Search Results (377)

This study addresses the critical challenges of interfacial stress mismatch, fiber degradation, and unstable clad geometry in manufacturing continuous carbon fiber-reinforced aluminum composites (Cf/Al) via laser cladding, driven by rapid thermal gradients. A dual-ellipsoid heat source-based thermoelastic–plastic finite element model was developed in Abaqus, integrating phase-dependent material properties and latent heat effects to simulate multi-physics interactions during single-track deposition, resolving transient temperature fields peaking at 1265 °C, and residual stresses across uncoated and Ni-coated fiber configurations. The work identifies an optimal parameter window characterized by laser power ranging from 700 to 800 W, scan speed of 2 mm/s, and spot radius of 3 mm that minimizes thermal distortion below 5% through gradient-controlled energy delivery, while quantitatively demonstrating nickel interlayers’ dual protective role in achieving 42% reduction in fiber degradation at 1200 °C compared to uncoated systems and enhancing interfacial load transfer efficiency by 34.7%, thereby reducing matrix tensile stresses to 159 MPa at fiber interfaces. Experimental validation confirms the model’s predictive capability, revealing nickel-coated systems exhibit superior thermal stability with temperature differentials below 12.6 °C across interfaces and mechanical interlocking, achieving interfacial void fractions under 8%. These results establish a process–structure linkage framework, advancing defect-controlled composite fabrication and providing a digital twin methodology for aerospace-grade manufacturing. Full article

Ferronickel slag and ground granulated blast-furnace slag (GGBFS) are solid waste by-products from the metallurgical industry. When incorporated into concrete, they help promote resource utilization, reduce hydration heat, and lower both solid waste emissions and the carbon footprint. To facilitate the application of ferronickel slag–GGBFS concrete in 3D printing, this study examines how aggregate size and nozzle diameter affect its performance. The investigation involves in situ printing, rheological characterization, mechanical testing, and scanning electron microscopy (SEM) analysis. Results indicate that excessively large average aggregate size negatively impacts the smooth extrusion of concrete strips, resulting in a cross-sectional width that exceeds the preset dimension. Excessively small average aggregate size results in insufficient yield stress, leading to a narrow cross-section of the extruded strip that fails to meet printing specifications. The extrusion performance is closely related to both the average aggregate size and nozzle diameter, which can significantly influence the normal extrusion stability and print quality of 3D printed concrete strips. The thixotropic performance improves with an increase in the aggregate size. Both compressive and flexural strengths improve with increasing aggregate size but decrease with an increase in the printing nozzle size. Anisotropy in mechanical behavior decreases progressively as both parameters mentioned increase. By examining the cracks and pores at the interlayer interface, this study elucidates the influence mechanism of aggregate size as well as printing nozzle parameters on the mechanical properties of 3D printed ferronickel slag–GGBFS concrete. This study also recommends the following ranges. When the maximum aggregate size exceeds 50% of the nozzle diameter, smooth extrusion is not achievable. If it falls between 30% and 50%, extrusion is possible but shaping remains unstable. When it is below 30%, both stable extrusion and good shaping can be achieved. Full article

A continuous mixing process with a twin-screw extruder was investigated for graphite-based negative electrode pastes for high-power applications. In the extrusion-based mixing process, the first kneading concentration is one of the key processing parameters for systematic optimization of relevant electrode paste properties like viscosity and particle size distribution. For different active materials at a constant electrode paste composition, a clear correlation of increasing kneading concentration with decreasing viscosity can be observed up to a certain reversal point, initiating a change in the trend and the rheological behavior, thus indicating a process limit. The fundamental effects causing this change and the associated impact on materials and battery performance were evaluated by applying further analytical methods and electrochemical characterization. It is revealed that the change in viscosity is associated with enhanced de-agglomeration of the carbon black additive and with partial particle grinding of the active material and thus a partial change in the interlayer distance of graphene layers and, correspondingly, the electrochemical behavior of the active material. Beyond this, correlations between processing parameters and product properties are presented. Furthermore, indicators are suggested with which monitoring of the machine parameters enables the detection of changes in the electrode paste characteristics. Full article

