Surface Contact Angle Research Articles

Microscopic Effect of Mixed Wetting Capillary Characteristics on Spontaneous Imbibition Oil Recovery in Tight Reservoirs

The understanding of the mechanisms that govern water spontaneous imbibition in mixed wetting capillary channels plays a significant role in operating the oil extraction and energy replenishment for the tight oil reservoirs. In this work, the conservative form phase-field model together with the Navier–Stokes equation is employed to investigate the influence of the mixed wetting distribution and the wetting degree on the imbibition oil recovery effects and microscopic flow characteristics. Results indicate that there exist different oil detachment modes of spontaneous imbibition, and these modes are determined by the coupled effect of mixed wetting fraction and contact angle size. For the mixed wetting capillary with strong oil wetting, when fw is low, spontaneous imbibition can only partially detach the oil. Low fw slows down the fluid flow velocity and leads to the small imbibition oil recovery rate. After that, the influence of the surface contact angle size of the mixed wetting capillary is discussed. For the complete detachment mode, the capillary tube presents a form of water phase saturated filling, achieving the optimal imbibition oil recovery effect. For the mixed wetting capillary tube with the combination of weak water wetting and strong oil wetting (i.e., θw = 75° and θo = 165°), local spontaneous imbibition turbulence can only detach very little oil at the inlet of the water wetting area, ultimately achieving a recovery efficiency of less than 10%. This work illuminates the spontaneous imbibition oil recovery mechanisms and flow potentiality for the different mixed wetting capillary channels.

Surface Hydrophilic Modification of Polypropylene by Nanosecond Pulsed Ar/O2 Dielectric Barrier Discharge.

Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux reduction, which greatly hinders the applications of PP membranes. Dielectric barrier discharge (DBD) is an effective technique for surface modification of materials because it generates a large area of low-temperature plasma at atmospheric pressure. In this study, O2 was added to nanosecond pulsed Ar DBD to increase its reactivity. Electrical and optical diagnostic techniques were used to study the discharge characteristics of the DBD at varying O2 contents. The uniformity of the discharge was quantitatively analyzed using the observed discharge images. Water contact angle measurements were used to assess the surface hydrophilicity of polypropylene. The surface morphology and chemical composition of the PP materials before and after treatment were analyzed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the moderate addition of O2 enhances surface hydrophilicity and the uniformity of the modification. By increasing the O2 addition from 0% to 0.1%, the average power increased from 4.19 W to 5.79 W, and the energy efficiency increased from 17.78% to 21.51%. The water contact angle of the DBD-treated PP showed a tendency to decrease and then increase with increasing O2 content, with the optimum O2 addition determined to be 0.1%. Under this condition, the water contact angle of the PP surface decreased by 31.88°, which is 52.31% lower than the untreated surface. O2 increases the number of oxygen-containing polar groups (-OH, C=O, and O-C=O) on the surface of the material, and deepens and densifies the grooves on the surface of the PP material, resulting in an increase in the hydrophilicity of the PP surface.

Levofloxacin-loaded silicone contact lenses materials for ocular drug delivery

Silicone contact lenses (SCL), as an emerging ocular drug delivery system, achieve controlled drug release. However, the existing drug loading methods have limitations such as low drug uptake, complicated operation process, poor welling rate and transmittance of the lens after drug loading. In this study, an effective microemulsion soaking method was proposed to increase the drug-loading capacity of silicone contact lenses. Levofloxacin (LVF) was encapsulated into the microemulsion by direct agitation, then the microemulsion was loaded into silicone contact lenses using the immersion method. The adsorption capacity of levofloxacin and its effect on drug release kinetics were explored. The results showed that the particle size of the microemulsion was approximately 160 nm. The levofloxacin microemulsion soaking method (LVF-ME-SCL) significantly enhanced the drug loading of levofloxacin in the silicone contact lenses, achieving a maximum drug loading of 216.32 ± 1.15 μg/lens ( p > 0.05). The total release rate of levofloxacin was 95.96% when the sustained release time was 10 h, and the drug leakage observed after 10 h was negligible. The survival rate of E. coli and S. aureus in LVF-ME-SCL-1 (LVF concentration was 4.8 mg/mL) group was 0 and 19.33 ± 0.02% ( p < 0.0001), with a significant difference, indicating that the drug-loaded silicone contact lenses exhibited effective bactericidal properties against E. coli and S. aureus. Following the addition of maximum levofloxacin, the surface contact angle of silicone contact lenses decreased significantly to 32.88 ± 1.19° ( p > 0.05), while the swelling, mechanical properties, and oxygen permeability remained relatively unchanged. There was no significant decrease in the transmittance of the contact lenses after the addition of levofloxacin, which remained above 95%. In conclusion, these results show that the microemulsion impregnation method effectively improves the drug loading and sustained release time of levofloxacin, and maintains lens performance stability before and after drug loading, so it is expected to be used in ophthalmic treatment.

