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Degradation behavior of novel Fe/β-TCP composites produced by powder injection molding for cortical bone replacement

: Reindl, Andreas; Borowsky, Rouven; Hein, Sebastian Boris; Geis-Gerstorfer, J.; Imgrund, Philipp; Petzoldt, Frank


Journal of Materials Science : JMS 49 (2014), No.24, pp.8234-8243
ISSN: 0022-2461
ISSN: 1573-4803
Journal Article
Fraunhofer IFAM ()

When it comes to bone replacement in load-bearing areas, there are currently no adequate biodegradable implants available. Several non-degradable metallic materials fulfill the requirements of biocompatibility and mechanical strength. However, besides magnesium, only iron is a degradable metallic material. The aim of this long-term degradation study was to investigate the effects of iron beta-tricalcium phosphate interpenetrating phase composite on degradation rate and strength in comparison to pure iron. Cylindrical samples with 0–50 volume-% beta-tricalcium phosphate (β-TCP) were prepared by powder injection molding. In addition to dense samples, porous iron samples with a porosity of 60.3 % were produced with polyoxymethylene as a placeholder. Dense and porous samples were immersed in 0.9 % NaCl (sodium chloride) solution or in PBS (phosphate buffered saline) solution for 56 days. Following immersion, the degradation rate, compressive yield strength, and ion release were determined. A maximum degradation rate of 196 µm/year was observed after 56 days for iron with 40 volume-% β-TCP. This was found to be 28 % higher than for pure iron. After immersion, the compressive yield strength of pure iron decreased by 44 % (NaCl) and 48 % (PBS). In comparison, iron with 40 % β-TCP samples lost <1 % (NaCl) and 9 % (PBS) of strength following immersion. It was demonstrated that the solubility of calcium phosphate enhanced the corrosion processes and led to an increase in degradation, thus showing that the addition of β-TCP to pure iron can be a promising route for a novel degradable bone substitute material, particularly for load-bearing areas due to the increased strength.