The single-crystal diamond (SCD), owing to its extreme physical and chemical properties, serves as an ideal substrate for quantum sensing and high-frequency devices. However, crystal anisotropy imposes significant challenges on fabricating high-quality micro-nano structures, directly impacting device performance. This work investigates the effects of femtosecond laser processing on the SCD under two distinct crystallographic orientations via single-pulse ablation. The results reveal that ablation craters along the <100> orientation exhibit an elliptical shape with the major axis parallel to the laser polarization, whereas those along the <110> orientation form near-circular craters with the major axis at a 45° angle to the polarization. The single-pulse ablation threshold of the SCD along <110> is 9.56 J/cm², representing a 7.8% decrease compared to 10.32 J/cm² for <100>. The graphitization threshold shows a more pronounced reduction, dropping from 4.79 J/cm² to 3.31 J/cm² (31% decrease), accompanied by enhanced sp² carbon order evidenced by the significantly intensified G-band in the Raman spectra. In addition, a phase transition layer of amorphous carbon at the nanoscale in the surface layer (thickness of ~40 nm) and a narrow lattice spacing of 0.36 nm are observed under TEM, corresponding to the interlayer (002) plane of graphite. These observations are attributed to the orientation-dependent energy deposition efficiency. Based on these findings, an optimized crystallographic orientation selection strategy for femtosecond laser processing is proposed to improve the quality of functional micro-nano structures in the SCD. Full article

In comparison to shallow coal seams, deep coal seams exhibit characteristics of high temperature, pressure, and in-situ stress, leading to significant differences in reservoir properties that constrain the effective development of deep coalbed methane (CBM). This study takes the Carboniferous deep 8# coal seam in the Yulin area of Ordos basin as the research subject. Based on the test results from core drilling wells, a comprehensive analysis of the characteristics and variation patterns of coal reservoir properties and a comparative analysis of the exploration and development potential of deep CBM are conducted, aiming to provide guidance for the development of deep CBM in the Ordos basin. The research results indicate that the coal seams are primarily composed of primary structure coal, with semi-bright to bright being the dominant macroscopic coal types. The maximum vitrinite reflectance (R_o,max) ranges between 1.99% and 2.24%, the organic is type III, and the high Vitrinite content provides a substantial material basis for the generation of CBM. Longitudinally, influenced by sedimentary environment and plant types, the lower part of the coal seam exhibits higher Vitrinite content and fixed carbon (FC_ad). The pore morphology is mainly characterized by wedge-shaped/parallel plate-shaped pores and open ventilation pores, with good connectivity, which is favorable for the storage and output of CBM. Micropores (<2 nm) have the highest volume proportion, showing an increasing trend with burial depth, and due to interlayer sliding and capillary condensation, the pore size (<2 nm) distribution follows an N shape. The full-scale pore heterogeneity (fractal dimension) gradually increases with increasing buried depth. Macroscopic fractures are mostly found in bright coal bands, while microscopic fractures are more developed in Vitrinite, showing a positive correlation between fracture density and Vitrinite content. The porosity and permeability conditions of reservoirs are comparable to the Daning–Jixian block, mostly constituting oversaturated gas reservoirs with a critical depth of 2400–2600 m and a high proportion of free gas, exhibiting promising development prospects, and the middle and upper coal seams are favorable intervals. In terms of resource conditions, preservation conditions, and reservoir alterability, the development potential of CBM from the Carboniferous deep 8# coal seam is comparable to the Linxing block but inferior to the Daning–Jixian block and Baijiahai uplift. Full article

To address lithium extraction from clay-type lithium ore from the Qaidam Basin, this study identified key controlling factors through particle fractionation, acid-leaching–roasting experiments, and mineral characterization. The results demonstrate that particle size optimization enriched the lithium to 87.65 ppm, where a 74% leaching rate was achieved with 65 ppm extraction, which established intermediate-sized samples as optimal. During acid leaching, adsorbed lithium ions with a phyllosilicate interlayer were released via the ion exchange process instead of mineral dissolution, as verified by the Li-O/S-O peak shifts in the FTIR spectra. The roasting induced hydroxyl elimination, carbonate decomposition, and silicate restructuring but triggered lithium encapsulation via mineral phase reorganization, which caused a sharp leaching rate decline. Effective lithium extraction requires integrated particle size screening, acid-leaching optimization, and roasting-induced phase encapsulation disruption. This study established theoretical foundations for clay-type lithium ore exploitation. Full article

