Smart Nanocomposites Based on Fe–Ag and Fe–Cu Nanopowders forBiodegradable High-Strength Implants with Slow Drug Release
2020
The present paper deals with the development of
dense Fe–Ag and Fe–Cu high-strength nanocomposites from blends of
nanocomposite powders employing cold sintering (high-pressure
consolidation). Nanocomposite powders were obtained by high-energy
attrition milling of micron-scale powder of carbonyl iron (Fe) and
nanosized silver oxide powder (Ag2O) as well as of
nanopowders of Fe and cuprous oxide (Cu2O). Phase
identification was done by X-ray diffraction. Microstructure was viewed
in a high-resolution scanning electron microscope. Compacts with ~70%
theoretical density were annealed in hydrogen to reduce silver and
cuprous oxides to metals and to remove oxide layers from the powder
particle surface. This was followed by cold sintering, i.e.
consolidation in a high-pressure gradient at ambient temperature. The
obtained data on the specimen density were analyzed depending on the
applied pressure in the range 0.25–3.00 GPa. At the pressure 3.00 GPa,
all the nanocomposites are sintered to more than 95% theoretical
density. The compositions demonstrate high mechanical properties in
three-point bending and compression. The nanocomposites were found to
have substantially higher mechanical properties as compared to
composites with micron-scale grains. It was revealed that Fe–Ag and
Fe–Cu nanocomposites have a higher ductility as compared to
nanostructured Fe, which is due to more plastic Ag and Cu phases in the
nanocomposites as compared to the Fe phase. It was shown that loading of
antibiotic Vancomycin into the interconnected nanopore system of
cold-sintered nanocomposites results in nanoencapsulation of the drug
and its slow release from the nanocomposite.
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