Mechanism of Efficient Smithsonite Flotation with a Ternary Composite Collector Under Sulfur-Free Conditions.

The increasing demand for zinc resources and the declining availability of sulfide zinc ore reserves have made the efficient utilization of zinc oxide a topic of considerable interest. In this study, a ternary composite collector ABN (Al-BHA-NaOL system) was applied to the direct flotation of smithsonite. Micro-flotation studies showed that at pH 9, ABN exhibited better adsorption on smithsonite, achieving a recovery rate of 80.62%. Visual MINTEQ 3.1 and zeta potential analysis confirmed that ABN predominantly reacted with Zn(OH)2(aq) on the surface of smithsonite. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis results elucidated the formation of Al-O bonds through chemical adsorption on the smithsonite surface. Additionally, powder contact angle measurements indicated that ABN enhances the surface contact angle of smithsonite. These results illuminate that ABN is adsorbed by reacting with O sites on hydroxylated metal ions on the smithsonite surface, with Al serving as the adsorption center, thereby achieving separation and purification. Due to ABN's adsorption characteristics, smithsonite can achieve efficient and clean direct flotation recovery without sulfidization.

Study on the Influence of Surfactant Solution on the Wetting and Chemical Structure Characteristics of Coal at Different Temperatures.

To reduce the production of dust in the coal mine production process, the surface tension and contact angle of the solution at different temperatures were measured, and the temperature range of the surfactant to achieve the best wetting effect during the coal seam water injection was determined. The results show that the surface tension and contact angle of sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS) and of SDS and polysorbate 80 (Tween80) decrease rapidly at first and then increase slowly with the increase of temperature, the minimum surface tension values were 26.293 and 27.726 mN/m, and the minimum values of contact angles were 89.35 and 65.1°, respectively. The two kinds of composite solutions have the best wetting effect at 35-40 °C. In addition, the influence of surfactants on the chemical structure of coal under different temperature conditions was analyzed, and the variation rule between the chemical structure and the wetting property of coal was explored. The research results have important practical guiding significance for reducing dust generation in a coal mine.

Effect of Adjuvants on Physical–Chemical Properties, Droplet Size, and Drift Reduction Potential

Adjuvants alter the physical–chemical properties of pesticide formulations, influencing either the droplet size or drift phenomenon. Selecting the appropriate adjuvant and understanding its characteristics can contribute to the efficiency of Plant Protection Product (PPP) application. This reduces drift losses and promotes better deposition on the crop. The objective of this study was to evaluate the effects of four commercial adjuvants based on mineral oil (Agefix and Assist), vegetable oil (Aureo), and polymer (BREAK-THRU) on the physical–chemical properties (surface tension, contact angle, volumetric mass, electrical conductivity, and pH), droplet size, and drift, using pure water as the control treatment (no adjuvant). Surface tension and contact angle were measured with a DSA30 droplet shape analyzer, while droplet size measurements were determined through a laser diffraction particle analyzer (Malvern Spraytec), using a single flat fan spray nozzle (AXI 110 03) operating at 0.3 MPa. Drift reduction potential was evaluated inside a wind tunnel with an air speed of 2 m s−1. All adjuvants reduced surface tension and contact angle compared to water. volumetric median diameter (VMD) increased for Aureo, Assist, and Agefix, generating coarse, medium, and medium droplets, respectively, while BREAK-THRU formed fine droplets, similar to those generated by water. Aureo had the greatest reduction in Relative Span Factor (RSF), with a reduction of 30.3%. Overall, Aureo, Assist, and Agefix adjuvants significantly reduced the percentage of droplets <100 µm and increased those >500 µm. Drift reduction potential was achieved for all adjuvants, with Aureo showing the highest reduction of 59.35%. The study confirms that selecting the appropriate adjuvant can improve PPP application and promote environmental sustainability in agricultural practices.

