Jorge Enrique Rivera Salinas

Aluminum metallic foams are lightweight porous materials characterized by low density, high stiffness, and remarkable energy absorption capacity. The mechanical performance of these materials strongly depends on the microstructure of the metallic matrix and the porous structure. In this study, closed-cell A356 aluminum foams were produced by the Alporas melt-foaming method using barite (BaSO₄) as a thickening agent and calcium carbonate (CaCO₃) as a foaming agent. The effect of grain refinement on the microstructure and energy absorption behavior under quasi-static compression was investigated. Grain refinement was evaluated by adding four concentrations of Al-5Ti-1B master alloy (0.02, 0.05, 0.08, and 0.10 wt.%) to the unrefined foam. The addition of Al-5Ti-1B reduced the secondary dendrite arm spacing (SDAS) from 41.85 µm to a minimum of 32.96 µm at 0.05 wt.%, producing stronger and more homogeneous cell walls that increased the plateau stress from 0.525 to 1.549 MPa and the energy absorption capacity from 0.299 to 0.735 MJ/m³—improvements of 195% and 145%, respectively. The energy absorption efficiency analysis confirmed that any refiner concentration improved the compressive performance compared to the unrefined foam. In addition, the energy absorption efficiency (E) and the ideality energy absorption efficiency (I) confirm that the refinement of the dendritic structure through Al-5Ti-1B addition strengthens the foam cell walls, improving their mechanical behavior and performance as an energy-absorbing material under quasi-static compression.

Los materiales compuestos exhiben propiedades mecánicas controladas por el nivel de adhesión interfacial que une a sus fases constitutivas. Este trabajo demuestra el rol critico de la interfase en la distribución del esfuerzo local y, por ende, en la rigidez global de los materiales compuestos. Se llevó a cabo análisis por elementos finitos basado en micromecánica mediante una celda unitaria bidimensional (2D), con una matriz flexible y partículas rígidas embebidas considerando dos escenarios interfaciales: una unión ideal (coherente) y una unión débil. Las simulaciones se validaron con modelos analíticos clásicos de micromecánica, como el de Shioya y de teoría de campo medio como el de Mori-Tanaka, obteniendo una diferencia menor al 6 % de desviación. Los resultados mostraron que una interfase débil genera mayor concentración de esfuerzo local en la región ecuatorial de las partículas—duplicando los valores respecto a una interfase ideal— lo que incrementa la probabilidad de falla. En contraste, una interfase coherente favorece la transferencia efectiva de carga, incrementando el módulo elástico del compuesto respecto a la matriz pura. Ya que el índice crítico para determinar el rendimiento de un material es el módulo elástico —el cual influye directamente en el diseño de las estructuras— los resultados obtenidos aportan criterios de diseño aplicables a sistemas poliméricos, cerámicos y metálicos donde la sinergia entre fases define su funcionalidad.

Powder addition onto a molten-lead surface followed by stirring is widely used for desilvering during lead bullion refining operations. We model submerged zinc particle injection by coupling (i) a transient particle–metal reaction following Ohguchi with a time-dependent reaction efficiency E, (ii) a Stefan-type estimate of the zinc melting time Tf, and (iii) hydrodynamic descriptors of residence (τ_res) and mixing (τ_mix) times. The model is validated against experiments under a benchmark condition (gas velocity U = 3.32 m/s, 70% submergence), achieving a mean absolute percentage error of 1.13% for the experimental desilvering curve. A parametric study over lance submergence (30–90% of bath depth), injection velocity (3.32–9.79 m/s), and geometric scalings of lance and kettle identifies conditions where the hydrodynamic residence time τres approaches the Stefan melting time, maximizing liquid-Zn contact with molten Pb. Specifically, the proposed optimum balances the competing effects of plume buoyancy at high velocities—which tends to reduce residence time—against the deeper injection depth, ensuring that particles remain submerged long enough to fully melt and react. Within 16 simulated scenarios, the pair “90% submergence + U = 9.79 m/s” provides the best multi-criteria performance (desilvering fraction, E, and residence time) under realistic constraints. A parametric sensitivity analysis ranks injection velocity and submergence as the dominant levers, with geometry playing a secondary role over the tested ranges. The coupled hydrodynamic–kinetic framework provides quantitative guidance for optimizing industrial desilvering by particle injection and is extensible to other powder-injection refining operations.

