Materials, Volume 17, Issue 10 (May-2 2024) – 284 articles

Magnesium matrix composites are essential lightweight metal matrix composites, following aluminum matrix composites, with outstanding application prospects in automotive, aerospace lightweight and biomedical materials because of their high specific strength, low density and specific stiffness, good casting performance and rich resources. However, the inherent low plasticity and poor fatigue resistance of magnesium hamper its further application to a certain extent. Many researchers have tried many strengthening methods to improve the properties of magnesium alloys, while the relationship between wear resistance and plasticity still needs to be further improved. The nanoparticles added exhibit a good strengthening effect, especially the ceramic nanoparticles. Nanoparticle-reinforced magnesium matrix composites not only exhibit a high impact toughness, but also maintain the high strength and wear resistance of ceramic materials, effectively balancing the restriction between the strength and toughness. Therefore, this work aims to provide a review of the state of the art of research on the matrix, reinforcement, design, properties and potential applications of nano-reinforced phase-reinforced magnesium matrix composites (especially ceramic nanoparticle-reinforced ones). The conventional and potential matrices for the fabrication of magnesium matrix composites are introduced. The classification and influence of ceramic reinforcements are assessed, and the factors influencing interface bonding strength between reinforcements and matrix, regulation and design, performance and application are analyzed. Finally, the scope of future research in this field is discussed. Full article

In recent years, asphalt pavement has been subjected to varied environmental conditions during its service life, conditions that predispose it to deformation and cracking. To enhance the performance of asphalt pavement, rock asphalt has been selected as a modifier due to its good compatibility with virgin asphalt binder and its ability to improve the fatigue cracking resistance of asphalt mixtures. Although scholars have conducted some studies on rock asphalt mixtures, research on the fatigue and self-healing performance of these mixtures under conditions such as ultraviolet (UV) aging and freeze–thaw remains limited. This paper presents findings from a study that employs a combined fatigue-healing test to assess the impact of such complex environmental factors on the fatigue and self-healing properties of fine aggregate matrix (FAM) mixtures containing three types of rock asphalts, i.e., Buton, Qingchuan (QC), and Uintaite Modifier (UM). The analysis of fatigue-healing test results, grounded in viscoelastic continuum damage (VECD) theory, indicates that rock asphalt can extend the fatigue life of FAM mixtures, albeit with a concomitant decrease in their self-healing capabilities. The study further reveals that UV aging, freeze–thaw, and UV aging–freeze–thaw conditions all led to a diminution in the fatigue and self-healing properties of FAM mixtures. However, FAM mixtures containing rock asphalt demonstrated greater resilience against these reductions. Atomic force microscope (AFM) results indicate that UV aging reduced the number of bee-structures and enlarged their area, whereas the incorporation of rock asphalt enhanced the uniformity of these structures’ distribution, thereby improving the fatigue cracking resistance of FAM mixtures. Fourier transform infrared spectroscopy (FTIR) analysis reveals that while UV aging increased the carbonyl and sulfoxide indices within the asphalt binder, rock asphalt is effective in mitigating this effect to a certain degree, thereby enhancing the aging resistance of FAM mixtures. Full article

Cutlery and flatware designs are an everchanging phenomenon of the manufacturing industry. Worldwide hospitality businesses demand perpetual evolution in terms of aesthetics, designs, patterns, colours, and materials due to customers’ demands, modernisation, and fierce competition. To thrive in this competitive market, modern fabrication techniques must be flexible, adoptive, fast, and cost effective. For decades, static designs and trademark patterns were achieved through moulds, limiting production to a single cutlery type per mould. However, with the advent of laser engraving and design systems, the whole business of cutlery production has been revolutionised. This study explores the possibility of creating diverse designs for stainless steel 304 flatware sets without changing the entire production process. The research analyses three key laser process parameters, power, scanning speed, and number of passes, and their impacts on the resulting geometry, depth of cut, surface roughness, and material removed. These parameters are comprehensively studied and analysed for steel and zirconia ceramic. The study details the effects of power, scanning speed, number of passages, and fluence on engraved geometry. Fluence (power*number of passages/scanning speed) positively influences outputs and presents a positive trend. Medium power settings and higher scanning speeds with the maximum number of passages produce high-quality, low-roughness optimised cavities with the ideal geometric accuracy for both materials. Full article