A green, versatile, and facile strategy for anti-biofouling surface with ultra-high graft density polyethylene glycol

Implantable catheters are susceptible to severe complications due to non-specific protein adhesion on their surfaces. Polyethylene glycol (PEG) coatings, the gold standard for resistance to non-specific protein adhesion, present a challenge in achieving high-density grafting, which significantly restricts their use as anti-biofouling coatings. Herein, we exploited the strong interaction between polyphenols (PCs) and polycations (K6-PEG) to graft PEG onto the surface of PC-Cu (A network of metal polyphenols composed of proanthocyanidins and metal copper ions, with expectation for the coating with excellent resistance to non-specific protein adhesion (PC-Cu@K6-PEG). The introduction of K6-PEG resulted in enhanced stability and modulus of PC-Cu, as well as a reduction in the surface adhesion energy and contact angle of PC-Cu. In contrast to previously reported PEG coatings, PC-Cu@K6-PEG exhibited a markedly elevated grafting density of PEG (4.06 chains/nm²), which was more than double the highest value previously reported (1.9 chains/nm²), due to the diffusing ability of K6-PEG throughout the PC-Cu networks. PC-Cu@K6-PEG displays robust resistance to a variety of proteins, microbials, and platelet attachment, thereby preventing thrombosis. The coating ability of PC-Cu onto diverse substrates, combined with the simple, straightforward and environmentally benign process of fabricating PC-Cu@K6-PEG, suggests that this strategy has significant potential for use in anti-biofouling surfaces.

A Study on the Manufacture of CNT Composites Bipolar Plate for the Fuel Cell Using a Nanosecond Pulsed Laser

The channels of the graphite-based bipolar plate for hydrogen fuel cells were mainly manufactured through milling due to low forming elongation and processability. However, during the milling process, the machining precision is low due to tool wear and vibration, and there is a risk of breakage. Non-traditional laser processing can solve the problems of tool wear and vibration through non-contact processing. In this study, the interaction characteristics of the nanosecond pulsed laser and CNT composites were observed, and channels and bipolar plates were manufactured. The effect of scanning speed and pulse duration was observed for interaction characteristics. Defects were observed due to high thermal effects at low scanning speed and high pulse duration. Channels were created depending on parallel pitch distance [] and Number of scans (NOS). The channel was evaluated for depth, top width, bottom width, channel angle, material removal rate, and surface roughness, and significant changes were observed depending on . The chemical composition, surface resistance, and contact angle of the laser-processed channel were measured. The laser processed channel was oxidized, and the surface resistance and contact angle increased. Finally, the manufacturability of the CNT composites bipolar plate using laser was examined.

Correlation between surface wettability and fluid physics characteristics of lignite under compound solution regulation

The specific composition and ratio of the composite wetting agent will affect its dust reduction effect. Therefore, in order to study the effect of the composite wetting agent on the wettability and physical structure of lignite, the anionic surfactant sodium dodecyl sulfate was selected and mixed with different concentrations of sodium chloride to obtain different concentrations of the composite wetting agent. The correlation between the fluid physical properties of these composite wetting agents and the wetting of lignite surfaces was comprehensively explored by contact angle measurement, surface tension analysis, and low-temperature liquid nitrogen adsorption experiments, and the potential effects on pore structure were investigated. The results showed that as the sodium chloride concentration increased, the surface tension, contact angle, adhesion work, and surface free energy of the composite solution decreased, while the diffusion coefficient increased. There was a high linear correlation between the pore diameter of coal and the contact angle (R2 = 0.955), which revealed the close relationship between the permeability behavior of the fluid in the coal pores and the physical structure of the coal body. In addition, composite wetting agents with high sodium chloride concentrations exhibited a specific pore expansion effect, which helped optimize the coal's pore distribution and thus promoted effective coal wetting. This study not only deepens our understanding of the role of fluid physics principles in dust removal technology but also provides an important theoretical basis for selecting suitable composite wetting agents and their optimal ratios.

Measurement of surface tension and contact angle of solar salt at high temperature with axisymmetric drop-shape analysis

As interfacial properties of common materials enabled many practical applications, those for molten salts would do the same. While their properties are important for the safety and design of thermal energy storage and modular nuclear reactors, they are hard to obtain because of the measurements done in confined spaces inside a furnace at high temperatures. Moreover, a small amount is preferred due to the high cost of salts. To overcome these limitations, an accurate method to measure surface tension, γ, and contact angles, θ, of molten salts were sought. As a steppingstone toward using more complex salts, solar salt was used because of safety and availability. Because molten salts typically show low θ, they provide large errors by incorrectly predicting volume and/or geometry. Therefore, various solid materials on which solar salts show high θ were sought and boron nitride was identified to provide θ > 60°. Later, solar salt sessile droplets were analyzed with the axisymmetric drop-shape analysis (ADSA) method to measure γ over a temperature range, which showed a good agreement with literature. Thus, this paper sets an experimental protocol that can be possibly used for other complex and hazardous salts that are scarcer and hard to handle. This paper extends the current knowledge by identifying solid surfaces on which the salts show low wettability for accurate measurements. Compared to other accurate methods, such as maximum bubble pressure method, this method used a small amount of salt (< 100 μL) while keeping a high accuracy.

