Search Results (247)

This work is on magneto-electric (ME) interactions in multiferroic composites of electro-spun triaxial nanofibers composed of lead zirconate titanate (PZT), strontium ferrite, SrFe₁₂O₁₉, (SrM), and nickel ferrite NiFe₂O₄ (NFO). M-type hexagonal ferrite, SrM, with a high uniaxial magneto-crystalline anisotropy field, was chosen to achieve a self-magnetic bias, and NFO with high magnetostriction and piezomagnetic coefficient was chosen to strengthen the ME coupling in the composites. By integrating these three distinct ferroic phases, the triaxial design optimizes interfacial strain transfer to enhance the ME coupling strength in the absence of an external magnetic bias. Fibers with PZT core (Sample A), SrM core (Sample B), or NFO core (Sample C) were synthesized and annealed at 750 C for crystallization of the ferroic phases. X-ray diffraction and electron and scanning probe microscopy confirmed the production of continuous, defect-free fibers with well-defined boundaries and coexisting crystalline phases free of impurities. Magnetic, ferroelectric, and magnetostrictive characterization verified ferroic ordering across all samples. Measurements of the ME voltage coefficients (MEVC) were carried out at low frequencies and at electromechanical resonance (EMR) on rectangular platelets of the fibers. A strong zero-bias ME response was measured, indicating an efficient strain-mediated coupling that bypasses the need for magnetic bias fields. Sample-C with NFO core, PZT inner shell, and SrM outer shell showed the highest low-frequency MEVC of 26.7 mV/cm Oe, and that increased to 161 mV/cm Oe at EMR, both values at zero bias. The stacking order of the core and shell phases dictated the resulting ME interactions. The results indicate the potential of these triaxial fibers as candidates for miniature magnetic sensors and arrays, multifunctional devices, and energy harvesters. Full article

Although population-based metaheuristic algorithms have been widely applied to the One-Dimensional Cutting Stock Problem (1D-CSP), their performance is often limited by premature convergence and insufficient local search capability. This study presents a comparative investigation of the effect of local search on four population-based metaheuristic paradigms for the one-dimensional cutting stock problem (1D-CSP). Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Ant Colony Optimization (ACO), and Grey Wolf Optimizer (GWO) are evaluated both in their standard forms and after incorporating a common Simulated Annealing (SA)-based local refinement procedure. The objective is not to introduce a new hybridization strategy but to systematically examine whether and to what extent the same local search mechanism affects algorithms with different search characteristics. The methods are evaluated on two complementary benchmark datasets comprising 39 industrial instances from the Japanese chemical fiber industry and 1800 CUTGEN1 instances. Performance was evaluated using clipping loss, computational cost, Friedman ranks, win counts, and paired Wilcoxon signed-rank tests. According to the results, statistically significant differences were observed for GA, PSO, and GWO across both benchmark sets, while the difference between ACO and M-ACO was not statistically significant. The study provides a comparative assessment of how the common local search component affects different metaheuristic paradigms for full 1D-CSP. Full article

Aerospace and power equipment require precise temperature monitoring in extremely high-temperature environments, which often feature narrow and curved installation spaces. Since traditional thermocouples cannot provide both measurement performance and structural flexibility simultaneously, we propose a flexible fiber Bragg grating (FBG) temperature-sensing array. The sensor features a dual-layer composite packaging structure comprising an inner braided quartz-wool layer and an outer nickel-based alloy tube. Combined with a high-temperature annealing process, the packaged array was evaluated against a WRP-191 reference thermocouple. Over the investigated heating and cooling points up to 1000 °C, the maximum absolute indication error, max|T_FBG − T_ref|, was 2.02 °C and the mean absolute indication error was 1.25 °C. These quantities are comparison errors relative to the reference thermocouple and are not expanded uncertainties. The dual-layer design also allowed a minimum demonstrated bending radius of 22 mm, supporting deployment in confined and curved installation paths. Full article

