Page 11 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 287

facturing of parts with complex shapes and dimensions close
to those of the end products (near-net shape process). The
production of porous parts by space-holder technique using
organics comprises several steps, which are: (1) mixing organic
compounds with metal powder; (2) removal of the organic
binder by heat treatment, generating the porous green body;
(3) controlled sintering, in order to obtain porous structures
with desirable mechanical properties. In this study, we aimed
to produce porous implants of commercially pure titanium
(cp-Ti) and Ti-13Nb-13Zr alloy by space-holder and suspension
technique, using albumin as binder and natural polymers (corn
starch, rice starch, potato starch and gelatin). The structure
and surface features of the produced parts were analyzed by
X-ray diffraction microscopy techniques. Special attention is
given to understand the effect of surface nanoroughness on Figure 11: FEG-SEM images of the surfaces
the interaction between the implant surface and bone cells. of pore walls with (a) lower and (b) higher
magnification.

Porous Ti samples (40% of porosity) and Ti-13Nb-13Zr alloy samples (60% of porosity) with
interconnected pores and high surface roughness in nanoscale presented good response in
biocompatibility tests. The morphology of faceted pore walls with polygonal - like morphology is
attributed to the preferential growth of some crystallographic planes, probably the basal plane,
during the sintering process due to the lower surface energy of this compact plane (Figure 11).
The obtaining of porous, with addition of albumin or natural polymers by powder metallurgy,
results in an outstanding structure for osseointegration. In macroscale, the bone ingrowth is
favored by the high porosity and, on the nanoscale, the nanoroughness propitiated a suitable
surface for cell attachment, improving the bone implant contact area (Figure 12).

Figure 12: Confocal microscopy of the porous Ti implant: (a) surface of the implant before in vivo study; and (b) after in vivo study. Arrow
indicates a cell attached on a surface.