Exploring the Formulation and Efficacy of Phosphazene-Based Flame Retardants for Conventional Supercapacitor Electrolytes.

The formulation of safe electrolytes for supercapacitors based on phosphazene used as a flame-retardant (FR) is carried out. 3 molecules are used: hexafluorocyclotriphosphazene (FR1), (ethoxy)pentafluorocyclotriphosphazene (FR2) and pentafluoro(phenoxy)cyclotriphosphazene (FR3). A comparative study on the efficacy from a safety point of view is performed to determine the minimum percentages of each to be used in a conventional acetonitrile (ACN)/1.0 M tetraethylammonium tetrafluoroborate (Et4NBF4) electrolyte to make it non-flammable. Flammability tests have shown that 5 %FR1, 15 %FR2 or 20 %FR3 are required to do that. The FTIR coupled to the TGA as well as the measurements of surface tensions and contact angles showed that the FRs tend to protect the surface of the electrolyte. The transport properties always remain good, superior to PC/1.0 M Et4NBF4 for example, and the electrochemical stability windows determined in 3-electrode cells with platinum or activated carbon are at least 2.5 V. The cycling performances are also interesting because the AC|AC EDLCs made in this study are compatible with these FRs, which makes it possible to operate devices providing energies and powers of 23.0 Wh kg-1 and 3.7 kW kg-1 with the electrolytes based on FR1 or FR2 between 0 and 2.5 V.

New insights of the imprint at the catalyst-layer/ microporous-layer interface in PEMFC after heavy duty operation of commercial vehicles

Structural degradation and property decay of membrane electrode assemblies (MEAs) are primary causes for the stack performance and lifetime degradation. This study particularly investigates the structural damage and properties evolution of the catalyst-layer/microporous-layer (CL/MPL) interface in the MEA by conducting real-vehicle heavy-duty operational durability test and interfacial structure characterization. This research presents the first report and revelation of the causes and effects of CL/MPL interface imprints, and provides targeted advice for relieving MEA interfacial degradation. Results indicate that excessive assembly stress and stress variation during operation of stack causing the detachment of MPL materials at the region below the bipolar plate ridges is the essential cause of the imprints. The average surface contact angles of the aged CLs generally increase and the imprinted region exhibit stronger hydrophobicity than non-imprinted region due to the attachment of MPL materials. While the opposite is observed in MPL. Carbon corrosion induce structural degradation of the CL/MPL interface, leading to significant loss of carbon support and hydrophobic agent. The surface of aged CL become rougher and the pore size become more larger compared to the fresh CL. The formation of the interface imprint makes the contact between CL and MPL at the imprint region tighter, which reduces the interface resistance and inhibits the increase in ohmic polarization.

Characteristics of Aliphitic and Aromatic Ion-Exchange Membranes after Electrodialysis Tartrate Stabilization of Wine Materials

Color indication of anthocyanins, FTIR spectroscopy, measurement of surface contact angle values, determination of specific electrical conductivity, as well as voltammetry and parallel measurement of pH of desalted solutions were used to analyze the fouling characteristics of aliphatic (CJMA-3, CJMC-3) and aromatic (AMX-Sb, CMX-Sb) ion-exchange membranes used in electrodialysis tartrate stabilization of wine material. It has been shown that polyphenols form complexes with metal ions on the surface and in the subsurface layers of cation-exchange membranes, which do not interfere with the transfer of cations. Foulants affect the magnitude of limiting currents and enhance water splitting at the surface of all studied membranes, and also reduce the electrical conductivity of anion-exchange membranes. The use of a pulsed electric field instead of a continuous direct electric current, traditional for electrodialysis, weakens the negative impact of foulants on membranes’ electrical conductivity. These data can be useful for selecting membranes and current modes when carrying out electrodialysis tartrate stabilization of wine materials.