Against the backdrop of global energy transition and strict environmental regulations, supercritical carbon dioxide (scCO₂) fracturing and oil displacement technologies have emerged as pivotal green approaches in shale gas exploitation, offering the dual advantages of zero water consumption and carbon sequestration. However, the inherent low viscosity of scCO₂ severely restricts its sand-carrying capacity, fracture propagation efficiency, and oil recovery rate, necessitating the urgent development of high-performance thickeners. The current research on scCO₂ thickeners faces a critical trade-off: traditional fluorinated polymers exhibit excellent philicity CO₂, but suffer from high costs and environmental hazards, while non-fluorinated systems often struggle to balance solubility and thickening performance. The development of new thickeners primarily involves two directions. On one hand, efforts focus on modifying non-fluorinated polymers, driven by environmental protection needs—traditional fluorinated thickeners may cause environmental pollution, and improving non-fluorinated polymers can maintain good thickening performance while reducing environmental impacts. On the other hand, there is a commitment to developing non-noble metal-catalyzed siloxane modification and synthesis processes, aiming to enhance the technical and economic feasibility of scCO₂ thickeners. Compared with noble metal catalysts like platinum, non-noble metal catalysts can reduce production costs, making the synthesis process more economically viable for large-scale industrial applications. These studies are crucial for promoting the practical application of scCO₂ technology in unconventional oil and gas development, including improving fracturing efficiency and oil displacement efficiency, and providing new technical support for the sustainable development of the energy industry. This study innovatively designed an amphiphilic modified amino silicone oil polymer (MA-co-MPEGA-AS) by combining maleic anhydride (MA), methoxy polyethylene glycol acrylate (MPEGA), and amino silicone oil (AS) through a molecular bridge strategy. The synthesis process involved three key steps: radical polymerization of MA and MPEGA, amidation with AS, and in situ network formation. Fourier transform infrared spectroscopy (FT-IR) confirmed the successful introduction of ether-based CO₂-philic groups. Rheological tests conducted under scCO₂ conditions demonstrated a 114-fold increase in viscosity for MA-co-MPEGA-AS. Mechanistic studies revealed that the ether oxygen atoms (Lewis base) in MPEGA formed dipole–quadrupole interactions with CO₂ (Lewis acid), enhancing solubility by 47%. Simultaneously, the self-assembly of siloxane chains into a three-dimensional network suppressed interlayer sliding in scCO₂ and maintained over 90% viscosity retention at 80 °C. This fluorine-free design eliminates the need for platinum-based catalysts and reduces production costs compared to fluorinated polymers. The hierarchical interactions (coordination bonds and hydrogen bonds) within the system provide a novel synthetic paradigm for scCO₂ thickeners. This research lays the foundation for green CO₂-based energy extraction technologies. Full article

Fused Filament Fabrication (FFF) enables the manufacturing of complex polymer components. However, surface finish and dimensional accuracy remain key limitations for their integration into functional assemblies. This study explores the potential of conventional turning as a post-processing strategy to improve the geometric and surface quality of PLA reinforced with carbon fiber (CF) parts produced by FFF. Machinability was evaluated through the analysis of cutting forces, thermal behavior, energy consumption, and surface integrity under varying cutting speeds, feed rates, and specimen slenderness. The results indicate that feed is the most influential parameter across all performance metrics, with lower values leading to improved dimensional accuracy and surface finish, achieving the most significant reductions of 63% in surface roughness (Sa) and 62% in cylindricity deviation. Nevertheless, the surface roughness is higher than that of metals, and deviations in geometry along the length of the specimen have been observed. A critical shear stress of 0.237 MPa has been identified as the limit for interlayer failure, defining the boundary conditions for viable cutting operation. The incorporation of CNC turning as a post-processing step reduced the total fabrication time by approximately 83% compared with high-resolution FFF, while maintaining dimensional accuracy and enhancing surface quality. These findings support the use of machining operations as a viable and efficient post-processing method for improving the functionality of polymer-based components produced by additive manufacturing. Full article

