Browsing by Author "Ringuedé, Armelle"

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    A Tribological and Ion Released Research of Ti-Materials for Medical Devices
    (2021) Silva, Daniela ; Montero, M. Cecilia ; Guerra, Carolina ; Martinez Ugalde, Carola ; Li, Xuejie ; Ringuedé, Armelle ; Cassir, Michel ; Ogle, Kevin ; Guzman, Danny ; Aguilar, Claudio ; Paez, Maritza ; Sancy, Mamié
    The increase in longevity worldwide has intensified the use of different types of prostheses for the human body, such as those used in dental work as well as in hip and knee replacements. Currently, Ti-6Al-4V is widely used as a joint implant due to its good mechanical properties and durability. However, studies have revealed that this alloy can release metal ions or particles harmful to human health. The mechanisms are not well understood yet and may involve wear and/or corrosion. Therefore, in this work, commercial pure titanium and a Ti-6Al-4V alloy were investigated before and after being exposed to a simulated biological fluid through tribological tests, surface analysis, and ionic dissolution characterization by ICP-AES. Before exposure, X-ray diffraction and optical microscopy revealed equiaxed alpha-Ti in both materials and beta-Ti in Ti-6Al-4V. Scratch tests exhibited a lower coefficient of friction for Ti-6Al-4V alloy than commercially pure titanium. After exposure, X-ray photoelectron spectroscopy and surface-enhanced Raman spectroscopy results showed an oxide film formed by TiO2, both in commercially pure titanium and in Ti-6Al-4V, and by TiO and Al2O3 associated with the presence of the alloys. Furthermore, inductively coupled plasma atomic emission spectroscopy revealed that aluminum was the main ion released for Ti-6Al-4V, giving negligible values for the other metal ions.
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    Corrosion Analysis of a Ni-Al Bronze for Fuel Cell Applications
    (2025) Sancy, Mamié; Arcos, Camila; Guerra, Carolina; Ringuedé, Armelle; Noel, Corentin
    Global energy demand has increased significantly due to world population growth and the industrialization of developing economies. Its production has been based mainly on fossil-fuel energy, increasing the global warming effect upon the rise of greenhouse gases in the atmosphere, such as carbon dioxide (CO2). In this context, the International Energy Agency reported that the global temperature will increase by 2.7 °C by 2100, which can be decreased by using renewable energies, as written by the United Nations Framework Convention on Climate Change. Moreover, according to the last report of the Intergovernmental Panel on Climate Change, it is crucial to substantially reduce CO2 emissions and other greenhouse gases to improve air quality and stabilize global temperatures. However, nowadays, world energy generation from renewable resources, such as wind, solar, hydroelectric, biomass, tidal, and geothermal, only corresponds to 40%. Fuel cell technology is an excellent opportunity for reducing the dependence on fossil fuels and carbon footprint production. FC uses clean energy with a high conversion efficiency and system configuration that facilitates the easy capture of CO2. Different FC exists according to the operation temperature, the electrolyte chemical nature, and the fuel, increasing the conversion efficiency at higher temperatures, such as in Molten Carbonate Fuel Cells and Solid Oxide Fuel Cells, or even more recent Hybrid Fuel Cells, combining both previously mentioned technologies. Although FC has existed for decades, challenges exist to improve its efficiency. Therefore, developing new functional materials for innovative devices or applications is crucial in our changing world. New paradigms are necessary to produce cleaner energy or cheaper and more efficient materials for transport or other domains. This work focuses on the corrosion performance of a nickel-aluminum bronze alloy (NAB) obtained by laser powder bed fusion exposed to molten carbonate at high temperatures under a hydrogen/nitrogen atmosphere. Using electrochemical measurements and surface analyses, NAB samples were monitored before and after 120 hours of exposure between 550 and 650 °C. Scanning electron microscopy and X-ray photoelectron spectroscopy of NAB demonstrated that an oxide film was formed on the NAB surface, rich in Al2O3 and Cu2O. Open circuit potential and impedance analysis of NAB revealed that the oxide film was stable under the exposure condition. In addition, the impedance analyses showed a capacitive behavior associated with a porous behavior, relate to the oxide film, and a Warburg impedance