•Novel hollow lattice configurations are proposed and fabricated by SLM process.•Their specific energy absorption is superior to many existed lattices.•The two lattice configurations exhibit ...different strain rate sensitivity.•The anisotropy of hollow octet-truss lattice is insensitive to geometric parameter.•The FE simulations are in excellent agreement with the experimental results.
Inspired by the natural hollow structures, periodic lattice structures composed of hollow struts and spheres were designed and fabricated by selective laser melting (SLM) process with 316L stainless steel. Two architecture configurations with Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC) symmetry were taken into consideration. Finite element (FE) simulations based on representative volume element (RVE) models and cell-assembly models were conducted to investigate the elastic response and large deformation behavior of the hollow lattice materials, respectively. Afterwards, compression experiments were carried out on an electronic universal machine and a drop hammer (DH) system to explore the quasi-static and dynamic mechanical response of the lattice specimens. The complete deformation evolutions of the lattice samples under different loading velocities were captured through high-resolution photography and inspected by the digital imaging correlation (DIC) analysis. Both the experimental research and numerical simulations demonstrated that the hollow beam cross-sections contributed to the stable crushing response of the proposed lattice structures under either quasi-static or dynamic compression. Accordingly, the post-yield behavior of the tested lattice structures was quite smooth without any fluctuations. Meanwhile, the specific strength and energy absorption of the hollow lattice structures were found to be superior to many existed lattice materials with solid struts, and comparable with the reported triply periodic minimal surface (TPMS) lattice structures. Finally, the effect of the geometric characteristic parameters on the specific mechanical properties of the lattice structures was discussed according to the supplemental analysis by numerical simulations.
This study explores the impact of the electroplating additive JGB the surface characteristics and peel strength of electrolytic copper foils used in printed circuit boards. Utilizing Scanning ...Electron Microscopy and Atomic Force Microscopy, we found that optimal JGB concentrations enhance the morphology and roughness of the copper foil roughening layer while maintaining high peel strength. The ideal concentration of 3 mg/L achieved an average roughness of 0.953 µm and a peel strength of 0.946 N/mm. JGB's effectiveness in inhibiting copper deposition was confirmed through cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. Density Functional Theory calculations and in situ infrared spectroscopy elucidated JGB's adsorption and coordination actions, which have a synergistic effect on its inhibitory performance. Further investigations with molecular dynamics simulations and finite element analysis demonstrated JGB's preferential adsorption in areas of high electric field intensity, effectively controlling the copper grain morphology in the roughening layer. This research highlights the potential of dye-type additives in improving copper foil roughening for printed circuit boards applications. Future research should explore the long-term stability and environmental impact of JGB in industrial applications, while investigating other dye-type additives may further optimize the roughening process to meet diverse printed circuit boards manufacturing needs.
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The low breakdown strength (BDS) of antiferroelectric ceramics, which become failure before undergoing electrical field induced antiferroelectric-ferroelectric phase transition, have seriously ...restricted the progress of pulsed power capacitors. The method of refining grain sizes via the incorporation of glass additive is supposed to be an outstanding strategy to boost the BDS. Herein, the (Pb0.91Ba0.015La0.05)(Zr0.6Sn0.4)O3 (PBLZS) antiferroelectric ceramics with the introduce of BaO-B2O3-Al2O3-SiO2 (BBAS) glass are designed and synthesized by a traditional solid-state reaction. When the glass content is 0.4 wt%, the recoverable energy storage density (Wrec) increases by 215 % from 2.0 J/cm3 to 6.3 J/cm3, together with a greatly enhanced BDS up to 390 kV/cm versus 270 kV/cm of pure ceramics. Meanwhile, the corresponding sintering temperature is remarkably decreased from 1300℃ to 1100℃. The superior charge and discharge performance can be obtained under the electrical field of 310 kV/cm, including a giant current density (1184.7 A/cm2), a high power density (184.2 MW/cm3), and an ultra-fast discharge period (40 ns). The prominent energy storage properties and low sintering temperature make it become a good candidate for fabricating multilayer pulsed power ceramic capacitors.
