Solid-liquid Interface Research Articles

Microstructure and mechanical properties of Al-Cu alloy during wire and arc additive manufacturing by adding micron TiB2 particles

ABSTRACT Micron TiB2 particles were added to the 2319 aluminum alloy using a surface coating method during the additive process. The study focused on the formation, microstructure, and properties in order to achieve deposited components with a uniform microstructure and enhancing strength and plasticity. The critical migration velocity (Vcr = 335 μm/s) of with micron-sized TiB2 particles addition was larger than the solidification rate, which caused particles to be pushed by the solid-liquid interface and ultimately reside at the grain boundary position. The micron-sized TiB2 particles reduced the activation energy for nucleation of the precipitation of the θ’ phase, lowered the energy barrier for nucleation, and introduced dislocations to create lattice distortion channels. This enabled rapid diffusion of solute atoms and facilitated the precipitation and growth of the θ’ phase. Finally, the transverse strength and elongation were higher, reaching 339.07 MPa and 21.3%, which increased by 45% and 60% respectively.

Thermal Transport across Liquid–Solid Interface with a Single-Atomic Structure Based on the Radial Density Depletion Length at a Surface Solid Atom

Thermal Transport across Liquid–Solid Interface with a Single-Atomic Structure Based on the Radial Density Depletion Length at a Surface Solid Atom

Photocurrent Ambipolar Behavior in Phase Junction of a Ga2O3 Porous Nanostructure for Solar-Blind Light Control Logic Devices.

Photoelectrochemical (PEC) devices are the most similar artificial devices to the nervous system, which is expected to solve the problem of complex computer/nervous system interface (solid-liquid interface) and multifunctional integration (photoelectric fusion) required in the post-Moore era. Based on the different photocurrent ambipolar behavior and different deep ultraviolet solar-blind spectral photoresponse characteristics of α-Ga2O3 and β-Ga2O3, we designed and constructed the Ga2O3 porous nanostructure PEC device with an adjustable photocurrent bipolar behavior through constructing an α/β phase junction core-shell structure by adjusting the thickness and the surface state of the shell layer. The switching point of the α/β-Ga2O3 ambipolar photocurrent shifts toward negative values with the increase of β-Ga2O3 shell layer thicknesses, and adjustable Boolean logic gates are prepared using the voltage as the input source with a high accuracy manipulated by solar-blind deep ultraviolet light. The controllable solar-blind logic gates based on the ambipolar photocurrent behavior of α/β-Ga2O3 presented in this study offer a new path for the photoelectric device multifunctional integration needed in the post-Moore era, which can be used in the creation of Ga2O3 half adders and full adders, as well as in the construction of four-input OR gates.

In-situ self-assembly growth of controllable gold nanoparticles film

Because of the strong light absorption and/or scattering, nano scaled gold has many favorable optic and electric properties. With the continuous miniaturization of nano photoelectronic devices and nano electromechanical systems, there is an urgent demand for controllable and tailored gold nanoparticles film with excellent performance. Here, a modified HAuCl4-NaOH-CTAB (cetyltrimethylammonium bromide) aqueous solution system was utilized to self-assembly synthesize gold nanofilm on glass substrates. The high concentration NaOH is not only reducing Au3+ to Au0, but facilitating interfacial assembly of gold nanostructure at liquid–solid interface via etching glass surface. Based on this growth kinetic, the gradient, well-designed and in-situ growing gold nanoparticles film can be achieved on any SiO2 contained substrates by controlling the growth time in the reaction system. Furthermore, the in-situ self-assembled gold nanoparticles film can be act as plasmon substrates for surface-enhanced Raman scattering (SERS) or plasmonic enhanced semiconductor lasing, even gold electrodes.

