Search Results (229)

Laser-based powder bed fusion of metals (PBF-LB/M) is one of the most promising additive manufacturing technologies to fabricate complex-structured metal parts. However, its corresponding applications have been limited by technical bottlenecks and increasingly strict industrial requirements. Process optimization, a scientific issue, urgently needs to be solved. In this paper, a three-phase transient model based on the level-set method is established to examine the heat transfer and melt pool behavior in PBF-LB/M. Surface tension, the Marangoni effect, and recoil pressure are implemented in the model, and evaporation-induced mass and thermal loss are fully considered in the computing element. The results show that the surface roughness and density of metal parts induced by heat transfer and melt pool behavior are closely related to process parameters such as laser power, layer thickness, scanning speed, etc. When the volumetric energy density is low, the insufficient fusion of metal particles leads to pore defects. When the line energy density is high, the melt track is smooth with low porosity, resulting in the high density of the products. Additionally, the partial melting of powder particles at the beginning and end of the melting track usually contributes to pore formation. These findings provide valuable insights for improving the quality and reliability of metal additive manufacturing. Full article

Linalyl acetate (LA), a key volatile component in essential oils, is extensively utilized in fragrance, food, and cosmetic industries. Nevertheless, its practical applications are constrained by rapid evaporation and physicochemical instability. This study developed novel cyclodextrin–metal–organic frameworks (CD-MOFs) crystallized from β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) with potassium hydroxide, demonstrating superior structural properties for LA encapsulation. Through comparative analysis with native CDs, the synthesized CD-MOFs exhibited highly ordered crystalline architectures and uniform morphological characteristics. The LA encapsulation capacity of the γ-CD-MOF was systematically evaluated under different conditions using a three-level factorial design via RSM. Optimization revealed maximum encapsulation efficiency (25.9%) under ideal conditions—an LA:γ-CD-MOF mass ratio of 3.8:1, 60.9 °C incubation temperature, and 49.3 min processing time—representing a 2.39-fold enhancement over conventional CD encapsulation. Thermal stability analysis demonstrated remarkable improvement, with LA-γ-CD-MOF complexes showing an onset decomposition temperature of 215 °C, 135 °C higher than that of free LA. Compared with LA-γ-CD, LA coated with γ-CD-MOFs still retained 55.7% at 80 °C for 75 min, with the release rate reduced by about 45.3%. These findings establish the potential of γ-CD-MOFs as effective carriers for thermolabile and volatile compounds in functional food and cosmetic industries. Full article

The primary challenge associated with stainless steel in fuel cell operation is its susceptibility to corrosion, which leads to increased contact resistance and subsequent degradation of electrochemical performance. In general, the protective layers have been loaded onto the metal surface by widely used traditional techniques such as physical vapor deposition (PVD), or cathode arc ion plating. However, the above sputtering and evaporation ways require a high-vacuum condition, complicated experimental setups, higher costs, and an elevated temperature. Therefore, herein the achievement for uniform coatings over a large surface area has been realized by using a cost-effective strategy through a complete wet chemical process. The synergistic regulation of two conductive components and a plastic additive has been employed together with the entrapment of a surfactant to optimize the microstructure of the coating surface. The assembly of layered graphite and a polystyrene sphere could maintain both the high corrosion resistance feature and excellent electrical conductivity. In particular, the intrinsic vacant space in the above physical barriers has been filled with fine powders of indium tin oxide (ITO) due to its small size, and the interconnected conductive network with vertical/horizontal directions would be formed. All the key technical targets based on the U.S. Department of Energy (DOE) have been achieved under the simulated operating environments of a proton exchange membrane fuel cell. The corrosion current density has been measured as low as 0.52 μA/cm² (for the sample of graphite/mixed layer) over the applied potentials from −0.6 V to 1.2 V and its protective efficiency is evaluated to be 99.8%. The interfacial contact resistance between the sample and the carbon paper is much less than 10 mΩ·cm² (3.4 mΩ·cm²) under a contact pressure of 165 N/cm². The wettability has been investigated and its contact angle has been evolved from 48° (uncoated sample) to even 110°, providing superior hydrophobicity to prevent water penetration. Such an innovative approach opens up new possibilities for improving the durability and reducing the costs of carbon-based coatings. Full article

