Artículos (Ingeniería y Ciencia de los Materiales y del Transporte)
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Artículo Influence on the properties of TMCs of ceramic and intermetallic composite reinforcements (B₄C, TiₓAly and TiₓSiy) fabricated by inductive hot pressing(Elsevier, 2024-09-30) Arévalo Mora, Cristina María; Montealegre-Meléndez, Isabel; Neubauer, Erich; Kitzmantel, Michael; Lascano, Sheila; Pérez Soriano, Eva María; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los MaterialesAmbitious and competitive, the aerospace industry continuously demonstrates to be one of the leading engineering sectors either at exigence and new technologies development. As lightning the weight of aircrafts is one of the main targets, the spotlight is usually on material research by which new ones may be produced to pursue this aim and still offer the necessary performances. The combination of the properties of titanium and other materials as reinforcements provides really interesting results as titanium matrix composite materials, also known as TMCs. Various samples of titanium matrix composite materials with different reinforcements have been under study to determine the influence of the reinforcements and their respective proportions on the properties of the material. These samples composed of grade 1 commercially-pure titanium as matrix and B₄C, TiₓAly and TiₓSiy as reinforcements, have been manufactured through powder metallurgy in the same conditions of temperature and pressure via Inductive Hot Pressing (IHP). A total of eight composite materials have been arranged in several different groups to confront their compositions. Thus, this analysis reports results for the influence of the powder size of the matrix and the ceramic reinforcement, the effect of varying the volumetric composition of B₄C, and the selection of different intermetallic reinforcements. These tests and the obtained information serve for a project in which the main goal is to determine which compositions of the studied composite materials reach a high enough specific stiffness for a suitable application in the aerospace industry.Artículo Alloy exsolution in co-doped PrBaMn₂₋ₓTMₓO₅+δ (TM = Co and/or Ni) obtained by mechanochemistry(Elsevier, 2024-12-15) Gotor Martínez, Francisco José; Sayagués de Vega, María Jesús; Marrero-López, D.; García García, Francisco José; García García, Francisco José; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC); Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los MaterialesDoped-PrBaMn₂₋ₓTMₓO₅+δ samples with TM = Co and/or Ni were synthesized by a mechanochemical route from stoichiometric oxide precursor mixtures (Pr₆O₁₁, BaO₂, MnO, NiO and CoO) using a planetary mill at 600 rpm for 150 min. A disordered ABO₃ pseudocubic perovskite phase was obtained after the milling process that was transformed, as established by XRD, into the double layered AA’B2O₅+δ perovskite phase after annealing at 900 °C in a reducing atmosphere (10%H₂/Ar). The microstructural characterization by SEM, TEM, and HRTEM ascertained that this reducing treatment induced the exsolution of Ni and Co metallic nanoparticles from the doped samples. Ni-Co alloys were even exsolved when the layered manganite phase was co-doped with both transition metals. It was confirmed that the exsolution process was reversible by switching the working atmosphere from reducing to oxidizing. Polarization resistance values of the doped samples determined in symmetrical cells in air and H₂, as well as the electrochemical performance of electrolyte LSGM-supported planar cells suggested that these samples can be used as symmetrical electrodes in SOFCs.Artículo Enabling low molecular weight electrospinning through binary solutions of polymer blends(Elsevier, 2025-01) Pérez-Puyana, Víctor Manuel; Romero García, Alberto; Guerrero Conejo, Antonio Francisco; Moroni, Lorenzo; Wieringa, Paul; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla. Departamento de Ingeniería Química; Ministerio de Economía y Competitividad (MINECO). España; Universidad de Sevilla. TEP229: Tecnología y Diseño de Productos MulticomponentesThe formation of nanofibrous membranes via electrospinning is typically restricted to high molecular weight polymers in an appropriate solvent, correlated with the necessary formation of polymer chain entanglements that are needed to achieve successful production of electrospun fibers. The present work extends the electrospinning of low molecular weight polymers by investigating the