Search Results (219)

A novel (TaWZrHf)₉₅Y₅ refractory high-entropy alloy (RHEA) matrix was fabricated via vacuum hot pressing (VHP) sintering and subsequently modified through laser remelting (LR) surface treatment. Thermodynamic phase diagram calculations predicted the alloy’s dual-phase BCC structure, and the effects of LR on phase composition, microstructure, and mechanical properties were systematically investigated. LR induced a significant phase transition, promoting rapid solidification and substantial grain refinement. The surface hardness increased to 848 HV₀.₂, approximately 1.5 times higher than that of the matrix, while the compressive strength reached 1635 MPa, surpassing the matrix by 200 MPa without compromising ductility. Importantly, the LR process effectively mitigated rare-earth (yttrium) segregation and loss, a common challenge in conventional arc melting of refractory HEAs, thereby enhancing solid solution strengthening and phase stability. This work pioneers the application of laser surface engineering to VHP-sintered refractory HEAs, bridging critical gaps in fabrication, microstructural optimization, and performance enhancement, and offering valuable insights for the future design of high-performance multi-principal element alloy development. Full article

The present study investigates the combined influence of manufacturing route and material configuration on the mechanical, elastic, viscoelastic, and impact behavior of Kevlar–carbon hybrid laminates. Three eight-ply laminate configurations (V1, V2, and V3) were manufactured through distinct technological routes: fully prepreg-based hot pressing, Kevlar-prepreg/dry-carbon hand lay-up followed by vacuum curing, and multi-stage hybrid consolidation combining repeated hot pressing with subsequent vacuum curing. The experimental characterization included tensile tests according to ASTM D3039, compression tests according to ASTM D695, determination of Young’s modulus from extensometer measurements and Poisson’s ratio using strain-gauge instrumentation, dynamic mechanical analysis (DMA), and low-velocity impact tests under controlled energy conditions. The novelty of this work consists in the integrated process–configuration–property comparison of these Kevlar–carbon hybrid routes within the same experimental framework, rather than in a generic demonstration that manufacturing affects composite laminates. The V1 laminate exhibited the highest strength-related performance, reaching an average tensile strength of 335.88 MPa and a compressive strength of 165.85 MPa, and it also showed the highest DMA storage modulus at 30 °C, E’ = 53.42 GPa. The V2 laminate presented lower tensile performance but the most pronounced damping response, with the highest tanδ peak value. The Young’s modulus determined from the extensometer measurements was 29.26 ± 1.45 GPa for V1, 26.10 ± 0.22 GPa for V2, and 29.52 ± 1.27 GPa for V3, indicating comparable longitudinal stiffness for the V1 and V3 laminates. The results indicate that the measured behavior is governed by the combined effects of reinforcement form, matrix/resin arrangement, consolidation route, and laminate architecture. Direct quantification of laminate compaction, fiber volume fraction, and void content was outside the scope of the present experimental campaign and is identified as a necessary step for future validation. Full article

The reliable joining of graphite and Cu holds significant promise for applications in electronic heat dissipation and sliding electrical contacts. However, the substantial differences in their physicochemical properties, poor wettability, and mismatch in coefficients of thermal expansion often result in low joint strength. In this study, a two-step joining strategy combines surface modification with low-temperature sintering, and this is proposed for fabrication of Cu/graphite joints. First, the graphite surface is modified using an AgCuTi active filler alloy under vacuum conditions. Ti preferentially segregates at and reacts with the graphite interface, leading to the formation of an Ag-Cu eutectic modified layer on the graphite surface. Subsequently, low-temperature joining of the modified graphite to a Cu substrate is achieved via a hot-pressing sintering process using a Ag paste. In the sintered joint, the Ag sintered layer forms sound metallurgical bonds with both the Cu substrate and the graphite-modified layer. When the sintering temperature is 250 °C, the joint exhibits a shear strength of 30 MPa, which is significantly higher than that of a directly brazed joint. This strategy effectively reduces thermal residual stress in the joint during cooling and shifts the failure location from the brittle graphite substrate to the ductile Ag sintered layer, thereby substantially enhancing the mechanical performance. Full article