Conventional fabrication of high-efficiency organic solar cells (OSCs) predominantly relies on vacuum-evaporated metal top electrodes such as Ag and Al, which hinder large-scale industrial production. Gallium-based liquid metals (GaLMs), particularly the eutectic gallium–indium alloy (EGaIn), represent promising candidates to conventional vacuum-evaporated metal top electrodes due to their excellent printability and high electrical conductivity. In this study, we fabricated vacuum-free OSCs based on GaLM electrodes (Ga, EGaIn, and Galinstan) and analyzed the device performances. Rigid devices with EGaIn electrodes achieved a champion power conversion efficiency (PCE) of 15.6%. Remarkably, all-solution-processed ultrathin flexible devices employing silver nanowire (AgNW) bottom electrodes in combination with EGaIn top electrodes achieved a PCE of 13.8% while maintaining 83.4% of their initial performance after 100 compression–tension cycles (at 30% strain). This work highlights the potential of GaLMs as cost-effective, scalable, and high-performance top electrodes for next-generation flexible photovoltaic devices, paving the way for their industrial adoption. Full article

Spatters in the powder-based metal additive manufacturing processes influence deposition quality, part surface quality, and internal defects. We developed a novel video analysis method to monitor and count the melted spatter particles of biomedical-grade Co-Cr-Mo-4Ti powder particles in depositing layers using a micro-plasma transferred arc additive manufacturing (M-PTAAM) process. We captured the spatters using a weld-monitoring camera and building datasets of videos and monitored different combinations of M-PTAAM process parameters. We captured videos of the melted spatter particles and counted the melted spatter particles in real time using a Kalman filter. The weld-monitoring camera captured the melted spatter particles and the fumes generated by the evaporated spatter particles. The video processing algorithm was developed in this study to accurately capture melted spatter particles. In images without fumes, nearly all melted spatter particles were successfully detected. Even in images with the presence of fumes, the algorithm maintained a detection accuracy of 90%. The real-time melted spatter count particle exhibited a powder feed rate changing from 30 to 35 g/min and then to 50 g/min. The melted spatter particle count was lowest at a powder feed rate of 30 g/min and increased with the increasing powder feed rate. Full article

The creation of coatings by the cathodic arc evaporation method has outstanding advantages: these coatings are highly durable and wear-resistant, especially since the method has an intense ionization process and the atoms can penetrate deep into the surface substrates, resulting in excellent adhesion. Furthermore, this approach provides precise control over the chemical composition and thickness of the coating, ensuring consistent quality across the entire surface. However, uneven evaporation and ejection of molten metal droplets from the cathode during cathode arc deposition produce particles and droplets, resulting in an uneven coating surface. This study presents a new design for a magnetically controlled cathode arc source to effectively reduce particles and droplets during the cathodic arc deposition of multi-component alloy targets for nitride-based hard coatings. The study compares the performance of a new source with a conventional magnetic-controlled arc source for depositing TiAlNbSiN and AlCrSiN films. In the conventional source, the magnetic field is generated by a permanent magnet (PM), whereas in the new source, it is generated and controlled using an electromagnet (EM). Both films are produced using multi-component alloy targets (TiAlNbSi and AlCrSi) with identical composition ratios. The plasma characteristics of the two different arc sources are investigated using an optical emission spectrometer (OES), and the surface morphology, structural characteristics, deposition rate, uniformity, and surface roughness (Sa) are examined using scanning electron microscopy (SEM). When the EM was applied to have high plasma density, the hardness of the TiAlNbSiN film deposited with the novel arc source measured 31.2 ± 1.9 GPa, which is higher than that of the PM arc source (28.3 ± 1.4 GPa). In contrast, the AlCrSiN film created using a typical arc source exhibited a hardness of only 25.5 ± 0.6 GPa. This lower hardness may be due to insufficient ion kinetic energy to enhance stress blocking and increase hardness, or the presence of the h-AlN phase in the film, which was not detected by XRD. The electromagnet arc source, with its adequate ion bombardment velocity, facilitated a complementary effect between grain growth and stress blocking, leading to a remarkable hardness of 32.6 ± 0.5 GPa. Full article

Comparative analysis of red mud reduction techniques was performed using both carbothermal and hydrogen-based reduction methods, combining thermochemical modeling and experimental validation. The reduction process is mostly important because of the high contamination risk assessment of soil with disposed red mud. Therefore, the minimization of red mud during the reduction process can be a novel strategy for the production of metallic iron and solid residue for hydrometallurgical treatment. Different strategies of hydrogen and carbon reduction in static and dynamic conditions were studied between 700 °C and 1700 °C. The separation of solid residue and formed iron was analyzed using magnetic separation. The main aim was to study the advantages and disadvantages of using decarbonizing technologies for the treatment of red mud, aiming to develop an environmentally friendly process. Thermochemical analysis of the reduction offered new data about mass losses during our process through the evaporation, thermal decomposition, and formation of metallic carbide. Full article

