Artículos (Ingeniería y Ciencia de los Materiales y del Transporte)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11377

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The Impact of Steel Fiber Length and Dosage on Microstructure and Mechanical Performance in UHPFRC: A Hybrid Approach
(Asociación Española de Ingeniería Estructural (ACHE), 2025) Ruiz Martínez, Jaime Delfino; Ríos Jiménez, José David; Pérez-Soriano, Eva María; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Ingeniería Química y Ambiental; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España
This study evaluates the effects of steel fiber length (6 and 13 mm) and dosage on the microstructural and mechanical properties of an ultra-high-performance fiber-reinforced concrete (UHPFRC). The incorporation of 6 mm fiber significantly improved the material's workability characteristics. Microscopic evidence indicates better alignment and distribution of 13 mm fibers within the concrete matrix compared to 6 mm fibers, resulting in reduced porosity and enhanced matrix-fiber interaction. Mechanical testing confirmed that the inclu-sion of 13 mm steel fibers at various dosages consistently outperformed 6 mm fibers in enhancing compressive and flexural strengths. The optimal dosage, among those tested, for compressive strength was found to be 196 kg/m³ with 13 mm fibers, while the best performance in flexural strength was observed at 226 kg/m³. To address the challenges inherent in UHPFRC—specifically the intricate metallic fiber distri-bution and limited workability prompted a comprehensive investigation into fiber mixture optimization strategies. Hybrid fiber approach was explored by substituting 10%, 20%, and 30% of the 13 mm fiber dosage (196 kg/m³) with 6 mm steel fibers. Among these, the mix containing 80% of 13 mm steel fibers and 20% of 6 mm steel fibers demonstrated the highest flexural strength, even than those with higher steel fiber content (226 kg/m3). This hybridization suggests an optimized combination of fiber lengths for enhanced flexural performance without compromising compressive strength, providing insights into effective fiber-reinforcement strategies for UHPFRC applications.
Infiltrated 3D-printed zirconia scaffolds with biodegradable and bioactive polymer blend to improve their osseointegration
(Elsevier, 2025-12) Delgado-Pujol, Ernesto J.; Razavi, Ali; Begines Ruiz, Belén; Llanes, Luis; Morales, Miguel; Alcudia Cruz, Ana; Torres Hernández, Yadir; Fargas, Gemma; Ingeniería y Ciencia de los Materiales y del Transporte; Química Orgánica y Farmacéutica; Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; TEP123: Metalurgia e Ingeniería de los Materiales; FQM408: Química Farmacéutica Aplicada
Bone defects and skeletal disorders continue to demand advanced biomaterials that combine mechanical strength with enhanced bioactivity and customizability. While yttria-stabilized zirconia (YSZ) offers excellent mechanical properties and biocompatibility, its bioinert nature and processing challenges limit its effectiveness for patient-specific bone implants. This study addresses this gap by developing novel polymer-infiltrated ceramic network (PICN) scaffolds based on 3D-printed porous YSZ fabricated via Direct Ink Writing (DIW). The scaffolds were infiltrated with biodegradable polycaprolactone (PCL)/polyvinyl alcohol (PVA) blends loaded with nanohydroxyapatite (nHA) to impart bioactivity and tunable degradation. Scaffold designs with 40 % and 60 % infill were evaluated for infiltration efficiency, mechanical performance, degradation behavior, and apatite formation capacity. Results demonstrated high infiltration rates (up to 96 %, particularly in 40 % infill scaffolds), mechanical integrity comparable to cancellous bone (compressive strength within the range of 2–12 MPa), and enhanced in vitro apatite formation, especially for scaffolds with an 80:20 PCL/PVA blend containing 15 % nHA. The degradation analysis indicated that higher PVA content accelerated resorption, with the 50:50 blend showing faster surface changes, while the 80:20 blend maintained gradual porosity increase aligned with tissue replacement. Overall, this work presents a feasible strategy for fabricating patient-specific ceramic scaffolds with enhanced osseointegration potential, thereby bridging the gap between mechanical stability and biological functionality for future bone and dental implant applications.