Understanding the fracture behavior of short fiber‐reinforced syntactic foams under tensile loading is essential for improving the reliability and structural integrity of these advanced composite materials. In this study, tensile behavior and ductile failure mechanisms of short glass fiber‐reinforced nylon 6 (Ny6) syntactic foams were systematically investigated using three‐dimensional micromechanics‐based finite element analysis (FEA). The simulations provided detailed insights into the complex failure processes governing these thermoplastic syntactic foams. Regions of high tensile hydrostatic stress consistently developed in the matrix near the fiber tips, regardless of microsphere content. Both the glass fibers and microspheres exhibited a low probability of fracture. The failure was primarily governed by matrix failure, initiated by microvoid nucleation at fiber tips. Damage subsequently propagated along the fiber–matrix interface, inducing localized plastic deformation in narrow matrix regions. This facilitated interfacial failure between adjacent fiber tips and between opposing poles of neighboring microspheres, followed by matrix tearing and fiber slippage. Ultimately, a ductile crack grew to a critical size, triggering a transition to brittle fracture and leading to the complete collapse of the syntactic foam.

This study investigates the effect of hBN concentration (20–50 wt%) on the mechanical and thermal properties of (PA6+GF) _100‐x BN _x composites fabricated via twin‐screw extrusion and injection molding. The formation of thermally conductive networks by the hBN platelets increased the composite's bulk thermal conductivity from 0.335 to 2.357 W m ⁻¹ K ⁻¹ . TGA showed enhanced thermal stability, with decomposition onset shifting from 417°C to 437°C. DSC confirmed BN's nucleating effect, raising the crystallization onset temperature from 192°C to 195°C. A 53% increase in Young's modulus was observed at 50 wt% BN, while tensile strength declined by 27%, stabilizing at 65 MPa despite increasing filler content. Notably, the (PA6+GF) ₈₀ BN ₂₀ formulation achieved a favorable balance between thermal conductivity and mechanical integrity. These findings provide clear insight into the interplay between hBN loading and the performance of (PA6+GF) _100‐x BN _x composites.

Fossil fuels, including coal and natural gas, remain the dominant sources of energy worldwide. However, their excessive use has led to severe environmental consequences, including climate change and global warming. This study contributes to mitigating environmental challenges by presenting the design, fabrication, and performance evaluation of a novel nanocomposite-based solar water heater (N-SWH). The tubular finned profile was optimized using finite element analysis and fabricated via the extrusion of polypropylene (PP) reinforced with plasma-modified carbon nanofibers (CNFs [M]). The assembled system was then connected to an insulated storage tank and subjected to field testing, following standardized theoretical validation protocols. Results demonstrate that the incorporation of CNFs [M] significantly enhances the dispersion and interfacial compatibility within the polymer matrix, leading to a 535% increase in thermal conductivity (from 0.14 to 0.89 W/m·°C), while maintaining the mechanical properties (elastic modulus, yield stress, and rupture stress) and thermal stability of pipe-grade PP. Field testing recorded a maximum outlet water temperature of 42 °C under a solar irradiance of approximately 808 W/m², corresponding to a collector efficiency of 0.6. This temperature is suitable for preheating water in conventional gas heaters, enabling daily gas savings of up to 76.6%. With a surface area of only 0.8 m² and a weight of 1.2 kg, the developed solar collector exhibits excellent functional performance and material properties, positioning it as a lightweight, durable, cost-effective, and environmentally friendly alternative to conventional metallic systems.