electrospinning of a binary solution system consisting of two different low molecular weight polymers, using as a model system polycaprolactone (PCL) and gelatin in different ratios. The viscosities of the polymer solutions were characterized as a proxy for polymer chain entanglement and the resulting fibers were morphologically characterized by SEM imaging and further assessed water contact angle and molecular composition to determine the impact and homogeneity of the binary mixtures. We found that unitary solutions of either PCL or gelatin failed to generate proper fibers despite indications of chain entanglement. In contrast, binary solutions of low molecular weight PCL and gelatin generated different fiber quality and size distributions, depending on the ratio used, with direct correlations between fiber properties and the PCL:Gelatin ratio. It was discovered that the ratio of PCL to gelation was most predictive for successful fiber generation, with effective electrospinning occurring only for a define intermediate range of high blend ratios while both low and high blended binary solutions resulted in poor fiber production. Our study confirmed that this behavior was independent from absolute polymer concentration, indicating a unique interaction between these binary species which exists only under specific ratio concentrations and indicates promising new avenues to process low molecular weight polymers solutions.Artículo Hydrogels and Nanogels: Pioneering the Future of Advanced Drug Delivery Systems(MDPI, 2025-02-07) Delgado-Pujol, Ernesto J.; Martínez Muñoz, Guillermo; Casado Jurado, David; Vázquez Cabello, Juan; León-Barberena, Jesús; Rodríguez Lucena, David; Torres Hernández, Yadir; Alcudia Cruz, Ana; Begines Ruiz, Belén; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla. Departamento de Química Orgánica y Farmacéutica; Universidad de Sevilla. Departamento de Química Orgánica; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales; Universidad de Sevilla. FQM408: Química Farmacéutica AplicadaConventional drug delivery approaches, including tablets and capsules, often suffer from reduced therapeutic effectiveness, largely attributed to inadequate bioavailability and difficulties in ensuring patient adherence. These challenges have driven the development of advanced drug delivery systems (DDS), with hydrogels and especially nanogels emerging as promising materials to overcome these limitations. Hydrogels, with their biocompatibility, high water content, and stimuli-responsive properties, provide controlled and targeted drug release. This review explores the evolution, properties, and classifications of hydrogels versus nanogels and their applications in drug delivery, detailing synthesis methods, including chemical crosslinking, physical self-assembly, and advanced techniques such as microfluidics and 3D printing. It also examines drug-loading mechanisms (e.g., physical encapsulation and electrostatic interactions) and release strategies (e.g., diffusion, stimuli-responsive, and enzyme-triggered). These gels demonstrate significant advantages in addressing the limitations of traditional DDS, offering improved drug stability, sustained release, and high specificity. Their adaptability extends to various routes of administration, including topical, oral, and injectable forms, while emerging nanogels further enhance therapeutic targeting through nanoscale precision and stimuli responsiveness. Although hydrogels and nanogels have transformative potential in personalized medicine, challenges remain in scalable manufacturing, regulatory approval, and targeted delivery. Future strategies include integrating biosensors for real-time monitoring, developing dual-stimuli-responsive systems, and optimizing surface functionalization for specificity. These advancements aim to establish hydrogels and nanogels as cornerstones of next-generation therapeutic solutions, revolutionizing drug delivery, and paving the way for innovative, patient-centered treatments.Artículo Simulation of the electrical resistance sintering process by means of fnite diference in a spreadsheet(Springer, 2025) Montes Martos, Juan Manuel; Ternero Fernández, Fátima; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)In this work, a theoretical model for the metal powder consolidation technique known as Electrical Resistance Sintering (ERS) is proposed and validated. This technique consists of the consolidation of a mass of metal powder by the simultaneous action of pressure and the passage of a