Material design of novel TiNbTaHfMo high-entropy alloys for biomedical implants: Exploring an industry-adaptable route via FAST/SPS
(Elsevier, 2025-10) Chávez-Vascónez, Ricardo; Arévalo Mora, Cristina María; Sauceda, Sergio; Leiva, Jeremi; Oñate, Angelo; Pérez-Soriano, Eva María; Lozano Suárez, Juan Gabriel; Torres Hernández, Yadir; Lascano, Sheila; Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla; TEP123: Metalurgia e Ingeniería de los Materiales
Novel non-equiatomic Ti–Nb–Ta-Hf-Mo alloys were designed using β-Ti and high-entropy alloy formulation strategies to develop low-modulus materials for load-bearing biomedical implants. Ti₄₀₋ₓNb₂₅Ta₂₅Hf₁₀Moₓ (x = 0, 5, 10 at.%) alloys were designed by combining the d-electron method for β-Ti alloys with conventional HEA design parameters, aiming to develop low-modulus materials for load-bearing biomedical implants. Compositions were optimized through CALPHAD thermodynamic modeling and validated using a random forest machine learning approach, with predictions matching phase transformations detected during sintering. Alloys were fabricated via elemental powder blending and spark plasma sintering (FAST/SPS) under varied temperatures and dwell times, achieving densification from ∼90 % at 1250 °C/5 min to 98 % at 1350 °C or 10 min. Higher Mo content promoted and stabilized body-centered cubic (BCC) structures even at lower temperatures or shorter times. Mechanical testing confirmed Young's moduli of 16–74 GPa, tunable through densification control to balance strength and mitigate stress shielding. Despite a heterogeneous microstructure, the mechanical performance was comparable to alloys produced by longer, costlier routes. This work demonstrates FAST/SPS from elemental powders as a rapid, scalable, and industrially attractive method for producing biomedical HEAs.
Collagen/rGO/tannin hydrogels with a programmable biointerface for tunable electrical conductivity and antioxidant capacity in tissue regeneration
(Elsevier, 2026-01) González, Luisbel; Ruiz, Isleidy; Raposo, María; Aguayo, Claudio; Toledo, Jorge R.; Pérez-Puyana, Víctor Manuel; Romero García, Alberto; Fernández, Katherina; Ingeniería Química; Ingeniería y Ciencia de los Materiales y del Transporte; Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT). Chile; Ministerio de Ciencia e Innovación (MICIN). España
Restoring the endogenous bioelectric field while simultaneously protecting healing tissue from mechanical and oxidative stress remains a major challenge for next-generation wound dressings. Here we present an interface-programmed collagen hydrogel that integrates dopamine-reduced graphene oxide (rGO-PDA), polyethylene glycol (PEG) and condensed tannins (TA) into a single supramolecular network. rGO-PDA provides electronic pathways; TA forges multivalent π–π and hydrogen-bond bridges that immobilize rGO within the fibrillar matrix, confer radical-scavenging capacity and compatibilized the organic/inorganic phases; PEG acts as a hydrophilic spacer that tunes porosity and plasticity. Compared with the PEG-plasticized collagen control, the optimized COL/PEG20/TA10 formulation increased the storage modulus fourfold to 47 kPa, doubled the critical strain, raised the thermal decomposition onset by 80 °C and achieved stable conductivities of 10.3 mS/cm, comparable to native skin. The same interfacial design lowered the water-contact angle to 33 °, raised swelling to 150 % and enabled a biphasic release of TA that maintained 30 % DPPH inhibition for 4 h. Extracts enhanced human dermal fibroblast viability to 151 ± 5 % and accelerated in vitro scratch closure to > 95 % in 48 h. In a porcine full-thickness model the hydrogel achieved complete, scar-free re-epithelialization and highly organized dermal architecture within 21 days, while rabbit and guinea-pig tests confirmed it to be non-irritant. These results demonstrate that molecularly engineered collagen/rGO/TA interfaces can synchronously deliver mechanical reinforcement, bioelectronic stimulation and antioxidant defense, providing a scalable, all-natural platform for advanced wound management.
