Biomedical Engineering Reference
In-Depth Information
pressing, sintering, and electrochemical etching, the nanocrystalline
compacts achieved density of about 80% of the bulk ingots, which
is related to pores in the compacts. The electrolyte composition as
well as etching conditions also works very well during the etching
of pure microcrystalline Ti as well as Ti/ceramic nanocomposites
[28, 31], but does not work for microcrystalline Ti-6Al-4V alloy
ingots (Fig. 9.63c). The surface is slightly rough, revealing two-phase
microstructure.
The etched nanocrystalline alloy is very rough with pores, with
diameter up to 60 μm (Fig. 9.63a), which is very useful for the tissue
growth and ixing. Larger magniication and closer inspection of
the porous nanocrystalline compacts reveals that the remaining
surface material (particles) is also etched, with pores inside with
diameter of about 0.1-1 μm (Fig. 9.63b).
The EDS spectrum for the porous surface after etching is shown
on Fig. 9.64. The measured amount of Al is slightly larger from
the initial loaded stoichiometric 6% of Al powder. Probably
it is related with losses of some powders (mainly Ti) during the
milling, when a part of the powder strongly adheres to the milling
container and balls. The phosphorus is presented in the etched
compacts, as a remnant from the electrolyte. This effect was
observed for previously etched microcrystalline Ti as well as Ti/
ceramic nanocomposites [28, 31], too. The phosphorus content
in the alloy surface is useful for the osseointegration, because
phosphorus is a main component of the bone.
Figure 9.64
EDS spectra for the nanocrystalline Ti-6Al-4V after
electrochemical etching [29].
