Biomedical Engineering Reference
In-Depth Information
nanoporous structure was obtained (Fig. 9.57). Nanotube samples
prepared using 20 V, 30 V, and 40 V have average inner diameters
of 90 nm, 110 nm, and 180 nm, respectively and average tube wall
thicknesses of 10 nm, 15 nm, and 20 nm, respectively. Length of
the nanotubes is approximately 400 nm. The Ti-6Al-4V alloy
shows a dual phase of α + β microstructure. The β-phase region
is enriched with vanadium, which is etched preferentially by the
electrolyte (high solubility of V-oxides), resulting in some pits on the
surface (Fig. 9.57f). X-ray photoelectron spectroscopy revealed
that the etched samples are predominately titanium and oxygen,
with traces of aluminum and phosphorus. The sample etched at
20 V without annealing exhibits an amorphous structure [49].
Annealing of the nanotubes at 400°C, results in anatase phase,
whereas at 500°C it results in a mixture of anatase and rutile. After
600°C calcination temperature, the rutile phase dominates [49].
Figure 9.57
SEM images of top-view and cross section of the Ti-6Al-4V
arrays obtained at different voltages: (a) 10 V, (b) 20 V,
(c) 30 V, (d) 40 V, (e) 50 V after annealing at 400°C; (f) the
bi-phase region of the ilm obtained at 20 V [49].
Jeong
et al
. suggest application of Ti-Hf alloys for dental
application after the nanotubular surface formation [36]. The