high intensity electric current. This electric current heats the powder mass by the Joule effect, while softening it so that the imposed pressure causes its densification. The proposed model meets the set objective of seeking the greatest possible simplicity, without ignoring the key aspects of the technique. In line with this simplicity, the proposed model has a one-dimensional character and is solved numerically by means of Finite Difference through a simulator implemented in the Microsoft Excel™ spreadsheet environment, programming in VBA, with computation times not exceeding 5 min. The adopted strategy takes into account the strong electrical–mechanical-thermal coupling present in the process. The sensors incorporated in the ERS equipment allow the recording of the data necessary to construct the evolution curves of the global porosity and the thermal energy released. The theoretical predictions provided by the simulator have been compared with experimental curves obtained from the electrical consolidation experiments with commercially pure iron powder. Discrepancies between experimental and theoretical values for final global porosity are around 5% (although approaching 20% in the vicinity of critical conditions) and those for final specific thermal energy do not exceed 7%. The reasonable agreement between the experimental and theoretical curves gives confidence that the model, despite its simplifications, reproduces the main characteristics of the process.Artículo Porosity efect on the thermal conductivity of sintered powder materials(Springer, 2025-02) Montes Martos, Juan Manuel; Gómez Cuevas, Francisco de Paula; Cintas Físico, Jesús; Ternero Fernández, Fátima; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)In this work, the effective thermal conductivity of sintered powder materials is studied. The extensive literature related to the proposed models about this property in all kind of porous materials is reviewed, and a new equation is proposed as a function of the fully dense material conductivity, the porosity of the material and the tap porosity of the starting powder. This equation covers the porosity range of powder aggregates from the tap porosity to zero porosity, and also applies to sintered powders. The proposed equation has been experimentally validated by fitting to experimental data of metallic sintered powder materials measured at room temperature, resulting very good agreements. Also, alternative models proposed by other authors have been fitted to the same experimental data to check the relative goodness of the proposed model. The results allow to conclude that a percolation model can describe the behaviour of the effective thermal conductivity of sintered powder materials with low and medium porosity levels.Artículo Ion beam induced secondary electron tomography of acrylonitrile-styrene-acrylate/polycarbonate polymer blends for fused filament fabrication and injection moulding(Nature Portfolio, 2025) Hernández-Saz, Jesús; Moreno Sánchez, Daniel; Valencia Liñán, Luisa María; Gómez, Y.; Molina Rubio, Sergio Ignacio; Herrera Collado, Miriam; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Junta de Andalucía; European Union (UE)Polymer blending is an interesting strategy to broaden the combination of properties available for a variety of applications. To understand the behaviour of the new materials obtained as well as the influence of the fabrication parameters used, methods to analyse the distribution of polymers in the blend with resolution below the micrometer are required. In this work, we demonstrate the capability of focused ion beam (FIB) tomography to provide 3D information of the polymer distribution in objects obtained by blending acrylonitrile-styrene-acrylate (ASA) with polycarbonate (PC) (50 wt%), fabricated by Fused Filament Fabrication (FFF) and by Injection Moulding (IM). For this, ion beam induced secondary electron (iSE) images show the capability to distinguish unequivocally the two phases in the blend, providing enough contrasts to perform the 3D experiment. Additionally, Monte Carlo simulations show that the lateral spread for incident electrons in PC is 61.7 nm and for Ga+ ions of 26.2 nm, evidencing a better spatial resolution in iSE imaging. The sputtering rate under the ion beam has been quantified for both neat ASA and neat PC to find optimal parameters for the iSE tomography, resulting in a current of 0.05 nA and a dwell time of 3 µs. Our results reveal significant differences in the morphology of ASA/PC