A series of freeze–thaw cycling tests, as well as cyclic loading and unloading tests, have been conducted on nodular sandstones to investigate the effect of fatigue loading and freeze–thaw cycling on the damage evolution of fractured sandstones based on damage mechanics theory, the microstructure and sandstone pore fractal theory. The results show that the number of freeze–thaw cycles, the cyclic loading level, the pore distribution and the complex program are important factors affecting the damage evolution of rocks. As the number of freeze–thaw cycles rises, the peak strength, modulus of elasticity, modulus of deformation and damping ratio of the sandstone all declined. Additionally, the modulus of elasticity and deformation increase nonlinearly as the cyclic load level rises. With the rate of increase decreasing, while the dissipation energy due to hysteresis increases gradually and at an increasing rate, and the damping ratio as a whole shows a gradual decrease, with a tendency to increase at a later stage. The NRM (Nuclear Magnetic Resonance) demonstrated that the total porosity and micro-pores of the sandstone increased linearly with the number of freeze–thaw cycles and that the micro-porosity was more sensitive to freeze–thaw, gradually shifting towards meso-pores and macro-pores; simultaneously, the SEM (Scanning Electron Microscope) indicated that the more freeze–thaw cycles there are, the more micro-fractures and holes grow and penetrate each other and the more loose the structure is, with an overall nest-like appearance. To explore the mechanical behavior and mechanism of cracked rock in high-altitude and alpine areas, a damage model under the coupling of freeze–thaw-fatigue loading was established based on the loading and unloading response ratio theory and strain equivalence principle. Full article

Chromium- and cobalt-based alloys, as well as chrome–nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel–chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings. Full article

The tack of prepreg is a key factor affecting the automatic tape laying process. During the manufacturing process of large composite parts, prepreg material may be stored at room temperature for several days, resulting in a decrease in its tack. In this study, a new tack test tool was designed, and the decay rate of prepreg tack at different temperatures was tested. We proposed a prepreg tack decay model, which assumes that the main factor in tack decay is the reduction in resin chain activity during storage. The maximum deviation between the model calculation results and the experimental results of the tack decay rate is 9.7%. This study also proposed a new statistical unit for prepreg tack, which can establish the relationship between the tack of prepreg and its remaining storage time and reduce prepreg management costs. Full article

Co-condensation of mixed SiGe nanoclusters and impingement of SiGe nanoclusters on a Si substrate were applied using molecular dynamics (MD) simulation in this study to mimic the fast epitaxial growth of SiGe/Si heterostructures under mesoplasma chemical vapor deposition (CVD) conditions. The condensation dynamics and properties of the SiGe nanoclusters during the simulations were investigated first, and then the impingement of transient SiGe nanoclusters on both Si smooth and trench substrate surfaces under varying conditions was studied theoretically. The results show that the mixed nanoclusters as precursors demonstrate potential for enhancing epitaxial SiGe film growth at a high growth rate, owing to their loosely bound atomic structures and high mobility on the substrate surface. By varying cluster sizes and substrate temperatures, this study also reveals that smaller clusters and higher substrate temperatures contribute to faster structural ordering and smoother surface morphologies. Furthermore, the formed layers display a consistent SiGe composition, closely aligning with nominal values, and the cluster-assisted deposition method achieves the epitaxial bridging of heterostructures during cluster impingement, highlighting its additional distinctive characteristics. The implications of this work make it clear that the mechanism of fast alloyed epitaxial film growth by cluster-assisted mesoplasma CVD is critical for extending it as a versatile platform for synthesizing various epitaxial films. Full article

Advances in electronics and medical diagnostics have made organic dyes extremely popular as key functional materials. From a practical viewpoint, it is necessary to assess the spectroscopic and physicochemical properties of newly designed dyes. In this context, the condensation of 1,3-dimethylbarbituric acid with electron-rich alkylaminobenzaldehyde derivatives has been described, resulting in a series of merocyanine-type dyes. These dyes exhibit intense blue-light absorption but weak fluorescence. An electron-donating alkylamino group at position C4 is responsible for the solvatochromic behavior of the dyes since the lone electron pair of the nitrogen atom is variably delocalized toward the barbituric ring, which exhibits electron-withdrawing properties. This was elucidated, taking into account the different geometry of the amino group. The intramolecular charge transfer in the molecules is responsible for the relatively high redshift in absorption and fluorescence spectra. Additionally, an increase in solvent polarity moves the absorption and fluorescence to lower energy regions. The observed solvatochromism is discussed in terms of the four-parameter Catalán solvent polarity scale. The differences in the behavior of the dyes were quantified with the aid of time-dependent density functional theory calculations. The obtained results made it possible to find regularities linking the basic spectroscopic properties of the compounds with their chemical structure. This is important in the targeted search for new, practically important dyes. Full article

