Search Results (1,681)

The aim of this work is to investigate the effect of annealing (at temperatures ranging from 260 °C to 530 °C) of thin-walled Al-Mn-Mg-Ti-Zr samples manufactured by selective laser melting (SLM) on their tensile mechanical properties, hardness, and surface roughness. The results of this study may contribute to the development of post-processing modes for thin-walled products made of corrosion-resistant aluminum alloys with increased strength, manufactured using SLM technology. Hierarchical clustering methods allowed us to identify three groups of thin-walled samples with different strain-hardening mechanisms depending on the annealing temperature. The greatest hardening is achieved in the first group of samples annealed at 530 °C. Metallographic analysis showed that at this heat treatment temperature, there are practically no micropores (macrodefects) and microcracks. X-ray phase analysis showed the precipitation of Ti and Zr, as well as the formation of an intermetallic phase with a composition of Mg8Al16. At lower heat treatment temperatures, from 260 °C to 500 °C, the observed hardening is statistically significantly lower than at 530 °C. This phenomenon, combined with the formation of intermetallic phases and the precipitation of titanium/zirconium, contributes to the hardening of thin-walled Al-Mn-Mg-Ti-Zr alloy samples manufactured by SLM. The main results of this study show that the optimal strain hardening of thin-walled Al-Mn-Mg-Ti-Zr alloy samples manufactured by SLM is achieved by heat treatment at 530 °C for 1 h. The strengthening mechanism has two characteristics: (1) dispersion strengthening due to the formation of precipitates and (2) reduction in macrodefects at high temperatures. Full article

Thin films of nickel oxide (NiO) were deposited on a 5° miscut magnesium oxide (MgO)(100) substrate using electron-beam evaporation to pursue morphology-directed resistive switching. The atomic force microscope (AFM) confirmed a stepped surface with a terrace width of ~85 nm and a step height of ~7 nm. After deposition, the film resistance decreased from 200 MΩ to 25 MΩ by annealing under ambient air at 400 °C, attributed to the increase in the p-type conductivity through nickel vacancy formation. Top electrodes of Ag (500 nm width, 180 nm gap) were patterned parallel or perpendicular to the substrate steps using UV and electron-beam lithography. Devices aligned parallel to the step showed reproducible unipolar switching with 100% yield between forming voltages 20–70 V and HRS/LRS~10² at ±5 V. In contrast, devices formed perpendicular to the steps (8/8) subsequently failed catastrophically during electroforming, with scanning electron microscopy (SEM) showing breakdown holes on the order of ~100 nm at the step crossings. The anisotropic electrodynamic response is due to step-guided electric field distribution and directional nickel vacancy migration, illustrating how substrate morphology can deterministically influence filament nucleation. These results highlighted stepped MgO as a template to engineer the anisotropic charge transport of NiO, exhibiting a reliable ReRAM as well as directional electrocatalysis for energy applications. Full article

Fused filament fabrication of thermoplastic composites, despite its recyclability, increased strength, and efficiency, faces structural limitations under elevated temperatures. The literature on heat treatments for improving the thermal resilience of accessible 3D printed composites is limited. Therefore, this study comprehensively presents the efficacy of annealing on carbon fiber reinforced polyamide (PAHT-CF). The methodology includes uniaxial tensile testing of 200 samples across a wide temperature range (25–150 °C) and five different infill orientations, annealed as per the Technical Data Sheet (80 °C, 12 h). Scanning electron microscopy (SEM) of the fracture surfaces revealed the microstructural changes responsible for the improved properties after annealing. At 25 °C, annealing led to a 50% strength increase (63.88 MPa) and a 70% lower strain (2.65%). At 150 °C, the material maintained a 17.5% strength advantage (23.62 MPa) and a 17.5% reduction in strain (12.67%). The 0°, 90°, and 0/90° orientations exhibited the highest improvements, while the remainder displayed lower strengths and higher deformation beyond the glass transition temperature (70 °C). Overall, annealed PAHT-CF demonstrates high-temperature resilience, comparable to previously analyzed materials like carbon fiber reinforced polyether–ether–ketone (PEEK-CF). This makes it a potentially accessible alternative for the aerospace and automotive sectors. However, practical applications must consider the trade-off between its enhanced mechanical properties and the increased lead time from annealing. Full article