This study aims to demonstrate the feasibility of transferring alkali activation technology to the ceramic tile production by developing tiles based on metakaolin and ceramic tile waste by uniaxial pressing. Optimization of the tile formulations was achieved by adjusting precursor composition (metakaolin or combination of metakaolin and ceramic tile waste), NaOH molarity, and overall water content. After uniaxial pressing at 50 MPa, alkali-activated tiles were consolidated at 50 °C for 24 h. Physical and mechanical properties were assessed following ISO test methods for ceramic tiles, allowing direct comparison with the ISO classification requirements. The more promising formulations highlight a water absorption by vacuum test method (ISO 10545-3) equal to 15%, thus allowing a BIII classification according to ISO 13006. Finally, thermal stability up to 850 °C was determined, thus allowing alkali-activated tiles to be industrially glazed. Full article

The explosive demand for flexible wearable and portable devices imposes stringent requirements on the mechanical, energy storage, and sensing properties of functional materials. Although two-dimensional (2D) transition metal carbides and nitrides (MXene) possess high conductivity and pseudocapacitance, their severe self-restacking and intrinsic brittleness restrict their practical applications. Herein, a facile vacuum filtration and hot-pressing densification strategy is proposed to fabricate nacre-inspired MXene-based films. By incorporating one-dimensional (1D) high-aspect-ratio TEMPO-oxidized cellulose nanofibrils (TOCNFs), the self-restacking of MXene is effectively suppressed. The optimal M20F5 composite film exhibits a coordinated electromechanical balance, maintaining an electrical conductivity of 1.07 × 10⁶ S m⁻¹ while enduring 2124 folding cycles. For energy storage, the assembled symmetric supercapacitor delivers a specific capacitance of 828.92 F g⁻¹ at 0.5 mA cm⁻² and maintains an energy density of 13.75 Wh kg⁻¹ at a power density of 9500 W kg⁻¹. Furthermore, acting as a piezoresistive sensor, the film achieves reliable detection, spanning from bimodal gait recognition to subtle physiological pulses. This work establishes a viable material design strategy for next-generation supercapacitors and intelligent wearable systems. Full article

The problem of industrial waste disposal is becoming increasingly pressing. For a long time, one of the primary methods of managing hazardous industrial waste was to dispose of it for long periods (decades) in engineered landfills. However, over time, due to various climatic, geological, and other changes, landfills begin to cause significant harm to the environment and human health. Old landfills, many built in the mid-20th century, pollute the air, soil, and groundwater. Therefore, the issue of decommissioning “old” landfills is becoming increasingly pressing. This study aimed to develop technological solutions for the safe extraction and processing of hazardous liquid waste from an aged industrial landfill. An integrated treatment chain was designed, comprising extraction, multi-barrier water treatment, vacuum evaporation, and lithification. Optimal lithification compositions were identified: for the salt concentrate–sludge–spent media mixture, a ratio of 68.2% sorbent D, 28.0% salt concentrate, and 3.8% dewatered sludge/spent media yielded a loose granular geocomposite; for oil-containing waste, the optimal ratio using lime and opoka was 1:0.9:0.5 (bottom sediments/CaO/opoka). Biotesting confirmed that the lithified waste is Hazard Class V (non-hazardous), whereas the untreated waste is Class III (moderately hazardous). The resulting geocomposite is suitable for on-site technical reclamation, closing the material cycle. Full article