Aluminum-clad steel wires are widely used in ultra-high-voltage (UHV) transmission lines due to their excellent beneficial properties. To address the inadequate strength–ductility balance of aluminum-clad steel wires for UHV applications, this study investigates the effects of cold drawing and low-temperature annealing (200~330 °C) on the microstructure, aluminum/steel interface, and mechanical properties of 20SA (20.3% IACS) aluminum-clad steel wires. The results indicate that the cold-drawn steel core exhibits high strength due to its high dislocation density and strong <110> fiber texture. Low-temperature annealing promotes overall recovery and partial recrystallization of the microstructure. Specifically, annealing at 240~280 °C significantly enhances ductility while maintaining high strength, achieving optimal strength–ductility synergy; however, higher annealing temperatures result in an unacceptably low ultimate strength, rendering them impractical for application. Interfacial characterization reveals that the as-clad and cold-drawn processes, as well as annealing below 250 °C for 10 min, maintain stable metallurgical bonding at the aluminum/steel interface, whereas annealing at 300 °C for 10 min induces the formation of brittle Fe-Al intermetallic compounds, thereby compromising service reliability. Furthermore, the precipitation of cementite (Fe₃C) with increasing temperature partially compensates for the strength loss caused by overall recovery. This study identifies the optimal heat treatment window, providing a theoretical basis for the strength–ductility design and reliable service of UHV transmission lines. Full article

Rotational molding is a shear-free technology to produce hollow plastic parts. Rotomolded poly(lactic acid) (PLA) and its biocomposites remain in a largely amorphous state, which limits their stiffness, toughness, and thermal resistance. Post-processing thermal annealing develops crystallinity without additives, but its combined effect with natural fibers has rarely been quantified. This work evaluates annealing at 100 °C for 1 h on rotomolded PLA biocomposites reinforced with 10, 20, and 30 wt.% of agave, coir, or pine fibers. Crystallinity (DSC, XRD), density and porosity, morphology (SEM), water absorption, mechanical properties (tensile, flexural, Charpy impact, Shore D hardness), and 28-day disintegration under lab-scale composting conditions were measured for treated and untreated samples. Annealing raised the matrix crystallinity from below 21% to 41–56% and produced predominantly α crystals with a nearly constant average size of about 20 nm. The treatment improved the matrix-dominated properties for every formulation: for neat PLA, Charpy impact strength increased by 120% (28.1 to 61.7 J/m), flexural strength by 53% (61.1 to 93.4 MPa), and flexural modulus from 3264 to 4511 MPa. Tensile strength and modulus, in contrast, remained unchanged or decreased. Porosity, set by fiber content, was unaffected by annealing; at 30 wt.%, the matrix barrier nonetheless reversed, and annealed samples absorbed more water and disintegrated faster than untreated ones. Fiber content sets the balance between matrix crystallinity and the interfacial damage caused by crystallization-induced contraction. Full article

Material extrusion additive manufacturing, commonly implemented as fused deposition modeling (FDM) or fused filament fabrication (FFF), has evolved into a manufacturing route for reinforced thermoplastic composites, including particle-filled, short-fiber-reinforced, and continuous-fiber-reinforced systems. The process is governed by a layer-by-layer thermal cycle. Deposited roads cool rapidly, are repeatedly reheated by subsequent material deposition, and finally cool non-uniformly as part of the growing structure. This thermal history generates residual-stress that may cause warpage, build–platform detachment, delamination, dimensional error, and reduced mechanical performance. This review synthesizes residual-stress formation, measurement, modeling, parameter effects, and mitigation in material-extruded reinforced thermoplastic composites, with emphasis on short and continuous-fiber systems. Stress formation is discussed in terms of constrained thermal contraction, crystallization shrinkage, anisotropic stiffness, fiber-constrained deformation, porosity, and fiber–matrix thermal expansion mismatch. Experimental methods, including hole drilling, layer removal, curvature methods, embedded fiber Bragg gratings, digital image correlation, photoelasticity, and warpage metrology, are critically compared for anisotropic and porous printed composites. Analytical and numerical models are reviewed from layerwise shrinkage formulations to crystallization-coupled thermo-viscoelastic finite element simulations. Finally, mitigation strategies are evaluated. A central conclusion is that reinforcement can suppress visible distortion while increasing stress retained in a stiffer structure. Therefore, warpage alone is not a sufficient residual stress metric. Full article

