Melting Of Particles Research Articles

Enhancing the Efficiency and Sustainability of Producing Curcumin‐Infused Plant‐Based Milk Alternatives With a Two‐in‐One Post pH‐Driven Processing Strategy

ABSTRACTIncreasing food sustainability and health benefits is essential to meet the demands of a growing global population while minimizing environmental impact. This study used a green two‐in‐one post pH‐driven processing strategy to develop a sustainable and healthy plant‐based milk alternative. It achieved both extraction and encapsulation in one step by directly incorporating the health‐promoting curcumin from turmeric into soymilk. A high processing efficiency was observed, 94.2% ± 1.6%, with a high extraction efficiency of 96.4% ± 0.5%. Using raw turmeric instead of a purified curcumin significantly enhanced the sustainability in the use of raw materials, for example, reducing the CO2‐eq emissions by 22 times and energy use by 10 times, even with a very small percentage of curcumin (∼0.03 wt%) in the formulation. This strategy underscores the importance of using raw materials and minimizing processing steps to develop more sustainable foods. Additionally, the incorporation of curcumin was found to impart a yellow color to soymilk. No significant changes were observed in other physicochemical properties like particle size, zeta potential, and melting behavior, as most curcumin molecules were encapsulated within the lipid phase of soymilk. The curcumin‐infused soymilk powders also maintained excellent storage stability for 1 month under freezing temperature.

Effect of the Physicochemical Properties of PVdF on Dry-Sprayed Graphite Electrodes for Lithium-Ion Batteries for Electric Vehicle Applications

Abstract We investigated the fabrication of graphite/PVdF anodes using electrostatic dry spray-coating, employing two different PVdF binders with different physicochemical properties such as primary particle size, crystallinity, melting temperature, and viscosity. We examine and compare the morphological, mechanical, electrical, and electrochemical properties of the dry-sprayed electrodes (DSEs). Significant differences were observed, particularly in terms of adhesion/cohesion, electrical resistivity, tortuosity, and electrochemical performance, with the PVdF binder characterized by a smaller particle size (178 nm) and a slightly higher melting temperature range (165–172°C), demonstrating superior long-term cycling stability. Specifically, the best electrode made with this binder achieved 188.3 mAh g-1 with over 94.9% capacity retention after 200 cycles. In contrast, the best electrode made with the PVdF binder with a larger particle size (270 nm) and a lower melting temperature range (155–172°C), showed a performance of 173.9 mAh g-1 with 88.3% capacity retention under the same conditions. Our findings highlight the necessity of adjusting fabrication conditions according to the specific characteristics of each PVdF binder to optimize the overall performance of the DSEs.

Fabrication of micro holes with confined pitting corrosion by laser and electrochemical machining: pitting corrosion formation mechanisms and protection method

Laser and electrochemical hybrid machining (LECM) combines the advantages of high efficiency of laser processing and high surface quality of electrochemical machining and has been employed to process deep micro holes with high surface quality, high precision, and efficiency. However, surface pitting corrosion occurs around the entrance of the micro holes drilled by LECM, which deteriorates their surface quality and mechanical properties. This study revealed the mechanism of surface pitting corrosion formation mechanisms during LECM by characterizing surface micromorphology, chemical composition, microstructures, and surface stress. The difference between surface pitting corrosion area during LECM and the stray current corrosion during electrochemical machining was studied. Micro solid metal particles and inner microcavities were observed in micro pits. The depth of the micro pits was greater than that obtained using electrochemical machining. It has been concluded that in LECM, the surface pitting corrosion occurred owing to the enhanced stray current corrosion and the accumulation of solidified melt particles and cavitation microbubbles in the micro pits. Coaxial gas-assisted LECM was also proposed to restrict the surface pitting corrosion area. Experiments and simulations were conducted to verify the feasibility of minimizing the corrosion area using coaxial gas. The surface pitting corrosion area has been decreased by 85.1% at a coaxial gas pressure of 0.1MPa compared with that without coaxial gas assistance. Finally, the radial cooling holes with a diameter of 1.2mm and an aspect ratio of 125:1 in turbine blades with high surface quality were fabricated. This study provides a promising method to fabricate high-aspect-ratio micro-holes with high surface quality and high efficiency.