Interface issues with organic semiconductors on metal oxide challenge realizing a high‐performance anti‐ambipolar transistor (AAT) with stable operation. The motivation behind this research delves ...into the intricate landscape of AATs, elucidating their envisioned applications and constituent materials. Central to the authors, discourse is the pivotal role that fluoropolymers assume, acting as a bridge uniting n‐type metal oxide semiconductors (n‐oxide) with p‐type organic semiconductors (p‐organic), thereby unveiling a hitherto concealed facet of transistor advancement. Adopting a spatially separating layer (SSL) between p‐ and n‐type semiconductors of AAT is unconventional, but this p‐organic/SSL/n‐oxide junction (pSn) AAT exhibits stable operation also 215 days after fabrication and minimal hysteresis, which is 13.67 times smaller than a conventional p‐organic/n‐oxide junction (pn) AAT. The effect of SSL is closely studied through comparisons of the performance of single‐type transistors, trap density, and carrier behavior, which define the order of 1/f at low‐frequency noise analysis. In addition, the contribution of SSL is confirmed via the channel formation mechanism of AAT investigated through a two‐dimensional (2D) finite‐element simulation. The operation stability of pSn AAT is evaluated through combined stress tests, long‐term stability tests, and transient response tests. This research proposes SSL as a new design parameter to improve the AAT.
By adopting a spatially separating layer (SSL) between p‐ and n‐type semiconductors, this p‐organic/SSL/n‐oxide junction (pSn) antiambipolar transistor (AAT) exhibits stable operation and minimal hysteresis than a conventional p‐organic/n‐oxide junction AAT. This research proposes SSL as a new design parameter to improve the AAT.
Polymer-based dielectric materials with high power density, high energy density, and broad operating temperature range are critical to the development of cost-efficient and lightweight capacitors for ...modern high-power electrical systems. Here, NaNbO3 (NN)/polymer composites, especially two-dimensional (2D) NN platelets, were used to create new composite films for energy storage applications for the first time. The trilayered architecture composites comprised of two outer layers of 2D NN platelets dispersed in a poly(vinylidene fluoride) (PVDF) matrix to provide high dielectric constant and a middle layer of pristine PVDF to offer high breakdown strength. The breakdown strength and energy density of the trilayered architecture composite films were improved significantly via tailoring the contents of the 2D NN platelets. The composite films with an optimized filler content illustrate a high discharge energy density of 13.5Jcm−3 at 400MVm−1, far more than the best commercial biaxially- oriented polypropylenes. Moreover, the composite films show a superior power density of 2.68MWcm−3 and ultra-fast discharge speed of 0.127μs. Finite element simulation further revealed the breakdown strength and energy density of the composite films were much enhanced compared to the corresponding single layer composite films. Therefore, the new trilayered architecture composite films can be applied as an alternative promising high-performance electrostatic capacitor material.
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•The NaNbO3 two-dimensional platelets as fillers incorporation into the polymer matrix was proposed first.•Excellent discharge energy density of 13.5Jcm−3, superior power density of 2.68MWcm−3, and ultra-fast discharge speed of 0.127μs were obtained.•Finite element simulations reveal the significant implications of trilayered architecture on the dielectric and energy storage performances of polymer composites.