To meet the stringent industrial service requirements of magnesia–chrome refractory bricks, this study adopts a technical approach that synergistically combines precise component ratio optimization with a vacuum-pressure MgSO₄ salt impregnation process to investigate the performance optimization of magnesia–chrome bricks. Samples were prepared by controlled formulation mixing, pressing at 250 MPa, drying at 110 °C, and firing at 1750 °C. Phase composition, microstructure, and physical–mechanical properties were characterized by XRD, SEM, and standard refractory test methods. The optimal additions of chromite powder and Cr₂O₃ micro-powder were determined to be 3 wt.% and 2 wt.%, respectively, which reacted with periclase to form a secondary composite spinel, creating a dense spinel bridge network that connected adjacent grains. Furthermore, when the proportion of sintered magnesia powder (MgO > 97 wt.%) was increased to 11 wt.%, the material achieved efficient densification facilitated by enhancing sintering performance. Based on this optimized formulation, and due to the high elemental compatibility between MgSO₄ and the magnesia–chrome brick matrix as well as the excellent permeability of the solution, the MgSO₄ vacuum-pressure salt impregnation process was subsequently applied. The salt solution filled the open pores and microcracks of the material, forming a crystalline salt micro-pillar reinforcing phase. Consequently, the apparent porosity of the material decreased to 10.98%, the bulk density increased to 3.23 g/cm³, and the cold compressive strength and cold modulus of rupture reached as high as 113.52 MPa and 24.91 MPa, respectively. This study innovatively establishes a new pathway for enhancing the mechanical properties of magnesia–chrome refractory bricks through the synergistic design of component ratio optimization and salt impregnation process. The prepared magnesia–chrome refractory bricks exhibit both excellent mechanical properties and volume stability. Full article

Ti alloys are widely used in aerospace and biomedical fields due to their high mechanical properties under severe loading. Interest in additively manufactured Ti6Al4V has increased, but further research is needed to fully characterize their properties. This work compares the effects of surface properties, internal defects, microstructure, hardness, and Hot Isostatic Pressing (HIP) or Vacuum Heat Treatment (VHT) on the fatigue behavior of Ti6Al4V produced by Selective Laser Melting (SLM) and Electron Beam Melting (EBM). Printing parameters and post-processing were optimized to achieve high density and minimal porosity, providing a solid basis for realistic fatigue comparisons. Samples were characterized in terms of microstructure (optical microscopy and SEM), mechanical properties (hardness mapping), surface texture (confocal microscopy), and internal defects (image-based analysis). Uniaxial fatigue limits were determined by a Dixon-Mood staircase method, and failed specimens were analyzed for fracture surfaces and defect areas. Applied load on flaws was evaluated to identify root causes of fatigue failure. Results showed that fatigue of as-printed samples is governed by surface roughness, while machined specimens are controlled by internal defect size. Machining increased the fatigue limit roughly threefold, and HIP further improved it by 10–20% by reducing internal porosity. In conclusion, with properly optimized melting parameters, both EBM and SLM produce similar mechanical performance at comparable roughness, supporting their use for structural components. Full article

The rapid advancement of communication technologies exacerbates severe electromagnetic interference (EMI) pollution. Conventional flexible shielding materials rely heavily on non-degradable petroleum-based polymers, aggravating the electronic waste crisis. To address this dual challenge, sustainable biomass-derived TEMPO-oxidized cellulose nanofibrils (TOCNFs) emerge as ideal structural substrates. However, their intrinsic electrical insulation necessitates integrating conductive two-dimensional (2D) MXene, which suffers from severe self-restacking and brittleness. Herein, TOCNFs@MXene hybrid films are manufactured via vacuum filtration and hot-pressing densification. TOCNFs inhibit MXene self-restacking, constructing a highly ordered layered architecture via a dense hydrogen-bonded network. The optimized ultrathin film T5@M20 (~4.92 μm) exhibits an electrical conductivity of 1.09 × 10⁶ ± 5.06 × 10⁴ s m⁻¹ and an X-band shielding effectiveness (SE_Total) of 25.55 dB. Demonstrating an ultrahigh thickness-normalized specific shielding effectiveness (SSE/t) of 51,934.72 dB·cm²·g⁻¹, this sustainable architecture shows exceptional potential for next-generation flexible electronics. Full article

