WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 5Citation - Scopus: 8Micro-Arc and Thermal Oxidized Titanium Matrix Composites for Tribocorrosion-Resistant Biomedical Implants(Elsevier Science Sa, 2024) Sousa, Luis; Costa, Natalia A.; Rossi, Andre; Simoes, Sonia; Toptan, Fatih; Alves, Alexandra C.Superior tribocorrosion resistance is offered by titanium matrix composites (TMCs) compared to their unreinforced matrix metal, but bioactivity concerns are raised for biomedical applications. Simple methods such as micro -arc oxidation (MAO) and thermal oxidation (TO) are employed to enhance the bioactivity and degradation resistance of Ti. However, the impact of those surface treatments on TMC surfaces is poorly understood. Therefore, the present work aimed to explore the influence of MAO and TO treatments on the surfaces of in - situ Ti-TiB-TiC and ex - situ Ti-B 4 C composites, and to assess their corrosion and tribocorrosion performance. Corrosion and tribocorrosion tests were conducted in phosphate-buffered saline solution (PBS) at body temperature. Electrochemical assays were performed by means of potentiodynamic polarization scans while additional potentiostatic tests were performed for the untreated ex - situ composites. Tribo-electrochemical assays were conducted under open circuit potential (OCP) and under normal loads of 0.5 and 10 N against a 10 mm diameter alumina ball in a reciprocating ball -on -plate tribometer. Results revealed reinforcement detachments in ex - situ composites after both treatments. This was primarily attributed to oxide layer growth at the reinforcement/reaction zone interface. Hence, the use of MAO and TO on ex - situ Ti-B 4 C composites may not be appropriate for biomedical applications, mainly because the B 4 C particles tend to detach during the treatment. In contrast, TOtreated in - situ composites displayed excellent combination of corrosion and tribocorrosion performance, even under elevated applied loads, mainly due to the existence of the oxygen diffusion zone (ODZ) beneath the oxide surface produced by TO, together with the more stable electrochemical properties observed during steady -state conditions.Article Citation - WoS: 14Citation - Scopus: 20Influence of Al2o3 Reinforcements and Ti-Al Intermetallics on Corrosion and Tribocorrosion Behavior of Titanium(Elsevier, 2023) Sousa, Luis; Antunes, Rui D. M.; Fernandes, Joao C. S.; Alves, Alexandra Cruz; Toptan, FatihTi-Al2O3 composites have demonstrated favorable characteristics for use in load-bearing biomedical implant applications; however, the influence of Al2O3 reinforcement particles and Ti-Al intermetallics on the electrochemical and tribo-electrochemical responses of Ti are not well-understood. This study explored the corrosion and tribocorrosion characteristics of powder metallurgy-manufactured Ti-Al2O3 composites in a simple physiological saline solution at body temperature. Electrochemical analysis was performed by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization and tribo-electrochemical mechanisms were explored under open circuit potential (OCP) against a 10 mm diameter alumina ball in a ball-on-plate tribometer with reciprocating configuration. Results revealed that the corrosion behavior of Ti was adversely affected by the development of a heterogeneous oxide film on the Ti matrix and the Ti-Al intermetallic phases formed by the interaction of Ti and Al2O3 particles. However, there was a drastic improvement in tribocorrosion behavior, evidenced by decreased corrosion tendency under sliding and a marked reduction in wear volume, primarily as a result of the decreased wear damage resulting from the load-bearing reinforcements.Article Citation - WoS: 26Citation - Scopus: 29Tribocorrosion-Resistant Biofunctionalized Ti-Al2o3 Composites(Elsevier, 2021) Sousa, Luis; Basilio, L.; Alves, Alexandra Cruz; Toptan, FatihRecent studies have shown that titanium matrix composites have potential for load-bearing biomedical implants due to their improved tribocorrosion behaviour compared to Ti and its alloys. However, lack of bioactivity remains as a concern due to bioinert Ti matrix and the fact that most reinforcement phases are also bioinert. In this work, biofunctionalized Ti-Al2O3 composites were produced by performing micro-arc oxidation treatment on the Ti-Al2O3 composites processed by hot-pressing technique. The overall microstructure consisted of Al2O3 particles dispersed within a biofunctionalized Ti matrix having a micro-porous structure rich in Ca and P elements. The corrosion behaviour of the composites was greatly improved after MAO treatment, whereas the tribocorrosion behaviour of the composites was also further improved after MAO treatment.