Nanoindentation creep mechanism of gradient ultrafine lamellar γ+Ni5Zr eutectic using electromagnetic levitation coupled with fall casting

A quaternary Ni50Fe20Cr20Zr10 eutectic alloy was designed based on the Ni–Fe–Cr alloy, and the gradient ultrafine lamellar γ+Ni5Zr eutectic was achieved by means of electromagnetic levitation coupled with fall casting (EML-FC). The temperature field, the process of interface migration, microstructural characteristics and the nanoindentation creep property of the alloy were systematically analyzed. During the rapid solidification, since the conical surface served as the main heat dissipation channel, the solid-liquid interface moved from the conical surface towards the top of the cone axis. The gradual decrease in cooling rate from 105 to 103 K s−1 along this direction led to the formation of the gradient ultrafine lamellar γ + Ni5Zr eutectic with the size from 59 ± 12 to 140 ± 36 nm. The nanoindentation creep behavior and mechanism were analyzed by estimating the strain rate sensitivity and activation volume. As the interlamellar spacing of the eutectic decreased, the nanohardness and creep resistance of the alloy gradually increased owing to an increase in grain boundary density and the enhancement of coupling effect between dislocation and grain boundary. In addition, the creep behavior of alloy was sensitive to the loading rate. Increasing the loading rate led to an increase in strain rate sensitivity from 7.69 × 10−3 to 18.89 × 10−3 and a decrease in activation volume from 29 to 12 b3. This special eutectic structure and its improved nanohardness and creep resistance properties offered a potential opportunity to explore a new generation of alloys for the hot-end components of 972 K ultra-supercritical fossil-fired power plants.

Partial differential equation modelling of the solid–liquid phase process in iron sintering and interface control with backstepping method

Due to the highly continuous temporal and spatial distribution characteristics of the sintering process, the solid–liquid phase interface during sintering is uneven and discontinuous, which seriously affects the quality of sintered ore. In order to achieve real-time and effective control of the solid–liquid interface in the sintering system, this study proposes a spatiotemporally distributed partial differential equation (PDE) thermal system with Stefan interface boundaries. Slice the 3D sintering mixing space and establish a discrete 1D space multi-distributed system to achieve distributed control of the sintering thermal system. Based on this system, a distributed boundary controller is designed using the backstepping method to drive the solid–liquid phase interface to the desired position. This method fully adapts to the nonlinear problems of the sintering thermal system and can quickly respond to system changes. Based on real data from the sintering site, a multi-physics simulation model was designed to verify the correctness of the theoretical research. Comparing the simulation results with the actual sintering state shows that this control method can effectively control the position of the sintering solid–liquid interface, which plays a vital role in improving the quality of sinter and sintering efficiency.

Chitin extraction from crab shells and synthesis of chitin @metakaolin composite for efficient amputation of Cr (VI) ions

The present research study combines chitin from shrimp waste with the oxide-rich metakaolin. Metakaolin is a blend of mixed oxides rich in silica and alumina with good adsorbent properties. The chitin@metakaolin (CHt@M.K.) composite was synthesized and characterized using FTIR, SEM, TGA, XRD and XPS techniques. Cr(VI) removal studies were compared for chitin and CHt@M.K. through adsorption. It was found that the adsorption capacity of CHt@M.K. is 278.88 mg/g, almost double that of chitin, at pH 5.0 in just 120 min of adsorption. Isotherm models like Langmuir, Freundlich, Temkin and Dubinin–Radushkevich were investigated to comprehend the adsorption process. It was revealed that Langmuir adsorption isotherm is most suitable to elucidate Cr(VI) adsorption on CHt@M.K. The adsorption kinetics indicate that pseudo first order was followed, indicating that the physisorption was the process that limited the sorption process rate. The positive enthalpy change (20.23 kJ/mol) and positive entropy change (0.083 kJ/mol K) showed that the adsorption process was endothermic and more random at the solid-liquid interface. The negative free energy change over entire temperature range was an indicator of spontaneity of the process. Apart from all these, the non-covalent interactions between Cr(VI) and composite were explained by quantum calculations based models.