Design of high-capacity composite anode for next generation lithium-ion batteries

Ga is in primary focus for high-capacity anodes of Li-ion batteries (LIBs). Ga-based anode can form Li2Ga with Li at room temperature. Again, decoupling of Li and Ga is easy compared to other high-capacity materials like Si. Low melting temperature, volume changes, and particle agglomeration of Ga-based electrodes in lithiation and delithiation processes are serious challenges toward its commercialization. To overcome these obstacles, we propose a new composite using Mn-doped GaFeP engineered on N-rGO. Three Mn doping ratios (1, 5, and 10 %) were studied for optimization of electrochemical performance. We observed that the 5 % Mn-doped GaFeP/N-rGO delivered an impressive reversible capacity of 1099.9 mAh/g after 200 cycles at 0.3 A/g. Its retention rate capacity (97.6 %) was higher than those of other electrodes. Furthermore, an excellent rate performance and substantial long-term stability of 671.9 mAh/g was achieved at 1.5 A/g after 850 cycles. The reaction mechanism of the high-performance composite electrode is expounded. We hope our study provides new insights and guidelines to the development of Mn-doped Ga-based electrodes with high capacities, minimal volume change, and long cycle stabilities for next-generation LIBs.

Numerical Simulation of the Melting of Solid Particles in Thermal Convection with a Modified Immersed Boundary Method

A new immersed boundary method is proposed for the numerical simulation of the melting of solid particles in its own liquid at a high temperature. The main feature of the new method is the use of the modified direct-forcing immersed boundary method for the solution of the flow field and the sharp-interface immersed boundary method for the temperature field. The accuracy of the proposed method is validated via three problems: the sedimentation of a non-melting particle, the melting of a fixed particle under mixed thermal convection, and the sedimentation of a melting particle. The method is then applied to the investigation of the effects of various parameters, the particle interactions and the particle shape on the particle melting time. A correlation for the melting time of a circular particle in forced thermal convection is established as a function of the Reynolds, Prandtl, and Stefan numbers. The melting time of a particle in mixed thermal convection first increases and then decreases, as the Grashof number increases. The effects of the particle interactions on the melting time are complicated due to the natural convection between two particles. The sufficiently strong natural convection can even render the downstream particle melt faster than the single particle. For the same particle area, the elliptic particle with the aspect ratio being around 1.4 melts most slowly.

Investigation of Electrochemical Discharge Machining for Tungsten Carbide: Effects of Electrolyte Composition on Material Removal Rate and Surface Quality

Abstract Tungsten carbide (WC-Co) with a cobalt binder has been widely used in industrial application. Through their high wear resistance and hardness, which make it a challenge to machine. Electrochemical discharge machining (ECDM) is a newly developed hybrid technique used to machine conductive and nonconductive materials. Tungsten carbide machining is an area that needs more investigation. In this study, different types of electrolytes have been tested in the electrochemical machining of tungsten carbide. It has been concluded that tungsten carbide was successfully machined with electrolytes that were either neutral salts or a combination of neutral salts and hydroxides, the highest material removal rate achieved was (0.09250 g/min), and the average surface roughness achieved in this work was measured at (Ra 0.9275 µm). However, deposition took place on the surface of machined tungsten carbide when the samples were treated with sodium hydroxide and potassium hydroxide. EDX analysis of successfully machined tungsten carbide samples reveal the presence of carbon (C) due to diffusion from the base material and oxygen (O), most likely due to oxidation brought on by the high temperatures utilized. Scanning electron microscopy confirmed that the machined surfaces had craters, pores, restricted microcracks, and re-deposited melt particles, among other things.

