Search Results (2,149)

Functionally graded AA2024/B4C metal matrix composites were fabricated via mechanical alloying and hot pressing to investigate structure–property–radiation shielding relationships. Single-layer, two-layer, and three-layer architectures with varying B4C contents were systematically produced. Microstructural homogeneity and phase constitution were examined using SEM/EDS and XRD, while thermal stability was evaluated by thermogravimetric analysis. Density and porosity measurements were conducted to assess the influence of reinforcement distribution and functional grading on densification behavior. Gamma radiation shielding performance was experimentally evaluated using a 152Eu source and an HPGe detector over a wide photon energy range. Key shielding parameters, including linear and mass attenuation coefficients, half-value layer, tenth-value layer, mean free path, and radiation protection efficiency, were determined. The results reveal that functional grading significantly enhances radiation attenuation compared to monolithic composites. The three-layer AA2024/B4C composite exhibited the highest attenuation coefficients and the lowest HVL, TVL, and MFP values at all investigated energies, achieving nearly 100% improvement in shielding efficiency relative to unreinforced AA2024. These findings demonstrate that controlled B4C distribution and layered composite architecture provide a synergistic improvement in thermal stability, physical integrity, and radiation shielding performance, positioning functionally graded AA2024/B4C composites as efficient lightweight materials for advanced radiation shielding applications. These results indicate that the developed functionally graded AA2024/B4C composites are promising candidates for advanced radiation shielding applications in nuclear facilities, aerospace structures, and medical radiation protection systems, where lightweight and high-performance materials are critically required. Full article

This work explores a sustainable route for producing recycled AlNiCo-based magnetic composites by incorporating end-of-life AlNiCo-5 particles into a polyamide 12 (PA12) matrix, thereby eliminating conventional debinding requirements. The study emphasizes material circularity through the reuse of mechanically recovered magnetic waste and polymeric residues. Virgin PA12 powder was used as the matrix material for high magnetic filler loadings of 40, 60, and 70 wt.% AlNiCo-5, while stearic acid was introduced to enhance interfacial compatibility and overall processability. The resulting composites were shaped into filaments and processed via material extrusion additive manufacturing, demonstrating that commercially available fused filament fabrication systems can successfully handle highly filled metal-polymer blends when supported by appropriate formulation and process parameter optimization. The findings confirm the feasibility of manufacturing flexible, functional, and resource-efficient magnetic components using widely accessible equipment, highlighting a promising pathway toward the cost-effective recycling and reuse of AlNiCo magnetic materials. Full article

In this research, the effects of density and porosity on the mechanical properties of a stir-cast hybrid magnesium ZE41 alloy strengthened with 2% weight of silicon carbide (SiC) and boron carbide (B₄C) are assimilated. The experimental and theoretical densities of the ZE41 hybrid matrix were found and compared. From the results of density analysis, it can be inferred that the experimental density of hybrid matrix is smaller when compared to the pure ZE41 matrix. The percentage porosity of hybrid matrix was also analyzed, and it was observed that the hybrid matrix has a slight increase in porosity when compared to the pure ZE41 matrix. The ultimate strength and hardness of the ZE41 hybrid matrix have increased significantly due to its moderate density and acceptable porosity values. Full article

To address inherent limitations of chitosan-based edible films, including inadequate mechanical strength and poor moisture resistance, cellulose nanofibers (CNF) were employed as a synergistic film-forming component to partially substitute chitosan in the fabrication of ternary composite films (denoted as CSTF-CNFs). This approach was based on a previously developed chitosan matrix modified with tannin-Fe³⁺ nanoparticles (TF). It was hypothesized that CNF could function as a reinforcing scaffold to improve the dispersion of TF within the film matrix and, through hydrogen bonding and physical entanglement, form an interpenetrating fiber network with chitosan, thereby enhancing the structural and barrier properties of the films. The present study systematically evaluated the influence of varying CNF substitution ratios (0–30%) on the physicochemical characteristics of the resulting composite films and their performance in tomato preservation. The results demonstrated that an appropriate CNF incorporation facilitated the formation of a dense, cross-linked network with chitosan and TF via hydrogen bond interactions, significantly improving both mechanical strength and water resistance. Among all formulations, the CSTF-CNF20 film exhibited optimal comprehensive performance, achieving the highest tensile strength of 27.60 MPa. Moreover, its swelling ratio markedly decreased from 675.5% (CSTF-CNF0) to 120.9%, while the water contact angle increased to 113.7°, and the DPPH radical scavenging activity remained above 85%. Tomato preservation assays revealed that, in comparison with the untreated control and polyethylene film-wrapped groups, the application of CSTF-CNF20 coating effectively mitigated the decline in weight loss and firmness, preserved surface color integrity, and resulted in the highest L* value alongside the lowest soluble solids content. These findings suggest that the synergistic integration of CNF with nano-scale metal–phenolic networks offers a viable strategy for developing high-performance chitosan-based edible films. The CSTF-CNF20 composite film holds significant promise for application in the postharvest preservation of fruits and vegetables. Full article