The heat treatment of aluminum alloys is very important in industries where low weight in combination with high wear resistance, good strength, and hardness are important. However, depending on their chemical composition, aluminum alloys are subjected to different mechanical and thermal treatments to achieve the most favorable properties. In this study, an Al-Zn-Mg alloy was heat-treated including solution annealing at 490 °C for 1 h with subsequent artificial aging at 130, 160, and 190 °C for 1, 5, and 9 h. The hardness (HV1) and abrasive wear resistance with three different abrasive grain sizes were measured for all samples. The highest hardness was measured for the samples artificially aged at 130 °C/5 h, 227 HV1, while the lowest hardness was measured for the samples aged at 190 °C/9 h. The highest and the lowest wear resistance was also observed for the same state, i.e., artificially aged at 130 °C/5 h and 190 °C/9 h, respectively. The critical abrasive grain size was detected for some samples, where a decrease in wear rate was observed with an increase in the abrasive grain size from the medium value to the largest. The Response Surface Methodology (RSM) was applied to demonstrate the influence of the input parameters on the material wear rate. Full article

Garnet-type materials consisting of Y₃Al_5-2x(Mg,Ge)_xO₁₂ (x = 0, 1, 2), combined with Eu³⁺ or Ce³⁺ activator ions, were prepared by a solid-state method to determine the structural and optical correlations. The structure of Y₃Al_5-2x(Mg,Ge)_xO₁₂ (x = 1, 2) was determined to be a cubic unit cell (Ia-3d), which contains an 8-coordinated Y³⁺ site with octahedral (Mg,Al)O₆ and tetrahedral (Al,Ge)O₄ polyhedra, using synchrotron powder X-ray diffraction. When Eu³⁺ or Ce³⁺ ions were substituted for the Y³⁺ site in the Y₃Al_5-2x(Mg,Ge)_xO₁₂ host lattices, the emission spectra showed a decrease in the magnetic dipole f-f Eu³⁺ transition and a redshift of the d-f Ce³⁺ transition, related to centrosymmetry and crystal field splitting, respectively. These changes were monitored according to the increase in Mg²⁺ and Ge⁴⁺ contents. The dodecahedral and octahedral edge sharing was identified as a key distortion factor for the structure-correlated luminescence in the Eu³⁺/Ce³⁺-doped Y₃Al_5-2x(Mg,Ge)_xO₁₂ garnet phosphors. Full article

In recent years, tubular nanostructures have been related to immense advances in various fields of science and technology. Considerable research efforts have been centred on the theoretical prediction and manufacturing of non-carbon nanotubes (NTs), which meet modern requirements for the development of novel devices and systems. In this context, diatomic inorganic nanotubes formed by atoms of elements from the 13th group of the periodic table (B, Al, Ga, In, Tl) and nitrogen (N) have received much research attention. In this study, the elastic properties of single-walled boron nitride, aluminium nitride, gallium nitride, indium nitride, and thallium nitride nanotubes were assessed numerically using the nanoscale continuum modelling approach (also called molecular structural mechanics). The elastic properties (rigidities, surface Young’s and shear moduli, and Poisson’s ratio) of nitride nanotubes are discussed with respect to the bond length of the corresponding diatomic hexagonal lattice. The results obtained contribute to a better understanding of the mechanical response of nitride compound-based nanotubes, covering a broad range, from the well-studied boron nitride NTs to the hypothetical thallium nitride NTs. Full article