Size tuneability of highly efficient li-rich cathode materials using an emulsion-based synthesis route
(Elsevier, 2026-02) Rubio, Saúl; Beltrán, Ana M.; Arévalo Mora, Cristina María; Martínez, Gerardo T.; García-García, Francisco J.; Pérez-Soriano, Eva María; Montealegre-Meléndez, Isabel; Lozano Suárez, Juan Gabriel; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP123: Metalurgia e Ingeniería de los Materiales
Lithium- and manganese-rich transition metal oxides exhibit excellent specific capacities, making them strong candidates for the development of the next generation of Co-free lithium-ion batteries. In this study, the synthesis of size-tunable Li₁ꓸ₂Ni₀ꓸ₂Mn₀ꓸ₆O₂ using a synthetic route based on the formation of an emulsion, which is ultra-fast, cost-effective, and easily scalable to an industrial level is presented. We demonstrate that variations in the concentrations of hydrophobic, hydrophilic, and surfactant components, which lead to micelle formation within the emulsion, have a significant impact on the average particle size and size distribution of the synthesized material, and subsequently, on their electrochemical performance. Specifically, increasing the concentration of oleic acid as a surfactant results in an optimal average particle size, with discharge specific capacities exceeding 317 mAh g⁻¹ in the first cycle and 230 mAh g⁻¹ after 100 cycles, demonstrating an excellent battery performance comprising state-of-the-art lithium- and manganese-rich transition metal oxide materials.
Nanoscale imaging and atomic vibrations of eumelanin superstructures modulated by functionalized micronized graphene oxide
(Royal Society of Chemistry, 2025-09-17) Matassa, Roberto; Mattiello, Sara; Soares, Gustavo Guerreiro Candido; Lozano Suárez, Juan Gabriel; Beltrán, Ana M.; Zazza, Costantino; Sanna, Nico; Phua, Jun Wei; Rosolen, Jose Mauricio; Cicco, Andrea di; Rezvani, Javad; Gunnella, Roberto; Ingeniería y Ciencia de los Materiales y del Transporte; TEP123: Metalurgia e Ingeniería de los Materiales
Natural organic/inorganic materials with rational cooperative formations have long been of enormous interest owing to their hybrid self-assembling properties. Natural biomolecules are expected to produce attractive superstructures capable of sensing their environment, following their inherent biological functions and high biocompatibility. However, understanding their assembly strategies with inorganic materials is often challenging. Herein, we investigated the bioactive assembly of natural eumelanin superstructures. modulated by chemical functionalization of micronized graphene oxide, to study their strong structural affinity by analysing their vibrational–structural correlations. The application of complementary experiments of high-resolution electron nanoimaging coupled with vibrational Raman spectroscopy revealed intriguing and unique features of this complex hybrid material. In particular, high-resolution nanodiffraction/imaging analysis provided evidence of new nanocrystalline domains of pure natural eumelanin with different and irregular orientations forming irregular nanosheets. Interestingly, a hierarchical reassembly process of eumelanin units are actually evident not only on the oxide graphene surface but also located in high amounts on the edge of vertical graphene oxide, concretely supported by the analytical changes of the predominant resonance bands (D, D**, and G). This confirmed the ability of eumelanin to reassemble in spherical and elongated nanostructures when induced by an external stimuli of graphene oxide in an aqueous solution at room temperature. Thus, this work highlights the assembling mechanisms for designing a strategy to control bioactive molecules through environment modification.
Comparative Assessment of Injection and Compression Molding on Soy Protein Bioplastic Matrices for Controlled Iron Release in Horticulture
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-06-17) Castro Criado, Daniel; Jiménez Rosado, Mercedes; Pérez-Puyana, Víctor Manuel; Romero García, Alberto; Ingeniería Química; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
Conventional horticultural fertilization frequently leads to nutrient loss and environmental contamination, driving interest in biodegradable controlled-release systems. This work developed soy protein isolate (SPI) matrices containing 5 wt.% FeSO4·7H2O using injection. The matrices were evaluated for crosslinking, mechanical properties, water uptake (WUC), soluble matter loss (SML), iron-release kinetics in water and soil, and biodegradability under composting conditions. Injection-molded samples achieved very high crosslinking with moderate rigidity and water absorption and delivered iron rapidly in water, while compression-molded samples exhibited slightly lower crosslinking but greater stiffness, higher WUC, minimal SML, and sustained iron release. Notably, both processing methods yielded comparable iron-release profiles in soil and complete biodegradation within 71 days. Overall, compression molding produces SPI-based matrices with superior mechanical strength and water retention, positioning them as an ideal solution for long-lasting, sustainable nutrient delivery in horticulture.
