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Optimización del electropulido para el AISI 420
No full textEste proyecto aborda la problemática asociada a la caracterización metalográfica del acero inoxidable martensítico AISI 420 en estado Templado y Revenido (TR). La pasividad natural de este material y la presencia de carburos complejos dificultan su ataque mediante reactivos químicos convencionales, resultando a menudo en superficies manchadas o con picaduras que impiden un diagnóstico fiable. El estudio compara la eficacia del ataque químico tradicional (Reactivo Kalling II) frente a métodos electrolíticos (Ácido Oxálico 10%) asistidos por fuente de alimentación externa [1]. A través de cinco ensayos iterativos, se optimizó un protocolo que reduce el tiempo de preparación de 95 a 23 minutos, garantizando una observación nítida de la microestructura sin artefactos. El análisis económico valida la viabilidad industrial del método propuesto, equilibrando el incremento en el coste de consumibles con la drástica reducción de tiempos operativos.Este trabajo surge como un desafío técnico muy concreto, que fue la dificultad para preparar muestras de acero inoxidable martensítico AISI 420 con los métodos tradicionales. Debido a su elevada dureza y a la capa pasiva que lo protege, encontré que el ataque químico convencional el kalling II a menudo queda insuficiente, ofreciendo resultados borrosos o no idóneos para caracterizar la microestructura y los carburos.
La solución planteada fue no se limitó a probar un solo método, sino a diseñar una matriz experimental de cinco ensayos iterativos. El objetivo fue contrastar directamente distintas estrategias de desbaste, evaluando si realmente compensa usar diamante frente al carburo de silicio o la alúmina y comparar la eficacia del ataque químico frente al electrolítico con ácido oxálico. Durante el proceso, se ajustó variables críticas como el voltaje probando a 6v, 10v y 15 v y los tiempos de exposición detallados en el trabajo, sin perder de vista algo fundamental en la industria que es la rentabilidad y el coste de los consumibles.
La conclusión de mi investigación es contundente: el ataque electrolítico es técnicamente superior al químico para este material. Esta superioridad se define por la sustitución de la corrosión pasiva por una disolución anódica selectiva a 10 V, mecanismo capaz de eliminar la capa de material deformado (Capa de Beilby) y revelar la estructura virgen sin generar relieve topográfico ni tinciones artificiales. Bajo esta premisa, he validado el Ensayo 5 (Protocolo óptimo de preparación híbrida con ataque secuencial) como la solución óptima, pues logra una calidad visual de alto contraste y fidelidad microestructural, reduce el tiempo de proceso a 30 minutos y mantiene un coste viable, transformando un método incierto en un estándar robusto.This work arose as a very specific technical challenge, which was the difficulty in preparing samples of AISI 420 martensitic stainless steel using traditional methods. Due to its high hardness and the passive layer that protects it, I found that conventional chemical etching with Kalling II is often insufficient, producing blurred results that are unsuitable for characterising the microstructure and carbides.
The proposed solution was not limited to testing a single method, but rather to designing an experimental matrix of five iterative tests. The objective was to directly compare different roughing strategies, evaluating whether it really pays to use diamond over silicon carbide or alumina, and to compare the effectiveness of chemical etching versus electrolytic etching with oxalic acid. During the process, critical variables such as voltage were adjusted, testing at 6v, 10v and 15v, and the exposure times detailed in the work, without losing sight of something fundamental in the industry, which is profitability and the cost of consumables.
