Search Results (472)

Metal/graphene composites with a metal matrix and graphene reinforcement are very promising innovative materials due to their improved mechanical and physical properties. In this paper, the possibility of fabricating a composite from a graphene network filled with nickel (Ni), copper (Cu) and aluminum (Al) nanoparticles is shown by molecular dynamics simulation. Composites are obtained by hydrostatic compression at 0.7 of the melting temperature of the metal nanoparticles. It is found that the Ni/graphene composite exhibits the highest ultimate tensile strength (89.5 GPa) and Young’s modulus (296.9 GPa) compared to 35.1 and 65.9 GPa for Cu/graphene and 36.8 and 109.1 GPa for Al/graphene, respectively. The Ni nanoparticles were uniformly distributed throughout the graphene network, providing high strength. Indentation simulations confirm this trend: the Ni/graphene composite exhibits a hardness 1.7 times higher than that of pure crumpled graphene, while Al/graphene shows a value 2.2 times lower, which directly correlates with the tensile strength. The Cu/graphene composite has the best ductility (fracture strain of 0.75 versus 0.45 for Ni/graphene and 0.47 for Al/graphene) due to the easier sliding between the Cu nanoparticles and the graphene during tensile loading. The Al/graphene composite has low strength and ductility because the Al nanoparticles tend to coagulate inside the graphene network and hardly interact with the graphene. For Cu/graphene and Al/graphene composites, fracture occurs at the metal/graphene interface. The results show that it is possible to fabricate metal/graphene composites that are much stronger than pure metal by deformation-temperature treatment. In addition, the mechanical properties can be modified by varying the type of metal. Full article

Red mud is a waste byproduct of alumina production. Its release into the environment poses risks, highlighting the need for strategies to limit pollution. Using red mud as a filler in polymer-matrix composites can reduce the leaching of heavy metals and metalloids. We fabricated composites with high red mud content (up to 60 wt.%) using two particle fractions (<125 μm and <500 μm). The study examined how filler concentration and particle size affected the composites’ microstructure and mechanical properties. Results showed that composites with smaller particles had better encapsulation and enhanced structural qualities, such as reduced porosity and fewer cracks. Among four filler mass loadings (20, 30, 40, and 60 wt.%), composites with 40 and 60 wt.% red mud exhibited greater epoxy penetration into agglomerates and partial deagglomeration, resulting in small, uniformly dispersed red mud particles within the matrix. Calorimetry analysis demonstrated that increasing the red mud concentration slows the curing process: for composites with 20 wt.% red mud, the curing time is approximately 10 h, whereas for composites with 60 wt.%, approximately 35 h. We performed a thorough environmental safety evaluation of high-loaded red mud–epoxy composites in accordance with the standard AS 4439.3:2019. The tests showed that epoxy resin significantly reduces the levels of potentially hazardous elements, such as Na and Al, in the leachates, demonstrating the safety of the composites. Composites with 40 wt.% red mud (particle size < 125 μm) showed the most effective epoxy impregnation into red mud agglomerates and demonstrated the best encapsulation behaviour, releasing the least amount of metals compared to red mud during both 20 h and 4-week, long-term leaching tests. Full article

Cu-Sn-Ti metallic-bonded CBN (Cubic Boron Nitride) abrasives are widely applied in the precision grinding of superhard materials. However, their high density and high toughness easily lead to poor grain protrusion and inadequate self-sharpening. In this work, ceramic glass powder was incorporated to modify the Cu-Sn-Ti binder, thereby fabricating composite-bonded CBN abrasive blocks with qualified mechanical properties and excellent self-sharpening performance. Flexural strength of abrasive blocks and microhardness of composite binders were measured; microstructure was characterized, phase composition was analyzed by XRD, and tribological tests were carried out between CBN blocks and silicon nitride abrasives. The results indicate that at glass powder contents of 2.94–10.22 wt%, the flexural strength of CBN blocks decreases by 32.5–89.4%, and binder microhardness reduces by 26.5–58.3%. At high brazing temperature, Ti and Cu from Cu-Sn-Ti alloy react with Si and Al in glass powder at the interface to form new phases including Ti₂O₃, Ti₅Si₃ and Ti(Cu,Al)₂, which facilitates favorable interfacial bonding among the alloy matrix, glass phase and CBN grains. With increasing glass powder content, the strength decline gradually slows down. The overall wear resistance of abrasive blocks declines. SEM observations on worn CBN blocks and their composite binders reveal the formation of micropores within glass-containing binders, accompanied by a shift in the fracture mode of CBN abrasives upon glass powder addition. Comprehensive experimental analysis indicates that the No.3 sample with 8.33 wt% glass powder possesses the optimal overall performance. Full article