Cemented carbides are essential in applications requiring exceptional hardness and wear resistance. However, the reliance on cobalt as a binder raises concerns related to cost, supply security, and health. High-entropy alloys (HEAs) are promising cobalt-free binders offering favorable mechanical properties and potential grain-growth control. This work presents a new approach for the development of Co-free WC-based cemented carbide employing an HEA binder designed through CALPHAD-guided simulations. An optimized composition corresponding to Al5Cr5Cu10Fe35Mn10Ni35 (at%) alloy is predicted to be FCC-dominant with minimal σ-phase formation and good compatibility with WC. A preliminary batch of powder of the proposed binder was produced by blending elemental powders, arc remelting, and ultrasonic atomization, yielding predominantly spherical particles with a dendritic microstructure. WC–HEA composites (WC–12 wt% HEA) were then prepared by ball milling, pressing, vacuum sintering, and sinter-HIP for a first evaluation of the microstructure and achievable hardness. The microstructure exhibited residual porosity without significant WC grain coarsening. XRD analyses showed the dominant presence of WC, along with FCC and M₃W₃C phases (M mainly Fe and Mn), indicating thermal interaction between the binder and WC. Despite these effects, the composite achieved a hardness of 1913 HV and retained a fine WC grain size (0.86 μm). The proposed design approach allowed the definition of a promising Co-free binder composition based on HEA with the expected microstructure, which will need further evaluation, especially aimed at investigating toughness properties as a function of the WC content. Full article

TC4/Al₃Ti metal–intermetallic laminated (MIL) composites were fabricated by the vacuum hot-pressing process at 650 °C. The microstructure characteristics, i.e., grain boundary distribution, crystallographic orientation and Kernel Average Misorientation (KAM) map, were analyzed using EBSD. Meanwhile, the distribution of local strain and the fracture behavior of TC4/Al₃Ti MIL composites during tensile process were determined by Digital Image Correlation (DIC) and in situ tensile experiments, respectively. Results show that the TC4/Al₃Ti interfaces are well bonded and exhibit a distinct wavy morphology. The obvious Kirkendall pores and centerline are observed within the central region of the Al₃Ti layer. The texture components of (10-10) <0001> and (11-20) <10-10> are predominant in the TC4 layers; (100) <001> and (110) <001> are observed in the Al₃Ti layer. Additionally, the average geometrically necessary dislocation (GNDs) density is 2.53 × 10¹⁴ m⁻² in the TC4 layer, whereas it is 1.74 × 10¹⁴ m⁻² in the Al₃Ti layer. In the tensile test, the fracture resistance of TC4/Al₃Ti MIL composites is significantly improved by the plastic deformation of the TC4 layers and the suppression of crack-tip instability. It is found that the extrinsic toughening mechanisms contain crack deflection, crack blunting, crack bridging, multiple cracking modes, and the plastic deformation of ductile TC4 layers in TC4/Al₃Ti MIL composites. The real-time observation technique may provide more complete insights into the relationship between fracture behavior and enhanced toughness. Full article

Thorium carbide (${\mathrm{ThC}}_{2\pm x}$) nano-structured thin disc-like pellets were produced from thoria nanoparticles (${\mathrm{ThO}}_2$-NP) and multi-walled carbon nanotubes (MWCNT). These composites are to be studied as a target material candidate for radioactive ion beam (RIB) production via nuclear reactions upon impact with high-energy proton beams on a stack of solid pellets. The ${\mathrm{ThO}}_2$-NP precursor was produced via precipitation of thorium oxalate from a thorium nitrate solution with oxalic acid and subsequent hydrothermal oxidation of the oxalate, creating the thoria nanoparticles. The ${\mathrm{ThO}}_2$-NP were then mixed with MWCNT in isopropyl alcohol and sonicated by two different methods to create a nanoparticle dispersion. This dispersion was then heated under medium vacuum to evaporate the solvent; the resulting powder was pressed into pellets and taken to an inert-atmosphere oven, where it was heated to 1650 °C and carbothermally reduced to ${\mathrm{ThC}}_{2\pm x}$. The resulting pellets were characterized via XRD, SEM-EDS, and Raman spectroscopy. The resulting thorium pellets exhibited, at most, trace levels of the oxide precursor. Furthermore, the nanotube structures were still present in the final product and are expected to contribute positively towards faster radioisotope release times by lowering isotope diffusion times, which is required for the efficient extraction of the shortest-lived (<1 s half-life) radioisotopes. Full article