The conclusion of my research is clear: electrolytic etching is technically superior to chemical etching for this material. This superiority is defined by the replacement of passive corrosion with selective anodic dissolution at 10 V, a mechanism capable of removing the layer of deformed material (Beilby layer) and reveal the virgin structure without generating topographical relief or artificial staining. Under this premise, I have validated Test 5 (Optimal hybrid preparation protocol with sequential etching) as the optimal solution, as it achieves high-contrast visual quality and microstructural fidelity, reduces processing time to 30 minutes, and maintains a viable cost, transforming an uncertain method into a robust standard
RV.S1.C1.V4 Creación de Suelos y Cubierta
No full textVídeos docents de l'assignatura Representació Arquitectònica II (REVIT) impartida per Isidro Navarro, PDI de l'ETSA
Tracing marine litter sources along the Barcelona coastline: Insights from observations and numerical modelling
No full textPlastic debris concentrations in Barcelona coastal waters are among the highest in the Mediterranean Sea, comparable to those observed in subtropical gyres. This study quantifies the marine litter budget and fluxes along the Barcelona coastline using Lagrangian numerical backtracking simulations informed by one year of sampling data (2020–2021) from five urban and two metropolitan area beaches. Sensitivity analyses were conducted to determine optimal simulation parameters, identifying a simulation duration of -28 days and a median time of particles to come from a known source of -26.35 h. These parameters were used to develop a probabilistic module accounting for unresolved nearshore processes. Additional behavioural conditions for this module were derived from the sensitivity assessments. Analysis of beach water marine litter as simulation input revealed multiple pollution hot-spots, linking marine litter sources to known emission points such as combined sewer overflows, marinas, and coastal structures such as breakwaters. Marine litter amounts in urban beach waters reached 1.8 × 109 items km-2 y-1, with simulations indicating that >55% originated from outside the study domain. These findings highlight the Barcelona coastal zone as both a significant emitter and recipient of plastic debris due to regional hydrodynamic connectivity and transport. High levels of plastic pollution highlight the urgent need for upstream waste reduction and targeted mitigation measures to prevent litter from reaching the sea.The present study was developed within the TRAP (EsTRAtegias participativas para la gestión de la contaminación por Plástico del litoral transfronterizo) project (EFA147/03) funded by the POCTEFA Program/Interreg VI-A 2021–2027. Financial support was provided by the Catalan Government Grups de Recerca Consolidats grant (2021 SGR 01195), the ICREA Academia program, and the Surfing for Science projects funded by FECY.Peer ReviewedPostprint (published version
MATHEMATICAL MODELLING WITH PARTIAL DIFFERENTIAL EQUATIONS ( Examen Final, 1er Quadrimestre )
No full textExamen Final 1er Quadrimestre2025/20261r quadrimestr
Pla de conjunt d'Estel Blay Carreras i Anna Bach Valls rebent de mans de l'alcalde de Manresa Marc Aloy i Guàrdia el Premi Rosa Argelaguet i Isanta a la BCUM
No full textPla de conjunt de Mònica Roca i Aparici durant la seva intervenció a l'acte de lliurament del Premi Rosar Argelaguet i Isanta a la BCUM
No full textTEORIA D'ESTRUCTURES (Examen final 1r quadrimestre)
No full textProblemaResolved2025/20261r quadrimestr
Influence of WC grain size on the hot deformation behaviour of cemented carbides
No full textThis study explores the influence of WC grain size on the hot deformation behaviour of WC-Co. Cemented carbides with varying WC grain sizes (0.6–1.3 µm) and constant binder contents (10 wt% and 20 wt% Co) were compressed at temperatures ranging from 775 °C to 1000 °C, and strain rates between 0.0005 and 0.01 s-1. Fine-grained cemented carbides exhibited higher resistance to plastic deformation, but lost rigidity more rapidly at elevated temperatures due to grain boundary sliding and binder infiltration. A physically based constitutive model, previously developed by the authors, was extended to incorporate WC grain size, showing excellent agreement with experimental data. Model parameters revealed that finer carbides enhance WC load-bearing capacity but reduce WC-Co interaction strength, while coarser ones maintain stronger WC-WC interfaces in the range of grain sizes here analyzed. Microstructural analysis via electron back-scattered diffraction confirmed these trends, highlighting the role of grain boundaries and phase transformations in deformation mechanisms. These findings underline the importance of WC grain size in optimizing the high-temperature performance of cemented carbides and provide a robust framework for predictive modelling.Peer ReviewedPostprint (author's final draft
Probing CeO2-based materials for CO2 capture efficiency: Effect of synthesis mode and dopant
No full textThis study evaluates the effect of synthesis mode and La-dopant incorporation on the performance of CeO2-based materials for CO2 capture. Materials were prepared by conventional autoclave and microwave-assisted hydrothermal treatments to compare their efficacy. Microwave-assisted synthesis enables rapid and uniform volumetric heating, accelerating nucleation and crystal growth, consequently shortening synthesis time. Samples were characterized by powder X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy– Energy-Dispersive X-ray Spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET) analysis for surface area and pore volume, alongside CO2 adsorption measurements at 273 K. Microwave irradiation yielded CeO2 with smaller crystallites and higher surface area (107 m2·g-¿1) compared to the conventional hydrothermal method. The corresponding CO2 uptake for the microwave-assisted materials was 1.21 mmol·g-¿1. Furthermore, La-doped samples exhibited stronger basic sites and altered Ce4+/Ce3+ ratios, favouring the formation of bidentate and polydentate carbonates. CO2 adsorption data correlated better with the Freundlich model, and the adsorption kinetics were best described by the pseudo-second-order model. The results demonstrate that microwave-assisted hydrothermal synthesis effectively tailored the surface properties of CeO2-based materials, enhancing both interaction strength with CO2 and overall CO2 adsorption capacity.Peer ReviewedPostprint (author's final draft