Journal of Materials Science最新文献

Ag/TiO₂ nanocomposite films were successfully fabricated via a controllable magnetron sputtering strategy by regulating Ag sputtering power. Z-scan measurements under 515-nm laser excitation demonstrated that the composites significantly enhanced the nonlinear optical (NLO) performance of TiO₂. Among them, the 9W-Ag/TiO₂ sample exhibited the optimal performance, with its nonlinear absorption coefficient (β) and nonlinear refractive coefficient (n₂) reaching 3.41 and 3.84 times those of pure TiO₂, respectively. The core mechanism underlying the NLO performance enhancement lies in the synergy of multiple effects: Ag nanoparticles induce surface plasmon resonance (SPR) to amplify the localized light field; the work function difference between Ag and TiO₂ facilitates the directional transfer of excited carriers at the interface, and meanwhile, interfacial localized strain further modulates charge distribution and improves carrier separation efficiency, collectively optimizing the NLO response of TiO₂. This study provides a theoretical basis and experimental paradigm for the structural design and performance tuning of noble metal/transition metal oxide (TMO) composite NLO materials, while laying the foundation for their practical application in integrated optoelectronic devices such as optical limiters and ultrafast modulators.

The rational design of microcellular polyurethane elastomers (MPUEs) with dual-scale matrix–cellular synergy is realized through a novel high-pressure coupled chemical foaming (HPCCF) strategy. By employing pressurized impingement mixing, HPCCF synchronizes urea-network formation and bubble nucleation, thereby overcoming the intrinsic kinetic conflict in conventional foaming processes. Precise regulation of foaming pressure enables the construction of refined cellular architectures—achieving a 63% reduction in average cell size, a narrower size distribution, and a 12.5-fold increase in cell density. Multi-scale characterization techniques, including FOAMAT, SAXS, AFM, SEM, DIC, and in situ CT, demonstrate that HPCCF simultaneously enhances microphase separation and mechanical synergy. Quantitative analysis of deformation partitioning reveals that the cellular structure accounts for 86% (M-78) and 91% (M-210) of total deformation at 10% strain, decreasing to 80% and 82% at 50% strain, respectively. Such cooperative matrix–cellular load bearing promotes homogeneous strain distribution and enables over 90% elastic energy recovery across 100 compression cycles. This work pioneers a quantitative paradigm for dual-scale deformation management, establishing a generalizable framework for designing advanced vibration isolation materials with ultra-low energy dissipation and exceptional cyclic durability.

Flexible pressure sensors (FPSs) are gaining widespread attention for their potential applications in areas such as human kinematic studies and human–machine interfaces. The development of sustainable, low-cost, easy-to-manufacture piezoresistive composites that ensure reliability in FPS fabrication has remained a consistent focus. In this study, we present a facile approach for preparing hemp fabric-based piezoresistive composites to fabricate cost-effective FPSs. The hemp fabric is impregnated with acid-treated multi-walled carbon nanotubes (MWCNTs) through a simple dip-and-dry process. With an optimized MWCNT loading of 1.33 wt%, the MWCNT/hemp-based FPS operates within a pressure range of 0–300 kPa, displaying sensitivities of 0.2358, 0.02561, 0.00307, and 0.00054 kPa⁻¹ for the pressure intervals of 0–1 kPa, 1–6 kPa, 6–30 kPa, and 30–300 kPa, respectively. It also demonstrates a fast response time of 125 ms, a relaxation time of 42 ms, and impressive electromechanical durability exceeding 5300 cycles. The FPS shows significant promise for applications in human kinematics monitoring and gesture recognition. In addition to exhibiting high sensitivity in low-pressure conditions, the FPS is capable of responding to a broad pressure range of up to 300 kPa, attributed to the strong fibrous and porous structure of the hemp fabric.

For over a century, researchers have examined and utilized electroadhesion (EA), an electrically controlled adhesion mechanism, across a range of applications, including haptics, robotic gripping, active adhesion and attachment, and robotic crawling and climbing. Robotic applications leveraging electroadhesion (EA) provide the following benefits. The operation emphasizes energy efficiency with decreased maintenance demands, versatility across various surface conditions, an environmentally sustainable operational lifespan, robustness in extreme and airless environments, and the integration of sensory awareness functionalities. An understanding of advancements in materials engineering, predictive modeling, and functional mechanisms is essential for the scientific and technological development of forthcoming autonomous robotic systems. This publication thoroughly summarizes the chronology and development trajectory of EA technology from its inception to the latest breakthroughs, along with the complex interrelations among disciplines such as robotics, electrostatics, haptics, pick-and-place technologies, nanotechnology, and the Internet of Things.

This study focuses on typical nano-phase reinforced 2009Al matrix composites, aiming to clarify how reinforcement types affect their quench behavior. Results show significant differences in quench sensitivity between composites with different reinforcements, primarily attributed to reinforcement distribution and thermal mismatch with the matrix. For nano-sized SiC, its high surface energy leads to a tendency to segregate along grain boundaries in the composites. During quenching of SiC/2009Al composites, this distribution triggers significant Cu element segregation at grain boundaries. Additionally, the large difference in coefficients of thermal expansion (CTE) between SiC and the matrix results in a high density of thermal mismatch dislocations induced during quenching, which further reduces the stability of the supersaturated solid solution. Ultimately, this leads to significant performance degradation of thick-section components after quenching. In contrast, nano-sized Al₂O₃ has lower surface energy, allowing part of the reinforcements to easily disperse inside the grains. Consequently, the segregation of alloying elements along grain boundaries in Al₂O₃/2009Al composites during quenching is alleviated. Meanwhile, the smaller CTE difference between Al₂O₃ and the matrix reduces the density of thermal mismatch dislocations, improving the stability of the supersaturated solid solution. This thus substantially mitigates the performance degradation of thick-section components. These findings indicate that Al₂O₃ as reinforcement favors alleviating strength attenuation from quench sensitivity in large-sized Al matrix composite components.