In the finite element analysis of asphalt concrete (AC), it is nowadays common to incorporate the information from the underlying scales to study the overall response of this material. Heterogeneity observed at the asphalt mixture scale is analyzed in this paper. Reliable finite element analysis (FEA) of asphalt concrete comprises a set of complex issues. The two main aspects of the asphalt concrete FEA discussed in this study are: (1) digital reconstruction of the asphalt pavement microstructure using processing of the high-quality images; and (2) FEA of the asphalt concrete idealized samples accounting for the viscoelastic material model. Reconstruction of the asphalt concrete microstructure is performed using a sequence of image processing operations (binarization, removing holes, filtering, segmentation and boundaries detection). Geometry of the inclusions (aggregate) are additionally simplified in a controlled mode to reduce the numerical cost of the analysis. As is demonstrated in the study, the introduced geometry simplifications are justified. Computational cost reduction exceeds of several orders of magnitude additional modeling error occurring due to the applied simplification technique. Viscoelastic finite element analysis of the AC identified microstructure is performed using the Burgers material model. The analysis algorithm is briefly described with a particular focus on the computational efficiency aspects. In order to illustrate the proposed approach, a set of 2D problems is solved. Numerical results confirm both the effectiveness of the self-developed code and the applicability of the Burgers model to the analyzed class of AC analysis problems. Further research directions are also described to highlight the potential benefits of the developed approach to numerical modeling of asphalt concrete. Full article

This work is focused on a novel, promising low temperature phase change material (PCM), based on the eutectic Glauber’s salt composition. To allow phase transition within the refrigeration range of temperatures of +5 °C to +12 °C, combined with a high repeatability of melting–freezing processes, and minimized subcooling, the application of three variants of sodium carboxymethyl cellulose (Na-CMC) with distinct molecular weights (700,000, 250,000, and 90,000) is considered. The primary objective is to optimize the stabilization of this eutectic PCM formulation, while maintaining the desired enthalpy level. Preparation methods are refined to ensure repeatability in mixing components, thereby optimizing performance and stability. Additionally, the influence of Na-CMC molecular weight on stabilization is examined through differential scanning calorimetry (DSC), T-history, and rheology tests. The PCM formulation of interest builds upon prior research in which borax, ammonium chloride, and potassium chloride were used as additives to sodium sulfate decahydrate (Glauber’s salt), prioritizing environmentally responsible materials. The results reveal that CMC with molecular weights of 250 kg/mol and 90 kg/mol effectively stabilize the PCM without phase separation issues, slowing crystallization kinetics. Conversely, CMC of 700 kg/mol proved ineffective due to the disruption of gel formation at its low gel point, hindering higher concentrations. Calculations of ionic concentration indicate higher Na ion content in PCM stabilized with 90 kg/mol CMC, suggesting increased ionic interactions and gel strength. A tradeoff is discovered between the faster crystallization in lower molecular weight CMC and the higher concentration required, which increases the amount of inert material that does not participate in the phase transition. After thermal cycling, the best formulation had a latent heat of 130 J/g with no supercooling, demonstrating excellent performance. This work advances PCM’s reliability as a thermal energy storage solution for diverse applications and highlights the complex relationship between Na-CMC molecular weight and PCM stabilization. Full article

Carbon fibre-reinforced plastic (CFRP) composites, prized for their exceptional properties, often encounter surface quality issues during slotting due to their inherent heterogeneity. This paper tackles CFRP slotting challenges by employing multi-tooth mills in experiments with various fibre orientations and tool feed rates. In-plane scratching tests are performed under linearly varying loads; then, slotting experiments are conducted at different parameters. The scratching test results indicate that the fibre orientation and cutting angles have significant influences on forces and fracture process. The slotting experiments demonstrate that cutting forces and surface roughness S_a of the bottom slotting surface are notably affected by the fibre orientation, with disparities between up-milling and down-milling sides. Reorganising S_a data by local fibre cutting angle θ highlights consistent S_a variations between up-milling and down-milling sides for 0° ≤ θ ≤ 90°, with lower S_a on the up-milling side. However, for 90° < θ ≤ 150°, S_a variations diverge, with lower S_a on the down-milling side. Unexpectedly, S_a on the down-milling side decreases with increasing θ in this range. Additionally, the tool feed rate exerts a more pronounced influence on S_a on the up-milling side. Full article

