JOM最新文献

Epoxy resins possess excellent mechanical properties but are limited by inherently low thermal conductivity, particularly in electronic packaging. To address this issue, this study employs non-equilibrium molecular dynamics methods, aiming to elucidate the regulatory mechanism of the molecular structure of curing agents on the thermal conduction and mechanical behavior of epoxy resin crosslinked networks. Firstly, three all-atomic models with identical crosslinking degrees were constructed: the highly polar and symmetrical 4,4'-diaminodiphenyl sulfone, the asymmetric 3,3'-diaminodiphenyl sulfone, and the flexible alicyclic isophorone diamine. The following key conclusions were drawn through simulation and analysis: a crosslinked network of the 4,4'-diaminodiphenyl sulfone curing system has the lowest free volume fraction and the highest proportion of low-frequency phonons. Compared to isophorone diamine, the 4,4'-diaminodiphenyl sulfone system's thermal conductivity increased by 28%, its glass transition temperature increased by 27 K, and its Young's modulus improved by 68%. The innovation of this study lies in investigating the regulatory mechanism of curing agent structure on the thermo-mechanical properties of epoxy resin through heat flux decomposition technology and phonon vibration mode analysis. It demonstrates that curing agents with high symmetry and strongly polar groups can synergistically improve epoxy resin thermal conductivity and mechanical properties by optimizing phonon transport and strengthening network constraints, providing guidance for enhancing epoxy performance.

This study innovatively integrates a star-shaped structure with a concave hexagonal structure to design a novel honeycomb core. Building on this, a new type of auxetic honeycomb sandwich panel (AHSP), treated with a polyurea coating, is conceived to enhance its acoustic-vibration performance. A numerical model of the new auxetic honeycomb sandwich panel was established in ABAQUS, and its accuracy was verified. Using the finite element (FE) method, its natural frequency, damping loss factor (DLF), vibration acceleration level (VAL), sound transmission loss (STL), and sound pressure level (SPL) were simulated and compared with those of conventional AHSPs without a polyurea coating. The research findings demonstrate that both the specific location of the polyurea coating and the geometric morphology of the honeycomb core can effectively promote vibration reduction and noise suppression in the sandwich panels. Among the configurations, the honeycomb sandwich structure with symmetrically configured PML-A faceplates exhibited significantly superior performance in vibration attenuation and sound isolation compared to asymmetric structures. When the polyurea layer thickness (PLT) reached 6 mm, the reduction in the vibration acceleration amplitude of the sandwich panel was most significant, and the average STL increased by 8.5%. Furthermore, the acoustic-vibration performance of the sandwich panel reached its optimal level when the geometric tilt angle of the honeycomb core was set to − 45°.

To meet the application requirements of memristor electrodes for nanofilms, specifically dense surface, stable interior, and high-temperature resistance, direct current (DC) magnetron sputtering technology was employed to deposit tungsten thin films on silicon substrates in this study. The impact of sputtering working pressure and power on microscopic morphology, deposition rate, phase structure, resistivity, and corrosion resistance of tungsten nanofilms was examined. The findings indicated that elevated pressure resulted in a reduction in grain size from 145.12  nm to 17.50  nm, along with grain boundary gap expansion; in contrast, a rise in sputtering power leads to larger grain size and denser structure. All films exhibit a mixed phase of α-W and β-W, where α-W is dominant under all conditions, with the only exception being at the high pressure of 2.0  Pa, under which α-W becomes non-dominant and accounts for only 34.26%. The crystalline quality deteriorates as the pressure increases but improves with increasing power. The phase structure remains stable within the range of room temperature (RT) to 400 °C. The resistivity is highly sensitive to pressure variation, showing a significant jump as pressure increases yet maintaining excellent high-temperature stability within 400 °C. Corrosion resistance declines with the increase of pressure, which is associated with increased porosity of the film.

Nanomaterials synthesis for energy storage often involves toxic chemicals, high temperatures, and non-renewable resources harming the environment. To address this, eco-friendly green electrodes must be developed for sustainable energy solutions. In this context, we have synthesized nickel oxide nanoparticles (NiO-NPs) using a dual-phytochemical approach, leveraging the bioactive compounds derived from Eclipta prostrata and Ocimum tenuiflorum extracts. The synthesized NiO-NPs exhibited homogeneous spherical morphology and revealed a crystalline nature with the approximate particle size of 18.3 nm. The combined plant extract-derived NiO-NPs exhibit a half-cell gravimetric capacitance of 525 F/g. The fabricated asymmetric supercapacitor device with the as-prepared NiO-NPs as cathode and commercial activated carbon as anode delivered a full-cell gravimetric capacitance of ~ 101.35 F/g, an energy density of 106 Wh/kg at 1 A/g and a power density of 10,440 W/kg at 10 A/g. This device operates effectively up to 1.45 V in an alkaline medium. The device also delivered a maximum columbic efficiency of 92.59% over 12,000 cycles in ambient condition. Hence, the synergistic effects on the phytochemicals improved the electrochemical properties, making the NiO-NPs suitable as an electrochemical energy electrode. Thus, this work highlights the potential of dual-phytochemical synthesis in advancing the development of sustainable and efficient electrode materials for next-generation supercapacitors.