The aim of this article was to improve the solid-phase synthesis of Na₃V₂(PO₄)₃/C composite for sodium-ion battery cathode materials using an innovative technique for creating a protective reducing atmosphere, which is formed by incomplete oxidation of carbon fiber during annealing. The resulting Na₃V₂(PO₄)₃ phase has a rhombohedral structure of a sodium superionic conductor (NASICON) with particle sizes ranging from 0.5 to 20.0 μm. The encapsulation of Na₃V₂(PO₄)₃ granules with a carbon coating leads to a maximum specific capacity of 112.3 mAh g⁻¹ at a charge–discharge rate of C/5 (22.4 mA g⁻¹). After 200 charge–discharge cycles, the synthesized composite demonstrated a specific discharge capacity degradation of 0.107% per cycle. The apparent diffusion coefficients of Na⁺ ions in the resulting Na₃V₂(PO₄)₃/C composite were measured and found to be 5.87 × 10⁻¹¹ and 4.60 × 10⁻¹¹ cm² s⁻¹ for deintercalation and intercalation, respectively. Full article

After cold rolling of high-strength interstitial-free (IF) steel, the ferrite grains undergo plastic deformation associated with the formation of substructures and intense cold-rolling texture, which affects the microstructure and texture in the subsequent annealing process and determines the formability of the final sheet. To clarify the mechanisms of microstructure and texture formation during cold rolling of IF steel, a polycrystalline model was constructed based on the measured microstructure and texture features. A crystal plasticity model, along with a remeshing technique, was developed for IF steel. The model can calculate the deformation of the polycrystal after 70% cold rolling reduction, in which the calculated microstructure and texture features are consistent with the results from electron backscatter diffraction (EBSD). The results show that the deformed microstructure and texture are closely related to the initial crystal orientation, the interaction between neighbouring grains, and the cold rolling reduction. Grains with an initial texture orientation near <001>//ND are more stable during deformation and tend to retain their orientations after cold rolling. In contrast, grains initially deviating from the γ-fiber tend to rotate towards the <111>//ND orientation, while near-γ-fiber grains mainly retain their γ-fiber characteristics with intragranular orientation spreading during cold rolling. Multiple slip systems induce the formation of ingrain shear bands. These results establish a grain-scale link between initial orientation, intragranular substructure formation, and cold rolling texture evolution, and provide a mechanistic basis for optimizing cold rolling texture control and improving the formability of high-strength IF steel sheets. Full article

The influence of double continuous cold rolling followed by annealing on the texture evolution and mechanical properties of a commercial low-carbon ferritic steel was investigated. Ultrathin sheets (final thickness 0.22 mm) were produced through a two-stage cold rolling process with intermediate and final annealing at 690 °C for 35 s, followed by light temper rolling at 100 °C for 20 s. Texture evolution was characterized using Electron Backscatter Diffraction (EBSD) with Orientation Imaging Microscopy (OIM), producing pole figures and orientation distribution functions (ODFs). Mechanical properties were evaluated through Vickers microhardness and ultimate tensile strength measurements obtained from three independent locations per sample. Quantitative ODF analysis (φ₂ = 45°) revealed that γ-fiber ({111}//ND) intensity increased after each cold reduction stage and decreased after annealing due to recrystallization. The α-fiber (110/RD) and cube components (001//RD) showed a slight increase after annealing. The final ultrathin sheet exhibited moderate γ-fiber intensity (≈3 M.R.D), low Vickers microhardness (100–150 HV), and tensile strength (400–450 MPa). These results demonstrate controlled evolution of texture and microstructure during double cold rolling and annealing, providing a basis for future studies on forming-related behavior without directly assessing formability. Full article