Multi-Wall Carbon Nanotubes (MWCNTs) are under investigation for their use in biomedical applications, especially in neurological diseases, due to their electrochemical properties. Nevertheless, conflicting results have cast doubt on their safety. To advance their translational potential, we evaluated the cytotoxicity of two MWCNT samples in vivo in both vertebrate and invertebrate animal models. Pristine MWCNTs were, in part, used as prepared (MWCNTs), and, in part, annealed at 2400 °C (a-MWCNTs). The two samples differ in their electrochemical properties: MWCNTs are not electro-conductive, while a-MWCNTs are electro-conductive and negatively charged on their surface. We evaluated the effects of both intranasally delivered MWCNTs on several key markers of cell viability in the olfactory bulbs and hippocampus from healthy adult Wistar rats, as well as their impact on lifespan, genotoxicity, oxidative stress, and aging-related functional markers in the nematode Caenorhabditis elegans. Neither of the two MWCNT samples was cytotoxic towards neuronal cells in the hippocampus. In olfactory bulbs, only electro-conductive a-MWCNTs interacted with two positively charged mitochondrial proteins: Translocase of Outer Mitochondrial Membrane 20 (TOM20) and Cytochrome C (CytC). In C. elegans, neither type of MWCNT affected lifespan or brood size, and cytosolic ROS levels remained unchanged. Notably, treated worms exhibited a significantly delayed aging phenotype. Metallic MWCNTs are biocompatible in living organisms and possess the potential to modulate neural cells functioning in vivo. Full article

Gold (Au) is one of the noble metals most used as a catalyst in the growth of one-dimensional nanostructures. Usually, an ultra-thin Au film is coated followed by thermal annealing to obtain Au nanoclusters. Although annealing temperature, duration and film thickness parameters have been heavily studied, there are no studies on the sputter working gas pressure, which also greatly affects the film microstructure. In this study, low (5 mTorr) and high (15 mTorr) working gas pressures were examined in addition to Au film thicknesses of 2 nm, 5 nm and 8 nm. Additionally, copper indium gallium selenide (CIGS) films were deposited on Au films with different thicknesses and argon (Ar) gas pressures. It was confirmed from SEM and AFM images that the Au films undergo drastic morphology change from smooth to extremely porous film surfaces with increasing thickness regardless of gas pressure. However, the porosity of films is increased at higher growth pressure for each thickness. Specifically, the most porous film was obtained at a 5 nm thickness with 15 mTorr, and it was filled with nanomounds. Not surprisingly, the only apparent columnar-type formation was observed for CIGS deposition, which was carried out on the most porous film. It can be interpreted that Au nanomounds behave like catalysts on which the CIGS nanocolumns grow. Full article

3D printing of beta titanium alloys for biomedical applications is currently in great demand, both for material reasons and for the possibility of producing very complex replacements, often directly tailored to the patient. Gyroidal and similar structures are ideal for biomedical replacements but their manufacturing require specific additive technology and post-processing like annealing or etching. The aim of this work is to determine the mechanical properties of Ti25Nb4Ta8Sn alloy which overcomes Ti6Al4V in biomedical applications. The results showed that Ti6Al4V exhibited a significantly higher ultimate tensile strength (up to 1200 MPa) compared with the beta titanium alloy Ti25Nb4Ta8Sn (up to 360 MPa), while the latter demonstrated a substantially lower elastic modulus (∼40–50 GPa), beneficial for biomedical applications. Annealing improved strength and reduced internal stresses in both alloys, while etching effectively removed residual powder but slightly decreased mechanical integrity. These findings provide a quantitative basis for optimizing printing and post-processing parameters of beta titanium alloys for implant design. The properties will be used for future numerical simulations of implants made from Ti25Nb4Ta8Sn alloy based on discrete particle grid models. Full article

