the corrosion resistance of the Ti-6Al-4V