In the present work, we explore the influence of a surface-bulk coercivity gradient in Nd-Fe-B magnets produced by the Grain Boundary Diffusion Process (GBDP) on the overall coercivity. In our ...systematic and comprehensive study we diffused four different rare earth elements (Dy, Tb, Ce and Gd) in two different kinds of commercial Nd-Fe-B magnets, one very Dy-lean and one Dy-rich. By means of cutting the magnets into thin slices we obtain lateral coercivity profiles, from which diffusion constants are extracted. We find that in both magnets Tb diffuses significantly faster than Dy. The diffusion is generally slower in the Dy-lean magnet, which is attributed to the different chemistry and a smaller grain size. Ce diffuses slightly slower than Dy and the overall coercivity decrease is similar for Ce and Gd. With scanning electron microscopy it is revealed that, contrary to the magnets diffused with the heavy rare earths, the microstructure in the magnets treated with Ce show no (Nd,Ce)-Fe-B shells in the surface regions. While not of practical importance this allows some interesting insights into the metallurgy of (Nd,Ce)-Fe-B system. High-resolution scanning transmission electron microscopy coupled with electron probe microanalysis show the nano-scale distribution of Tb around the grain boundaries located in the bulk of the magnet. Finally, a simple model for the magnetization reversal in grain boundary diffusion processed gradient Nd-Fe-B magnets was developed and implemented into a FEM software. Our calculated demagnetization curves correspond very well for the Dy and Tb samples, but deviate significantly for Ce and Gd.
Coercivity changes in Nd-Fe-B permanent magnets after diffusion of several rare earth elements and resulting microstructures. Display omitted
Previous studies have shown that the kagome lattice has a remarkably high fracture toughness. This architecture is one of eight semi-regular tessellations, and this work aims to quantify the ...toughness of three other unexplored semi-regular lattices: the snub-trihexagonal, snub-square and elongated-triangular lattices. Their mode I fracture toughness was obtained with finite element simulations, using the boundary layer technique. These simulations showed that the fracture toughness KIc of a snub-trihexagonal lattice scales linearly with relative density ρ̄. In contrast, the fracture toughness of snub-square and elongated-triangular lattices scale as ρ̄1.5, an exponent different from other prismatic lattices reported in the literature. These numerical results were then compared with fracture toughness tests performed on Compact Tension specimens made from a ductile polymer and produced by additive manufacturing. The numerical and experimental results were in excellent agreement, indicating that our samples had a sufficiently large number of unit cells to accurately measure the fracture toughness. This result may be useful to guide the design of future experiments.
•We investigated the fracture toughness of three semi-regular lattices.•Two semi-regular lattices have a different behaviour from other prismatic lattices.•Fracture tests are in excellent agreement with finite element simulations.
Efficient thermal interface materials (TIMs) are urgently needed for heat dissipation of high-power density electronics. In this study, vinyl polydimethylsiloxane (PDMS) composites with the spatial ...alignment of carbon fibers (CFs) bridged by Al2O3 particles were fabricated by the flow field. The through-plane thermal conductivity (TPTC) of the composites with 24 vol% CFs and 47 vol% Al2O3 loading reached 38.0 W m−1 K−1. The oriented CFs bridged by Al2O3 acted as the efficient through-plane thermal conductive network. Furthermore, the effects of shape factor (b/a), spatial angle (γ) of CFs, and CF loading (Vf) on the TPTC were quantitatively discussed by steady-state finite element simulation combined with micro-computed tomography and machine learning. The positive contribution of the increased Vf to TPTC was in competition with the negative contribution of b/a and γ, both of which increased with the increase of Vf. Moreover, b/a exerted more negative effects than γ. The PDMS composites demonstrated excellent thermal stability (Td = 407.5 °C, CTE = −55.3 × 10−6 K−1), low compress modulus (1.71 MPa), and hardness (47 (Shore C)), which made them potential candidates for TIMs. This work offers a feasible method to prepare TIMs on large scale and refreshes the thermal conduction mechanism of TIMs by introducing the influencing factors (b/a and γ).
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•Efficient heat conduction paths were constructed by spatial alignment of CFs bridged by Al2O3.•The through-plane thermal conductivity of PDMS composites reached 38 W m−1 K−1.•The effect of spatial orientation angle of CFs on the thermal conduction property was revealed.•The PDMS composites with excellent comprehensive properties can be used as TIMs.