Herein, we report a method to additively manufacture carbon fiber-reinforced siliconized silicon carbide composites. The process involves the pyrolysis of a 3D-printed carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composite to produce a porous carbon fiber-reinforced carbon matrix composite preform, which is subsequently infiltrated with molten silicon to obtain a carbon fiber-reinforced siliconized silicon carbide composite. A key aspect of the method is limiting polymer melt flow during pyrolysis of PEEK, which is achieved by thermally annealing the 3D-printed carbon fiber-reinforced PEEK preform in air at a temperature below PEEK’s melting temperature. Rheological and differential scanning calorimetry (DSC) measurements demonstrate that the thermal annealing treatment altered the melting behavior of PEEK, while NMR and FTIR measurements provided a mechanistic explanation for the structural changes responsible for the behavior. It was also found that dimensional changes during pyrolysis were anisotropic with greater shrinkage in the stacking direction of the material. Full article

To overcome the limited high-temperature capability of silica-based fiber Bragg gratings (FBGs) and the accuracy degradation of gold-coated FBGs induced by residual stress, a temperature sensor based on a gold-coated FBG with high-temperature alloy packaging is proposed and fabricated. By introducing a high-temperature annealing pretreatment to the gold-coated fiber, residual stress is effectively relieved, enabling high-precision temperature measurement in high-temperature environments. Within the range of 20–800 °C, the annealed sensor achieves an accuracy of 0.72% F.S., a sensitivity of 9.65 pm/°C, and a linearity of 0.9997, in close agreement with theoretical predictions. After ambient vibration and high-temperature thermo-vibration tests, the maximum center wavelength shifts are 13 pm and 46 pm, corresponding to temperature variations of approximately 1.35 °C@24 °C and 4.77 °C@800 °C. These results demonstrate stable sensor performance under high-temperature testing conditions. In addition, a fitting formula applicable to different center wavelengths is proposed, significantly reducing calibration effort. The sensor features a simple structure, easy installation, and reliable performance, providing an effective solution for temperature sensing in extreme environments. Full article

This study investigates the formation mechanism of non-doped cubic lithium lanthanum zirconium oxide (c-LLZO) nanofibers using in situ synchrotron X-ray scattering techniques. Electrospun polymer precursor nanofibers were annealed at temperatures up to 800 °C, enabling real-time tracking of phase transitions via simultaneous small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and evolved CO₂ gas analysis. The results reveal a three-step transformation pathway: polymer decomposition, formation of La₂Zr₂O₇ (LZO), and direct conversion of LZO to c-LLZO without intermediate tetragonal phases detected within the sensitivity of our in situ WAXS measurement. Cryo-electron energy loss spectroscopy (EELS) further elucidates the role of lithium diffusion, showing Li enrichment at fiber surfaces and Li deficiency in the interior, which stabilizes the cubic phase. This Li segregation effect in nanostructured LLZO materials extends beyond the previously reported size effect. This work advances the understanding of c-LLZO formation mechanisms and provides practical insights for optimizing synthesis routes to achieve phase-pure c-LLZO for solid-state battery applications. Full article