High-nitrogen steels (HNSs) are valued for their superior mechanical strength and corrosion resistance, making them ideal for high-end industrial applications. However, nitrogen loss during gas metal arc welding additive manufacturing (GMAW-AM) often results in porosity and coarse microstructures, degrading component performance. This study introduces a coaxial ultrasonic-assisted GMAW-AM (U-GMAW-AM) process to mitigate nitrogen loss and refine the microstructure. Welding wires with 0.35 wt.% and 0.70 wt.% nitrogen were used to examine the effects of welding voltage (24.5–30 V) and ultrasonic power (0–2 kW). The results show that a higher voltage increases nitrogen evaporation, with a maximum loss of 0.22% at 30 V. In contrast, ultrasonic assistance reduces nitrogen loss by up to 29.17% for the 0.70 wt.% wire. Microstructural analysis reveals a significant reduction in ferrite and enhanced austenite formation due to better nitrogen retention. Mechanical testing shows that ultrasonic assistance improves tensile strength by 100 MPa (up to 919.1 MPa), elongation by nearly 10%, and hardness uniformity. These findings highlight the potential of ultrasonic assistance for optimizing high-nitrogen steel properties in additive manufacturing. Full article

The selection of a suitable plasma-facing material (PFM) that must protect the divertor, cooling systems, and structural components is an important challenge in the design of advanced fusion reactors and requires careful consideration. Material degradation due to melting and evaporation may lead to plasma contamination, which must be strictly avoided. Among the candidate materials, tungsten (W) is the most promising because of its thermo-mechanical and physical properties, which allow it to endure repeated exposure to extremely harsh conditions within the reactor. The plasma spraying (PS) technique is gaining increasing interest for the deposition of tungsten (W) coatings to protect heat sink materials, due to its relatively low cost, high deposition rates, and capability to coat complex-shaped surfaces and fix damaged coatings in situ. This review aims to provide a systematic assessment of tungsten (W) coatings produced by PS techniques, evaluating their suitability as PFMs. It discusses W-based materials, plasma spraying technologies, the role of the interface in joining W coating and metallic substrates such as copper alloys and steels, and the main issues related to coating surface erosion under steady-state and transient heat loads associated with advanced fusion reactor operation modes and off-normal events. Quantitative data available in the literature, such as porosity, oxygen content, thermal conductivity of the coatings, residual stresses accumulated in the coating–substrate interface, surface temperature, and material loss following heat load events, were summarized and compared to bulk W ones. The results demonstrate that, following optimization of the fabrication process, PS-W coatings exhibit excellent performance. In addition, previously mentioned advantages of PS technology make PS-W coatings an attractive alternative for PFM fabrication. Full article

The purpose of this study is to examine the performance of a new cooling system whose mechanism is integrated with an immersion cooling system and a heat pipe mechanism. The study comprises an experimental test and a numerical analysis using the 1-D model. In the experiment, a metal heating block that simulated the pouch-type cell was used. It was composed of multiple heaters and thermal sensors, working as a heating model of the battery while observing the thermal behavior of the cell at the same time. The temperature of the heating block was influenced by the types of working fluid and wick structure, which are the key points of this system. Their role is to promote the heat exchange process by facilitating the evaporation and condensation processes. Their performance was evaluated based on different types of shapes and materials of wicks. The simulation model was designed and its feasibility verified with the experiment results. Furthermore, different types of dielectric working fluids and variations in porosities were examined through the simulation model, which are crucial to determining the characteristics of the wick structure. Full article

The original Glancing Angle Deposition (GLAD) technique was developed using the evaporation process, i.e., in high vacuum, with a nearly punctual source, and with the substrate aligned with the source axis. In this specific case, the substrate tilt angle can be assumed to be equal to the impinging incidence angle of evaporated atoms. With the sputtering process, the deposition pressure is higher, sources are larger, and substrates are not intrinsically aligned with the source. As a result, deviations from the growth models applied for evaporation are reported, and the substrate tilt angle is no longer relevant for describing the impinging atomic flux. To control the inclined nanostructure of metallic films, a relevant description of the atomic flux is required, applicable across all deposition configurations. In this work, transport simulation is used to determine the resultant incidence angle, a unique criterion relevant to each specific deposition condition. The different representations of the flux are described and discussed, and some typical examples of the resultant angles are presented. Ten elements are investigated: three hcp transition metals (Ti, Zr, and Hf), six bcc transition metals (V, Nb, Ta, Cr, Mo, and W), and one fcc post-transition metal (Al). Full article

