Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
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Article Citation - WoS: 8Citation - Scopus: 10Impact of Simulated Inflammation and Food Breakdown on the Synergistic Interaction Between Corrosion and Wear on Titanium(Elsevier, 2024) Lima, A.R.; Pinto, A.M.P.; Toptan, F.; Alves, A.C.This paper investigates the impact of lactic acid and phosphoric acid additives in artificial saliva (AS), simulating inflammation and food breakdown, on the electrochemical and tribo-electrochemical behavior of titanium. The results showed that, unlike lactic acid, phosphoric acid significantly reduced corrosion resistance, mainly due to local damage and heterogeneities on the passive film. Non-additivated AS caused greater wear volume loss, with mechanical wear identified as the main mechanism. However, when additives were present, a synergistic interplay between corrosion and wear was observed. The study concludes that prolonged exposure to food breakdown could accelerate material degradation in titanium. © 2024 Elsevier LtdArticle 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: 8Citation - Scopus: 8Crystallization and Additional Oxide Interlayers Improve the Tribocorrosion Resistance of Tio2 Nanotubular Surfaces Formed on Ti6al4v(Elsevier, 2023) Çaha, İhsan; Türü, İrem Cemre; Erdoğan, Ece; Pinto, Ana Maria Pires; Cansever, Nurhan; Deepak, Francis Leonard; Toptan, Fatih; Alves, Alexandra C.TiO2-based nanotubular surfaces have promising properties for various industrial applications, such as solar cells, fuel cells, photocatalysis, energy storage, gas sensors, and biomedical applications. However, they have very limited use in real applications, and one of the major limiting factors is the weak adhesion of nanotubular surfaces to the substrate. In this study, nanotubular surfaces are formed on Ti6Al4V alloy by anodic treatment followed by a heat treatment at 500 °C for 3 h under an open atmosphere. Microstructural investigations revealed self-organized nanotubes grown on both ? and ? phases. High-resolution TEM/STEM analysis showed crystallization of the nanotubular layer and formation of additional oxide interlayers resulting in a drastic improvement in tribocorrosion resistance. These findings indicated that a simple heat treatment can significantly alter the properties of nanotubular layers and can widen their usage mainly for load-bearing implant applications in corrosive environments. © 2023 Elsevier B.V.Article Citation - WoS: 3Citation - Scopus: 6Investigation of the Influence of High-Pressure Torsion and Solution Treatment on Corrosion and Tribocorrosion Behavior of Cocrmo Alloys for Biomedical Applications(MDPI, 2023) Yılmazer, Hakan; Caha, İhsan; Dikici, Burak; Toptan, Fatih; Işık, Murat; Niinomi, Mitsuo; Nakai, Masaaki; Alves, Alexandra CruzIn this study, the influence of the high-pressure torsion (HPT) processing parameters and solution treatment (ST) on the corrosion and tribocorrosion behavior of CoCrMo (CCM) alloys was investigated for possible usage in biomedical applications. The corrosion behavior of the CCM alloys was investigated by using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) tests. Tribocorrosion tests were carried out in a reciprocating ball-on-plate tribometer at 1 Hz, 1 N load, and 3 mm stroke length for 2 h. All electrochemical measurements were performed using a potentiostat in standard phosphate-buffered saline (PBS) solution at body temperature (37 +/- 2 degrees C). The samples were characterized by using a scanning electron microscope (SEM), transmission electron microscope (TEM), optical microscope (OM), and X-ray diffraction (XRD). The deepness and width of wear tracks were examined by using a profilometer. The results showed that HPT and ST processes did not affect significantly the corrosion resistance of samples. However, the ST-treated samples had a higher material loss during sliding in standard phosphate-buffered saline (PBS) at body temperature as compared to HPT-treated samples.Article Citation - WoS: 6Citation - Scopus: 6Tribocorrosion-Resistant Ti40nb-Tin Composites Havingtio(2)-Based Nanotubular Surfaces(American Chemical Society, 2022) Çaha, İhsan; Alves, Alexandra Cruz; Chirico, Caterina; Pinto, Ana Maria; Tsipas, Sophia; Gordo, Elena; Toptan, FatihA novel multifunctional material was developed byhard TiN particle reinforcement addition to a beta-type Ti40Nb alloy,followed by surface functionalization, yielding the formation of ananotubular layer. Corrosion and tribocorrosion behaviors wereinvestigated in a phosphate-buffered saline solution at bodytemperature. The results revealed that the Ti40Nb-TiNcomposites presented similaripassandE(i=0)values together withrelatively similarRoxandCox. However, its tribocorrosion resistancedrastically improved (wear volume is almost 15 times lower than anunreinforced alloy) as a consequence of the load-carrying effectgiven by the reinforcement phases. The corrosion and tribocorro-sion behaviors were further improved through surface functionaliza-tion as observed by significantly loweripassand higherRoxvalues andalmost undetectable wear volume loss from tribocorrosion tests dueto the formation of a well-adhered anatase-rutile TiO2-based nanotubular layer.Article Citation - WoS: 10Citation - Scopus: 11Improved Tribocorrosion Behavior Obtained by In-Situ Precipitation of Ti2c in Ti-Nb Alloy(MDPI, 2022) Gonçalves, Vinícius Richieri Manso; Çaha, İhsan; Alves, Alexandra Cruz; Toptan, Fatih; Rocha, L. A.Novel in-situ Ti-based matrix composites (TMCs) were developed through the reactive hot pressing of Ti + NbC powder blends. Due to the chemical reaction that occurred in the solid-state during processing, the produced samples were composed of an Nb-rich β-Ti phase that formed a metallic matrix along with Ti2C as a reinforcing phase. By employing different proportions of Ti:NbC, the phase composition of the alloys was designed to contain