The NiO/Al₂O₃-CaO, CuO/Al₂O₃-CaO and CoO/Al₂O₃-CaO catalytic systems were investigated for the decomposition of ozone. Each of the three different Al₂O₃-CaO carriers was obtained after treatment of the initial precursor at 1100 °C for 2, 4 and 6 h, respectively, to examine the effect of annealing on support calcination. AAS, XRD, XPS, EPR, SEM and BET were applied for sample characterization. The carrier comprises a mixture of corundum α-Al₂O₃, θ-Al₂O₃ and Ca₃Al₂O₃. The XRD spectra of the active phases of the catalysts show the existence of Co₃O₄, NiO, Ni₂O₃ and CuO. The SEM micrographs reveal spherical particles for the NiO/Al₂O₃–CaO sample. In contrast, the CoO/Al₂O₃–CaO sample exhibits a morphology composed of wool-like fibers and perpendicularly oriented plate-like structures. The CuO/Al₂O₃–CaO sample consists not only of fibrous structures but also of distinct, separated aggregates. The obtained catalysts have highly developed specific surface areas. Their catalytic activity depends on the calcination conditions of the support, and the best results are observed after 2h treatment for all of the investigated samples due to the smaller crystallite size and higher specific surface area. The activity of the investigated catalysts for the ozone decomposition reaction follows the order NiO/Al₂O₃-CaO > CoO/Al₂O₃-CaO > CuO/Al₂O₃-CaO. Full article

In this study, electrospun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopapers were produced by annealing electrospun fiber mats from two commercial grades (151C and X131A) and compared with films prepared by the conventional melt-mixing/compression molding method. To obtain continuous biopapers, the fiber mats were subjected to mild thermal post-processing at various temperatures. The selected annealing temperatures were 140 °C (151C) and 130 °C (X131A), where interfiber coalescence occurred within a short annealing time (10 s), yielding continuous fibrous films (biopapers). To elucidate the structural mechanisms underlying interfiber coalescence, time-resolved synchrotron SAXS/WAXS and temperature-dependent FTIR spectroscopy were performed. These analyses showed that coalescence occurred through an interplay between thermally induced local ordering at sub-melting temperatures and premelting/partial melting of thin, ill-defined lamellae, with grade-dependent contributions. The resulting biopapers were evaluated against compression-molded films for optical, mechanical, and barrier properties relevant to packaging. All samples showed similar transparency, although compression-molded films were slightly more opaque. The lower-rigidity grade (151C) exhibited more ductile and tougher behavior than X131A. Biopapers showed slightly lower water and oxygen barrier performance than compression-molded films, attributed to differences in material compactness. Overall, brief mild annealing after electrospinning enabled continuous PHBH biopapers with balanced properties, supporting their potential for sustainable PHBH-based food-packaging applications. Full article

This article describes a study on the synthesis and annealing processes of thin-film coatings of vanadium oxide on flat, parallel substrates made of quartz glass, sapphire, and silicon, as well as optical fibers using an organometallic precursor, triisopropoxy vanadium (V) oxide. For the first time, optical constants of nanomaterials were estimated in real time during synthesis and subsequent annealed using the lossy-mode resonance effect. The coatings produced in an inert atmosphere after deposition were amorphous, comprising a mixture of VO₂, V₂O₅, V₆O₁₃, and V₃O₅. This method allowed for accurate determination of the threshold temperature for the transformation of oxide mixtures into a monocomponent phase. Optimal conditions for synthesis and annealing were determined for the production of vanadium dioxide (VO₂) and pentoxide (V₂O₅). Morphological changes in coated surfaces were observed as a result of heat treatment. The composition and properties of these samples were studied using optical, terahertz and Raman spectroscopy, as well as temperature-dependent analysis of electrical resistance. The morphology of the coating surface was determined using a scanning electron microscope and an atomic force microscope. The reduction of VO_x to VO₂ was studied in an atmosphere of hydrogen and argon during annealing after deposition, with its effectiveness being compared. It was shown for the first time that the reduction of higher vanadium oxides is due to the presence of elemental carbon in the volume of the material formed from a metalorganic precursor during growth of vanadium oxide. Coatings obtained by annealing in hydrogen had a smaller hysteresis loop width (~5 °C) during phase transition compared to coatings obtained by argon annealing (~9 °C). Both types of coatings demonstrated a 50–60% increase in transmission at 1 THz frequency and in the IR region, accompanied by a 10³–10⁴-fold change in electrical resistance. Full article