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Title: Hydroxyapatite reinforced Ti6Al4V composites for load-bearing implants
Titanium has been used in various biomedical applications; however, titanium exhibits poor wear resistance, and its bioinert surface slows osseointegration in vivo. In this study, directed energy deposition (DED)-based additive manufacturing (AM) was used to process hydroxyapatite (HA) reinforced Ti6Al4V (Ti64) composites to improve biocompatibility and wear resistance simultaneously. Electron micrographs of the composites revealed dense microstructures where HA is observed at the β-phase grain boundaries. Hardness was observed to increase by 57% and 71% for 2 and 3 wt.% HA in Ti64 composites, respectively. XRD analysis revealed no change in the present phases. Tribological studies revealed an increase in contact resistance due to in situ HA-based tribofilm formation, reduction in wear rate when testing in DMEM with a ZrO2 counter wear ball, ˂1% wear ball volume loss, and suppression of cohesive failure of the Ti matrix. Histomorphometric analysis from a rat distal femur study revealed an increase in the osteoid surface over the bone surface (OS/BS) for 3 wt.% HA composite over the control Ti64 from 9 ± 1% to 14 ± 1%. Shear modulus was also observed to increase from 17 ± 3 MPa for control Ti64 to 32 ± 5 MPa for the 3 wt.% HA composite more » after 5 weeks. Our study demonstrates that the addition of HA in Ti64 can simultaneously improve bone tissue-implant response and wear resistance. « less
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Acta biomaterialia
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National Science Foundation
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