blends depending on the fabrication method. Blends obtained by FFF exhibit strong directionality and a co-continuous morphology, whereas IM objects present a droplet-matrix structure. Also, the interface area between the ASA and PC is quantified to be of 3200 μm² for the FFF sample and 1400 μm² for the IM sample, approximately double in FFF than in IM. The reasons for the different morphologies obtained in the studied blends and possible effects in their mechanical properties are discussed.Artículo Compositional and microstructural study of joining methods in archaeological gold objects(John Wiley and Sons Ltd, 2017-03) Scrivano, Simona; Gómez-Tubio, Blanca María; Ortega-Feliú, Inés; Ager Vázquez, Francisco José; Paúl Escolano, Antonio; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). EspañaThis work arises in response to the need to understand the production techniques of pre-roman gold jewels, starting from the systematic characterization of the different methods of metal joining used in antiquity to produce these objects. To meet this requirement, different procedures used in antiquity were reproduced by means of experimental archaeology. These models correspond to three metal-joining methods reported by ancient recipes: solid-state diffusion with copper salt, brazing and autogenous welding. These techniques were studied by different analytical methods in order to characterize them at both compositional and microstructural level (SEM-EDS, metallography, μ-XRF and μ-PIXE). The results obtained show that the solid-state diffusion bonding with copper salt presents a crystal hexagonal structure without phase changes in the joining point, where only a variation in the grain size is observed. At the compositional level, this soldering method is characterized by a local increase in copper concentration and a small decrease in gold content. In contrast, brazing shows a dendritic-porous structure due to the superposition of the soldering alloy and the crystal structure of the original foils. Besides, the compositional analysis revealed an increment of silver and copper concentrations and a simultaneous reduction of gold concentration. Finally, in the autogenous welding, no changes at the microstructural and compositional levels were observed. The results obtained have also demonstrated the usefulness of a portable μ-XRF system for the in-situ characterization of ancient jewels.Artículo Combining XRF and GRT for the analysis of ancient silver coins(Elsevier, 2016-05) Ager Vázquez, Francisco José; Gómez-Tubio, Blanca María; Paúl Escolano, Antonio; Gómez-Morón, A.; Scrivano, Simona; Ortega-Feliú, Inés; Respaldiza Galisteo, Miguel Ángel; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economía y Competitividad (MINECO). EspañaArchaeological silver-copper alloys are usually affected by silver enrichment of the near surface layers, either intentional or fortuitous. In previous studies we have shown that surface composition of archaeological bronzes and leaded copper coins obtained by XRF can be corrected by means of gamma-ray transmission (GRT) to obtain the bulk composition. In the present work, we have studied the applicability of this method to silver-copper alloys and established the most suitable conditions for the GRT correction calculation. The analysis of the microstructure of the core and the corrosion layers of a set of silver roman coins shows that copper could be leached from the surface during corrosion and cleaning treatments, resulting in an apparent silver surface enrichment. After the correction calculations by GRT method, the concentrations of the major elements, Ag and Cu, were found to be in good agreement with the bulk composition obtained by direct analysis of the cut cross-sections of the coins. The GRT method shows to be a useful tool to study metal artefacts having a surface composition modified by corrosion or cleaning treatments.Artículo Camphene/polystyrene solutions: A rheological approach for material processing industry(John Wiley & Sons Inc., 2019-05-11) Félix Ángel, Manuel; Pérez-Puyana, Víctor Manuel; Paúl Escolano, Antonio; Sepúlveda Ferrer, Ranier Enrique; Universidad de Sevilla. Departamento de Ingeniería Química; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Economia, Industria y Competitividad (MINECO). EspañaRheological properties of polymer–camphene solutions are very relevant as they affect their stability, and they have many implications in operation costs. This work elucidates the rheological properties of polystyrene (PS–camphene) solutions with industrial applications. Unfortunately, the assessment of the very low shear viscosities of camphene-based materials (below 0.005 Pa s) is still a challenge with commercial rheometers. Flow curves, stress growth tests, and small amplitude oscillatory shear (SAOS) measurements were carried out as a function of PS concentration (0, 2.5, 5.0, 10, and 20 wt % PS) to understand the rheological behavior of these systems. Results indicate that liquid camphene has a shear-thinning behavior (flow index = 0.99) when the increase of polymer concentration involves changes in the structure of these systems (flow index = 0.10 for 20 wt % PS). An increase in PS concentration leads to a forwarding in the shear-thinning zone, and the Newtonian region (from ∼1 s−1, for 0 wt % PS, to 10−3 s−1 for 20 wt % PS). Eventually, these results evidence the high dependence of η∞ on PS concentration (from ∼1.16 ± 0.01 Pa s, for 0 wt % PS, to 631.5 ± 0.2 Pa s for 20 wt % PS). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47953.Artículo Conformal TiO₂ Aerogel-Like Films by Plasma Deposition: from Omniphobic Antireflective Coatings to Perovskite Solar Cell Photoelectrodes(American Chemical Society, 2024-07-20) Obrero Pérez, José M.; Contreras Bernal, Lidia; Aparicio Rebollo, Francisco Javier; Rojas, Teresa C.; Ferrer Troyano, Francisco Javier; Orozco, Noe; Saghi, Zineb; Czermak, Triana; Pedrosa, José María; López Santos, Carmen; Ostrikov, Kostya Ken; Borrás Martos, Ana Isabel; Sánchez Valencia, Juan Ramón; Barranco Quero, Ángel; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla. Departamento de Lenguajes y Sistemas Informáticos; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía; Universidad de Sevilla; European Union (UE). H2020; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los MaterialesThe ability to control the porosity of thin oxide films is a key factor determining their properties. Despite the abundance of dry processes for synthesizing oxide porous layers, a high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultraporous titanium dioxide thin films at room or mild temperatures (T ≤ 120 °C) by a sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85% that are comparable to those of advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures, presenting a distribution of anatase clusters embedded in the sponge-like open porous structure. Surprisingly, the porous structure remains after annealing the films at 450°C in air, which increases the fraction of embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive, becoming superhydrophilic when subjected to ultraviolet light irradiation. The supported, percolated, and nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel-like film thickness, which reaches efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and applicable to ultrahigh porous conformal oxides of different compositions, with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.Artículo Design, processing and characterization of advanced titanium scaffolds with controlled radial porosity: a new sequential compaction device(Elsevier, 2016) Pavón, Juan; Trueba Muñoz, Paloma; Rodríguez, José Antonio; Torres Hernández, Yadir; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los MaterialesBiological systems like those that are involved in many human tissues are perhaps one of the most exciting and inspiring examples of graded highly anisotropic hierarchical materials. In this work, we are initially focused on phenomenological relationships between bone structure, its mechanical properties and most frequent damages. Current status of biomedical materials for bone replacement clearly indicates that titanium (Ti) and some of its alloys are still the better metallic material clinically used to that purpose. The stiffness mismatch between Ti and bone, around one-order magnitude (~110 GPa against ~20GPa), is one of those current challenges that require to be overcome; the associated stress shielding is main the cause of the clinically observed bone resorption around Ti implants. This is an ideal scenario in which functionally graded materials (FGMs) become a powerful alternative to offer new alternatives for better bone implants. The aim of this work is the development of a novel compaction device that responds to necessity of fabricating new components with controlled graded radial porosity.Artículo Effect of Copper Addition on Pitting Corrosion of MA-Al(Polish Academy of Sciences, 2016-04) Aranda, B.; Cuevas, F. G.; Cintas