The Influence of Electrostatic Separation Parameters on the Recovery of Metals from Pre-Crushed PCBs
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) López-Paneque, Antonio Manuel; Gallardo García-Orta, Victoria Humildad; Gallardo Fuentes, José María; Sepúlveda Ferrer, Ranier Enrique; Chicardi Augusto, Ernesto; Ingeniería Energética; Ingeniería y Ciencia de los Materiales y del Transporte; European Institute of Innovation and Technology (EIT)
Electrostatic separation is a promising technology for the recovery of valuable metals from electronic waste, particularly from printed circuit boards (PCBs). This study explores the application of electrostatic separation for the selective recovery of metallic and non-metallic fractions from crushed PCBs (PCBs). The process exploits the differences in electrical properties between conductive metals and non-conductive polymers and ceramics, facilitating their separation through applied electric fields. The raw materials were pre-treated via mechanical comminution using shredders and hammer mills to achieve an optimal particle size distribution (<3 mm), which enhances separation efficiency. Ferrous materials were removed prior to electrostatic separation to improve process selectivity. Key operational parameters, including particle size, charge accumulation, environmental conditions, and separation efficiency, were systematically analysed. The results demonstrate that electrostatic separation effectively recovers high-value metals such as copper and gold while minimizing material losses. Additionally, the process contributes to the sustainability of e-waste recycling by enabling the recovery of non-metallic fractions for potential secondary applications. This work underscores the significance of electrostatic separation as a viable technique for e-waste management and highlights optimization strategies for enhancing its performance in large-scale recycling operations.
Cobalt and Iron Double Doped B-Site Perovskite La0.5Ca0.5CoXFe1−XO3: Synthesis Strategy to Make High-Performance Oxygen Evolution Reaction Catalysts
(Wiley, 2025) Prakash P A, Jithin; Jose E, Tomlal; Thomas, Jasmine; Thomas, Tony; Chicardi Augusto, Ernesto; Periyasami, Govindasami; Jeffery, A. Anto; Thomas, Nygil; Ingeniería y Ciencia de los Materiales y del Transporte; King Saud University. Saudi Arabia
We developed a sustainable solution combustion method to synthesize the perovskite compounds of La0.5Ca0.5CoxFe1−xO3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) to enhance its electrocatalytic activity in oxygen evolution reactions by varying the ratios of iron (Fe) and cobalt (Co) at the B sites. The incorporation of Fe3+ and Co3+ in varying proportions at the B site is confirmed by PXRD, FTIR, FESEM, HRTEM, and XPS analyses. The synthesized polycrystalline spherical porous material, La0.5Ca0.5CoxFe1−xO3, exhibits thermal stability up to 1000 °C. Electrochemical investigations utilizing cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and Tafel plots have identified La0.5Ca0.5Co0.4Fe0.6O3 as the most effective electrocatalyst among a series of synthesized perovskites. This material exhibits a Tafel slope of 70.32 mV/dec and an overpotential of 364 mV at a current density of 10 mA/cm2. The enhanced OER activity stems from several factors, including a larger electrochemically active surface area, lower charge transfer resistance, a porous structure, and varying proportions of B-site ions.
Insights into Preformed Human Serum Albumin Corona on Iron Oxide Nanoparticles: Structure, Effect of Particle Size, Impact on MRI Efficiency, and Metabolization
(ACS Publications, 2019-06) Moya, Carlos; Escudero, Remei; Malaspina, David C.; Mata, María de la; Hernández-Saz, Jesús; Faraudo, Jordi; Roig, Anna; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; TEP973: Tecnología de Polvos y Corrosión
In the past decade, profuse research efforts explored the uses of iron oxide particles in nanomedicine. To a great extent, the efficiency and fate of those magnetic nanoparticles depend on how their surfaces interface with the proteins in a physiological environment. It is well reported how an ungoverned protein corona can be detrimental to cellular uptake and targeting efficiency and how it can modify the nanoparticles biodistribution. Novel strategies are emerging to achieve enhanced and more reproducible performances of engineered nanoparticles with a custom-built protein corona. Here we report on a generalized protocol to preform a monolayer of human serum albumin (HSA) on superparamagnetic iron oxide nanoparticles (SPIONs) of different sizes. The resulting molecular structures are described by molecular dynamics simulations of the hybrid nanoconjugates. The simulations outcomes regarding the number of proteins in the corona and their monolayer arrangement on the particle surface are in agreement with the results obtained from dynamic light scattering and electronic microscopy analysis. Using tryptophan fluorescence quenching, we revealed the existence of a strong interaction between the SPIONs and the HSA which endorses the robustness of the protein−nanoparticle conjugates in this system. Moreover, we evaluated the effect of the HSA corona on the SPIONs efficiency as magnetic resonance imaging (MRI) contrast agents in water, human serum, and saline media. The protein corona did not affect the efficiency of the SPIONs as T2 contrast agents but reduce their T1 efficiency. In addition, we observed a greater stability for HSA-SPIONs nanoconjugates in saline and in acid media, preventing nanoparticle dissolution in extreme gastric conditions.
