Biomedical Engineering Reference
In-Depth Information
resistance of the steel. The nitrogen adsorption treatment of
FeCrMnMoN results in the change of its microstructure from
ferrite to austenite without forming CrN or Cr
2
N that leads to higher
Vickers microhardness. These facts suggest that austenitization
by adsorbed nitrogen contribute to higher corrosion resistance,
which may be a key factor in providing higher cytocompatibility of
produced materials.
Both mechanical alloying and nitriding of Ni-free steels are
very effective ways to improve the corrosion resistance and
microhardness. Nitrogen absorption treatment contributes to the
higher corrosion resistance and also in the presence of wear. With
regard to austenitic stainless steels, it could help obtain better
biomedical implants (e.g. stents) with better mechanical properties,
corrosion resistance, and biocompatibility.
6.3 NickelFree Stainless Steels/
Hydroxyapatite Nanocomposites
Hydroxyapatite (HA) ceramics have been intensively studied for
bone repair and replacement applications. That is because of their
high biocompatibility and ability to bond to bone [2]. However,
compared to the mechanical properties of natural bone, HA
ceramics need improvement [13, 20]. Recently, various HA based
composites have been investigated [23]. Many reinforcements have
been proposed, e.g. zirconia [12] and ceramic ibers [22]. Results
obtained for FeCr alloy reinforcement [5] and HA-316L stainless
steel composites [15] are very promising. Thus, since nickel-free
austenitic stainless steels seem to have better mechanical properties,
corrosion resistance, and biocompatibility compared to 316L
stainless steels [27], it is possible that composite made of this steel
and HA could have improved properties.
Nickel-free austenitic stainless steel/hydroxyapatite
composites can be produced by means of mechanical alloying and
nitrogen absorption treatment, which leads to metallic-ceramic
nanocomposite. Obtaining nanostructure via mechanical alloying
process as well as high biocompatibility of hydroxyapatite and
good mechanical properties of stainless steel seem to be excellent
combination of complementary parameters that could results in
new promising biomaterial.
