BUSCADOR RECOLECTA

The corrosion resistance of AZ31B magnesium alloy was evaluated after a two-step surface treatment consisting of a permanganate–fluorozirconate conversion layer followed by Flash-PEO in a silicate–fluoride (SiF) electrolyte. Electrochemical tests after 24 hours immersion in 0.5 wt.% NaCl demonstrated that the structured coating reduced the corrosion rate when compared to the reference Flash-PEO SiF coating ((3.4 ±1.0)x10-6 mm·yr-1 versus (1.3±0.8)x10-5 mm·yr-1). After 72 hours, this trend persisted, with impedance values at low frequency one order of magnitude higher than its counterpart without precursor layer ((1.4±1.0)x107 Ω·cm2 versus (2.6±1.0)x106 Ω·cm2). Notably, Flash-PEO coatings in both cases preserved electrochemical integrity even in the presence of pre-existing surface defects. The permanganate–fluorozirconate precursor layer promoted, after Flash-PEO processing, a distinctive “coral reef-like” morphology with reduced interconnected porosity, thereby enhancing barrier properties by limiting substrate exposure to the corrosive environment. Complementary characterization confirmed the incorporation of zirconium and manganese species, along with compounds typically derived from the Flash-PEO SiF electrolyte.

Conjunto de datos utilizados durante la investigación que lleva a la tesis doctoral De los códices diplomáticos denominados Becerros. Estudio y propuesta de corpus digital

Vídeo impresión 3D prisma T-ORG-6. Adjunto de la Tesis Doctoral titulada: "Formulación de ionogeles e hidrogeles de celulosa procedente del fraccionamiento de la madera y su aplicación en la impresión 3D" de Cynthia Hopson.

Esta cartografía o visualización relacional de datos forma parte de la investigación "Nuevas estéticas energéticas desde el arte", publicada en versión de capítulo de libro colectivo, con título "Estéticas", y un archivo/web con título homónimo. La cartografía muestra 41 proyectos artísticos que abordan las consecuencias ecosistémicas de la petrodependencia constitutiva de la modernidad y de nuestra ecodependencia energética contemporánea. Prácticas que no solo critican la herencia fósil, sino que además proponen nuevas estéticas en torno a las problemáticas energéticas. Esta investigación es producto del proyecto «Humanidades energéticas. Energía e imaginarios socioculturales entre la Revolución industrial y la crisis ecosocial» (PID2020-113272RA-100, HUMENERGE), financiado por MICIU/AEI /10.13039/501100011033. La investigación ha sido llevada a cabo por Bárbara Fluxá (coord.ª), Santiago Morilla, Jorge Yeregui y Coco Moya, integrantes del Taller permanente de investigación artística del proyecto. Para más información sobre la investigación y la cartografía consulte el archivo/web: https://esteticafosil.csic.es/nuevas-esteticas-energeticas/

Base de datos SUMMA Signum. Estructura y datos de investigación utilizados durante el proyecto de investigación: El castellano norteño en la Edad Media. Estudio Lingüístico de la documentación palentina. Ministerio de Economía, Industria y Competitividad. FFI 2016-80230P

The present work aims to provide corrosion performance data for an additively manufactured Ti6Al4V alloy in saline and polluted environments. The as-received additively manufactured material underwent heat treatment at 850 °C for 3 h to transform the acicular α’ microstructure into a lamellar α microstructure. Comparative corrosion assessments were conducted between the heat-treated substrates, the as-received condition, and a conventionally mill-annealed alloy. Potentiodynamic polarization experiments were carried out in saline (3.5 wt.% NaCl) and acid aqueous media ((NH4)2SO4 containing Harrison’s solution). The corrosion performance of additively manufactured substrates matched or surpassed that of the conventional alloy in Harrison’s solutions while remaining inferior in saline medium, despite forming a thicker passive film. Overall, the XY plane showed better corrosion performance, particularly after the elimination of the acicular α’ martensite by the applied heat treatment. The results also suggested that the presence of the coarse β phase was beneficial in 3.5 wt.% NaCl solution and detrimental in Harrison’s solutions, more so in acidified and fluorinated conditions.

Bioactive plasma electrolytic oxidation (PEO) coatings were developed on a wrought Mg0.5Zn0.2Ca alloy using a transparent electrolyte for easy maintenance and waste disposal, compared to a conventional suspension-based solution. Treatment times of 300, 600, and 900 s were evaluated for their effects on coating morphology, composition, and corrosion resistance. A short-time electrochemical impedance spectroscopy (EIS) screening was utilized to identify coatings with optimal corrosion protection. To assess the degradation rate and corrosion mechanisms, hydrogen evolution was monitored under pH-controlled quasi-in vivo conditions over extended immersion periods. Coating thickness increased by only 3% from 300 to 900 s of treatment (13 and 18 µm, respectively), with pore bands formed near the barrier layer at 900 s. The short-term EIS screening revealed that the coatings produced at 600 and 900 s were less protective and consistent than those at 300 s due to the presence of pore bands, which increased permeability. Hydrogen evolution measurements during 5 days of immersion at pH 7.4 indicated a tenfold higher degradation rate of the PEO-coated alloy compared to the bare substrate. Therefore, none of the PEO coatings provided effective corrosion protection after 24 h of immersion, which is attributed to crack formation at the PEO/corrosion products interface. This highlights the importance of crevices in the corrosion of Mg-Zn-Ca alloys. The presence of ZnO exacerbates the corrosion of magnesium in crevice areas.

In this study, a phosphate-based conversion coating (PCC) was applied as a precursor before forming silicate-fluoride (SiF) and silicate-phosphate-fluoride (SiPF) based flash-plasma electrolytic oxidation (Flash-PEO) coatings on AZ31B magnesium alloy. The main novelty is the successful incorporation of calcium, zinc, manganese and phosphate species into the Flash-PEO coatings via a precursor layer rather than using the electrolyte. The precursor also led to longer lasting and more intense discharges during the PEO process, resulting in increased pore size. Corrosion studies revealed similar short-term performance for all coatings, with impedance modulus at low frequencies above 107 Ωcm2, and slightly better performance for the SiPF-based coating. Nonetheless, the enlarged pores in the PEO coatings functionalized with the PCC precursor compromised the effectiveness of self-healing mechanisms by creating diffusion pathways for corrosive species, leading to earlier failure. These phenomena were effectively monitored by recording the open circuit potential during immersion in 0.5 wt.% NaCl solution. In summary, this study demonstrates that conversion coatings are a viable option for the functionalization of PEO coatings on magnesium alloys, as they allow for the incorporation of cationic and other species. However, it is crucial to maintain a small pore size to facilitate effective blockage through self-healing mechanisms.

Corrosion fatigue is a major factor leading to sudden failures in load-bearing orthopaedic implants, particularly in biodegradable ones that corrode more quickly than permanent implants. In the current study, we developed a novel modified-in vitro corrosion fatigue (MICorF) rig that incorporates several key parameters—such as loading mode, blood buffering capacity, gradual bone healing processes, and the synchronization of corrosion and cyclic damage—aimed at closely mimicking in vivo conditions. The functionality of the MICorF was tested with an experimental extruded ZX00 (Mg-0.5Zn-0.5Ca) Mg alloy. The results showed that the ZX00 Mg alloy possesses a limited biomechanical performance. Based on the SEM micrographs, the presence of intermetallic particles in the alloy microstructure and the subsequent galvanic corrosion phenomena could be taken as the main cause of failure. According to the results yielded by the MICorF, the ZX00 alloy withstands at least 20 days under the studied physiological conditions and polarization corresponding to the pitting conditions.

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