The significant impact of Nb on ferrite transformation, both in terms of solute drag effect (SDE) and interphase precipitation, was investigated quantitatively. Ferrite transformation kinetics were characterized using thermal expansion experiments and theoretical calculations. The microstructures were characterized using high−temperature confocal laser scanning microscopy (CLSM), a field−emission scanning electron microscope (FESEM), and a transmission electron microscope (TEM). Under a higher driving force, interphase precipitations were observed in the sample with a higher Nb content. A three−dimensional (3D) reconstruction method was used to convert the two−dimensional (2D) image of interphase precipitation into a three−dimensional model for a more typical view. The SDE and interphase precipitation had opposite effects on the kinetics of ferrite transformation. A lower Nb content showed a strong contribution to the SDE, which delayed ferrite transformation. A higher concentration of Nb was expected to enhance the SDE, but the inhibition effect was eliminated by the interphase precipitation of NbC during interfacial migration. Both the experimental results and theoretical calculations confirmed this phenomenon. Full article

This comprehensive review delves into the world of hyaluronic acid (HA) hydrogels, exploring their creation, characteristics, research methodologies, and uses. HA hydrogels stand out among natural polysaccharides due to their distinct features. Their exceptional biocompatibility makes them a top choice for diverse biomedical purposes, with a great ability to coexist harmoniously with living cells and tissues. Furthermore, their biodegradability permits their gradual breakdown by bodily enzymes, enabling the creation of temporary frameworks for tissue engineering endeavors. Additionally, since HA is a vital component of the extracellular matrix (ECM) in numerous tissues, HA hydrogels can replicate the ECM’s structure and functions. This mimicry is pivotal in tissue engineering applications by providing an ideal setting for cellular growth and maturation. Various cross-linking techniques like chemical, physical, enzymatic, and hybrid methods impact the mechanical strength, swelling capacity, and degradation speed of the hydrogels. Assessment tools such as rheological analysis, electron microscopy, spectroscopy, swelling tests, and degradation studies are employed to examine their attributes. HA-based hydrogels feature prominently in tissue engineering, drug distribution, wound recovery, ophthalmology, and cartilage mending. Crafting HA hydrogels enables the production of biomaterials with sought-after qualities, offering avenues for advancements in the realm of biomedicine. Full article

In this research, we developed boron-rich nanoparticles that can be used for boron neutron capture therapy as potential carriers for boron delivery to cancerous tissues. Functionalized carbonated boron nitride nanostructures (CBNs) were successfully synthesized in self-propagating combustion waves in mixtures of high-nitrogen explosives and boron compounds. The products’ composition, morphology, and structural features were investigated using Fourier transform infrared spectroscopy, powder X-ray diffraction, low-temperature nitrogen sorption analysis, thermogravimetric analysis, high-resolution scanning electron microscopy, and high-resolution transmission electron microscopy. The extreme conditions prevailing in combustion waves favor the formation of nanosized CBN hollow grains with highly disordered structures that are properly functionalized on the surface and inside the particles. Therefore, they are characterized by high porosity and good dispersibility in water, which are necessary for medical applications. During biological tests, a concentration-dependent effect of the obtained boron nitride preparations on the viability of normal and neoplastic cells was demonstrated. Moreover, the assessment of the degree of binding of fluorescently labeled nanoparticles to selected cells confirmed the relationships between the cell types and the concentration of the preparation at different incubation time points. Full article

In the realm of modern architecture, the demand for materials that combine strength, durability, and aesthetic flexibility is ever-growing. Addressing this need, this paper presents a study on the innovative use of aluminum extrudates in construction. Focusing on the AA6005 alloy, which is known for its excellent balance of strength, corrosion resistance, and weldability, this research delves into the development of an extrusion process that yields thin-walled, lightweight, yet high-strength structural components. Using FEM simulations, a new extrudate of the AA6005A was developed. It is compatible with standard façade systems, with high-strength properties and a weight reduced by 20% compared to that of conventional extrudates made of the AA6063 alloy. Using CAD engineering and FEM simulations of aluminum extrusion process, an innovative die was designed for the extrusion process, ensuring uniform flow of metal from the bearing and minimizing the elastic deflection of the die. This resulted in an increase in the extrusion velocity of thin-walled extrudate from AA6005A by 24% compared to conventional profiles extruded from AA6063. As part of the research, a trial test was carried out in production conditions and the quality of the extrudates was tested by 3D optical scanning, mechanical and structural properties tests, and microstructure observation. Full article