Físico, Jesús; Herrera García, Marta; Urban, Petr; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU)This paper is intended to highlight the effect of copper addition on the pitting corrosion resistance of aluminium-base powder metallurgy parts. Results obtained on these mechanically alloyed (MA) specimens are compared with parts of MA-Al without added copper, as well as with commercial aluminium alloys. Immersion tests from 2 to 96 hours in 3.5% NaCl solutions, and potentiostatic techniques, were used to study the pitting corrosion. It was concluded that copper addition, in a similar way that in commercial aluminium alloys, produces a negative effect on the pitting corrosion resistance, because of the formation of Al2Cu. These precipitates produce galvanic cells that favour the specimen pit. Therefore, increasing the copper content of MA-Al, although improving their ductility, worsens the pitting corrosion resistance of these alloys.
Artículo Development and characterization of Fe2O3 nanoparticles doped with Al2O3 / TiO2 for green hydrogen production(Elsevier, 2025-02) Paúl Navarrón, Miguel; Lloreda Jurado, Pedro Javier; Chicardi Augusto, Ernesto; Balu, Krishnakumar; Dieuzeide, María Laura; Tejeda, R.; Avendaño, Roger; Sepúlveda Ferrer, Ranier Enrique; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission. NextGeneration EU; Universidad de Sevilla. TEP973: Tecnología de Polvos y CorrosiónIron oxide is an inexpensive raw material capable of producing hydrogen based on the water-splitting reaction. However, the reaction is limited by the active surface area available on the particle. In this study, Fe2O3 nanoparticles doped with Al2O3 and TiO2 oxide (95 wt% Fe2O3 - X wt% Al2O3 - (5-X) wt% TiO2; X = 2, 2.5 and 3) were prepared by a double coprecipitation method to obtain a single solid solution. The synthesis of a solid solution resulted in particles with higher porosity. The use of Al resulted in the formation of pores of approximately 3 μm, which effectively prevented grain growth. Conversely, the substitution of Ti ions increased the oxygen mobility, resulting in a higher hydrogen consumption at temperatures below 700 °C, leading to a deeper reduction reaction. Indeed, the reactivity of the particle surface was strongly influenced by the Al/Ti atomic ratio, and the Fe3Al2Ti formulation seems to be the most promising due to its compositional and morphological design to create an oxide functional ceramic for H2 production.Artículo Design, fabrication, and characterization of novel dental implants with porosity gradient obtained by Selective Laser Melting(Elsevier, 2025-03) Robau-Porrua, Amanda; González, Jesús E.; Arancibia-Castillo, Roberto; Picardo Pérez, Alberto; Araneda-Hernández, Eugenia; Torres Hernández, Yadir; Universidad de Sevilla. Departamento de Ingeniería del Diseño; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; European Commission. Fondo Social Europeo (FSO); Universidad de Sevilla. TEP992: Diseño e Ingeniería; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los MaterialesPorous dental implants represent a significant advancement in dentistry, offering improved osseointegration, reduced bone resorption and minimized stiffness to better interact with surrounding bone. This study focuses on the development of Ti6Al4V implants with immediate loading and controlled porosity (40 vol% and 600 µm pore size) to improve vascularization and bone ingrowth, which are crucial for successful integration and long-term performance. Dense implants, fully porous implants, and a hybrid design combining a porous surface with a dense core were fabricated using Selective Laser Melting, enhancing fatigue resistance under cyclic loads. Porosity was quantified, revealing 19 % through image analysis and 13 % via the Archimedes method. Finite Element Analysis demonstrated that porous implants improve stress distribution, facilitate load transfer to peri-implant trabecular bone, and achieve uniform stress and strain distributions between thread fillets, with values ranging from 1.1 MPa to 1.6 MPa for stress and 0.0002 to 0.0030 for strain, promoting bone growth. Comparisons with β-Ti alloy implants featuring a porous structure and dense core revealed reduced stress concentrations and a lower risk of fatigue failure. These findings highlight the potential of hybrid and β-Ti designs for personalized dental implants, balancing mechanical performance with biological compatibility to meet patient-specific needs.Artículo Aerogels Based on Chitosan and