Micromechanical and Tribological Characterization of Fabricated Ti–6Al–4V Alloy Using Laser Powder Bed Fusion

Abstract In the dynamic era of advanced manufacturing technology, laser powder bed fusion (L-PBF) have gained popularity in different domains due to its capability to build parts from bulk to miniature size with higher efficiency and precision. Ti–6Al–4V, a bio-inert metal alloy, possesses a unique blend of profound mechanical and biocompatibility attributes, making it highly suitable for implant applications. This study reports the fabrication of Ti–6Al–4V alloy for implant application via the L-PBF process. The objective is to enhance the micromechanical and tribological properties of the fabricated Ti–6Al–4V component by identifying the optimal processing conditions. The fabricated component exhibited a maximum hardness of 395.26 HV and a minimum frictional coefficient of 0.3193 at 195 W laser power, 900 mm/s scanning speed, and 70 μm hatching distance. The wear-rate and absorbed wear volume were measured as 1.265 × 10−5 mm3 N−1 min−1 and 0.3162 mm3, respectively, under sliding conditions. At optimal processing state, the printed surface displayed an alpha-phase morphology with homogeneous microstructural features due to uniform melting of powder particles that improved bond strength and minimized defects. This study offers an experimental insight into operational attributes, paving the way for accelerated production of Ti–6Al–4V alloy components using the L-PBF method and tailoring tribological properties to meet specific functional requirements.

Nonlinear Theory of the Growth of New Phase Particles in Supercooled Metal Melts

Nonlinear Theory of the Growth of New Phase Particles in Supercooled Metal Melts

Additive manufacturing of polyamide 12 bulk structures using directed energy deposition with a thulium laser: Effect of process conditions on morphology and mechanical performance

Laser-based directed energy deposition of polymers (DED-LB/P) is a highly flexible additive manufacturing process capable of fabricating three-dimensional structures with a high degree of customization on free-form surfaces. In this article, the manufacturability of polyamide 12 bulk structures using DED-LB/P in combination with a thulium laser operating at a wavelength of 1.94 μm is investigated for the first time. The typical absorption bands at this wavelength eliminate the need for additives such as carbon-based nanoparticles, which would limit the range of applications. The generated structures were analyzed regarding porosity, thermal behavior, and mechanical properties to evaluate the potential of DED-LB/P with a thulium laser. As a consequence of the evaporation of absorbed moisture or ethanol residues resulting from powder preparation, a thermal pretreatment of the polymer powder reduced the porosity of the DED-LB/P structures to 0.9%. Depending on the processing parameters, the crystallinity of the produced structures ranged from 25.6% to 29.9%. For the tensile tests, the required geometries were milled from the DED-LB/P bulk structures. The results show that an ultimate tensile strength of up to 52 MPa, an elongation at break of up to 58%, and Young's modulus of up to 1590 MPa can be achieved. These remarkable mechanical properties are primarily attributed to the complete melting of the powder particles in DED-LB/P and the improved surface quality resulting from the milling process.

Effect of Process Parameters on Yttria‐Stabilized Zirconia Particles In‐Flight Behavior and Melting State in Atmospheric Plasma Spraying

The preparation of coatings by atmospheric plasma spraying gives rise to complex physical processes, which present challenges to the study of plasma jet characteristics and particle in‐flight behavior. Herein, a 3D numerical model that integrates multiple physical phenomena, including electromagnetism and thermal and gas dynamics, to simulate the heating, acceleration, and melting of particles under the thermal–mechanical effect, is developed. Meanwhile, yttria‐stabilized zirconia (YSZ) coatings are prepared under varying process parameters. The DPV‐2000 system is employed for the diagnosis of particle velocity, surface temperature, and diameter. Following comparison, the simulation exhibits errors of 4.5% and 14.8% for the maximum temperature and velocity, respectively. An increase in current intensity from 500 to 600 A results in a rise in the proportion of particles exhibiting temperatures above the melting point (2963 K), from 75.1 to 93.4%, accompanied by an increase in average velocity of ≈16.6%. As the spraying distance increases from 60 to 100 mm, the proportion of particles melting decreases from 93.5 to 66.3%, and the average velocity decreases by ≈9.2%. This work will provide a theoretical foundation for the optimization of process parameters to adjust particle behavior and melting state, thus achieving an optimal spraying effect.