Synthesis of all equiatomic five-transition metals High Entropy Carbides of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups by a low temperature route
(Elsevier, 2020-09) Chicardi Augusto, Ernesto; García Garrido, Cristina; Hernández-Saz, Jesús; Gotor, F. J.; Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla; TEP973: Tecnología de Polvos y Corrosión
The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC5, TiZrHfVTaC5, TiZrHfNbTaC5, TiZrVNbTaC5, TiHfVNbTaC5 and ZrHfVNbTaC5, were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC5, TiZrVNbTaC5 and ZrHfVNbTaC5, were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800–2200 °C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites.
Evaluation of Corrosion Behavior of Zn–Al–Mg-Coated Steel in Corrosive Heterogeneous Soil
(MDPI, 2025-08-20) Lloreda Jurado, Pedro Javier; Chicardi Augusto, Ernesto; Ingeniería y Ciencia de los Materiales y del Transporte; Universidad de Sevilla; TEP973: Tecnología de Polvos y Corrosión
The long-term durability of steel structures in contact with soil remains a critical challenge due to the complex and aggressive nature of many soil environments. This study presents a thorough evaluation of the corrosion resistance and microstructural evolution of Magnelis® ZM430-coated steel exposed to highly aggressive, heterogeneous soils. Gravimetric analysis revealed that the Magnelis® ZM430 coating exhibits low corrosion rates and enhanced initial barrier properties, even under severe soil conditions. Although the literature frequently reports that Zn–Al–Mg coatings outperform conventional hot-dip galvanized coatings, our results highlight that this superiority is not universal and may be limited under highly aggressive, heterogeneous soils. Microstructural characterization by optical microscopy, SEM/EDS, and XRD demonstrated that the as-received coating consists of a homogeneous layer with well-distributed Zn-, MgZn2-, and Al-rich phases. Upon soil exposure, corrosion preferentially initiates in the Mg- and Al-rich interdendritic and eutectic regions, leading to selective phase depletion and localized breakdown of the protective layer. Despite these localized vulnerabilities, the overall performance of Magnelis® ZM430 remains superior, especially during the early stages of exposure. While no direct comparisons were performed in this work, our findings align with previous literature reporting superior performance of Zn–Al–Mg coatings compared to conventional hot-dip galvanized coatings in similar environments. Importantly, the integration of precise corrosion rate data with detailed soil characterization enables accurate prediction of coating service life, allowing for optimized coating thickness selection and proactive maintenance planning. These findings underscore the value of combining advanced Zn–Al–Mg coatings with site-specific environmental assessment to ensure the long-term integrity of buried steel infrastructure.
Editorial for the Special Issue Novel Food and Beverages: Production and Characterization: 2nd Edition
(MDPI, 2025) Pérez-Puyana, Víctor Manuel; Romero García, Alberto; Jiménez Rosado, Mercedes; Ingeniería y Ciencia de los Materiales y del Transporte; Ingeniería Química; TEP229: Tecnología y Diseño de Productos Multicomponentes
Stress singularities in the generalised Comninou frictional contact model for interface cracks in anisotropic bimaterials
(Elsevier, 2025-10) Herrera Garrido, María Ángeles; Mantic, Vladislav; Ingeniería y Ciencia de los Materiales y del Transporte; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP131: Grupo de Elasticidad y Resistencia de Materiales
Characterisation of the singular asymptotic solution at the tip of interface cracks between dissimilar materials is essential for assessing the structural integrity of heterogeneous material systems. In the present article, the Comninou contact model, one of the most relevant and widely used models, originally introduced for isotropic bimaterials, is generalised for the first time to any anisotropic linear elastic bimaterial under generalised plane strain, considering a frictional sliding contact zone adjacent to the crack tip. The classical Coulomb friction law is considered. A novel procedure, based on the Stroh formalism of linear anisotropic elasticity, is developed to derive a system of two new coupled nonlinear eigenequations given in closed form for two unknown parameters of such singular solutions, the singularity exponent 𝜆 and the sliding angle 𝜔 in the contact zone. In general, this eigensystem is solved by an iterative method, although in some cases, closed-form solutions are provided. Parametric studies of the influence of material orientations and the friction coefficient value on variations of 𝜆 and 𝜔 reveal several surprising features of this asymptotic solution. The present approach is successfully verified by comparing some of the results obtained with those reported in previous studies, wherever possible. Note that previous studies essentially focused on bimaterials with specific orientations, considerably simplifying the problem. The singular solutions obtained can also be used in the asymptotic analysis of elastic fields at the boundary between stick and slip zones in partial slip contact problems for anisotropic materials.