Ageing vessels are critical to the sensory maturation of Baijiu, yet the interfacial material processes by which traditional ceramics modulate liquor chemistry remain insufficiently defined. Here, Zisha and ceramic-clay particles with distinct aluminosilicate frameworks, mineral compositions, and pore structures were investigated to elucidate their roles in sauce-flavor Baijiu ageing. Ceramic characterization was combined with elemental and volatile analyses using ICP-MS, GC-MS, and GC-IMS. The results showed that pore development in Zisha was primarily governed by fluxing metal oxides and the Si/Al framework, whereas metal-ion migration into Baijiu was regulated by the SiO₂-rich matrix, pore accessibility, and trace elemental composition. Metal elements exhibited reversible interfacial exchange rather than simple leaching, revealing a dynamic metal-ion cycling process during ageing. This process was associated with selective remodeling of the volatile profile. Compared with ceramic-clay particles, Zisha promoted the accumulation of acetophenone, 3-pentanone, and pyrazine derivatives while reducing dimethyl disulfide and heptanal. Sensory evaluation of Baijiu aged in ceramic jars further validated these findings. These findings identify Zisha ceramics as active material–flavour interfaces and provide a mechanistic basis for the rational design of ceramic ageing vessels to direct Baijiu flavour maturation. Full article

The activity and stability of Ni-based catalysts for CO₂ methanation strongly depend on the morphology and chemical composition of the support. In this work, Ni catalysts with four oxidic supports (SiO₂, Al₂O₃, CeO₂, ZrO₂) were synthesized via a one-step spray pyrolysis approach. Comprehensive characterization by STEM-EDS, XRD, and N₂ adsorption was used to resolve support morphology, Ni particle size, and nanoparticle incorporation into the support matrix. Beyond steady-state activity and reaction mechanism, the support material also affects the activation period and initial stability of the catalysts. By combining temperature-programmed methanation scans on fresh and spent samples with long-term stability tests, we clearly identify support-dependent changes in initial activity and their correlation with Ni–support interactions. Enhanced physical embedding and stronger chemical binding of Ni nanoparticles significantly reduce activity changes during the first hours on stream. Overall, this study demonstrates that the support and the corresponding metal–support interactions not only affect reaction pathways and activity, but also the pretreatment and activation required to reach a stable operating point, which is of crucial importance in kinetic catalysis research. Full article

The electrification of high-temperature industrial processes requires refractory materials that combine thermal stability with tailored electrical functionality. In this study, Ta/Nb-Al₂O₃ composites were prepared by spark plasma sintering (SPS) to investigate densification, metal-phase deformation, electrical conductivity and percolation behavior. Coarse, fine and superfine alumina powders were combined with tantalum or niobium and sintered at 1300–1600 °C for 5 min with 50 MPa uniaxial pressure. The results show that the alumina particle size and morphology strongly influence the formation of conductive metal networks. Coarse alumina promotes deformation and elongation of the metallic phase, thereby improving metal-phase connectivity and lowering the operational percolation threshold. Fine and superfine alumina enhance densification but can delay percolation by embedding metal particles in a dense ceramic matrix. Combining these fractions, both effects can be balanced, enabling improved densification while maintaining effective conductive pathways. An operational percolation threshold of 7.5 vol.-% was obtained for Ta/coarse alumina, indicating highly effective metal-phase connectivity after SPS. Microstructural analysis supports the interpretation that matrix-controlled metal-particle deformation and spatial distribution govern the electrical response. Tailored alumina matrix design can reduce the refractory metal content required for conductive ceramic–metal composites. Full article