Modeling of Melting Layer in Cross‐Platforms Radar Observation Operator ZJU‐AERO: Multi‐Stage Melting Particle Model, Scattering Computation, and Bulk Parameterization

AbstractThis study presents an implementation of a new melting layer model in the ZJU‐AERO radar observation operator (Accurate and Efficient Radar Operator designed by ZheJiang University). The proposed model utilizes a coated spheroid to represent melting snow and graupel. It consists of three stages–coating, soaking, and melting–to account for the dielectric and density effects of melting particles. The scattering properties of the melting particles are computed with the Invariant‐Imbedding T‐Matrix (IITM) method, and the results are tabulated as look‐up tables for the radar operator. Regarding the parameterization of bulk optical properties, a flux‐conservation scheme is employed to estimate the size distribution of melting particles. To demonstrate its flexibility and superiority, the single and bulk scattering properties of our multi‐stage melting model are compared against the traditional homogeneous model, which uses the effective medium approximation (EMA). The effectiveness of the multi‐stage melting model has also been assessed by mapping model states in the regional mesoscale model of the China Meteorology Administration (CMA‐MESO) to radar observations. In the microphysics package of CMA‐MESO, the melting process is not explicitly represented, and we assume that melting hydrometeors occur where solid and liquid phases overlap. When compared with observations, the present multi‐stage melting model successfully reproduces melting layer signatures, highlighting its potential for microphysic validation, quantitative precipitation estimations, and data assimilation studies.

Microwave scattering properties of ice crystal particles during the melting process.

Ice crystal particles play an important role in the study of cloud resolution, climate models, and radiative forcing. During the melting process, significant changes occur in the microphysical properties of ice crystal particles, such as the ice phase state, morphology, and mixing state. This process further affects the scattering and radiation characteristics properties of ice crystal particles. In this study, we constructed a non-spherical and inhomogeneous particle model based on the melting process of ice crystal particles. The scattering properties of melting ice crystal particles under four selected microwave frequency bands (92 GHz, 220 GHz, 280 GHz, and 340 GHz) are investigated by using discrete dipole approximation (DDA) method. The influence of ice crystal content (ICC) and particle aspect ratio on the scattering properties of ice crystal particles under thin coating and medium coating conditions are emphasized. The results show that the melting process significantly affects the scattering properties of melting ice crystal particles in a frequency dependent manner. Additionally, even slight melting of ice crystal particles leads to drastic changes in their scattering properties. Furthermore, we found that the morphology of ice crystal nuclei has a significant impact on their scattering characteristics even at medium levels of melting degree. In summary, this study confirms that it is essential to consider morphology and inhomogeneous characteristics during the melting process for microwave detection of ice crystal particles. This research may have significant implications for studies related to detection and inversion techniques for ice crystal particles.

Removal and distribution behaviors of inclusion particles in the steel melt under different rotation modes during continuous casting

This work investigated the removal and distribution behaviors of non-metallic inclusion particles caused by the flow of molten steel under two rotational modes, i.e. from edge to center (E-C) and from center to edge (C-E). Three-dimensional mathematical models discovering the relation between fluid flow, temperature distribution, solidified shell growth of large round bloom, and the movement of inclusions were established to investigate the mechanism of the differences. The obtained results show that under the C-E rotational mode, the removal rate of inclusions is 7 times and the highest local agglomeration number density of inclusions is reduced by 38.4 % compared to the E-C rotational mode. The current work proposes that the C-E rotating flow of molten steel can effectively raise the removal and uniform distribution of inclusions, thereby providing a new strategy for effective control of inclusion during the continuous casting process utilizing the novel electromagnetic metallurgy.