An organic-inorganic interface structure for CFRP and the enhancement of mechanical properties at room/high temperature

The performance of carbon fiber reinforced polymers (CFRP) depends on various factors, with particular emphasis on the intricate microscopic interface. Through the combined interface modification by nanomaterials (ZrO2) and polyimide (PI), an organic-inorganic interface enhanced structure of CFRP with phenolic resin (PR) have been successfully devised and fabricated. The analysis encompassed the surface morphology, contact angle and surface energy of carbon fibers (CF), aimed at characterizing the interaction of grafted ZrO2/PI on interfacial properties. Single fiber pull-out testing was employed to ascertain both the failure mode of the interface and the interfacial shear strength (IFSS). The results revealed that the surface modification augmented the IFSS by 70 %. The fortified organic-inorganic interface layer resulted in enhancements of 14 % and 15 % in tensile strength and flexural strength, respectively, in comparison to untreated CFRP. Moreover, even under high-temperature condition (300 °C), the tensile properties of modified CFRP exhibited only 22 %–26 % reduction, which demonstrated the advantages of composites in harsh environments. This can be primarily attributed to the strengthened layers of ZrO2/PI, which securely anchored the matrix and reinforcement, thereby mitigating stress concentration in CFRP under extreme conditions.

Fabrication of Papillary Composite Microstructured Aluminum Surfaces by Laser Shock Imprinting and Ablation

Laser shock ablation is incorporated into laser shock imprinting for the fabrication of papillary composite microstructures on aluminum surfaces. The primary papillary structures are fabricated using laser shock imprinting. Subsequently, secondary structures were fabricated on the surface of these primary structures using laser shock ablation, forming composite papillary microstructures. The influence of various laser shock ablation process parameters on the formation effect of these papillary composite microstructure surfaces was investigated. The results indicate that both laser shock energy and shock frequency affect the integrity of the secondary microstructure coverage on the material surface, the height of the composite microstructure, and the surface morphology. Through comparative optimization, the optimal process parameters were determined to be 675 mJ of energy and one shock ablation. Additionally, the differences in the flow behavior of metallic materials between the center and the periphery of the beam spot, caused by the shock wave, were analyzed. The wettability of the composite microstructure aluminum surface was also explored. The variation mechanism of wettability was explained by detecting changes in the contact angle on the aluminum surface at different time intervals and analyzing changes in surface chemical composition before and after aging. Specifically, after laser shock ablation, the aluminum surface contains a large number of polar groups, making it hydrophilic. During aging treatment, these polar groups continuously adsorb non-polar alkyl organic compounds, eventually leading to hydrophobicity, with a stabilized average surface contact angle of 143°. Fluorination treatment can further achieve superhydrophobicity, with a contact angle of 151° achieved shortly after processing the composite microstructure aluminum surface.

Natural Organic Pectin Polysaccharide Based Resistive Random Access Memory

Nowadays, non-volatile memory technologies have been widely applied in different areas. Of these memory technologies, non-volatile resistive random access memory (ReRAM) is attractive because of its simple device architecture and fabrication process, high scalability and data density, good performances in terms of switching speed, high power efficiency and reasonably wide memory window. In order to address the issues of disposable and degradation of electronic waste by typical ReRAM with the active layer made of inorganic oxide materials and fossil-fuel based polymeric materials, a green and sustainable strategy has been adopted in producing ReRAM by using natural organic-based materials based on protein and carbohydrate, such as honey, fructose, aloe vera, etc. Among these materials, pectin-polysaccharide thin film has demonstrated promising resistive switching characteristics. The two ranges of pectin concentrations that have been investigated are ³5 mg/ml and £1.5 mg/ml, and it showed that pectin with concentration <1.5 mg/ml reveals a higher ON/OFF ratio. However, the resistive switching characteristics with pectin concentration between 1.5 mg/ml and 5 mg/ml have yet been explored and reported. In this work, pectin with concentrations of 1.5~5 mg/ml were prepared from pectin-polysaccharide solution into the active switching layer, and ReRAM devices with such pectin resistive switching layer were fabricated. The pectin-polysaccharide solution, pectin resistive film, and ReRAM devices were systematically investigated. Surface tension and contact angle of pectin-polysaccharide precursor solutions as a function of pectin concentration on the substrate were measured by a goniometer. Surface topography of solidified thin films was characterized by an atomic force microscope (AFM) and a field-emission scanning electron microscope (FE-SEM). Chemical functional groups of the pectin-polysaccharide precursor solutions and solidified thin films were examined by a Fourier transform infrared (FTIR) spectroscopy. The resistive switching behaviors were characterized and compared by electrical measurement. The results show that 4 mg/ml recorded the highest ON/OFF ratio compared to ever reported values, as well as desirable memory window, non-volatility in retention, and stability over 100 cycles. This study proves that pectin-polysaccharide is a promising green and sustainable bio-organic material for non-volatile ReRAM for electronic applications such as in emerging neuromorphic computing systems.