Collagen Modified with Fe₂O₃ and Fe₃O₄ Nanoparticles: Fabrication and Characterization(Multidisciplinary Digital Publishing Institute (MDPI), 2025-01-08) Granados Carrera, Carmen M.; Castro Criado, Daniel; Abdullah, Johar Amin Ahmed ; Jiménez Rosado, Mercedes; Pérez-Puyana, Víctor Manuel; Universidad de Sevilla. Departamento de Ingeniería Química; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). EspañaThe necessity to mitigate the intrinsic issues associated with tissue or organ transplants, in order to address the rising prevalence of diseases attributable to increased life expectancy, provides a rationale for the pursuit of innovation in the field of biomaterials. Specifically, biopolymeric aerogels represent a significant advancement in the field of tissue engineering, offering a promising solution for the formation of temporary porous matrices that can replace damaged tissues. However, the functional characteristics of these materials are inadequate, necessitating the implementation of matrix reinforcement methods to enhance their performance. In this study, chemical and green iron oxide nanoparticles, previously synthesized and documented in existing research, were incorporated into hybrid aerogels combining collagen (C) and chitosan (CH). The characterization of these aerogels was conducted through rheological, microstructural, and functional analyses. The results demonstrate that the incorporation of iron oxide nanoparticles has a significant influence on the properties of the aerogels fabricated with them. In particular, the incorporation of these nanoparticles has been observed to modify the mechanical properties, with an increase in strength and porosity that may support cell proliferation.Artículo Enhanced porous titanium biofunctionalization based on novel silver nanoparticles and nanohydroxyapatite chitosan coatings(Elsevier, 2025-04) Castillejo, Ana; Martínez Muñoz, Guillermo; Delgado-Pujol, Ernesto J.; Villalobo Polo, Eduardo; Carrillo de la Fuente, Francisco; Casado Jurado, David; Pérez Bernal, Juan Luis; Begines Ruiz, Belén; Torres Hernández, Yadir; Alcudia Cruz, Ana; Universidad de Sevilla. Departamento de Química Orgánica y Farmacéutica; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla. Departamento de Ingeniería Química; Universidad de Sevilla. Departamento de Microbiología; Ministerio de Ciencia e Innovación (MICIN). EspañaTitanium is widely used for implants however it presents limitations such as infection risk, stress shielding phenomenon, and poor osseointegration. To address these issues, a novel approach was proposed that involves fabricating porous titanium substrates, to reduce implant stiffness, minimizing stress shielding and bone resorption, and applying polymeric coatings to improve bioactivity. Composite coating prepared from chitosan, silver nanoparticles, and nanohydroxyapatite was optimized to enhance antibacterial properties and promote osseointegration. Chitosan with 80.5 % of deacetylation degree was used to prepare composites with diverse compositions, including different methodologies of adding silver nanoparticles, with silver concentrations below toxic level. Antibacterial activity was tested with three different strains, including Gram+ and Gram− bacteria, demonstrating excellent inhibition after 21 days. In addition, the induction of hydroxyapatite formation was investigated. Finally, the optimal porous metallic substrate that exhibited a more suitable stiffness (29 GPa) (close to the cortical bone tissue they intend to replace) was chosen to be infiltrated with the selected composites. In summary, this synergistic approach based on the combination of porous titanium substrates with 60 vol% porosity and a 355–500 μm pore size distribution coated with 3%CS-nHA-AgNPs-TPP-AgNPsbath composite provided a potential solution to provide implants with improved biomechanical balance and biofunctionality.Artículo Structural and physical-chemical properties of milk fat globules fractionated by a series of silicon carbide membranes(Elsevier, 2024-09) Dons, Tobías; Kirkensgaard, Jacob J.K.; Candelario, Víctor M.; Andersen, Ulf; Ahrné, Lilia; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del TransporteDriven by the acknowledged health and functional properties of milk fat globules (MFGs), there is a growing interest to develop gentle methodologies for separation of fat from milk. In this study, separation of fat from raw milk and fractionation in streams containing MFGs of different size was achieved using a series