Surface Treatment of the Ti-Based Nanomaterials - Bionanomaterials for Dental Applications - page 237

competition reaction between F − and P O 4 3− ions. This leads to a local
dissolution of the oxide, allowing for the formation of nanotubes
[44].
a: aqueous 1 wt% HF at 60 V.
b: aqueous 1M H 3 PO 4 + 1 wt% HF at 60 V.
c: aqueous 5M H 3 PO 4 + 1 wt% HF at 60 V.
d: aqueous 10M H 3 PO 4 + 1 wt% HF at 60 V.
e: aqueous 1M H 3 PO 4 at 60 V.
f: aqueous 1M H 3 PO 4 at 200 V.
g: aqueous 1M H 3 PO 4 + 1 wt% HF at 20 V
Figure 9.16 MTT results of osteoblasts cultured for 1, 3, and 7 days,
respectively [44].
Figure 9.17 developed by Kim et al . is a map showing a different
surface morphologies formed at different anodic conditions
[44]. In 1 wt% HF electrolyte at 60 V, dot-like structures are
produced due to a fast dissolution of the formed oxide (Fig. 9.17a).
In 1M H 3 PO 4 nanopowder consisting of granules is formed on the
dot-like structures (Fig. 9.17b). Increase of H 3 PO 4 concentration
results in formation of single nanopowders (Fig. 9.17c) and
coexistence of nanopowders with nanotubes (Fig. 9.17d). The
microporous structures can be formed in a single H 3 PO 4 (without
HF) electrolyte above the breakdown potential (Fig. 9.17f). Barrier
oxide layers with bursts and cracks are synthesized below the
breakdown potential (Fig. 9.17e) and nanotubular structures can
be formed in a mixture of aqueous 1M H 3 PO 4 and 1 wt% HF at a
moderate potential (Fig. 9.17g). As shown by Kim et al . [44], the