different ratios of α-Ti and β-Ti. The present work investigated the corrosion and tribocorrosion behavior of the composites, compared to unreinforced Ti, in a phosphate-buffered solution (PBS) at body temperature. Corrosion tests included potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Tribocorrosion tests were carried out using a ball-on-plate tribometer with sliding performed at open circuit potential (OCP) and under anodic potentiostatic conditions. Results showed that the stabilization of the β phase in the matrix led to a decrease in the hardness. However, the formation of the in-situ reinforcing phase significantly improved the tribocorrosion behavior of the composites due to a load-carrying effect, lowering the corrosion tendency and kinetics under sliding. Furthermore, localized corrosion was not observed at the interface between the reinforcing phase and the matrix.Article Citation - WoS: 10Citation - Scopus: 10Influence of Calcium Acetate Concentration in Electrolyte on Tribocorrosion Behaviour of Mao Treated Titanium(MDPI Multidisciplinary Digital Publishing Institute, 2021) Sousa, Luis; Mendes, Ana Rita; Pinto, Ana Maria Pires; Toptan, Fatih; Alves, Alexandra CruzTi-based materials are widely used for dental and orthopaedic implant applications due to their adequate mechanical properties, corrosion behaviour and biocompatibility. However, these materials are biologically inert and display poor wear resistance. In one of the most studied processes that aims to overcome these drawbacks, Ti surfaces are often covered by anodic oxide films with the incorporation of bioactive agents such as Ca and P. Although there are several works on the tribocorrosion behaviour of MAO-treated Ti surfaces, the influence of electrolyte composition on the corrosion kinetics under sliding is yet to be fully understood. In the present work, anodic oxide films were produced on cp-Ti surfaces with different calcium acetate concentrations in the electrolyte. Tribocorrosion behaviour was investigated by reciprocating sliding tests performed in 8 g/L NaCl solution at body temperature, under potentiostatic conditions. The results showed that higher concentrations of calcium acetate had a detrimental effect on tribocorrosion kinetics, however, they resulted in less mechanical damage due to alterations in the topography and structure of the MAO layer.Article Citation - WoS: 20Citation - Scopus: 20Preliminary Tribo-Electrochemical and Biological Responses of the Ti-Tib In-Situ Composites Intended for Load-Bearing Biomedical Implants(Elsevier, 2022) Sousa, Lia; Toptan, Fatih; Alves, Alexandra C.; Costa, N. A.; Gemini Piperni, Sara; Rossi, Andre Linhares; Ribeiro, Ana R.; Simöes, Sönia; Toptan, FatihPoor tribocorrosion resistance of Ti and its alloys remains as a concern for load-bearing biomedical implants. Despite being an effective method to improve tribocorrosion resistance, titanium matrix composites (TMCs) have yet to be used in this type of applications. In-situ TiB (titanium boride) and TiC (titanium carbide) reinforcement phases have been considered as one of the best options to produce TMCs once these phases present high compatibility and strong interfacial bonding with Ti. Although the effect of these phases on the mechanical properties of Ti has been thoroughly researched in the last years, their effect on corrosion, tribocorrosion and biocompatibility of Ti is yet to be fully understood. In this work, in-situ Ti-TiB-TiCx composites obtained by reactive hot pressing showed identical corrosion response compared to the unreinforced Ti but displayed improved tribocorrosion behaviour. Under 0.5 N load, composites presented as average a reduction of 51% in wear volume loss and under 10 N the reduction was up to 93%. Early biological tests showed promising results, as composites were biocompatible and induced osteoblasts spreading and possibly proliferation most probably due to composite chemistry and surface hardness.Article Citation - WoS: 32Citation - Scopus: 36Corrosion and Tribocorrosion Behaviour of Ti-B4c Composites Processed by Conventional Sintering and Hot-Pressing Technique(Elsevier, 2021) Sousa, L.; Alves, A. C.; Guedes, A.; Toptan, FatihIn this work, low volume reinforcement ex-situ Ti-B4C composites were produced using two different routes: conventional powder metallurgy (PM) and hot-pressing (HP). The effect of reinforcement phases and processing method on corrosion and tribocorrosion behaviour were studied. Composites processed by PM lost the typical passive behaviour of Ti matrix, while composites processed by HP presented similar behaviour to unreinforced Ti. Tribocorrosion tests showed that both composite groups presented two times decrease in corrosion kinetics under sliding compared to pure titanium. An antagonistic effect between wear and corrosion was observed for composites with at least two times decrease in wear volume compared to titanium. (C) 2021 Elsevier B.V. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 12Highly Porous Ti as a Bone Substitute: Triboelectrochemical Characterization of Highly Porous Ti Against Ti Alloy Under Fretting-Corrosion Conditions(Pergamon-Elsevier Science Ltd, 2021) Costa, A.I.; Viana, F.; Toptan, Fatih; Geringer, J.Highly porous Ti was investigated under fretting-corrosion conditions as a function of load and amplitude. To obtain a correlation between mechanical and electrochemical responses according to amplitude, a new representative master curve was suggested: the A ratio (dissipated energy over total energy) vs. 1st OCP drop that fitted well the fretting-corrosion behaviour. Fretting-corrosion mechanisms were presented and a fretting map was illustrated. There was a significant load- and amplitude-dependent response, showing gross slip and partial slip regimes can occur with expected OCP variations. The promising structure of highly porous Ti was preserved after 16 h of fretting-corrosion under severe solicitations.