The manufacturing techniques, structural features, and optical attributes of titanium dioxide (TiO₂) nanoparticles are highlighted in this study. These nanoparticles are notable for their remarkable photocatalytic activity, cheap cost, chemical stability, and biocompatibility. TiO₂ consists of three polymorph structures: anatase, rutile, and brookite. Because of its electrical characteristics and large surface area, anatase is the most efficient for photocatalysis when exposed to UV light. The crystallinity, size, and shape of titania nanoparticles (NPs) are influenced by diverse production techniques. Sol-gel, hydrothermal, solvothermal, microwave-assisted, and green synthesis with plant extracts are examples of common methods. Different degrees of control over morphology and surface properties are possible with each approach, and these factors ultimately affect functioning. For example, microwave synthesis provides quick reaction rates, whereas sol-gel enables the creation of homogeneous nanoparticles. XRD and SEM structural investigations validate nanostructures with crystallite sizes between 15 and 70 nm. Particle size, synthesis technique, and annealing temperature all affect optical characteristics such as bandgap (3.0–3.3 eV), fluorescence emission, and UV-visible absorbance. Generally speaking, anatase has a smaller crystallite size and a greater bandgap than rutile. TiO₂ nanoparticles are used in gas sensing, food packaging, biomedical coatings, dye-sensitized solar cells (DSSCs), photocatalysis for wastewater treatment, and agriculture. Researchers are actively exploring methods like adding metals or non-metals, making new composite materials, and changing the surface to improve how well they absorb visible light. Full article

In this paper, we demonstrate a simplified method for fabricating ohmic contacts on 4H-SiC substrates using pulsed UV laser surface modification followed by application of a silver-based conductive adhesive. Even a small number of laser passes significantly improved the contact interface, while ten or more repetitions produced linear I–V characteristics with low voltage drops. SEM analysis revealed surface ablation and an expanded effective area of the contact. Raman spectroscopy proved that laser processing leads to surface amorphization of the SiC sample. DFT simulations showed that the amorphous SiC layer is a material with no band gap, explaining the elimination of the Schottky barrier. Our approach enables the manufacturing of reliable, low-resistive contacts without high-temperature annealing and offers a practical route for rapid SiC device prototyping. Full article

Advancements in flexible, low-cost, and recyclable alternatives to transparent conductive oxides (TCOs) are critical challenges in the sustainability of third-generation solar cells. This work introduces a copper mesh-based transparent electrode for dye-sensitized solar cells, replacing conventional fluorine doped-tin oxide (FTO)-coated glass to simultaneously reduce spectral reflection losses, enhance mechanical flexibility, and enable material recyclability. Titanium dioxide (TiO₂) photoanodes were synthesized and directly deposited onto the mesh via a single-step, low-energy ball milling process, which eliminates TiO₂ paste preparation and high-temperature annealing while reducing fabrication time from over three hours to 30 min. Structural and surface analyses confirmed the deposition of high-purity anatase-phase TiO₂ with strong adhesion to the mesh branches, enabling improved dye loading and electron injection pathways. Optical studies revealed higher visible light absorption for the copper mesh compared to FTO in the visible range, further enhanced upon TiO₂ and Ru-based dye deposition. Electrochemical measurements showed that TiO₂/Cu mesh electrodes exhibited significantly higher photocurrent densities and faster photo response rates than bare Cu mesh, with dye-sensitized Cu mesh achieving the lowest charge transfer resistance in impedance analysis. Techno–economic and sustainability assessments revealed a decrease of 7.8% in cost and 82% in CO₂ emissions associated with the fabrication of electrodes as compared to conventional TCO electrodes. The synergy between high conductivity, transparency, mechanical durability, and a scalable, recyclable fabrication route positions this architecture as a strong candidate for next-generation dye-sensitized solar modules that are both flexible and sustainable. Full article