Efficient joining of hard metals to steels is crucial for supporting sustainable manufacturing under emissions strategies to minimize CO₂. CoNiCrFeCu high-entropy alloy containing scandium (Sc) was designed as a filler for laser braze-welding of WC-Co and steel. The designed compositions with different Sc levels were melted and cast in a high-vacuum non-consumable arc furnace. The results showed that the as-cast microstructure was a complex mixture of a networked Ni₂Si, elongated Cr-Fe-Co solid-solution phase, and Fe-Ni-Co-Cu solid-solution phase. Scandium was shown to have formed compounds with nickel/cobalt and copper. The TG-DSC analysis confirmed that the melting points of the designed compositions were between 973.7 °C and 981.5 °C. The maximum spreading area of the CoNiCrFeCu-0.9Sc composition on AISI 1045 steel was 64.83 mm², and on the WC-Co cermet it was 78.63 mm². The interface between the fusion zone and AISI 1045 steel exhibited an epitaxial growth of dendrites from the steel base metal. The interface between WC-Co and the fusion zone exhibited a partial penetration of brazing filler into the Co matrix, forming a metallurgical bonding between the dissimilar materials. Sc, as an alloying element in the filler metal, enhanced the bond formation because it decreased the solidus temperature and increased wetting. Full article

Arsenic pollution is a prevalent challenge worldwide due to extensive use dating back thousands of years, and the pentavalent species arsenate (As(V)) is of particular interest because it predominates in oxygenated groundwater. Metal–organic frameworks (MOFs), characterized by their high surface area and tunable surface chemistry, have emerged as promising adsorbents for its rapid and efficient removal. This study systematically evaluated the adsorption performance, physicochemical properties, and regeneration behavior of monometallic Fe-BTC MOF and bimetallic Fe/Cu-BTC for As(V) removal under application-relevant conditions. Fe-BTC exhibited the highest adsorption capacity of As(V) (117.5 mg·g⁻¹), whereas Fe/Cu-BTC showed a lower capacity (74.6 mg·g⁻¹). Adsorption in tap water decreased slightly for both materials (19–23%), indicating mild competition from coexisting ions. The adsorption behavior followed the Freundlich model, indicating competitive occupation of high-energy sites on Fe-BTC. In contrast, the surface heterogeneity of Fe/Cu-BTC remained unchanged, highlighting its robust characteristics. Adsorption was strongly pH-dependent, reaching a maximum at neutral pH, and regeneration experiments identified ethanol as the most effective desorption agent for Fe-BTC, enabling reuse. Metal-leaching analysis confirmed superior Fe-BTC MOF stability and minimal leaching, whereas Fe/Cu-BTC instability demonstrated risk of secondary Cu contamination. Overall, these findings establish that Fe-BTC and Fe/Cu-BTC MOF are effective for As(V) adsorption, but Fe-BTC outperforms Fe/Cu-BTC as a practical adsorbent. Significantly, Fe-BTC performance is strongly influenced by water matrix composition and regeneration solvent, highlighting considerations for real-world applications. Full article

Binder Jetting 3D Printing (BJ3DP) offers an effective pathway for the rapid fabrication of complex high-entropy alloy (HEA) components. In this study, the macroscopic characteristics, microstructural evolution and mechanical properties of Al_0.5Cr_0.9FeNi_2.5V_0.2 HEA green parts prepared via BJ3DP were investigated under various sintering conditions. Results showed that the relative density of the sintered parts increased significantly with temperature, transitioning from a low density (<90%) at 1300–1330 °C to near-fully dense (~98%) at 1340–1350 °C. Consequently, the mechanical properties were remarkably improved. The yield strength (σ_0.2) increased from 300 MPa to 710 MPa (a 136% increase), and the ultimate tensile strength (σ_b) rose from 310 MPa to 780 MPa (a 148% increase) as sintering temperature rose from 1300 °C to 1350 °C. Microstructural analysis revealed that at lower sintering temperatures, the alloy exhibited high porosity and a non-coherent structure composed of an FCC matrix and Cr-rich BCC phase, with Al/Ni intermetallic compounds distributed around pores. Conversely, at the final sintering stage, pore closure was achieved, and a coherent structure consisting of an FCC matrix and scale-like L1₂ precipitates was formed. Optimal mechanical properties (tensile strength ≥ 700 MPa) were achieved when sintering at 1340 °C, primarily attributed to densification and precipitation strengthening. Full article