Composite hydrogel based on acrylic acid and acrylamide, modified with metal ions (Ni²⁺, Al³⁺, Fe²⁺, Fe³⁺) with concentration 0.3 wt%, were synthesized in water or polyethylene glycol (with a molecular weight of 400 Da) at three monomer ratios (7/3, 1/1, 3/7). Dynamic mechanical analysis shows that the equilibrium modulus of elasticity ($G_e$) of unmodified hydrogels increases with acrylamide content due to higher crosslinking density ($n_e$) and smaller cell size. ${AlCl}_3$ or ${NiCl}_2$ strengthen the structure ($G_e$ increases +53.5% in a 1/1 ratio), while iron salts cause softening (decreases to 90% when using ${FeC}_2{O}_4$). Partial replacement of polyethylene glycol reduces the elasticity but when using ${AlCl}_3$ happens synergistic increase $n_e$ 1.9 times in the ratio 3/7. The self-healing efficiency reaches ~100% for ${FeCl}_3$ in PEG gel in a ratio of 1/1 and 72.1% for ${Fe\left({NH}_4\right)}_2{\left({SO}_4\right)}_2$ hydrogel in 3/7. The electrical conductivity of hydrogels increases in the range of ${Al}^{3+}>{Ni}^{2+}>{Fe}^{3+}$, while matrix based on polyethylene glycol reduces the conductivity by an order of magnitude. For ${Ni}^{2+}$-containing samples, pinched hysteresis loops are observed in both water and polyethylene glycol. In contrast, ${Al}^{3+}$ causes rapid passivation in the water matrix, while in the matrix based on polyethylene glycol, the current–voltage characteristics follow ohmic behavior. The results demonstrate the possibility of directional regulation of the mechanical, electrical, and self-healing efficiency of hydrogels by selecting the ratio of monomers, the nature of the ion modifier, and the type of solvent. Full article

Copper and its alloys are widely used in electrical, automotive, aerospace, and energy applications because of their excellent thermal and electrical conductivity. However, the low hardness and poor wear resistance of pure Cu limit its use under tribologically demanding sliding conditions. In this study, Cu matrix composites reinforced with 1 wt.% boron carbide (B₄C), boron (B), chromium (Cr), cobalt (Co), alumina (Al₂O₃), and graphite (Gr) were fabricated by powder metallurgy and comparatively evaluated under identical processing and testing conditions. Phase constitution and microstructural characteristics were analyzed by XRD, SEM, and EDS, while mechanical and tribological behavior was assessed by Vickers hardness and dry sliding wear tests. All reinforcements improved the hardness of the Cu matrix compared with unreinforced Cu. The hardness increase followed the order Cu–B₄C (68.91%) > Cu–B (66.43%) > Cu–Gr (63.97%) > Cu–Al₂O₃ (61.79%) > Cu–Cr (42.69%) > Cu–Co (36.04%). Dry sliding wear tests, performed under a 10 N normal load, 0.05 m s⁻¹ sliding speed, and 1000 m sliding distance against a 316L stainless-steel ball, showed that all reinforced composites exhibited lower mass loss and more stable sliding behavior than pure Cu. Among all samples, Cu–B₄C displayed the best wear performance, with a 154.8% improvement in wear resistance relative to pure Cu. SEM analysis of the worn surfaces revealed that reinforcement addition reduced severe plastic deformation, groove formation, and delamination, leading to a more stable wear regime. Graphite- and boron-containing composites benefited from interfacial lubrication and contact stabilization, whereas B₄C and Al₂O₃ improved wear resistance through rigid-particle strengthening and enhanced load-bearing capacity. By comparing ceramic, metalloid, metallic, oxide, and solid-lubricating reinforcements at the same low addition level and under identical processing and testing conditions, this study provides a reinforcement-selection framework for Cu-based composites requiring improved hardness and dry-sliding durability. Full article