The article presents the results of research on the effect of 160 MeV xenon ions irradiation on the mechanical and tribological properties of the Nimonic 90 superalloy. The alloy samples were irradiated with xenon ion fluences ranging from 1 × 10¹⁴ to 5 × 10¹⁴ Xe²⁴⁺/cm² at a temperature of 60 °C. The investigations revealed significant changes in the crystal structure of the material, including the formation of new phases and partial amorphisation of the surface layer, particularly pronounced at the highest irradiation fluence. Measurements of microhardness, coefficient of friction, and wear revealed a deterioration in the mechanical and tribological properties of the samples irradiated with fluences of 1.0 and 2.5 × 10¹⁴ Xe²⁴⁺ ions/cm², attributed to the formation of radiation-induced defects. Increased friction and wear were observed at depths greater than the predicted range of xenon ions, indicating the occurrence of a long-range effect. After irradiation with a 5.0 × 10¹⁴ Xe²⁴⁺ ions/cm² fluence, a radiation annealing effect was observed, leading to a partial reduction in the earlier damage and resulting in improved microhardness and reduced wear. To our knowledge, this is the first observation of a radiation annealing effect under these specific irradiation and test conditions. The findings suggest limitations in the application of the Nimonic 90 superalloy in environments exposed to intense ionizing radiation, such as nuclear reactors. Full article

The study of effect of solvent annealing on the optoelectronic properties of polymers is not new research hotspot, but the influence of solvent annealing on the electrochemical and electrochromic properties of PEDOT remains unexplored. This paper investigates the effects of three different solvents—chlorobenzene (CB), tetrahydrofuran (THF), and dimethylformamide (DMF)—on the self-assembly of PEDOT films and compares their thermal, morphological, electrochemical, and electrochromic properties. PEDOT annealed with DMF exhibits a highly crystalline film morphology, which increases the difficulty of ionic doping/undoping and leads to suboptimal electrochemical and electrochromic stability. After CB annealing, PEDOT forms a relatively gentle melting peak. In addition to a certain degree of crystallinity, the polymer film also exhibits cracking, which severely impairs the electrochromic performance. After THF annealing, PEDOT exhibits a gentler melting peak, a surface morphology that is more favorable for electrochemical and electrochromic performance, ultimately achieving an optical contrast of 28%, the fastest response time of 1.1 s, and the highest coloration efficiency of 184 cm² C⁻¹. The impact of solvent annealing on PEDOT’s electrochromism is significantly different, which will guide the electrochemical and electrochromic properties of PEDOT analogs and derivatives under the influence of different solvents. Full article

The primary objective of this research is to simplify and make the industrial manufacturing process of coated maraging steels more economical by combining the advantages of additive manufacturing with simultaneous bulk (aging) and surface (nitriding) treatment in an effective manner. With this aim, preliminary experiments were performed that demonstrated the hardness (and related microstructure) of an as-built MS1 maraging steel, produced by selective laser melting (SLM), is comparable to that of the bulk maraging steel products treated by conventional solution annealing. The direct aging of the solution-annealed and as-built 3D printed maraging steel resulted in similar hardness, indicating that the kinetics of the precipitation hardening process are identical for the steel in both conditions. This assumption was strengthened by a thermodynamic analysis of the kinetics and determination of the activation energy for precipitation hardening using Differential Scanning Calorimetry (DSC) measurements. Industrial target experiments were performed on duplex-coated SLM-printed MS1 steel specimens, which were simultaneously aged and salt-bath nitrided, followed by PVD coating with three different ceramic layers: DLC, CrN, and TiN. For reference, similar duplex-coated samples were used, featuring a bulk Böhler W720 maraging steel substrate that was solution annealed, precipitation hardened, and salt-bath nitrided in separate steps, following conventional procedures. The technological parameters (temperature and time) of the simultaneous nitriding and aging process were optimized by modeling the phase transformations of the entire heat treatment procedure using DSC measurements. A comparison was made based on the in-depth hardness profile estimated by the so-called expanding cavity model (ECM), demonstrating that the hardness of the surface layer of the coated composite material systems is determined solely by the type of the coatings and does not influenced by the type of the applied substrate materials (bulk or 3D printed) or its heat treatment (whether it is a conventional, multi-step treatment or a simultaneous nitriding + aging process). Based on the research work, a proposal is suggested for modernizing and improving the cost-effectiveness of producing aged, duplex-treated, wear-resistant ceramic-coated maraging steel. Full article