A hydrophobic electroless copper-nickel fabric with dual drive energy conversion for all-weather anti-icing/icephobic and deicing

Ice can lead to inconvenience and disasters in human activities, making it a widely concern for researchers to find solutions to prevent icing. Hydrophobic materials have been developed for passive anti-icing with a long time, but without active deicing effect. Recently, researchers have explored hydrophobic photothermal materials with passive anti-icing and active deicing ability, which are limited on cloudy days and the night. Consequently, developing materials with anti-icing/icephobic and deicing capabilities for all-weather use has emerged as an innovative strategy. This paper develops hydrophobic PDMS/Cu-Ni@PET with photo/electric thermal properties to support all-weather anti-icing/icephobic and deicing, which is synthesized using copper-nickel and hydrophobic polydimethylsiloxane (PDMS). The PDMS/Cu-Ni@PET exhibits an outstanding anti-icing performance with a delayed icing time of 1224 s at -10 °C, and achieves a surface equilibrium temperature of 68.9 °C under 1 sunlight intensity, enabling the melting of surface ice particles within 614 ± 118 s. When a voltage is applied to both sides of the fabric, the equilibrium temperature can be reached within 60 s, and attained 158 °C at 6 V, enabling the melting of surface ice within 97 s. It provides a novel approach for developing photo/electric thermal superhydrophobic coatings that can maintain all-weather deicing performance.

Self-healing carbon fiber/epoxy laminates with particulate interlayers of a low-melting-point alloy

In order to prolong the service life of fiber-reinforced polymer composites, the implementation of self-healing ability with the micro-encapsulated healing agent has been extensively studied. However, such microcapsule-based self-healing composites typically suffer from degraded mechanical properties due to the liquid-phase inclusions, thereby limiting their proliferation. Here, a low-melting-point alloy is utilized as the particulate inclusions of carbon fiber/epoxy laminated composites. Field's Metal particles (melting point: 62 °C) are distributed between woven carbon fiber preforms followed by the resin impregnation to realize laminated composites with a Field's Metal-enhanced interlayer(s). The resulting laminated composites demonstrate the autonomic repair of interlaminar failure with a 40 % of healing efficiency. Most of all, the mechanical properties of these self-healing laminated composites are comparable to the conventional laminated composites attributed to the rigid inclusions that can be compressed to increase the fiber volume. Since the Field's Metal particle inclusions can bestow polymer composites with self-healing ability and the potential increase in mechanical properties, Field's Metal-enhanced fiber-reinforced polymer composites are expected to unlock the practical utility of self-healing composites.

Deactivation of iron particles during combustion and reduction

Iron is a promising carbon-free renewable energy carrier to replace fossil fuels. However, during a redox cycle, iron may experience deactivation due to structural changes, which can shorten the cycle lifetime. In this work, deactivation of iron particles in terms of changes in reactivity and morphology during the oxidation and reduction process was investigated, under both fixed-bed and suspension conditions. Simple thermal treatment in an inert atmosphere at 1200 °C had no influence on the reactivity of particles towards oxidation, even at long exposure resulting in mild agglomeration. In fixed-bed oxidation at 600 to 1100 °C, solid sintering was found to be rapid and severe at higher temperatures. However, the sintering showed no influence on the reactivity of particles towards H2 under slow-heating conditions in a TGA. In pulverized-fuel combustion in a drop tube reactor, the intensive combustion and heat release led to melting of particles and morphology change from irregular to spherical. As the reactor temperature was increased from 800 to 1200 °C, the particle reactivity in terms of reduction degree (fractional conversion from Fe2O3 to Fe) slightly decreased from 78 % to 72 %, possibly related to a minor loss of surface area. TGA experiments involving successive redox cycles showed a steady decline in reduction reactivity (750 °C, 2.5 % H2), slightly enhanced by agglomeration, while the oxidation degree (950 °C or 1200 °C, 21 % O2) remained constant. The present work indicates that both deactivation and loss of iron due to evaporation may serve to limit the energy release in iron combustion over extended cycles.

An on-demand source of nanoparticles for optomechanics

The generation of nanoparticles on demand, with good control over their size and shape, has been a challenge for nanotechnology and the rapidly growing field of levitated optomechanics. Here, we present the preparation, launch, and detection of single nanoparticles in both a buffer gas and in vacuum. A tightly focused ultrashort laser beam with low energy is used to melt, form, and release individual particles. Surface tension supports the creation of spherical particles from molten droplets whose radii can be controlled, here in the range r=80−200 nm, by varying the pulse energy. The particle source is compact and compatible with high vacuum. It can be applied equally to dielectrics and metals as demonstrated here for silicon and gold. The method is unique in its capability to generate pristine silicon spheres directly in vacuum, which would rapidly oxidize when formed in air. Silicon is of interest for levitated optomechanics, cavity cooling, and emerging quantum interference experiments because of its high infrared polarizability and its low work function. Combining the source with an infrared cavity, we characterize the launch velocity and transit dynamics for silicon and gold nanoparticles in a high-finesse cavity field.