A theoretical reassessment of the onset of plastic deformation in single crystals: beyond the Estrin-Kubin framework
(Elsevier, 2025-11) Moshtaghion, Bibi Malmal; Bejarano-Palma, José Antonio; López Arenal, Jesús; Cumbrera Hernández, Francisco Luis; Gómez García, Diego; Ingeniería y Ciencia de los Materiales y del Transporte; Física de la Materia Condensada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; FQM393: Propiedades Mecánicas, Procesado y Modelización de Cerámicas Avanzadas
Dislocations are the fundamental carriers of plastic deformation in single crystals. Their multiplication, interaction, mutual blocking, and annihilation collectively govern the material’s plastic response across all strain regimes. Classical modeling approaches, such as the Kocks-Mecking and Estrin-Kubin formulations, aim to capture these mechanisms through balance equations for free and blocked dislocations. This manuscript develops a mathematical framework enabling an analytical solution to the Estrin-Kubin equations in both the low- and high-strain limits. The analysis reveals that the model’s validity is confined to a narrow range of parameter values. More critically, the dislocation capture term—intended to account for work hardening—fails to reproduce the observed hardening behavior at early strain stages. The theoretical predictions diverge significantly from experimental observations. In response, an alternative model is proposed, which addresses the limitations of the Estrin-Kubin formulation. Notably, the new model preserves inversion symmetry, a fundamental physical property absents in the original equations.
Effective Electrical and Thermal Conductivities of Porous Sintered Metallic Compacts
(2025) Montes Martos, Juan Manuel; Ternero Fernández, Fátima; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); TEP971: Ingeniería de Materiales Avanzados
In this paper, five laws proposed to describe the influence of porosity on the effective conductivity (both electrical and thermal) of porous materials, which include a single microstructural parameter, are analyzed. These five laws are as follows: (1) the linear law with threshold, (2) the power law without threshold (Archie’s law), (3) the power law with threshold (percolation law), (4) the exponential law without threshold (decay law), and (5) the exponential law with threshold (Mooney-type law). These laws are discussed and derived from statistical reasoning (taken from the field of Stereology) or from probabilistic reasoning (taken from the field of risk analysis). The five laws are contrasted with the experimental values of electrical and thermal conductivities measured on metallic samples with different porosity, obtained by cold pressing and furnace sintering of four elementary powders (2 of iron, nickel, and aluminum). The study carried out allows to conclude that all the laws analyzed provide satisfactory agreements, but the percolation law is slightly superior to the others, since the values of its microstructural parameter remain within the uncertainty range to support a coherent physical interpretation, which is not the case for the other laws. Finally, the work also addresses the variability with porosity of the Wiedemann–Franz law, finding that it holds reasonably valid for low porosities, but not for higher porosities, which has been justified as a result of the different influence that the oxide layers of the metal powder particles exert on the electrical and thermal conductivities.
On the calculation of the density of multi-component solid solutions
(Elsevier, 2025) Montes Martos, Juan Manuel; Ternero Fernández, Fátima; Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
In this paper, twelve methods that can be used to calculate the density of a multi-component solid solution are discussed. All the methods considered are mathematically simple and involve composition-weighted averages, sometimes with added corrections. Two of the density calculation methods discussed here are proposed for the first time and are innovative in using the polydispersity index of radii. The various methods have been tested by predicting the density of 60 multi-component solid solutions and comparing the value obtained with the density value reported (or calculated from their composition and lattice parameter) from papers found in the literature. The results may seem surprising, but they indicate that some (but not all) methods based on simple mixing laws can be very accurate. The more sophisticated methods also give good results (especially one of those proposed for the first time in this paper) and have the additional advantage of better explaining the underlying physics, which gives them additional value. Finally, expressions are proposed for calculating the various input parameters of the different methods so that there is consistency between them.