Due to the outstanding thermal stability of diamond film, diamond films have extensive application prospects in fields such as electronics, optics, biomedicine, and aerospace, and are one of the important materials driving the development of modern science and technology. Moreover, the cost of single-crystal diamond substrates is high, and it is difficult to achieve large-scale batch production. A direct current arc plasma jet chemical vapor deposition method, combined with post-treatment steps such as nano-diamond seed crystal implantation, surface modification, and high-temperature annealing, is used to prepare high-quality diamond films. The relationship between the thermal conductivity and optical properties of diamond films is analyzed in detail. The experimental results showed that diamond film has a relatively smooth surface, with a surface roughness that can reach 3 nm. As the temperature rises, diamond films exhibit good crystal orientation and thermal stability, the FWHM of reflection peaks become smaller, and thermal conductivity can reach 1734 W/(m·K). The infrared testing analysis also confirmed that the diamond film has excellent thermal diffusion properties. When the diamond film is applied to power device chips, it can effectively reduce the junction temperature of 30 °C. The preparation method proposed in this paper is expected to break through the cost and scale limitations of high-performance diamond films, thereby promoting the wide application of diamond films in industries. Full article

Aluminum-based seawater activated batteries (Al-SWBs) are highly cost-effective energy storage systems, with aluminum exhibiting a theoretical specific capacity of 2.98 Ah/g, second only to lithium, making it a promising candidate for next-generation sustainable energy storage and conversion technologies. However, severe hydrogen evolution and self-corrosion side reactions hinder the practical application of Al-SWBs, leading to unsatisfactory utilization of aluminum anodes. This review systematically summarizes the fundamental principles and strategies for enhancing the utilization efficiency of aluminum anodes from the perspectives of influencing factors and improvement approaches. In terms of alloying element doping, attention should be paid not only to elements that enhance performance but also to the impact of harmful impurities. Microstructure control can be achieved through advanced preparation techniques and subsequent annealing processes. Furthermore, the addition of corrosion inhibitors to the electrolyte can form a protective layer on the electrode surface, effectively suppressing self-corrosion behavior. This review aims to provide valuable insights and guidance for the development of sustainable and high-performance Al-SWBs, contributing to the advancement of green energy technologies. Full article

This paper presents the growth and in situ optical characterization of silicon nanowires (Si NWs) on Al₂O₃(0001) substrates that are thermally faceted using the atomic low angle shadowing technique (ATLAS) method. Annealing Al₂O₃ substrates in air before surface faceting was used for the first time, as identified by atomic force microscopy (AFM). Planar Si NW arrays were subsequently deposited and characterized in real-time by reflectance anisotropy spectroscopy (RAS). RAS measurements detected irreversible spectral changes during growth, e.g., red-shift in peak energy for marking amorphous Si NW formation. Blue-shifts in RAS spectra following annealing post-growth at varied temperatures were found to be associated with structural nanowire development. AFM analysis following annealing detected dramatic changes in morphology, e.g., quantifiable differences in NW height and thickness and complete disappearance of nanowire structures at high temperatures. These results confirm the validity of in situ RAS as a monitoring tool for nanowire growth and illustrate Si NW morphology’s sensitivity to thermal processing. Full article