Bio-based, biodegradable, and renewable polymers offer a promising alternative to traditional synthetic polymers derived from petroleum or other non-renewable resources. However, their use is limited by suboptimal properties and high costs. Incorporating sustainable reinforcements into the polymer matrix significantly improves biopolymer performance while preserving key properties, sustainability, and cost-effectiveness. Bio-based polymeric composites have emerged as a crucial category of biopolymers, playing a key role in advancing a sustainable, circular economy. This review provides an updated overview of bio-based polymer composites and nanocomposites, focusing on reinforcement strategies using natural nanofillers and engineered nanoparticles. We summarize key synthesis and processing methods, discuss structure–property relationships, and highlight recent advances in applications such as food packaging, biomedical devices, energy systems, environmental remediation, 3D printing, and supercapacitors. Polymer nanocomposites are versatile, with their performance depending on the type, size, and interactions between the fillers and the polymer matrix. Progress in metallic, ceramic, carbon-based, natural, and hybrid fillers has improved their properties. Using bio-based polymers and renewable fillers supports sustainability. Natural nanofillers derived from renewable sources and industrial byproducts offer a sustainable approach to developing high-performance, biodegradable nanocomposites. Smart nanocomposites can react to external stimuli by integrating specialized fillers that enhance their mechanical and mobility properties. Shape memory nanocomposites can be remotely activated—using heat, electricity, magnets, or light—enabling advanced applications. Finally, we address major challenges and outline future directions for scalable, circular-material solutions, drawing on perspectives from the circular economy and life cycle assessment (LCA). Full article

Bacterial cellulose (BC) has emerged as a structurally robust, biologically compatible, and highly adaptable biomaterial with significant potential for next-generation wound-care technologies. Its nanofibrillar, extracellular-matrix-like architecture provides exceptional moisture retention, mechanical stability, and conformability, enabling BC to function as an active scaffold rather than a traditional dressing. Advances in chemical modification, composite engineering, and bioactive functionalization, including antimicrobial metals, chitosan, biosurfactants, enzymes, and growth factors, have expanded BC’s therapeutic capabilities. Emerging smart BC dressings integrate biosensors, stimuli-responsive drug release, and 3D-printed architectures tailored to patient-specific wound geometries. Parallel developments in artificial intelligence (AI) are transforming BC production by optimizing bioprocessing, guiding genetic engineering, reducing culture media costs, and enabling real-time quality control, thereby improving scalability and industrial feasibility. These combined innovations position BC as a multifunctional, immunologically instructive, and digitally integrated platform for advanced regenerative wound care. This review reframes BC within the contemporary pathophysiology of chronic wounds, emphasizing its roles in immunomodulation, macrophage polarization, angiogenesis, mechanotransduction, and the disruption of mixed bacterial–fungal biofilms that characterize diabetic foot ulcers and other non-healing wounds. BC hydrogels typically contain >90–99% water and exhibit tensile strengths exceeding 200 MPa, enabling robust mechanical performance in wound environments. Advances in BC composites have demonstrated antimicrobial reductions of 3–5 log units against common chronic-wound pathogens. Full article