Three-dimensionally printed cement-based composites emerge as a research hotspot in the fields of construction engineering in recent years. Current research primarily focuses on the reinforcement mechanisms of individually incorporated fibres, while a significant gap remains in the synergistic effects of hybrid fibre systems. This study investigates the effects of mono-doping (0.2 wt.% and 0.4 wt.% by the mass of the cement) and hybrid-doping (0.1 wt.% + 0.1 wt.% by the mass of the cement) with 3 mm polypropylene, basalt, and carbon fibres on the fresh-state properties and mechanical behaviours. Through quantitative characterisation of the flowability and mechanical performance of short-fibre-reinforced 3D-printed cementitious composites (SFR3DPC), coupled with comprehensive testing including digital image correlation, X-ray diffraction, and scanning electron microscopy, several key findings are obtained. The experimental results indicate that the addition of excess fibres reduces fluidity, which affects the mechanical performance and make the anisotropy of the composites more pronounced. While the single addition of 0.2 wt.% CF shows the most significant improvement in flexural and compressive strengths, the hybrid combination of 0.1 wt.% CF and 0.1 wt.% BF shows the greatest increase in interlayer bond strength by 26.7%. The complementary effect of the hybrid fibres contributes to the damage mode of the composites from brittle fracture to quasi-brittle behaviour at the physical level. These findings offer valuable insights into optimising the mechanical performance and improving defects of 3D-printed cementitious composites with short fibres. Full article

In this study, a new fibre combination for an interlayer hybrid fibre-reinforced polymer laminate was investigated to achieve pseudo-ductile behaviour in tensile tests. The chosen high-strain fibre for this purpose was S-Glass, and the low-strain fibre was flax. These materials were chosen because of their relatively low environmental impact compared to carbon/carbon and carbon/glass hybrids. An analytical model was used to find an ideal combination of the two materials. With that model, the expected stress–strain relation could also be predicted analytically. The modelling was based on preliminary tensile tests of the two basic components investigated in this research: unidirectional laminates reinforced with either flax fibres or S-Glass fibres. Hybrid specimens were then designed, produced in a heat-assisted pressing process, and subjected to tensile tests. The strain measurement was performed using distributed fibre optic sensing. Ultimately, it was possible to obtain repeatable pseudo-ductile stress–strain behaviour with the chosen hybrid when the specimens were subjected to quasi-static uniaxial tension in the direction of the fibres. The intended damage-mode, consisting of a controlled delamination at the flax-fibre/glass-fibre interface after the flax fibres failed, followed by a load transfer to the glass fibre layers, was successfully achieved. The pseudo-ductile strain averaged 0.52% with a standard deviation of 0.09%, and the average load reserve after delamination was 145.5 MPa with a standard deviation of 48.5 MPa. The integrated fibre optic sensors allowed us to monitor and verify the damage process with increasing strain and load. Finally, the analytical model was compared to the measurements and was partially modified by neglecting the Weibull strength distribution of the high-strain material. Full article

We report the fabrication of CoFeP-Ni(OH)₂/nickel foam (NF) composite electrodes via a two-step strategy involving the hydrothermal synthesis of Ni(OH)₂ on nickel foam followed by the electrochemical deposition of CoFeP. The integration of the Ni(OH)₂ interlayer not only provides a structurally robust interface but also facilitates synergistic redox activity, thereby significantly boosting the pseudocapacitive behavior of the electrode. Comparative analysis with bare CoFeP/NF reveals that the presence of the Ni(OH)₂ layer contributes to enhanced charge transfer efficiency and an increased electroactive surface area. Among the samples prepared under varying deposition cycles, the optimized CoFeP-Ni(OH)₂/NF electrode exhibits a high areal capacitance of 4244 mF cm⁻² at 2 mA cm⁻². Furthermore, an asymmetric supercapacitor device assembled with CoFeP-Ni(OH)₂/NF as the positive electrode and activated carbon as the negative electrode delivers a maximum energy density of 0.19 mWh cm⁻² at a power density of 0.37 mW cm⁻² and excellent cycling stability, retaining 72% of its initial capacitance after 5000 cycles at a high current density of 8 mA cm⁻². Full article

Films of functionalised multiwalled carbon nanotubes (MWCNTs) were fabricated as interlayers (interfacial layers between the cathode and separator) in a lithium–sulfur battery (LSB). Phenylsulfonate functionalisation of commercial MWCNTs was achieved via diazotisation to attach lithium phenylsulfonate groups and was characterised by IR and XPS spectroscopies. SEM-EDX showed sulfur and oxygen colocations due to the sulfonate groups on the interlayer surface. However, CHNS elemental microstudies showed a low degree of functionalisation. Without an interlayer, the LSB produced stable cycling at a capacity of 600 mA h g⁻¹_sulfur at 0.05 C for 40 cycles. Using an unfunctionalised interlayer as a control gave a capacity of 1400 mA h g⁻¹_sulfur for the first cycle but rapidly decayed to the same 600 mA h g⁻¹_sulfur at the 40th cycle at 0.05 C, suggesting a high degree of polysulfide shuttling. Adding a lithium phenylsulfonated interlayer gave an initial capacity increase to 1100 mA h g⁻¹_sulfur that lowered to 800 mA h g⁻¹_sulfur at 0.05 C by the 40th cycle, showing an increase in charge storage (33%) relative to the other cells. This performance increase has been attributed to lessened polysulfide shuttling due to repulsion by the phenylsulfonate groups, increased conductivity at the separator-cathode interface and an increase in surface area. Full article