Critical Assessment of Migration Strategies for Corrosion in Molten Salts
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Pavón Moreno, María del Carmen; López-Paneque, Antonio Manuel; Gallardo Fuentes, José María; Paúl Escolano, Antonio; Díaz Gutiérrez, Eduardo; Prieto Ríos, Cristina; Ingeniería Energética; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This review article examines the corrosion phenomena and mitigation strategies associated with molten salts used in thermal energy storage (TES) and heat transfer applications. Corrosion presents a critical challenge in concentrated solar power (CSP) plants and other high-temperature systems, affecting the durability and cost-efficiency of materials in storage tanks, heat exchangers, and piping. This study offers a comprehensive comparison of corrosion test methods and results, analyzing factors such as operating conditions, salt compositions, and material properties. Emphasis is also placed on strategies such as molten salt purification, the addition of corrosion inhibitors, and the application of protective coatings. This review aims to advance research and development in the TES sector by highlighting knowledge gaps and proposing directions for future experimentation.
Role of arsenic(V) and bismuth in the recovery of antimony by hydrolysis and precipitation from eluates produced during copper electrorefining
(Elsevier, 2025) Díaz Gutiérrez, Eduardo; Hernández-Saz, Jesús; Maldonado Calvo, José A.; Gallardo Fuentes, José María; Paúl Escolano, Antonio; Ingeniería y Ciencia de los Materiales y del Transporte; Corporación Tecnológica de Andalucía (CTA)
The recovery of antimony from side stream is challenging due to impurities like arsenic and bismuth which affect extraction efficiency and product quality. This study examines the individual and combined effects of As and Bi on antimony hydrolysis from eluates produced during copper electrorefining. Synthetic and process eluates were analysed to optimise operating conditions and understand impurity interactions. Hydrolysis experiments across pH values (0.25–0.9) revealed an optimal pH range (0.6–0.7) for maximizing antimony recovery (>90 %) in impurity-free conditions. Arsenic reduced the antimony recovery by 8 %–13 %, destabilising precipitates and forming amorphous phases. Bismuth caused a smaller reduction (3 %–7 %) but had a diminished effect in the presence of As, which dominated the system's chemistry. Process eluates exhibited greater variability, particularly in extraction yields, underscoring the need to validate findings based on synthetic solutions against industrial matrices. This study provides insights into optimizing antimony recovery through impurity management and highlights the value of combining the analyses of synthetic and process eluates.
Boosting the capacity of Mg-stabilized Na0.66Ni0.27Mg0.06Mn0.66O2 cathodes via particle size control in an emulsion-based synthesis route
(Royal Society of Chemistry (RSC), 2025) Rubio González, Saúl; Pérez-Soriano, Eva María; Arévalo Mora, Cristina María; Du, Xiaoqiong; Guo, Xuyun; García-García, Francisco J.; Montealegre-Meléndez, Isabel; Beltrán, Ana M.; Nicolosi, Valeria; Lozano Suárez, Juan Gabriel; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); TEP123: Metalurgia e Ingeniería de los Materiales
In this work, the production of ultra-high efficient Na₀ꓸ₆₇Ni₀ꓸ₂₇Mg₀ꓸ₀₆Mn₀ꓸ₆₆O₂ cathodes synthesized via an emulsion-based organic synthesis route, along with a comprehensive atomic-scale characterization using advanced electron microscopy techniques, is presented. It is demonstrated that increasing the ratio of the surfactant to hydrophobic and hydrophilic components in the emulsion leads to optimized particle size and a significantly more uniform particle size distribution. As a result Na₀ꓸ₆₇Ni₀ꓸ₂₇Mg₀ꓸ₀₆Mn₀ꓸ₆₆O₂ exhibits superior electrochemical performance, delivering an initial discharge capacity of 260 mA h g⁻¹ and maintaining a discharge capacity of 170 mA h g⁻¹ after 100 cycles, with 99% coulombic efficiency. This enhancement is attributed to the synergistic effect of Mg-induced structural stabilization and the optimization of particle size and distribution. These factors collectively facilitate the accommodation of strain induced by repeated charge–discharge cycles without substantial structural degradation while preserving efficient sodium de-intercalation pathways.

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