Flexible resistive bend sensors are essential for monitoring human movement in smart rehabilitation and soft robotics. However, widespread adoption is currently hindered by a trade-off between the high cost of metal-film technologies and the performance degradation (significant hysteresis and non-linearity) of low-cost carbon/polymer composites. This study presents a geometrically customizable bending sensor fabricated from conductive thermoplastic polyurethane (TPU) using Fused Deposition Modeling (FDM) technology as an accessible alternative to commercial sensors. By parametrically optimizing physical dimensions—including trace width, layer thickness, and pattern geometry—the sensors were tailored to achieve target resistance values within a target window of 20–50 kΩ (achieved: ~44 kΩ nominal) for specific finger-joint applications. Electromechanical characterization revealed a negative gauge factor (GF), where resistance decreases upon bending or elongation due to conductive pathway formation and densification within the polymer matrix. This behavior cannot affect sensor operation, and required bend-resistance responses were acquired using geometrical optimization. To compensate for inherent viscoelastic-induced hysteresis and non-linear behavior, a third-degree polynomial modeling approach was implemented. This modeling approach yielded a coefficient of determination (R²) of approximately 0.90. Compared to standard commercial sensors, the proposed FDM-printed design successfully overcomes geometric limitations while offering a cost-effective, high-performance solution for tailor-made wearable technologies and smart rehabilitation gloves. Full article

Boron carbide (B₄C)-reinforced metal matrix composites (MMCs) are promising candidates for biomedical implants due to their mechanical properties and potential biological compatibility. In this study, in vitro biocompatibility and cytotoxicity of B₄C-reinforced CoCrMo, Ti, and 17-4 PH alloys were systematically evaluated using human osteoblast (HOB) cells. Composites were fabricated via powder metallurgy with varying B₄C reinforcement ratios (CoCrMo and Ti: 5–10 wt%; 17-4 PH: 3–12 wt%). Extracts prepared according to ISO 10993-12 standards were applied at different concentrations (100%, 50%, 25%, 12.5%) to assess cell viability using the MTT assay over 24, 48, and 72 h. Results demonstrated a clear dose-dependent cytotoxic effect across all composite systems. Ti composites exhibited the highest biocompatibility, with cell viability largely preserved even at higher B₄C ratios. CoCrMo composites showed moderate cytotoxicity, which decreased upon extract dilution, indicating low-concentration compatibility. In contrast, 17-4 PH composites revealed significant cytotoxicity at higher extract concentrations, exacerbated by increasing B₄C content. Literature-supported findings confirm that B₄C incorporation enhances hardness, wear resistance, and elastic modulus, yet excessive reinforcement can induce local stress and particle detachment, affecting cellular tolerance. Diluted extracts of Ti and CoCrMo composites maintained cell viability at a biocompatible level consistent with ISO 10993-5 criteria. These results highlight the promising biocompatibility of B₄C-reinforced Ti and CoCrMo alloys for biomedical applications and provide a biological basis for the design of next-generation composite implants. Full article

Composite gears have emerged as game-changing mechanical components across various engineering fields due to their multifunctional physical properties, such as low density, thermal resistance, and mechanical robustness. Although traditional metallic gears are well established and reliable, their efficiency is limited in certain applications. In contrast, composite gears reinforced with carbon, glass, or polymer fibers offer superior strength-to-weight ratios, enhanced corrosion and wear resistance, and improved vibration damping characteristics. The studies demonstrate that hybrid and fiber-reinforced composite gears can achieve weight reductions of 20–50% compared with steel gears, while maintaining comparable stiffness and load-carrying capability. Polymer and reinforced composite gear systems show operating temperature reductions of up to 40% due to improved tribological behavior and thermal dissipation. In metal–matrix composite systems, compressive strength improvements up to around 60% have been reported. Additionally, composite architectures provide improved fatigue life, reduced transmission error, and enhanced vibration damping. Developments in gear design, composite materials, and their integration into composite gear systems were identified through a structured literature survey using Scopus and Google Scholar, systematically compiling manufacturing methods, material performance characteristics, and applications. Targeted keywords related to gears, composites, additive and hybrid manufacturing, lightweight design, and power transmission yielded 132 relevant publications, which were subsequently refined through screening and cross-referencing, with the final section focusing specifically on composite gear applications. The review highlights key opportunities, current challenges, and potential future directions for the development of high-performance composite gear systems. Full article

