Browsing by Author "Sancy, M."

Now showing 1 - 7 of 7
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    Corrosion analysis of AISI 430 stainless steel in the presence of Escherichia coli and Staphylococcus aureus
    (2021) Guerra, C.; Ringuede, A.; Azocar, M. I.; Walter, M.; Galarce, C.; Bedioui, F.; Cassir, M.; Sancy, M.
    AISI 430 stainless steel is an attractive material to be used in the healthcare industry, particularly as a sensor due to its low cost, corrosion resistance, as well as being Ni-free. AISI 430 was evaluated in an artificial sweat solution with the presence of Escherichia coli, and Staphylococcus aureus. Surface microbial analyses did not reveal colonization of bacteria on metallic surfaces, even when bacteria adhesion was investigated in a Miieller-Hinton solution. However, by electrochemical techniques, the AISI 430 surfaces demonstrated clear signs of corrosion mainly in a sterile medium after two weeks of exposure.
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    Effect of Sn content on the passivity of Ti-Ta-Sn alloys
    (2023) Valverde, B.; Sancy, M.; Martinez, C.; Botello, E.; Pio, E.; Aguilar, C.
    In this work, Ti-13Ta-xSn samples were manufactured using the powder metallurgy technique with a porosity near 35 %. The microstructural analysis revealed that increased Sn content decreased the alpha-Ti and alpha'-Ti phases. Furthermore, scanning electron microscopy and X-ray photoelectron spectroscopy showed that the chemical composition of the passive oxide film was influenced by the Sn content. Moreover, the electrochemical analysis revealed that the protective properties of oxide film improved with the Sn addition.
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    Electrochemical characterization of aluminum alloy AA2024-T3 influenced by bacteria from Antarctica
    (2017) Alvarado, C.; Sancy, M.; Blamey, J.; Galarce, C.; Monsalve, A.; Pineda Parra, Fabiola Makarena; Vejar, N.; Paez, M.
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    Enhanced Corrosion of 7075 Alloy by the Presence of Bacillus megaterium
    (2016) Vejar, N.; Sacre, J.; Collao, B.; Pérez C., José Ricardo; Paez, M.; Pineda Parra, Fabiola Makarena; Worker, B.; Sancy, M.
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    Evolution of synthesis of FCC nanocrystalline solid solution and amorphous phase in the Ti-Ta based alloy by high milling energy
    (2021) Aguilar, C.; Pio, E.; Medina, A.; Martinez, C.; Sancy, M.; Guzman, D.
    Pure Ti and Ti-based alloys exhibit two equilibrium phases: at lower temperatures they have a hexagonal close packed (alpha-Ti) crystalline structure while at higher temperatures they possess a body-centered cubic (beta-Ti) structure. However, in special conditions, they could exhibit a metastable face-centered cubic (gamma-Ti) crystalline structure. This paper aims to investigate the influence of Sn amount and milling time on the formation of gamma-Ti phase on the Ti-Ta based alloy. Four alloys with compositions Ti-13Ta-xSn (x: 3, 6, 9 and 12 at. %) were obtained by high energy milling. The alloys were analyzed by X-ray diffaction patterns, transmission and scanning electron microscopy. For the Ti-13Ta-3Sn alloy, the beta-Ti phase is formed in greater quantity, similar to 70% at 100 h. For the Ti-13Ta-6Sn and Ti-13Ta-9Sn alloys, the phase that is in greater quantity is gamma-Ti, around 100% at 100h. The Ti-13Ta-6Sn alloy shows a greater tendency to form the gamma-Ti phase, since the quantity is close to 100% at 50 h milling time. Thermodynamic calculations are comparable with experimental data. The calculations were made using the MAAT software based on Miedema's model. The MAAT is a free software that can be download from www.rpm.usm.cl. (C) 2020 Elsevier B.V. All rights reserved.
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    Improving mechanical properties and antibacterial response of a/b ternary Ti-Ta alloy foams for biomedical uses
    (2023) Aguilar, C.; Martin, F. San; Martinez, C.; Camara, B.; Claverias, F.; Undabarrena, A.; Sancy, M.; Salinas, V.; Munoz, L.
    This study investigates the potential of Ti-Ta-Sn alloys for biomedical applications due to their excellent mechanical properties and biocompatibility, with a particular focus on their use in trabecular bone replacement. This work aims to analyze the influence that of Sn has on the mechanical properties and antibacterial response of a -b ternary Ti-13Ta-xSn (x:3, 6, 9, and 12 at.%) alloy foams. The Ti-based alloys were designed considering three aspects; (i) final microstructure, (ii) alloying element types, and (iii) thermodynamics while using MAAT and ThermoCalc software. The alloys were obtained by mechanical alloying, with used milling times being 30 h for Ti-13Ta-3Sn, 10 h for Ti-13Ta-6Sn, 10 h for Ti-13Ta-9Sn, and 15 h for Ti-13Ta-12Sn. The foams were obtained using NaCl as the space holder (50 v/v% porosity) and consolidated by a hot pressing method at 780 & DEG;C for 30 min, applying a load of 40 MPa. Both the Staphylococcus aureus ATCC 6538 strain and Escherichia coli ATCC 8739 strain were used to evaluate the antibacterial responses of Ti-based alloy foams. The Ti-based alloy foams were composed mostly by a mix of a and b-phases. The metallic foams exhibited relative homogeneous pore distribution with a size between 100 and 450 mm and having an average porosity slightly higher than 50%. The samples showed elastic modulus values be-tween 1 and 2 GPa, compressive yield strengths over 150 MPa, and microhardness over 450 HV. All Ti-based alloy foams showed no antibacterial activity nor bacterial adhesion, indicating that there is bacterial adhesion inhibition.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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    Sol-gel coatings doped with encapsulated silver nanoparticles: inhibition of biocorrosion on 2024-T3 aluminum alloy promoted by Pseudomonas aeruginosa
    (2019) Gonzalez, E. A.; Leiva, N.; Vejar, N.; Sancy, M.; Gulppi, M.; Azocar, M. I.; Gomez, G.; Tamayo, L.; Zhou, X.; Thompson, G. E.; Paez, M. A.
    Silanol type hybrid polymers modified with silver nanoparticles encapsulated with SiO2 for biocorrosion protection of 2024-T3 aluminum alloy were studied through electrochemical characterization and surface analysis techniques. Two different encapsulated silver nanoparticles were synthesized using tetraethoxysilane as a core shell. The hybrid polymer was prepared by the sol-gel technique by mixing tetraethoxysilane and triethyl(octyl)silane in 1-propanol, followed by the incorporation of silver nanoparticles or encapsulated silver nanoparticles. Relatively uniform coatings were observed by a scanning electron microscopy analysis. Transmission electron microscopy and dynamic light scattering results indicated that the diameter of the silver nanoparticles was around 20 nm, whereas the encapsulated silver nanoparticles presented diameters between 24 and 30 nm. The viability results showed that polymers modified with encapsulated nanoparticles exhibit higher antibacterial properties than the polymer modified with free silver nanoparticles. This fact may be associated with a higher hydrophobicity of the coatings modified with silver encapsulated nanoparticles. Additionally, impedance measurements revealed a protective effect of all synthesized coatings for 2024-T3 aluminum alloy in chloride media inoculated with Pseudomonas aeruginosa. (C) 2019 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.