Reversible optical regulation has potential applications in optical anti-counterfeiting, storage, and catalysis. Compared to common power materials, the reverse opal structure has a larger specific surface area and an increased contact area for optical regulation, which is expected to achieve higher regulation rates. However, it is difficult to achieve reversible and repeatable regulation of the luminescent properties of photonic crystals, especially with the current research on the structural collapse of photonic crystals. In this work, WO₃: Yb³⁺, Er³⁺ inverse photonic crystals were prepared by the template approach, and reversible multi-mode optical modification was investigated. Upon heat treatment in a reducing atmosphere or air, the color of the photonic crystals can reversibly change from light yellow to dark green, accompanied by changes in absorption and upconversion of luminescence intensity. The stability and fatigue resistance of this reversible optical modification ability were explored through cyclic experiments, providing potential practical applications for photocatalysis, optical information storage, and electrochromism. Full article

The frontiers of antibacterial materials in the biomedical field are constantly evolving since infectious diseases are a continuous threat to human health. In this work, waste-wool-derived keratin electrospun nanofibers were blended with copper by an optimized impregnation procedure to fabricate antibacterial membranes with intrinsic biological activity, excellent degradability and good cytocompatibility. The keratin/copper complex electrospun nanofibers were multi-analytically characterized and the main differences in their physical–chemical features were related to the crosslinking effect caused by Cu²⁺. Indeed, copper ions modified the thermal profiles, improving the thermal stability (evaluated by differential scanning calorimetry and thermogravimetry), and changed the infrared vibrational features (determined by infrared spectroscopy) and the chemical composition (studied by an X-ray energy-dispersive spectroscopy probe and optical emission spectrometry). The copper impregnation process also affected the morphology, leading to partial nanofiber swelling, as evidenced by scanning electron microscopy analyses. Then, the membranes were successfully tested as antibacterial materials against gram-negative bacteria, Escherichia coli. Regarding cytocompatibility, in vitro assays performed with L929 cells showed good levels of cell adhesion and proliferation (XTT assay), and no significant cytotoxic effect, in comparison to bare keratin nanofibers. Given these results, the material described in this work can be suitable for use as antibiotic-free fibers for skin wound dressing or membranes for guided tissue regeneration. Full article

The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers’ offerings indicates that new technical solutions are being developed to integrate two or more technological operations. However, these examples have numerous limitations and are mostly not suitable for machining surfaces with complex shapes. An example of such solutions is the use of a dual-tool grinding head, which integrates the process of rough grinding with a ceramic grinding wheel and finish grinding with a flexible grinding wheel. Unfortunately, it has the disadvantage of being limited by the angular shape of the ceramic grinding wheel, making it unable to adapt to the complex geometries of the shaped surfaces being ground. The need to overcome this limitation became the motivation for the research work described in this article. By means of experimental research, it was verified what effect the radial outline on the periphery of a ceramic grinding wheel realized by rough grinding would have on the surface roughness parameters obtained in the process of grinding shaped surfaces. For this purpose, grinding processes using a ceramic wheel with a conical and radial outline were compared. The result of the study was a summary of the surface roughness parameters Sa, St, Sq, Spk, Str, and Sds obtained after two-stage machining (rough and finish grinding). The obtained analysis results showed that changing the axial outline of the ceramic grinding wheel makes it possible to significantly expand the range of applications of the dual-tool head without negatively affecting the quality of the machined surface. Thus, such an improvement will make it possible to increase the applicability of the head by grinding shaped surfaces with a radial profile of curvature. Full article

The emergence of additive manufacturing technologies for fiber-reinforced thermoset composites has greatly bolstered their utilization, particularly within the aerospace industry. However, the ability to precisely measure the interface strength between the fiber and thermoset matrix in additively manufactured composites has been constrained by the cumbersome nature of single-fiber pull-out experiments and the need for costly instrumentation. This study aims to introduce a novel methodology for conducting single-fiber pull-out tests aimed at quantifying interface shear strength in additively manufactured thermoset composites. Our findings substantiate the viability of this approach, showcasing successful fiber embedding within composite test specimens and precise characterization of fiber pull-out strength using a conventional mechanical testing system. The test outcome revealed an average interfacial strength value of 2.4 MPa between carbon fiber and the thermoset epoxy matrix, aligning with similar studies in the existing literature. The outcome of this study offers an affordable and versatile test methodology to revolutionize composite material fabrication for superior mechanical performance. Full article