Face milling of aluminum 7075 hybrid metal matrix composites with 10 wt.% TiO₂ and 3 wt.% graphite (HMMCs) are needed to improve performance and sustainability. This study focuses on optimizing the milling process for Al7075 HMMCs using the desirability approach and advanced multi-criteria decision-making (MCDM) methodologies, including the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and the Combined Distance-based Assessment (CODAS). Surface roughness (SR), cutting force (CF), carbon emissions (CE), and energy consumption (EC) were systematically evaluated and ranked using the L₁₈ Taguchi Orthogonal Array. Minimum Quantity Lubrication (MQL) and cryogenic CO₂ cooling techniques were used to achieve a superior surface finish and reduce friction at the tool-workpiece interface, thereby minimizing scratches and thermal damage. Desirability evaluation results showed the optimal machining conditions for milling of Al7075 (HMMCs) occurred at a cutting speed (V_c) of 200 m/min, a feed rate (f) of 0.02 mm/rev, and a depth of cut (a_p) of 0.3 mm, proving the potential of integrating MCDM tools with effective cooling strategies. The desirability method favored a balanced compromise, while entropy-weighted TOPSIS/CODAS emphasized energy and carbon-related responses. Improvements of 6% in cutting force, 7% in surface roughness, and a 7% reduction in energy consumption, along with 8% lower carbon emissions, were achieved, demonstrating the effectiveness of hybrid cooling strategies in promoting eco-friendly and resource-efficient processes. Full article

Zeolite-based composite nanomaterials represent a versatile and mechanistically rich platform for the removal of organic micropollutants (OMPs)—including pharmaceuticals, endocrine-disrupting compounds, pesticides, and per- and polyfluoroalkyl substances (PFAS)—from contaminated water systems. Although pristine zeolite frameworks provide well-defined microporous architectures, tunable Si/Al ratios, and ion-exchange capacity, their intrinsic hydrophilicity restricts interaction diversity and limits performance toward the structurally heterogeneous OMPs prevalent in real aquatic environments. Composite integration with carbonaceous nanophases, functional polymers and surfactants, and catalytically active metal oxide nanoparticles substantially extends this interaction repertoire, yielding multifunctional materials whose adsorption performance exceeds that of the individual components. Drawing on a systematic survey of peer-reviewed literature published between 2016 and 2026, this review develops a mechanism-oriented, structure–property–performance framework examining five dominant adsorption mechanisms—electrostatic attraction, π–π stacking, hydrogen bonding, hydrophobic partitioning, and micropore confinement—in relation to composite nanoarchitecture, surface chemistry, and structural parameters. The modulating influence of realistic water matrix conditions on adsorption efficiency is critically assessed, alongside challenges of regeneration, long-term stability, metal leaching, and the persistent gap between laboratory-scale synthesis and scalable deployment. Priority research directions are identified, including standardized performance evaluation under environmentally representative conditions and rational design of hierarchical multifunctional nanocomposites from earth-abundant and waste-derived precursors. Full article

Titanium matrix composites (TMCs) are increasingly vital in aerospace for their high specific strength and wear resistance, with compositional gradient design serving as a key strategy to mitigate thermophysical mismatches between ceramic and metal phases. This study utilized laser-directed energy deposition with concurrent wire-powder feeding (LDED-WP) to fabricate TiC/Ti6Al4V gradient composites, employing a laser power of 2700 W, wire feed rates of 110–150 cm/min, and calibrated powder feed rates ranging from 50.22 to 497.13 g/h. Along the build direction, the TiC content was progressively increased from 10 wt.% to 60 wt.%. Investigations into microstructural evolution revealed that the reinforcement morphology transitions from chain-like eutectic TiC to dendritic primary TiC, while the lamellarα-Ti width refines significantly from 4.07 ± 1.15 μm to 0.45 ± 0.29 μm. EBSD analysis confirmed that higher TiC concentrations weaken the characteristic <001> solidification texture, reducing intensity from 11.24 to 7.64. Furthermore, KAM analysis highlighted that thermal expansion and elastic modulus mismatches trigger substantial geometrically necessary dislocation (GND) accumulation at interfaces. Consequently, Vickers hardness improved by 164% along the gradient, peaking at 950 HV. Although the composite achieved an ultimate tensile strength of 630 MPa, the elongation was limited to 2.4% due to crack nucleation in TiC-rich regions and interfacial instability. Full article

