Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4719

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Access Right: Closed AccessAuthor: search.filters.author.Alves, Alexandra C.

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  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Crystallization 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: 24
    Citation - Scopus: 27
    Atomic–scale Investigations of Passive Film Formation on Ti-Nb Alloys
    (Elsevier, 2023) Çaha, İhsan; Alves, Alexandra C.; Chirico, Caterina; Maria Pinto, Ana; Tsipas, Sophia; Gordo, Elena; Bondarchuk, Oleksandr; Leonard Deepak, Francis; Toptan, Fatih
    This study extensively investigates the passive film formation mechanisms on Ti-xNb alloys by using several electrochemical techniques, including electrochemical impedance spectroscopy (EIS) before and after potentiostatic polarization at the passive zone, and Mott-Schottky (MS) measurements in 9 g/l NaCl electrolyte at 37 °C, together with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis. Overall, the Ti40Nb presented lower corrosion resistance due to a thinner passive film as compared to commercial pure Ti (grade 2) and Ti12Nb. The passive film formed on Ti12Nb and Ti40Nb alloys at a steady-state condition (+0.5 VAg/AgCl for 60 min) is composed of amorphous phases of TiO, Ti2O3, TiO2, Nb2O5 and crystalline phases of TiO2 (anatase) and Nb2O5. © 2022 Elsevier B.V.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 27
    Improved Tribocorrosion Behavior on Bio-Functionalized Β-Type Titanium Alloy by the Pillar Effect Given by Tin Reinforcements
    (Elsevier, 2021) Çaha, İhsan; Alves, Alexandra C.; Chirico, Caterina; Pinto, Ana Maria; Tsipas, Sophia; Gordo, Elena; Toptan, Fatih
    A novel multi-functional material was developed by hard TiN particle reinforcement addition to a beta-type Ti alloy, following by bio-functionalization of its surface through Ca and P rich oxide layer. Corrosion and tribocorrosion behavior of this multi-functional material was investigated in phosphate buffer solution at body temperature. Bio-functionalization drastically improved the corrosion and tribocorrosion behavior of the unreinforced and reinforced samples, where the bio-functionalized beta-type titanium alloy matrix composite presented the best tribocorrosion behavior due to the load-carrying role of the hard reinforcement phase that gave a support to the functionalized surface layer.