In this study, alumina ceramics with hierarchical pores were successfully fabricated using freeze casting. Experimental studies show that both the solid loading of the slurry and the thermal insulation layer at the interface of the slurry and cooling plate can influence the pore characteristics of cast samples. In order to examine the pore characteristics and evaluate the permeability of the freeze-cast samples fabricated under different conditions, a generative adversarial network (GAN) method was employed to reconstruct the three-dimensional (3D) microstructure from two-dimensional (2D) scanning electron microscopy (SEM) images of the samples. Furthermore, GAN 3D reconstruction was validated against X-ray tomography 3D reconstruction results. Based on the GAN reconstructed microstructures, the permeability and pore distribution of the various samples were analyzed. The sample cast with 35 wt.% solid loading shows an optimal permeability. Full article

The high-temperature stability of RuAl-based electrodes for application in microelectronic devices is analyzed for long-term duration. The electrodes are prepared on Ca₃TaGa₃Si₂O₁₄ (CTGS) substrates using SiO₂ and Al-N-O cover and barrier layers as oxidation protection. The samples are annealed at 600, 700, or 800 °C in air for 192 h. Minor degradation is observed after thermal loading at 700 °C. The annealing at 800 °C for 192 h leads to a partial oxidation of the Al in the extended contact pad and to a complete oxidation of the Al within the structured interconnect electrodes. The different degradation of the interconnect electrodes and the contact pads is caused by their different lateral dimensions. In summary, long-term high-temperature stability is demonstrated up to at least 700 °C in air. Less oxidizing atmospheres should allow the application at higher temperatures and for a significantly longer duration. Full article

This study investigates the surface topography of microfinishing abrasive films and their machining capability on the Nimonic 80A superalloy, a high-performance nickel-based alloy commonly used in aerospace and gas turbine engine applications. Surface analysis was conducted on three abrasive films with nominal grain sizes of 30, 15, and 9 μm, exploring wear patterns, contact frequency, and distribution. To assess the distribution of grain apexes, Voronoi cells were employed. Results revealed distinct wear mechanisms, including torn abrasive grains and cracked bond surfaces, highlighting the importance of efficient chip removal mechanisms in microfinishing processes. Larger grain sizes exhibited fewer contacts with the workpiece but provided more storage space for machining products, while smaller grain sizes facilitated smoother surface finishes. The research demonstrated the effectiveness of microfinishing abrasive films in reducing surface irregularities. Additionally, surface analysis of worn abrasive tools provided insights into wear mechanisms and chip formation, with the segmentation of microchips contributing to efficient chip removal. These findings underscore the significance of selecting appropriate abrasive films and implementing effective chip removal mechanisms to optimize microfinishing processes and improve surface finishing quality in advanced material machining applications. It is worth emphasizing that no prior research has investigated the microfinishing of components crafted from Nimonic 80A utilizing abrasive films, rendering this study truly unique in its contribution to the field. Full article

Li-N₂ batteries present a relatively novel approach to N₂ immobilization, and an advanced N₂/Li₃N cycling method is introduced in this study. The low operating overpotential of metal–air batteries is quite favorable to their stable cycling performance, providing a prospect for the development of a new type of battery with extreme voltage. The battery system of Li-N₂ uses N₂ as the positive electrode, lithium metal as the negative electrode, and a conductive medium containing soluble lithium salts as the electrolyte. In accordance with its voltage-distribution trend, a variety of lithium-nitrogen molecule intermediates are produced during the discharge process. There is a lack of theoretical description of material changes at the microscopic level during the discharge process. In this paper, the first-principles approach is used to simulate and analyze possible material changes during the discharge process of Li-N₂ batteries. The discharge process is simulated on a 4N-graphene anode substrate model, and simulations of its electrostatic potential, Density of States (DOS), HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) aspects confirm that the experimentally found Li₃N becomes the final stabilized product of the Li-N₂ battery. It can also be seen in the density of states that graphene with adsorption of 4N transforms from semiconducting to metallic properties. In addition, the differential charge also indicates that the Li-N₂ material has a strong adsorption effect on the substrate, which can play the dual role of electricity storage and nitrogen fixation. Full article