Effects of pH-varying thermal modification on sewage sludge: A focus on releasing nitrogen- and phosphorus-containing substances

Sewage sludge is promising for the recovery and utilisation of nutrient components, but its complex nature hinders the release of these components. The combination of pH and thermal modifications shows promise for the release of nutrient components from sludge. However, comprehensive studies on the full spectrum of pH levels and corresponding mechanisms of pH-varying thermal modification are lacking. In this study, the main nutrient components, physicochemical properties, molecular structure, and noncovalent interactions of sludge were comprehensively investigated through pH-varying thermal modification (within a pH range of 2.0 to 12.0 under the same thermal condition). The experimental results showed that the release of main organics, particularly nitrogen (N)-containing organics, was well-fitted, with a tick-like function (R2: 0.74–0.96). The thermal protons exhibited a notable accumulative mutagenic effect on the N-containing organics release, while the thermal hydroxyl ions had a more direct effect, as revealed by the changes in multivalent metals and molecular structures with the protonation–deprotonation of carboxyl groups. The driving force for the release of N-containing organics was identified as the fluctuation of electrostatic interactions at the solid–liquid interface of the sludge. However, the release of phosphorus (P)-containing substances exhibited a contrasting response to that of N-containing substances with varying pH, likely because the reaction sites of thermal protons and thermal hydroxyl ions for P-containing substances were different. Moreover, high concentrations of thermal protons and hydroxyl ions collapsed the Lifshitz–van der Waals interactions of sludge, resulting in a decrease in viscoelasticity and binding strength. These propositions were further confirmed through statistical analyses of the main indicators of the main nutrient components, physicochemical properties, and noncovalent interactions of sludge. These findings can provide a basis for optimising characteristic-specific methods to recovery nutrient components (N/P) from sludge.

Recovery of Rare Earth Elements from Ion-Adsorption Deposits Using Electrokinetic Technology: The Soil Conductivity Mechanism Study

Rare earth elements (REEs) are essential raw materials for modern industries but mining them has caused severe environmental issues, particularly the recovery of heavy REEs (HREEs) from ion-adsorption deposits (IADs). Very recently, an emerging technology, electrokinetic mining (EKM), has been proposed for the green and efficient recovery of REEs from IADs. However, the conduction mechanism of the weathering crust soil, which is also a prerequisite for EKM, remains unclear, making the EKM process unpredictable. Here, we systematically investigated the conductivity of weathering crust soil in the presence of light REEs (LREEs, i.e., La3+ and Sm3+) and HREEs (Er3+ and Y3+), respectively. Results suggested that the voltage was dynamically and spatially redistributed by the movement of REEs and water during EKM, and the conventional assumption of the linear distribution of voltage leads to an inaccurate description of soil voltage. We proposed an improved Archie’s equation by coupling the mechanisms of liquid phase and solid-liquid interface conduction, which can predict soil conductivity more precisely. Moreover, the extended Archie’s equation is able to recalculate the voltage distribution at distinct times and spaces well during EKM. More importantly, the water content in field-scale weathered-crust soils can be retrieved by the newly proposed Archie’s equation, which helps optimize the leaching wells and improve the recovery rate of REE. This study focuses on the conduction mechanism of weathering crust soil, which provides a theoretical basis for better use of the EKM technology and promotes mining efficiency fundamentally.

Multi-Interface Electromagnetic Wave Absorbing Material Based on Liquid Marble Microstructures Anchored to SEBS.

The direct application of liquid marbles in electromagnetic wave (EMW) absorption is challenging due to their poor stability, susceptibility to gravitational collapse, and shaping difficulties. To address this issue, a novel strategy is proposed to incorporate liquid marble microstructures (NaCl/nano-SiO2) encapsulated in organic phases (Octadecane) into the rubber-matrix (SEBS) using the ultrasound-assisted emulsion blending method. The resulting NaCl/SiO2/Octadecane microstructures anchored to SEBS offer a substantial solid-liquid interface consisting of NaCl solution and SiO2. When subjected to an alternating electromagnetic (EM) field, the water molecules and polysorbate within SiO2 exhibit heightened responsiveness to the EM field, and the movement of Na+ and Cl- within these microstructures leads to their accumulation at the solid-liquid interface, creating an asymmetric ion distribution. This phenomenon facilitates enhanced interfacial polarization, thereby contributing to the material's EMW absorption properties. Notably, the latex with 16wt% SEBS (E-3), exhibiting a surface morphology similar to human cell tissues, achieves complete absorption of X-band (fE=4.20GHz, RLmin=-33.87dB). Moreover, the latex demonstrates light density (0.78gcm-3) and environmental stability. This study not only highlights the predominant loss mechanism in rubber-based wave-absorbing materials but also provides valuable insights into the design of multifunctional wave-absorbing materials.