In this study, the effects of cadmium (Cd) on 4 different alloys developed by casting the Mg-Al-Mn ternary composition, in which the second element is aluminum (Al), and the third element is manganese (Mn), based on magnesium (Mg) metal, which is known as the lightest of the metallic materials in the field of engineering, were investigated. The base alloy Mg-Al-Mn (AM60) (Q1) and the Q2, Q3, and Q4 alloys were produced by adding Cd to the base alloy at rates of 0.2%, 0.5%, and 1.0%, respectively. The effects of element addition were determined by conducting Optical Microscopy (OM), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), hardness tests, potentiodynamic polarization corrosion tests in a 3.5% NaCl environment, and wear tests under 20 N and 40 N loads. The effect of 3.5% NaCl on the alloys in corrosion and wear tests was tested. In the Mg-Al-Mn ternary alloy, the expected α-Mg, β-Mg₁₇Al₁₂, Al₈Mn₅ and AlMn phases were observed, and Cd was found to be predominantly dissolved in the matrix at the micro-level. Cd showed a fine, uniform distribution in the structure. In the hardness tests, the hardness of the alloy containing 1.0% Cd increased by approximately 16%. According to the potentiodynamic polarization corrosion test values, the corrosion potentials of the alloys were negative, but the corrosion rate (CR) increased with increasing Cd content of the alloys. In corrosive wear tests, based on the aggressive corrosive wear mechanism in a 3.5% NaCl environment, an increase in wear of approximately 25% was observed at the end of 400 m as the load increased from 20 N to 40 N. The effect of hardness on corrosive wear was found to be limited. However, it can be stated that the Cd content of the Q2 alloy, being insufficient in accelerating galvanically induced wear, may reduce friction. In the Q3 and Q4 alloys, the increasingly discontinuous β-phase morphology altered the galvanic coupling geometry, contributing to accelerated abrasive wear. In corrosive wear, only the Q2 samples performed well under both 20 N and 40 N loads in a NaCl environment. Full article

The main aim of the work was to analyse the microstructure and selected properties of a metal-matrix surface composite reinforced with a product of vitrification of asbestos-cement waste (ACW) and glass cullet from cathode-ray tubes (CRTs). The composite matrix was an AA7075 (Al-5.5Zn-2.4Mg-1.6Cu-0.2Cr) aluminium alloy. The FSP (friction stir processing) method was used to produce the composite. The composites were tested in the context of the possibility of using vitrified material as a substitute for other reinforcing materials. As a result of treatment, a composite surface layer was obtained, characterised by uniform distribution of the reinforcing phase with a good bond with the matrix. This process was accompanied by strong grain refinement in the stirring zone and partial dissolution of intermetallic phases. These microstructural changes, combined with the introduction of hard particles into the metal-matrix, resulted in a significant increase in the composite’s hardness and wear resistance. As a result of the conducted research, it was found that using the product of vitrification of ACW and CRT cullet in the composites manufacturing process is beneficial, as it is not only a competitive solution to other reinforcing phases, but also an effective way to manage waste hazardous to the environment and humans, thus adding new functionalities to products processed in this way. Full article

In this study, a polyethylene glycol (PEG)-based solid electrolyte composite (PEG)₁₀LiClO₄/NaAlOSiO suitable for anodic bonding packaging was successfully fabricated via a combined ball milling and hot pressing process. The micromorphology, ion transport characteristics, and mechanical packaging properties of the composite were systematically investigated using characterization techniques including electrochemical impedance spectroscopy, X-ray diffraction, scanning electron microscopy, and anodic bonding performance tests. The results demonstrate that doping with NaAlOSiO molecular sieve can effectively reduce the crystallinity of the polymer matrix, construct more efficient carrier transport pathways, and simultaneously enhance the ionic conductivity and mechanical properties of the material. When the mass fraction of NaAlOSiO doping is 8 wt.%, the composite exhibits a room temperature ionic conductivity of up to 1.31 × 10⁻⁵ S·cm⁻¹. Under room temperature and a bonding voltage of 800 V, the sample with this doping ratio achieves the optimal anodic bonding with metallic Al, and the tensile strength of the bonding interface reaches 5.93 MPa, showing excellent application prospects in micro–nano-packaging. 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