Micro Light Emitting Diode (Micro-LED) technology, characterized by exceptional brightness, low power consumption, fast response, and long lifespan, holds significant potential for next-generation displays, yet its commercialization hinges on resolving challenges in high-density interconnect fabrication, particularly micrometer-scale bump formation. Traditional fabrication approaches such as evaporation enable precise bump control but face scalability and cost limitations, while electroplating offers lower costs and higher throughput but suffers from substrate conductivity requirements and uneven current density distributions that compromise bump-height uniformity. Emerging alternatives include electroless plating, which achieves uniform metal deposition on non-conductive substrates through autocatalytic reactions albeit with slower deposition rates; ball mounting and dip soldering, which streamline processes via automated solder jetting or alloy immersion but struggle with bump miniaturization and low yield; and photosensitive conductive polymers that simplify fabrication via photolithography-patterned composites but lack validated long-term stability. Persistent challenges in achieving micrometer-scale uniformity, thermomechanical stability, and environmental compatibility underscore the need for integrated hybrid processes, eco-friendly manufacturing protocols, and novel material innovations to enable ultra-high-resolution and flexible Micro-LED implementations. This review systematically compares conventional and emerging methodologies, identifies critical technological bottlenecks, and proposes strategic guidelines for industrial-scale production of high-density Micro-LED displays. Full article

Metal inert gas (MIG) brazing was used to join galvanized thin sheets with thicknesses in the range of 0.8 to 2 mm in a lap joint configuration using CuAl₈ wire as filler. The process was used to manufacture built-up cold-formed steel beams composed of corrugated steel webs and flanges made from thin-walled cold-formed steel lipped channel profiles. The effect of heat input and sheet thickness on joint properties, such as macro- and microstructure, wettability, and mechanical characteristics such as microhardness and tensile strength were investigated. The bead geometry was assessed by studying the wettability of the filler material. The microstructure was investigated by digital and scanning electron microscopy, and the composition in the heat-affected zone (HAZ), interface, and bead was determined by energy dispersive spectroscopy. Formation of Fe–Al intermetallics was observed in the bead at the bead–base material interface. Some pores were noticed that formed due to the evaporation of the zinc coating. The bead shape and mechanical properties were found to be the best when 1.2 and 2 mm sheets were brazed using a heat input of 121.4 J/mm. This suggests that not only the heat input but also the thickness of the sheet metal play a crucial role in the production of MIG brazed joints. Full article

This study systematically investigated the behavior of impurity removal during the electron beam melting (EBM) process of V-Al alloy. Characterization techniques such as ICP, GDMS, SEM, EPMA, and TEM were used to analyze the composition content and microscopic element distribution of V-Al alloy and purified metal samples. Additionally, based on thermodynamic principles, the saturation vapor pressure and evaporation coefficients of impurity elements were calculated. The results indicate that the evaporation coefficients of Al, Fe, Co, Ni, Cr, and Ti exceed 1, enabling their effective removal during the melting process, thereby reducing their concentrations. In contrast, Si, Mo, Nb, and W exhibit evaporation coefficients significantly lower than 1, making their removal difficult. Instead, their concentrations increase due to the enrichment effect. Microstructural analysis reveals that Al migrates toward high-temperature regions, forming enrichment zones at the surface layer in contact with the electron beam. In contrast, Si, C, and O exhibit bidirectional migration characteristics, accumulating at both the upper and lower surfaces of the plate-shaped ingot. TEM observations indicate that some C reacts with V to form V₂C, which has a higher melting point than vanadium, making further removal difficult. Full article

The global shortage of freshwater resources and the energy crisis have propelled solar-driven interfacial evaporation (SDIE) coupled with photocatalytic technology to become a research focus in efficient and low-carbon water treatment. Graphene-based materials demonstrate unique advantages in SDIE–photocatalysis integrated systems, owing to their broadband light absorption, ultrafast thermal carrier dynamics, tunable electronic structure, and low evaporation enthalpy characteristics. This review systematically investigates the enhancement mechanisms of graphene photothermal conversion on photocatalytic processes, including (1) improving light absorption through surface morphology modulation, defect engineering, and plasmonic material compositing; (2) reducing water evaporation enthalpy via hydrophilic functional group modification and porous structure design; (3) suppressing heat loss through thermal insulation layers and 3D structural optimization; and (4) enhancing water transport efficiency via fluid channel engineering and wettability control. Furthermore, salt resistance strategies and structural optimization significantly improve system practicality and stability. In water treatment applications, graphene-based SDIE systems achieve synergistic “adsorption–catalysis–evaporation” effects, enabling efficient the degradation of organic pollutants, reduction in/fixation of heavy metal ions, and microbial inactivation. However, practical implementation still faces challenges including low steam condensation efficiency, insufficient long-term material durability, and high scaling-up costs. Future research should prioritize enhancing heat and mass transfer in condensation systems, optimizing material environmental adaptability, and developing low-cost manufacturing processes to promote widespread application of graphene-based SDIE–photocatalysis integrated systems. Full article