Dislocation interaction with vicinally faceted groove at grain boundary in multi-crystalline silicon

The morphology of the solid–liquid interface and the GB development during directional solidification process of multi-crystalline silicon (mc-Si) has been studied with an in situ observation system. A small angle grain boundary was observed to have a gradually increasing faceted groove, finally reaching a steady state. A geometric model is used to simulate the growth of groove facets with consideration of different facet growth kinetics. It appears that the kinetics of a face vicinal to a {111} plane is most likely to reproduce the observed behavior. Later on, variations of groove size and grain boundary direction occurred. The geometric simulation results show that such perturbations could be produced by the interaction of single dislocations with one of the vicinal facets.

Effects of surfactant types on anthracite dust wettability: Experimental and molecular simulations

To study the wetting mechanism of surfactants at the solid–liquid interface of anthracite, a combination of experiments and molecular simulation was used to explore the adsorption and wetting processes of four surfactants, namely, fatty alcohol polyoxyethylene ether N = 9 (AEO9), Triton X-100, rapid penetrant T (PRT), and sodium alkyl ether sulfate (AES) on anthracite. The wetting mechanism of surfactants on anthracite was analyzed at both macroscopic and microscopic levels by surface tension, contact angle, settling time, and changes in surface morphology and functional groups on the anthracite surface. The presence of OH-π and C = O was determined to significantly enhance anthracite wettability. The anthracite/surfactant/water system was constructed from a microscopic perspective, and the interaction energies, relative concentration distributions along the Z-axis, diffusion coefficient (D) of water molecules, radial distribution functions (RDF) of hydrophilic groups and water molecules, and coordination numbers of the components were analyzed. The results show that the wetting effect depends on the adsorption state of the surfactant at the anthracite/water interface and the strength of the interaction between the surfactant and water molecules. The addition of surfactants enhances the adsorption thickness of water molecules along the Z-axis and generates more hydrogen bonds, which play a role in fixing water molecules and lead to a decrease in the D of water molecules. RPT forms the highest number of hydrogen bonds with water molecules and has the lowest D of 0.479 × 10-5 cm2/s, indicating strong wetting ability. The RDF of O atoms in surfactants and water molecules shows a similar trend, with two peaks one strong and one weak. The coordination numbers are 1.356, 1.057, 1.003, and 0.903, respectively. The final wettability of the surfactant on the anthracite depends on the synergistic interaction between the oxygen functional groups (OGs) as compared to the coordination number of the individual OGs.

Pore-scale study of melting characteristic of phase change material embedded with novel open-celled metal foam

Metallic porous structure is a prevailing heat transfer enhancer for the melting of phase change material (PCM), while the effect of the structure on the enhancement performance is yet to be understood. In this work, a pore-scale numerical study on PCM melting embedded in a truncated cuboctahedron porous structure, referred as TCD metal foam, was performed. The solid–liquid interface, temperature and the variation of liquid fraction were analyzed and compared with those with the tetrakaidecahedron porous structure, referred as TKD metal foam. The effects of natural convection, porosity, pore density and heating temperature are explored. It is found the natural convection shortens the PCM melting time by about 7 % with the considered porosity range and thus cannot be ignored. Results also show that the TCD metal foam better enhances PCM melting near the porous cell corners compared to the TKD metal foam. Further analysis shows the TCD metal foam can better enhance melting at the former stage due to the larger surface area, while the TKD metal foam can better enhance melting at the later stage due to the thicker metallic ligaments. With essentially the same melting time at ɛ = 0.941, the half-melting takes 17.2 % of the complete melting time for TCD metal foam and 20.3 % of the complete melting time for TKD metal foam. A critical porosity value exists when comparing the enhancement performance of these two metal foams, below which the better melting enhancement is shifted from the case with TCD metal foam to the case with TKD one. The critical porosities are 0.941, 0.923 and 0.899 at the pore densities of 10, 20 and 30 PPI respectively.