This study examines the longitudinal shortening of clay blanks during extrusion and introduces a hybrid soft sensor framework for early prediction of ceramic roof tile performance. Targeted properties include shrinkage, water absorption, and saturation. The models integrate real-time process data collected after vacuum extrusion and pressing with clay-specific descriptors such as carbonate content and granulometry, alongside additional variables including moisture, firing temperature, and length reduction. Partial Least Squares (PLS) regression was adopted as the core method due to robustness against multicollinearity and ease of industrial integration. In contrast to complex machine learning pipelines, PLS-based soft sensors enable lightweight edge deployment without reliance on IoT infrastructure. Complementary regression and machine learning models were used to benchmark predictive accuracy and explore nonlinear effects. The results confirm reliable prediction of key performance indicators and reveal mechanistic links between extrusion-induced deformation and downstream behavior. Although developed for clay systems, the framework is generalizable and can be adapted to other traditional ceramic processes or industries seeking interpretable, locally deployable solutions for process control. Full article

High-quality drilled holes are critical in thin fabric-reinforced composites used in many industrial applications; however, the influence of woven architecture on drilling performance without a backup plate remains insufficiently defined. This paper introduces the first comprehensive experimental and statistical framework for evaluating unsupported drilling of thin woven glass fiber-reinforced polymer (GFRP) laminates. The framework integrates the effect of support opening width, fiber weight fraction (wf), feed per tooth, and fabric architecture to quantify their combined effects on delamination, cutting forces, and surface roughness. The samples consisted of vacuum mold-pressed GFRP laminates. Drilling tests were conducted on plain and twill-woven plates, and hole quality was evaluated using thrust force, delamination factor, and surface roughness (Sa). A statistical DOE and multifactorial ANOVA were applied to quantify the effects of the main parameters. For plain-woven GFRP, the best results were obtained with a 65 mm support opening width, 45% fiber wf, and 0.04 mm/tooth feed. Plain-woven laminates exhibited lower average surface roughness (Sa ≈ 5.0–6.5 µm) than twill-woven laminates (Sa ≈ 6.0–7.0 µm). The study demonstrates how fabric architecture and drilling parameters jointly influence hole quality in thin GFRP composites, providing practical guidance for manufacturing applications. Full article

High-performance SiC_p/Al composites were fabricated via a vacuum hot-pressing powder metallurgy process. The effects of SiC particle size on the composite microstructures and their thermal and mechanical properties were systematically investigated. The vacuum hot-pressed SiC_p/Al composites exhibited a well-bonded interface between the SiC particles and Al matrix, while not exhibiting any Al₄C₃ brittle phase. Particle gradation effectively enhanced the densification of SiC_p/Al composites, resulting in dense bulks with a relative density of 99.7%. When the SiC particle size increased from 5 to 50 μm, the fracture morphologies gradually transitioned from intergranular to transgranular, while the relative density, bending strength, and thermal conductivity increased. Overall, SiC_p/Al composites with excellent thermal conductivity (201.42 W/(m·K)) and bending strength (523 ± 29.45 MPa) were obtained. To address the scarcity of research on SiC_p/Al composites’ thermal properties, this study establishes SiC size/gradation–property relationships, innovatively filling the gap in thermal performance regulation. Full article