Biomedical Engineering Reference
In-Depth Information
Bone composed of nano-iber HA in a collagen matrix and cells
are preferentially interacting with nanostructured surfaces, and
osteoblast functions increase on nano-structured materials [2, 60,
94]. Hence, Ti surface containing nano-grained HA provides better
cell bioactivity than the surface containing coarse-grained HA.
By employing current densities higher than 20 mA/cm
2
and using
ultrasonated bath, it is possible to produce coatings containing
nano-grained HA. Ultrasonics helps in the formation of nano-
grained calcium phosphate and also increases the evolution
rate of hydrogen at the cathode surface. This evolved hydrogen
dispels the calcium ions from the vicinity of the cathode and
resulting in coatings with a Ca/P ratio close to unity [60]. Increase
of the current density from 20 to 50 mA/cm
2
leads to the increase of
the hydrogen evolution rate, too, and also transports more calcium
ions to the implant surface.
Xiao
et al
. [106] improve the bonding strength of the HA
coating, by modifying hydrothermal-electrochemical (HTEC)
method. In this process, the Ti particles are introduced to the
Figure 9.69
Surface morphologies of HA/Ti composite coatings at diff-
erent magniication: (a) ×200, (b) ×2000, (c) ×5000; HA
coating (d) ×1000 [106].