X65 pipeline steel is widely used in the field of offshore oil and gas exploitation due to its excellent performance. However, due to the complex environment in the ocean, X65 pipeline steel is faced with a great risk of microbial corrosion failure. Therefore, it is of great significance to study the corrosion mechanism of X65 pipeline steel by microorganisms. In this paper, the corrosion effect of Pseudomonas aeruginosa (P. aeruginosa) secreting phenazine compounds on X65 pipeline steel was studied by the weight loss method, biofilm scanning electron microscopy analysis, surface corrosion morphology observation, electrochemical testing and medium pH test corrosion products. The results showed that the inoculation of P. aeruginosa accelerated the corrosion of X65 steel. After knocking out the phzM and phzS genes that regulate the synthesis of PYO, P. aeruginosa can still produce biofilms on the surface of X65 steel consistent with the morphology of wild-type P. aeruginosa, but the corrosion of X65 steel is significantly reduced. It is proved that PYO plays an important role in the corrosion process of P. aeruginosa on steel. Full article

The adhesive force between two contact surfaces often leads to an increase in the friction force of the rubber seal O-ring after a certain dwell time, forming dwell time effects and affecting the reliability of sealing. The dwell time effect may result in substantial instability with respect to the frictional behavior of rubber O-rings, which needs to be carefully taken into account in the design of rubber seals. Therefore, in this paper, the dwell time effect of the friction force was studied experimentally for intermittent reciprocating rubber seal O-rings coupled with stainless steel 316L and a sealing air medium. The friction force of three kinds of rubber materials, including fluorine rubber (FPM), silicone rubber (SI), and nitrile rubber (NBR), was measured under different dwell times, compression ratios, and seal pressure. The results showed that there was a rolling frictional force, and the second peak value of the frictional force caused by the O-ring's rolling under shear action and after the maximum static frictional force was observed at the starting stage of reciprocating motion. For FPM O-rings, the rolling friction force was much greater than the maximum static frictional force at about four times the value of the compression ratio at 9% and seal pressure at 0; moreover, the force was much greater at greater compression ratios. The dwell time effect was significant in the friction forces of rubber O-rings. The friction force increases with an increase in dwell time. The increase in maximum static friction force exceeded 50% after 5 dwell days. The increase in seal pressure led to the disappearance of the rolling friction feature and the rapid increase in friction during the starting stage. Under gas seal pressure conditions, the dwell time effect still led to a significant increase in friction force. The obtained results might provide guidance for the material selection of sealing designs. Full article

This research is dedicated to optimizing the design of microfluidic cells to minimize mass transfer effects and ensure a uniform flow field distribution, which is essential for accurate SPR array detection. Employing finite element simulations, this study methodically explored the internal flow dynamics within various microfluidic cell designs to assess the impact of different contact angles on flow uniformity. The cells, constructed from Polydimethylsiloxane (PDMS), were subjected to micro-particle image velocimetry to measure flow velocities in targeted sections. The results demonstrate that a contact angle of 135° achieves the most uniform flow distribution, significantly enhancing the capability for high-throughput array detection. While the experimental results generally corroborated the simulations, minor deviations were observed, likely due to fabrication inaccuracies. The microfluidic cells, evaluated using a custom-built SPR system, showed consistent repeatability. Full article

Nanomagnetism and spintronics are currently active areas of research, with one of the main goals being the creation of low-energy-consuming magnetic memories based on nanomagnet switching. These types of devices could also be implemented in neuromorphic computing by crafting artificial neurons (ANs) that emulate the characteristics of biological neurons through the implementation of neuron models such as the widely used leaky integrate-and-fire (LIF) with a refractory period. In this study, we have carried out numerical simulations of a 120 nm diameter, 250 nm length ferromagnetic nanowire (NW) with the aim of exploring the design of an artificial neuron based on the creation and destruction of a Bloch-point domain wall. To replicate signal integration, we applied pulsed trains of spin currents to the opposite faces of the ferromagnetic NW. These pulsed currents (previously studied only in the continuous form) are responsible for inducing transitions between the stable single vortex (SV) state and the metastable Bloch point domain wall (BP-DW) state. To ensure the system exhibits leak and refractory properties, the NW was placed in a homogeneous magnetic field of the order of mT in the axial direction. The suggested configuration fulfills the requirements and characteristics of a biological neuron, potentially leading to the future creation of artificial neural networks (ANNs) based on reversible changes in the topology of magnetic NWs. Full article