The demand for natural fiber‐reinforced polymer composites is increasing in the automotive industry, and Mexican blue‐gave fiber (AF) is getting attention from automakers. Quantitative characterization of the tensile behavior of AF allows for a better ascertain of fiber performance. This work developed a model to study the elastoplastic behavior of AF prior and after its incorporation within a thermoplastic matrix. Finite element predictions showed excellent agreement with both theoretical and experimental values from literature. It was revealed that the increase in the fiber aspect ratio hastens the interaction between nearby defects within the fiber with earlier coalescence of voids, and ultimately fosters the loss of both fiber ductility and load carrying capacity. Moreover, the preponderant character of the damage in AF is controlled by nucleation and growth of voids. On the other hand, AF reinforced thermoplastic composites exhibit a microfailure based essentially on the matrix failure, and the composites become more damage tolerant with the increase in fiber aspect ratio. Stiffer AF leads to a more uniform interfacial shear stress distribution, with higher stiffness of the composite. Therefore, the effectiveness of AF to reinforce polymeric matrixes depends strongly on the elastic mismatch of the coupled materials.Highlights: Local stress state in AF is correlated to macroscopic stress. AF may be recognized as a von Mises material. Ductile fracture in AF is controlled by nucleation and growth of voids. Increasing the fiber aspect ratio leads to more damage tolerant composites. Stiffer AF led to a more uniform interfacial shear stress distribution.

It is frequently emphasized that the action of interfacial adhesion is a critical parameter to improve the stiffness and toughness of polylactic acid/thermoplastic starch (PLA/TS) blends. In this work, the micromechanical behavior of PLA/TS blends with droplet morphology selected from literature is predicted and analyzed systematically by finite element analysis. A quantitative assessment of the effect of interface (perfect or imperfect) on the elastic behavior and craze initiation for toughening of PLA/TS blends is presented. For the elastic behavior, the PLA phase is the blend's load‐bearing component as the TS is more compliant than PLA, so an interface perfectly bonded reduces the blend's elastic modulus when compared to the modulus obtained if the interface is weakly bonded. Regarding the toughening behavior, as a compliant phase, the TS has the potential to nucleate stable crazes in the host PLA matrix independently of the degree of interfacial adhesion because the highly stressed region lies near the equator of the particle; nonetheless, the critical stress for craze initiation is very sensitive to the TS particle size. On the other hand, as the TS is less capable than PLA to develop large hydrostatic stresses, the TS has a low potential to dissipate energy by cavitation.

Incorporating carbon nanoparticles (CNPs) into polymers can enhance their mechanical behavior; however, enhancement depends strongly on compatibility and homogeneous dispersion. Actual methods to succeed high dispersion and compatibility are complicated, have solvent‐associated problems, and long processing times. The present work proposes the increase of the dispersion and compatibility of CNPs in a polypropylene (PP) matrix to obtain a nanocomposite with high mechanical properties, using simple, fast, and green methodologies: the modification of the CNPs by cold propylene plasma and the synergistic effect resulting from mixtures of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) with PP matrix by melt mixing. Mixtures of CNFs and GNPs in 9:1, 8:2, and 7:3 ratios at 1 and 5 wt/wt% with and without surface modification by cold propylene plasma were fabricated. The compatibility and dispersion of the CNPs in the PP matrix were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, and the results were related to the mechanical properties. The results show that the use of mixtures improved the dispersion in the system and hindered the reagglomeration of CNPs, whereas surface modification with plasma promotes higher compatibility between the phases. The elastic modulus of PP reached an increase of 127.40% using a modified mixture by plasma in a 7:3 ratio (CNF:GNPs) at 5 wt/wt%, while when the CNPs were used individually, the modified CNFs and GNPs at 5 wt/wt%, reached 97.77% and 111.85%, respectively. In addition, a finite element analysis shows that the stresses in nanocomposites fabricated with mixtures of CNPs are supported to a greater extent by GNPs than CNFs due to their morphology with a low number of graphene sheets, which allows them to have greater flexibility.

This work is aimed to analyze the effect of concentration of Cu2+ and Pb2+ ions in flotation process water with Sphalerite activation, the analysis was performed at Cozamin Mining flotation circuit. This analysis demonstrates that (i) It is possible to determine the relationship between Sodium...