Metal-organic frameworks as an active substrate for cell-interaction studies and cell-on-a-chip platforms

Metal-organic frameworks (MOFs) are an emerging class of materials with immense biomedical potential for their unique interactions with biological and organic materials. In this work, we select two candidate two-dimensional (2D) MOF systems based on Fe3+ and Ni2+ metal centers and 2-aminoterephthalate acid ligand (Fe-MOF and Ni-MOF) and evaluate their performance as an active interface for study of cell-interactions. 2D Fe-MOF and Ni-MOF were synthesized onto hydroxyl-modified gold and glass substrates using a layer-by-layer liquid-phase-epitaxy (LbL-LPE) growth at room temperature and used as active substrates (Fe-MOF/glass, Fe-MOF/Au, Ni-MOF/glass and Ni-MOF/Au, respectively) for MTT cell-proliferation and reactive oxygen species tests using the PC-12 cell-line in order to investigate the biocompatibility. Immunostaining and morphological analyses of PC-12 cells on MOF interfaces suggested a stronger cell-substrate interaction in comparison to glass and were further characterized using the Electrical Cell-substrate Impedance Sensing (ECIS) technique, here for the first time, employed to study cell attachment, spreading and proliferation on 2D Fe-MOF. The 2D Fe-MOF showed superior long-term stability in cell culture medium by recording impedance over 24 hours, crucial to monitor cell-dynamics at a solid-liquid interface. A significant increase of interfacial impedance was observed in ECIS, due to PC-12 cells adhering onto 2D Fe-MOF, which was also confirmed by the focused ion beam etching followed by scanning electron microscopy. Our novel findings, therefore, suggest 2D MOFs as highly suitable platform for the study of cell-related interactions using electrical techniques and potentially pave the way for future use of MOFs for bioelectronics and biosensor applications.

Liquid-solid interface diffusion behaviors of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper

Furfural as an ageing product of cellulose paper can be detected by the furfural content in the oil. With the construction of green power grid, more and more power equipment adopts environmentally friendly insulating fluids. The investigation of the diffusion behaviors of furfural at different oil-paper interfaces can provide a basis for fault detection in power transformers. The liquid-solid interface diffusion behaviors of furfural in natural ester-cellulose paper and mineral oil-cellulose paper insulating systems are investigated by molecular dynamics simulation in this paper. Results show that the range of center-of-mass movement distances of furfural in mineral oil-cellulose paper is about 5 times that of natural ester-cellulose paper. The main reason for this is that the long-chain macromolecules composing the natural ester undergo curling in the extended flow. As polar molecules, natural ester can attract furfural, which is also a polar molecule. And the electrostatic potential mapping interval of furfural is about 4.4 times that of mineral oil, but 1.1 times that of natural ester, with which it overlaps more. These hinder the diffusion of furfural molecules in the natural ester-cellulose paper liquid-solid interface. This research provides theoretical support for the diffusion of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper. It also provides useful guidance for fault detection in transformers using natural ester insulating fluids.

From Interface Effect to Bulk Effect: Probing the Capacitive Coupling Enhancement Mechanism to Achieve High Performance DC Droplet-Based Nanogenerator

The DC droplet-based nanogenerator (DNG) technology has opened up a new avenue for high-entropy water energy harvesting. However, the conventional DC DNG relies on the interface effect to generate a limited surface charge density, which severely restricts its electrical performance. Here, inspired by the MOS transistors, a novel total current DNG (TC-DNG) platform with back-gate modulation structure is developed, successfully realizing the transform from interface effect to bulk effect. By using the rationally patterned DNG as triboelectric probe, an intriguing capacitive coupling enhancement mechanism is discovered. With such a mechanism, the nanogenerator could employ both the capacitive coupling effect of the back-gate electrode and the self-exciting effect of droplet charge-shuttles to achieve a significantly enhanced performance in both charge transfer and voltage output. As a result, this TC-DNG provides a transferred charge of 30 nC per droplet and an output voltage of 800V and is capable of illuminating 480 high-brightness LEDs without using any power management circuit. In addition, this TC-DNG could easily adapt to a wide range of application scenarios owing to the interchangeability of the back-gate material. This work could inspire further innovations in energy transfer mechanism and harvesting technology at the liquid-solid interface.