In this study, the rolling process of Mg/Al composite with a thickness of 0.05 mm was innovatively developed, resulting in composite foils with a final thickness of 0.05 mm. Subsequently, the composite foils were annealed at 200, 250, 300, and 350 °C for 10 min, followed by the implementation of micro deep drawing (MDD) experiments. The experimental results demonstrate that the samples annealed at 300 °C display the optimal formability. During MDD process, this significantly mitigates defects such as wrinkles, cup mouth cracks, and earing, and attains the most uniform distribution of cup mouth thickness and wall thickness. Further investigation into the height difference between the two materials at the cup mouth, caused by the differing properties of Mg and Al, show that both excessively low and high annealing temperatures could induce defects during forming, thereby exacerbating the height difference between the Mg and Al layers. An analysis was conducted on the influence of annealing treatment on the mechanical properties and microstructure of Mg/Al composite foils. The results indicate that when annealed at 300 °C, the Mg/Al composite foils exhibit optimal ductility. The microstructure on the Mg layer is basically recrystallized. Annealing treatment can eliminate the local shear bands generated in the rolling process of the material, improve interface structure, disperse and weaken the texture, and enhance the deformation stability. In summary, annealing treatment at 300 °C for 10 min can effectively enhance the formability and forming quality of micro deep drawn cups.

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Ionic gating offers a highly reversible and precise means to modulate the thermoelectric (TE) properties of low-dimensional semiconductors. However, how the molecular structure of electrolytes affects the efficiency of such modulation remains poorly understood. In this work, we constructed organic electrochemical transistors (OECTs) based on single-walled carbon nanotubes (SWCNTs) to investigate thermoelectric modulation via ionic gating. Two imidazolium-based ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]), were employed to examine the influence of cation structure on electric double layer configuration and the resulting modulated effects on thermoelectric response of both the p- and n-type. Notably, the [BMIM][TFSI] system facilitated an earlier transition from p- to n-type conduction at relatively low gate voltages (VG), with the n-type region exhibiting strong TE responsiveness, indicating enhanced carrier tunability. Molecular dynamics (MD) simulations further revealed that variations in ionic liquid molecular structure influenced the electric double layer (EDL) strength, thereby affecting carrier transport characteristics. This study offers both experimental and theoretical insights into the structure–property relationship of ionic gating systems, and provides a viable strategy for designing high-performance, gate-tunable TE devices.

Traditional fabrication of superhydrophobic surfaces usually relies on fluorine modification, which causes environmental pollution. Existing processes struggle to achieve a balance between high hydrophobicity, low adhesion, and mechanical durability. Inspired by the unique groove arrays and tiny surface protrusions of rice leaves, we developed a fluorine-free superhydrophobic surface by combining SLM technology with CNT modification. Bionic microstructures were fabricated using SLM technology, followed by constructing multi-scale hierarchical morphologies with a CNT/polydimethylsiloxane composite coating. After 8 optimized spray cycles, the surface exhibited superior contact angle of 154.3° and low sliding angle of 8.3°, surpassing traditional fluorosilane-modified surfaces. We found that the CNT-modified surface demonstrated excellent droplet rebound characteristics with reduced contact time and enhanced rebound dynamics, attributable to its extremely low adhesion force of only 21.8 μN. CNT-modified specimens were evaluated for mechanical durability, chemical stability, and outdoor weather resistance, showing superior performance compared to fluorosilane-modified counterparts. Furthermore, the surface also exhibited remarkable self-cleaning performance. In fluid dynamic drag reduction tests, the CNT-modified surface achieved a significant drag reduction efficiency of 35.89%, much higher than the 31.25% observed on the fluorosilane-modified surfaces. This enhanced performance is attributed to the composite micro–nanostructures outstanding ability to stabilize the air film, thereby promoting interfacial slip. This study presents a promising fluorine-free strategy for designing robust superhydrophobic surfaces with combined anti-adhesion, self-cleaning, and drag reduction functions.

Graphical Abstract

Based on molecular dynamics simulation, the tensile mechanical properties and plastic deformation mechanisms of nanomaterials with twin boundaries located at different positions are studied in this work. The tensile simulation results show that twin boundaries located several layers of atoms underneath the surface are beneficial to the improvement of the material’s yield strength. This phenomenon is manifested in various metallic materials with different stacking fault energies and under various loading conditions. Further calculation of the reaction path of dislocation nucleation shows that twin boundaries beneath the free surface can inhibit the deformation mechanism of surface dislocation nucleation, and the initial plastic deformation occurs in the form of internal dislocation loop nucleation. The calculation results also indicate that the nucleation of dislocation loop inside the material requires higher activation energy and activation volume, which suppresses the initial plastic deformation in the material and thus improves the material’s yield strength. These findings will shed light on the understanding of mechanisms of twin boundaries induced the surface strengthening.