A statistical analysis of the first stages of freezing and melting of Lennard-Jones particles: Number and size distributions of transient nuclei.

The freezing/melting transition is at the heart of many natural and industrial processes. In the classical picture, the transition proceeds via the nucleation of the new phase, which has to overcome a barrier associated with the free energy cost of the growing nucleus. The total nucleation rate is also influenced by a kinetic factor, which somehow depends on the number of attempts to create a nucleus, that translates into a significant density of proto-nuclei in the system. These transient tiny nuclei are not accessible to experiments, but they can be observed in molecular simulations, and their number and size distributions can be acquired and analyzed. The number distributions are carefully characterized as a function of the system size, showing the expected behavior, with limited spurious effects due to the finite simulation box. It is also shown that the proto-nuclei do exist even in the stable phase, in agreement with the fact that the (unfavorable) volume contribution to their free energy is negligible in the first stages of nucleation. Moreover, the number and size distributions evolve continuously between the stable and the metastable phases, in particular when crossing the coexistence temperature. The size distributions associated with any nucleus and with the largest one have also been calculated, and their relationship recently established for bubbles in a liquid [Puibasset, J. Chem. Phys. 157, 191102 (2022)] has been shown to apply here. This is an important relation for free energy barrier calculations with biased molecular simulations.

Three-dimensional simulation on phase change heat transfer of moving spherical particle

Investigating the motion process of paraffin particle under a mesoscopic scale is very helpful to master the heat transfer mechanism of the mushy zone in solid–liquid phase change. Prior researches predominantly focused on either particle motion or phase change, without accounting for their coupling. In this study, the three-dimensional finite element method is used to solve the motion and heat transfer of the particle, taking into account the coupling of motion and phase change. The moving grid is employed to trace the interface of moving particles and liquid using the Arbitrary Lagrangian-Euler method, which is able to calculate flow and heat transfer in fluid region and allow grid deformation in solid region. The results indicate that uneven fluid velocity around the particles results in non-uniform temperature gradients on particle’s surface. In areas with larger temperature gradient, it melts more quickly and its deformation is obvious. The maximum is located at particle orientation angle 30°. Changing the size and direction of fluid velocity will reinforce or inhibit the movement of particle. The changing time of motion direction when fluid velocity is −0.03 m/s shorten 2.7 times than when fluid velocity is −0.01 m/s. The initial temperature of the surrounding fluid has a positive relationship with the particle melting rate. The channel width affects significantly the motion and melting of particle. The initial position of particle has an important effect on it’s falling movement, and the closer is close to the wall of channel, the greater the displacement of left and right movement.

Influence of high-reactivity energetic materials on microstructure and performance on iron-based cladding layer under low laser power

Abstract Under low laser power conditions, the cladding layer is constrained by inadequate energy density, resulting in incomplete melting of certain powder particles and the occurrence of defects such as cracks and pores within the layer. This paper utilizes a QT500 substrate and synergistically integrates high-reactivity energetic materials (H-REMs) with metal powder. By external laser energy ignition, the localized combustion of the H-REMs (Al + Fe2O3) is induced, thereby providing additional heat input during the laser cladding process. Through in-depth analysis of extensive experimental data, the influence of H-REMson microstructure and performance of alloy cladding layerhas beenrevealed. The research results demonstrate that the inclusion of H-REMs leads to a 450 K increase in the maximum temperature of the molten pool. By incorporating high-reactivity energetic materials, the energy density utilization of the composite material increased from 0.2663 to 0.7375. The combustion wave generated by H-REMs induces mixing in the molten pool, resulting in cladding layer grain refinement and an average hardness increase of 80 HV1. The friction coefficient decreases from 0.71024 (prior to the addition of H-REMs) to 0.35809, representing a reduction of approximately 49 %.