Emergence of rapid solidification microstructure in additive manufacturing of a Magnesium alloy

Abstract Bioresorbable Mg-based alloys with low density, low elastic modulus, and excellent biocompatibility are outstanding candidates for temporary orthopedic implants. Coincidentally, metal additive manufacturing (AM) is disrupting the biomedical sector by providing fast access to patient-customized implants. Due to the high cooling rates associated with fusion-based AM techniques, they are often described as rapid solidification processes. However, conclusive observations or rapid solidification in metal AM — attested by drastic microstructural changes induced by solute trapping, kinetic undercooling, or morphological transitions of the solid-liquid interface — are scarce. Here we study the formation of banded microstructures during laser powder-bed fusion (LPBF) of a biomedical-grade Magnesium-rare earth alloy, combining advanced characterization and state-of-the-art thermal and phase-field modeling. Our experiments unambiguously identify microstructures as the result of an oscillatory banding instability known from other rapid solidification processes. Our simulations confirm that LPBF-relevant solidification conditions strongly promote the development of banded microstructures in a Mg-Nd alloy. Simulations also allow us to peer into the sub-micrometer nanosecond-scale details of the solid-liquid interface evolution giving rise to the distinctive banded patterns. Since rapidly solidified Mg alloys may exhibit significantly different mechanical and corrosion response compared to their cast counterparts, the ability to predict the emergence of rapid solidification microstructures (and to correlate them with local solidification conditions) may open new pathways for the design of bioresorbable orthopedic implants, not only fitted geometrically to each patient, but also optimized with locally-tuned mechanical and corrosion properties.

Gas-driven triboelectric nanogenerator for mechanical energy harvesting and displacement monitoring

Gas as an energy carrier has been widely studied, ranging from small bubble motions to steam strike turbines. Despite the remarkable results, fewer studies have investigated the gas-driven liquid column movement commonly used in hydraulic systems, oil extraction, and other fields. Herein, we proposed a gas-driven triboelectric nanogenerator (GD-TENG) with liquid column motion for mechanical energy harvesting and displacement monitoring. When the gas drives a single liquid column to move inside a polytetrafluoroethylene (PTFE) tube, the solid-liquid interface of the GD-TENG can achieve efficient sliding friction and generate an open-circuit voltage of 15.9 V. Meanwhile, the influence of some critical parameters such as liquid column length, PTFE tube wall thickness and liquid column motion speed on the output performance of the GD-TENG were systematically investigated. Furthermore, the GD-TENG can successfully harvest mechanical energy to power microelectronic devices. A sensing system was designed based on the GD-TENG device for displacement monitoring of moving objects. This work provides a new research path in the field of mechanical energy harvesting and self-powered displacement monitoring.

Microcalorimetry Techniques for Studying Interactions at Solid–Liquid Interface: A Review

Solid–liquid interfacial phenomena play an essential role in our everyday lives and are often regarded as the outcome of interactions at the solid–liquid interface. However, the intricately intrinsic mechanism underlying interfacial interactions renders in situ simulations and direct measurements challenging. As an effective analytic method for studying solid–liquid interfacial interactions, microcalorimetry can provide the most basic thermodynamic information (including changes in enthalpy, entropy, and Gibbs free energy during solid–liquid binding/separation processes), which is extremely crucial for understanding interaction directionality and limitation. This review is dedicated to highlighting the pivotal role of microcalorimetry in studying solid–liquid immersion and adsorption processes. Specifically, we provide an overview of the commonly employed microcalorimetric methods, including differential scanning calorimetry (DSC), isothermal titration calorimetry (ITC), and immersion microcalorimetry (IM), and delve into the influence factors of enthalpy change, and finally discuss the specific applications of microcalorimetry in studying various solid–liquid binding processes. There remains a vast expanse of thermodynamic information regarding solid–liquid interactions that await exploration via calorimetry.

Homogeneous Growth of 3C-SiC Crystal Surface at Solid–Liquid Interface and Its Competitive Relationship

Homogeneous Growth of 3C-SiC Crystal Surface at Solid–Liquid Interface and Its Competitive Relationship