Biobased hybrid semiconducting composites are attracting significant attention as sustainable alternatives to traditional inorganic photocatalysts for environmental remediation and energy-related applications. Recent research progress in biobased hybrid photocatalytic systems is critically reviewed to outline their design strategies, photocatalytic mechanisms, and environmental applications. These composites integrate bioderived polymers with metal oxide semiconductors, forming hybrid architectures that improve interfacial contact at the molecular level, enhance charge transfer efficiency, and impart higher structural flexibility. The polymer matrix not only provides mechanical adaptability and functional surface groups, but also serves as an environmentally friendly support that can modulate surface electronic states and influence the photoinduced electron–hole dynamics in the inorganic phase. By controlling the molecular interactions between the polymer chains and metal oxide surfaces, these hybrids can mitigate key limitations of conventional metal oxides, such as rapid electron–hole recombination and restricted visible-light absorption. This review first summarizes the fundamental electronic and structural properties of widely employed metal oxide semiconductors and highlights their intrinsic limitations in photocatalytic processes. It then examines the role of biopolymers from the perspective of molecular structure, charge transport pathways, and interfacial interaction mechanisms with the inorganic component. Various synthesis strategies—including sol–gel, hydrothermal, in situ nanoparticle generation, green synthesis, and surface functionalization—are discussed, with emphasis on their ability to tune the nanoscale morphology and interfacial chemistry of the hybrids. Applications of these biohybrid systems in dye degradation, pharmaceutical pollutant removal, heavy metal reduction, and antimicrobial photocatalysis are analyzed alongside mechanistic insights into charge separation efficiency and band alignment at the molecular interface. Furthermore, challenges related to long-term stability, reproducibility, scalability, and performance in real wastewater matrices are also addressed. Overall, this review provides a thorough discussion on the design principles, photocatalytic mechanism, and environmental applications of biobased hybrid semiconductors, while emphasizing future opportunities for the development of efficient and sustainable photocatalytic systems. Full article

To address the limited simultaneous optimization of mechanical performance and heavy-metal stabilization in waste-based alkali-activated systems, this study investigates the development and characterization of a novel composite cementitious material for potential construction applications, utilizing lead and zinc smelting slag (LZSS) and electroplating sludge (ES) as precursors. The novelty of this study lies in the co-modification of an LZSS-based alkali-activated matrix with PVA and KH792 to improve both compressive behavior and heavy-metal stabilization in ES-containing specimens. Based on single-factor optimization, the optimal matrix was obtained at 3.5% alkali content, a water-glass modulus of 1.4, and a liquid-to-solid ratio of 0.22, followed by 28 days of curing before testing. On this basis, ES and PVA-KH792 were introduced to investigate their effects on mechanical behavior, heavy-metal leaching, and immobilization mechanisms. The results showed that adding ES reduced the compressive strength of the alkali-activated matrix, whereas PVA-KH792 modification partially restored matrix integrity and improved performance. At 5% ES content, the compressive strength of the modified specimen increased by 7.66% compared with that of the unmodified ES-containing sample. More importantly, under the sulfuric acid–nitric acid leaching method, the Cr leaching concentration decreased from 20.1 mg/L to 13.7 mg/L, meeting the relevant regulatory limit (GB5085.3-2007 and EPA limit). Microstructural and spectroscopic analyses indicated that the beneficial effect of PVA-KH792 was associated with matrix densification and enhanced heavy-metal immobilization. The immobilization mechanisms were mainly attributed to Cr(VI) reduction by Fe(II), complexation/coordination with functional groups introduced by PVA-KH792, and physical encapsulation within the alkali-activated matrix. The findings provide a promising approach to waste valorization and the development of sustainable building materials, contributing to resource efficiency and reducing the environmental impact of the construction sector. Full article

Accurate modeling of smart composite dampers is crucial for simulation and model-based control. This study focuses on the constitutive modeling of a novel damper that synergistically combines an Entangled Metallic Wire Mesh (EMWM) with a magnetorheological (MR) fluid. Unlike traditional MR dampers, the interaction between the field-responsive MR fluid and the rate-sensitive, deformable EMWM matrix introduces strong coupled current–frequency dependence. To capture this essential characteristic, a control-oriented, bivariate (current–frequency) hysteresis model is formulated, wherein all parameters are explicit, continuous functions of both the control current (I) and excitation frequency (f). A systematic two-step identification method is employed to derive these functions from dynamic tests. A key finding is that the identified damping exponent (α) consistently exceeds unity across the tested operational range. This quantitatively indicates a transition from viscous-dominated to inertial-flow-dominated dissipation within the EMWM matrix, a distinctive mechanism attributed to non-Darcian flow in its porous structure. The fully parameterized model demonstrates high fidelity (R² > 0.99) within the characterized low-frequency, small-amplitude regime and shows reliable predictive capability for interpolated conditions. The presented model serves as a ready-to-use constitutive tool for the simulation and design of low-frequency vibration isolation systems utilizing EMWM-MR composites, and the revealed inertial flow mechanism provides fundamental insight for the development of next-generation adaptive dampers. Full article