Titanium alloy/carbon fiber-reinforced polymer (TA1/CFRP) laminates, representing the latest fourth generation of fiber metal laminates (FMLs), is a kind of high-performance composite material. However, the fragility of the fiber/resin and metal/resin interface layers in these composites directly impacts their mechanical properties. To enhance these properties, this paper investigates the preparation process of multi-walled carbon nanotube (MWCNT)-reinforced ultra-thin TA1/CFRP laminates and explores the impact of MWCNT content on the interlayer properties of these ultra-thin TA1/CFRP laminates. Initially, the challenge of dispersing carbon nanotubes using ultrasonic dispersion devices and dispersants was addressed. Vacuum-curing pressure studies revealed minimal overflow at 0.8 bar vacuum. Subsequently, the impact of MWCNT content on interlayer properties was investigated. The results indicated a significant increase in interlayer shear strength and interlayer fracture toughness with MWCNT additions at 0.5 wt% and 0.75 wt%, whereas the interlayer properties decreased at 1.0 wt% MWCNT. Fracture morphology analysis revealed that MWCNT content exceeding 0.75 wt% led to agglomeration, resulting in resin cavity formation and stress concentration. Full article

This study addresses the efficiency and cost challenges of hydrogen evolution reaction (HER) catalysts in the context of carbon neutrality strategies by employing a synergistic approach that combines cation vacancy anchoring and transition metal doping on two-dimensional (2D) MXenes. Using an in situ LiF/HCl etching process, the aluminum layers in Ti₃AlC₂ were precisely removed, resulting in a few-layer Ti₃C₂T_x MXene with an increased interlayer spacing of 12.3 Å. Doping with the transition metals Fe, Co, Ni, and Cu demonstrated that Fe@Ti₃C₂ provided the optimal HER performance, characterized by an overpotential (η₁₀) of 81 mV at 10 mA cm⁻², a low Tafel slope of 33.03 mV dec⁻¹, and the lowest charge transfer resistance (R_ct = 5.6 Ω cm²). Mechanistic investigations revealed that Fe’s 3d⁶ electrons induce an upward shift in the d-band center of MXene, improving hydrogen adsorption free energy and reducing lattice distortion. This research lays a solid foundation for the design of non-precious metal catalysts using MXenes and highlights future avenues in bimetallic synergy and scalability. Full article

Lithium–sulfur batteries (LSBs), possessing excellent theoretical capacities, advanced theoretical energy densities, low cost, and nontoxicity, are one of the most promising energy storage battery systems. However, some issues, including poor conductivity of elemental S, the “shuttle effect” of high-order lithium polysulfides (LiPSs), and sluggish reaction kinetics, hinder the commercialization of LSBs. To solve these problems, various carbon-based aerogels with developed surface morphology, tunable pores, and electrical conductivity have been examined for immobilizing sulfur, mitigating its volume variation and enhancing its electrochemical kinetics. In this paper, an extensive generalization about the effective preparation methods of carbon-based aerogels comprising the combined method of carbonization with the gelation of precursors and drying processes (ambient pressure drying, freeze-drying, and supercritical drying) is proposed. And we summarize various carbon carbon-based aerogels, mainly including graphene aerogels (Gas) and carbon nanofiber (CNF) and carbon nanotube (CNT) aerogels as cathodes, separators, and interlayers in LSBs. In addition, the mechanism of action of carbon-based aerogels in LSBs is described. Finally, we conclude with an outlook section to provide some insights into the application of carbon-based aerogels in electrochemical energy storage devices. Based on the discussion and proposed recommendations, we provide more approaches on nanomaterials in high-performance liquid or state LSBs with high electrochemical performance in the future. Full article