of two silicon carbide ceramic membranes. A first step consisting of a 1.4 µm membrane aimed to concentrate the bulk of the fat, i.e. the larger MFGs (D[4,3] ∼ 4 µm) followed by a 0.5 µm fractionation aimed to concentrate the residual milk fat in the permeate, i.e. fraction with the smaller MFGs (D[4,3] ∼ 1.8–2.4 µm. The fat separation performance showed a yield of 92 % for the 1.4 µm membrane and 97 % for the 0.5 µm membrane. Both fat enriched retentates showed, by the confocal laser scanning microscopy, intact MFGs with limited damage in the MFG membrane. The fatty acid profile analysis and SAXS showed minor differences in fat acid composition and the crystallization behavior was related to differences in the fat content. The 0.5 µm permeate containing the smallest MFGs however showed larger aggregates and a trinomial particle size distribution, due to probably pore pressure induced coalescences. The series of silicon carbide membranes showed potential to concentrate some of MFGM proteins such as Periodic Schiff base 3/4 and cluster of differentiation 36 especially in the 0.5 µm retentates. A shift in casein to whey protein ratio from 80:20 (milk) to 50:50 was obtained in the final 0.5 µm permeate, which opens new opportunities for product development.Artículo Novel B4C supports for ceramic membrane filtration(Elsevier, 2024) Madrigal, Juan R.; García-Galán, Manuel A.; Guiberteau, Fernando; Candelario, Víctor M.; Ortiz, Ángel L.; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU). EspañaNovel complex-shaped porous B4C supports were fabricated for use in ceramic membrane filtration applications, the processing of which is described in detail. Firstly, an extrudable ceramic paste was formulated and homogenised, containing a high content of B4C of super-coarse and ultrafine grades, plus water as liquid medium and various organic additives as thickener, binder, plasticiser, and lubricant. Secondly, tubular honeycomb parts (i.e., cylinders of ∼26 mm outer diameter with 30 inner channels of 3 mm diameter each) were extruded at ∼25 bar and dried in air at 120 °C for 24 h, resulting in robust green B4C membrane supports without macro- or micro-defects. Thirdly, suitable debinding conditions were identified by thermogravimetry of the paste and its components, and the dry membrane supports were debinded at 700 °C for 1.5 h in high vacuum (<0.1 Pa) confirming that they retain their shape with minimal isotropic shrinkage (∼0.13–0.15 %). And fourthly, the debinded membrane supports were pressureless sintered at 2000 °C for 3 h in inert atmosphere undergoing only an additional 1 % isotropic shrinkage, resulting in B4C membrane supports with low apparent density (∼0.89(1) g/cm3), high porosity (∼38–39 %), open interconnected micrometre pores (in the range ∼0.5–16 μm, and d50∼1.5 μm), and low skeletal density (∼2.455(1) g/cm3). Importantly, their only partial densification makes them both sufficiently strong mechanically (∼68(2) MPa compressive strength) and highly permeable to water (∼13131(418) l/(m2·h·bar) permeability at ∼1.3 bar). These attributes, together with the intrinsic lightness and durability of B4C ceramics, make these novel supports in principle very appealing for ceramic membrane filtration and other applications.Artículo Electrical conductivity of metal powders under pressure(Springer, 2011-12) Montes Martos, Juan Manuel; Cuevas, F.G.; Cintas Físico, Jesús; Urban, Petr; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Ministerio de Ciencia y Tecnología (MCYT). EspañaA model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles has been derived. A theoretical tool previously developed by the authors, the so-called ‘equivalent simple cubic system’, was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of deforming spheres packed in a simple cubic lattice, which is much easier to examine. The proposed model relates the effective electrical conductivity of the powder mass under compression to its level of porosity. Other physically measurable parameters in the model are the conductivities of the metal and oxide constituting the powder particles, their radii, the mean thickness of the oxide layer and the tap porosity of the powder. Two additional parameters controlling the effect of the descaling of the particle oxide layer were empirically introduced. The proposed model was experimentally verified by measurements of the electrical conductivity of aluminium, bronze, iron, nickel and titanium powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases