International Journal of Mechanical and Materials Engineering最新文献

Researchers in condensed matter physics are currently exploring new materials for specific use in various applications. The peculiar properties of quantum materials (QMs) have garnered significant attention because they have the potential to serve as building blocks for entirely new technologies in modern science and technology. QMs exhibit emerging phenomena governed by quantum confinement, strong electronic correlations, topology, and symmetry, making them exceptional materials. This review paper provides an overview of these unique properties, different types of QMs, and their applications with the latest case studies, presenting a prospective outlook on QMs in multiple domains.

This study reports a pulsed laser deposition-assisted synthesis of highly metallic titanium nitride (TiN) and a series of semiconducting titanium oxynitride (TiN_xO_y) compounds in thin film form with tunable plasmonic properties by carefully altering the nitrogen (N)-oxygen (O) ratio. The N/O ratio was controlled from 0.3 (highest oxygen doping of TiN) to ~ 1.0 (no oxygen doping of TiN) by growing the TiN films under nitrogen pressures of 50, 35, and 10 mTorr and high vacuum conditions of 2 × 10⁻⁶ Torr with no external gas introduced. The presence of nitrogen in the deposition chamber during the film growth affects the gas phase oxidation of TiN to TiN_xO_y by increasing the mean free path-dependent N and O inter-collisions per second by two to three orders of magnitudes. The evidence of increased oxidation of TiN to TiN_xO_y with an increase in nitrogen deposition pressure was obtained using X-ray photoelectron spectroscopy analysis. While the TiN samples deposited in high vacuum conditions had the highest reflectance, TiN_xO_y thin films were also found to possess high reflectance at low frequency with a well-defined edge around 20,000 cm⁻¹. Furthermore, the vacuum-deposited TiN samples showed a large negative dielectric constant of -330 and the largest frequency of zero-crossing at 25,000 cm⁻¹; the TiN_xO_y samples deposited in the presence of nitrogen ambient also showed promising plasmonic applications at the near-mid infrared range. A comparison of the dielectric constant and loss function data of this research with the literature values for noble metals seems to indicate that TiN and TiN_xO_y have the potential to replace gold and silver in the visible and near-infrared spectral regions.

The structural, electronic, elastic, mechanical, and thermodynamic properties of the ternary MgCu₄Sn intermetallic compound are investigated by means of first-principle calculations within density functional theory (DFT), in combination with the quasi-harmonic Debye model. Local density approximation (LDA) and generalized gradient approximation (GGA) are made for electronic exchange–correlation potential energy. The lattice constant is in good agreement with experimental data. We determine the elastic constant tensor of the compound from the calculated stress–strain relation in both approximations. Once the elastic constants are obtained, the bulk modulus B, shear modulus G, Young’s modulus E, Poisson’s ratio ν, anisotropy factor A, and the ratio B/G for MgCu₄Sn compound were deduced using Voigt-Reuss-Hill (VRH) approximation. The ground-state structure of MgCu₄Sn is predicted to be thermodynamically and mechanically stable. The obtained band structure and density of states reveal metallic character of MgCu₄Sn. The calculation results show also that this intermetallic crystal is a stiff, elastically anisotropic and ductile material. The Debye temperature is also determined from elastic constants. The temperature dependence of the constant volume heat capacity Cv, the entropy S, and the volumetric thermal expansion coefficient α in a quasi-harmonic approximation have been obtained from calculated energy E as a function of the volume V of a MgCu₄Sn crystal and discussed for the first report.

We investigated the NiO/PS/Si and the NiO/Si electrodes to highlight the effect of the PS porous silicon on the enhancement of the electrode performance. We elaborated the PS with the stain etching method, whereas the NiO nickel oxide was synthesized using sol–gel and deposited through the spin coating technique. We showed that PS porous silicon significantly increased the active surface area and improved the electrical and electrochemical properties. Thus, we obtained promising results for NiO/PS/Si. The effective series resistance and interfacial resistances were reduced from 1.8 Ω cm² and 42 Ω cm² to 0.05 Ω cm² and 0.29 Ω cm² from NiO/Si to NiO/PS/Si, respectively. The capacitance increased from 12.34 µF cm⁻² for NiO/Si to 9.64 mF cm⁻² for NiO/PS/Si. We found similar capacity values from the CV cyclic voltammetry curves and IS impedance spectroscopy Nyquist plots. We obtained equivalent effective series resistance values from the charge–discharge and Nyquist plots, confirming our results. The NiO/PS/Si electrode showed good stability with only a 3% loss for 5000 galvanostatic cycles. The energy efficiency is estimated from the charge–discharge curves to be 91%.

With the rising awareness about the impact of excessive urbanization on the environment, alternative and more eco-friendly materials such as natural fibre-reinforced composites (NFRCs), which have lower embodied energy, can be considered in modern application ranging from construction housing to urban infrastructures in order to promote the concept of sustainable development. One of the current challenges faced by material engineers is to develop NFRCs with optimized durability performance which correspond to high mechanical attributes during their service lifetime while possessing satisfactory degradability trait in the disposal phase. This proposed review study principally covered the state-of-the-art progress made in the development of sustainable composite material such as advanced and biodegradable NFRC. In the first section, the review covered key aspects of NFRC fabrication including fibres and matrix selection, property-enhancing treatment for fibres and influence of nanostructures in biodegradable composites. In the second phase of this review, the fibre-matrix interaction and their corresponding physical and mechanical performance were discussed. The typical failure modes observed in NFRCs were outlined and means to improve their facture toughness were proposed. Finally, the third section comprised the durability and degradation assessment of key components of the biodegradable NFRCs, namely the fibre reinforcement, matrix and interface sections. Additionally, the impact of disposing of similar composite materials in the environment was assessed, and present-day recycling techniques were discussed. Further research on the mechanical performance, durability traits and degradability aspects of NFRCs as enumerated in this study will unquestionably promote their use and integration into a wider range of engineering applications in our modern society.

Physicochemical features of nano-carbon (NC) particles significantly influence the microwave absorption performances of NC-containing materials. Here, we report the development of rare earth neodymium (Nd)-doped barium ferrite (BaM) composites with carbon nanotubes (CNTs) and other NC materials (onion-like carbon and graphene oxide) to enhance microwave absorption. Nd_0.15-BaM composites containing 8% CNTs demonstrate a minimum reflection loss of − 123.12 dB at 7.97 GHz, with an effective absorption bandwidth of 5.46 GHz in the 2–18 GHz range. CNTs improve impedance matching and synergize with Nd_0.15-BaM, boosting absorption properties. The absorption performance is further tuned by adjusting the type and content of NC materials. These results highlight the potential of these composites for applications in wave absorption.

Upconversion nanoparticles (UCNPs) have attracted considerable interest for the imaging of solid tumors because of their unique optical features. These applications can be expanded towards anticancer therapeutics by developing UCNP-graphene oxide (GO) composites. This strategy addresses low loading capacity and poor dispersibility of UCNPs in physiological media. These aspects have been covered in this article. We begin by discussing the synthesis methods and challenges associated with UCNPs, along with their surface modification strategies. Next, we describe the approaches of designing UCNP-GO composites and their applications in imaging, biosensing, and different therapeutic platforms.

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Surface-activated bonding (SAB) of a 3D-printed Ti-6Al-4V pillar structure (fabricated by selective laser melting) to pure bulk aluminum at room temperature has been investigated. Argon beam irradiation was used to remove surface contaminants and “activate” the surfaces prior to bonding. The surface chemistry of the Ti-6Al-4V surface was analyzed using Electron Spectroscopy for Chemical Analysis (ESCA) to make sure any oxides had been removed by the irradiation procedure. The two materials were successfully bonded via SAB using special bonding apparatus, and scanning transmission electron microscopy (STEM) observation revealed a flat well-bonded interface with no obvious porosity. Furthermore, no thick reaction layer that could compromise the strength of the bond was evident. An oxide layer approximately 2 nm in thickness was observed at the interface by high-resolution TEM, but this is not considered sufficient to have a detrimental effect on bond integrity. The results of the investigation show that 3D-printed materials and structures can be successfully joined to aluminum by SAB techniques.

High-velocity impact response of honeycomb sandwich structures (HSS) with Al/Al₂O₃ and Al/B₄C functionally graded plasma-sprayed (FGPS) faceplates are investigated in present work. FGPS structures improve the specific material properties and make the structure distinct from the substrate material. The metal and ceramic content was varied across the thickness of the FGPS coating in the present work. The HSS having honeycomb core sandwiched between two Al/Al₂O₃ FGPS faceplates were manufactured initially. Further, HSS having honeycomb core sandwiched between two Al/B₄C FGPS faceplates were manufactured. Such HSS are repeatedly impacted with a spherical projectile using a single-stage gas gun at a constant impact energy of 260 J, and the results are quantified and compared. The central deflection and dent diameter of FGPS plates as well as HSS were determined, and they increased with the number of impacts. The HSS’s energy absorption was dissipated by top faceplate indentation and core compression. The incorporation of a core prevented FGPS coating delamination and top faceplate penetration. The Al/Al₂O₃ and Al/B₄C FGPS faceplates had dent diameters that were 14.30% and 18.70% smaller than the non-coated Al 6061-T6 faceplate, respectively, which proves the enhancement of high-velocity impact resistance through FGPS coating. The central deflection and dent diameter of the Al/B₄C FGPS HSS are 6.04% and 3% lesser than the Al/Al₂O₃ FGPS HSS, respectively. The energy absorption of the Al/B₄C FGPS HSS is better than that of the Al/Al₂O₃ FGPS HSS. As a result, the present research enhances the knowledge on the impact energy absorption of two distinct FGPS coated plates and HSS, which is highly useful in aerospace and defence applications.

Target detection of defence technologies is being rapidly upgraded with modern surveillance technologies. The latest techniques of surveillance are already being implemented for defence applications. Self-protection and hiding from opposing forces are the key principles for the protection of special team in defence. Camouflage textiles aim to create confusing objects for target detection of military personnel. These textiles are applied for military protection such as clothing, weapons, vehicles and location hiding nets/tents. The urgent need for camouflage textiles has been formulated with a technical solution and implementation of the right camouflage materials for concealment of defence target signature against dry leaves, green leaves and tree bark-woodland combat background; water-marine combat background; sand-desertland combat background; stone-stoneland combat background; snow-snowland combat background; sky combat background; ice-iceland combat background; and concrete-concreteland combat background (DGTWSICB) in ultraviolet–visible-infrared (UV–Vis-IR) spectrums. This hypothesis of optical and surveillance engineering, digital imaging and hyperspectral imaging has been coalesced for the advancement of UV–Vis-IR-DGTWSICB camouflage textile technology. The principle of camouflage engineering has been approached by broader spectrum probes in UV–Vis-IR rather than Vis ranges only. Furthermore, camouflage materials, camouflage weapon designs, and formulations of camouflage textiles have been proposed for multidimensional CBs-DGTWSICB. The electromagnetic spectrum, reflection, electron energy, photonic signal and imaging mechanism in UV–Vis-IR have been presented for optical engineering of concealment, detection, recognition and identification of target signature against DGTWSICB. The spectrum relationship of camouflage materials and DGTWSICB materials has been illustrated and compared in UV–Vis-IR spectrums. Camouflage material design, method design and spectral design; textile colorants and technologies; adaptive camouflage; techniques for camouflage textile assessment for digital camera and hyperspectral camera imaging; image processing techniques; and a hierarchical model have been demonstrated for augmentation of camouflage textiles in UV–Vis-IR illumination. Therefore, the anticipated design of camouflage textiles may enhance high-performance innovation for modern surveillance of military protection related to digital camera, hyperspectral camera and radar. This hypothesis includes advanced guidelines for the advanced design of camouflage textiles for multidimensional CBs-DGTWSICB. The challenges, limitations, innovation and defence applications of camouflage engineering for multidimensional combat backgrounds have been coalesced for concealment, detection, recognition and identification of defence target signature.