Influence of thermal-cycling or staining medium on the surface properties and color stability of conventional, milled, and 3D-printed base materials

The study of denture base resin fabricated by digital technology with surface properties or color stability remains limited. In this study, thermal cycling and staining media (distilled water, artificial saliva, green tea, and Coca-Cola) immersion were used to simulate the intraoral environment to assess the surface properties and color stability of CAD/CAM (milled) and 3D-printed base resin materials, the conventionally polymerized base served as the control group. After thermal cycling, all groups showed increased surface roughness, contact angle (i.e. hydrophilicity) and color difference (∆E), the 3D-printed group had the most significant increase among the 3 groups (P<0.001). While there were no significant difference (or the difference is very small) between the conventional and milled groups. After 7 and 30 days of immersion in four staining media, the ∆E values remained highest in the 3D-printed group (∆E ≥ 3.34) (P<0.001), exceeding the clinically acceptable threshold (∆E = 2.7) at 30 days. Additionally, all groups showed significantly higher ∆E values after 30 days compared to 7 days (P<0.05). The 3D-printed group exhibited a rougher surface, poorer hydrophilicity, and reduced color stability compared to the conventional or milled groups, indicating that further improvements are needed before clinical application.

An Advanced Allen-Cahn Navier-Stokes Coupled Lbm Model to Predict Two-Phase Flow Dynamics at the Pore-Scale inside a Polymer Electrolyte Water Electrolyzer

Polymer Electrolyte Water Electrolyzers (PEWEs) stand as promising energy storage solutions, leveraging variable renewable energy sources to produce hydrogen. Simulating the intricate two-phase fluid dynamics within these systems necessitates the use of complex numerical models since direct experimentation to capture these dynamics is difficult. Currently, most models adopt a macroscopic continuum approach. However, integrating various modeling scales, especially coupling two-phase flow interactions between channels and the porous media within such systems, remains challenging1.This works attempts to address the challenge by developing an advanced Allen-Cahn Navier-Stokes (AC-NS) coupled Lattice Boltzmann Method (LBM) model. Unlike traditional diffuse-interface LBM models based on the Shan-Chen model2, the AC-NS approach demonstrates enhanced stability and accuracy, with minimal parasitic velocities at fluid interfaces. By implementing Allen-Cahn formulation to minimize the free-surface energy of the fluid interfaces3,4, this work showcases the ease of coupling a phase-field (to capture both liquid and gas phase interactions) with the incompressible Navier-Stokes equations using a LBM framework. This highlights the model’s efficacy in predicting the flow dynamics for binary fluid systems with high density and viscosity ratios within porous media (as shown in Figure 1) at relatively low computational costs.Furthermore, such a model emphasizes the advantage of incorporating natural boundary conditions and using physical parameters such as surface tension and contact angles, tailored to fluid and geometric properties. Lastly, a methodology to integrate the pore-scale model with existing macroscopic continuum scale models will be presented. Such a framework is essential to accurately calculate the mass transport limitations within PEWEs and predict the performance of a PEWE5,6. Therefore, this work achieves a major step towards enhancing the predictive capabilities of numerical models in advancing the design and optimization of PEWE systems.

Recent Advances in Aluminum Alloy Surface Treatment Technology and Bonding Properties

Aluminum alloys are widely used in lightweight automotive structures due to their excellent properties. To deeply explore the development of surface bonding technology, aluminum alloy is selected as the object, and current research status of aluminum alloy surface treatment methods is reviewed. The adhesion mechanism during joint preparation, the method of adhesive selection, and the bonding process are summarized. This overview discusses the impact of different surface treatment processes on aluminum alloy joints from two perspectives: substrate characteristics and joint failure modes. It examines how these processes affect surface roughness, surface morphology, surface contact angle, surface free energy, surface chemical composition, and bonding performance. Additionally, it looks ahead to key directions for future research on adhesive joint performance. The results indicate that surface treatment increases the surface roughness of aluminum alloys, reduces the contact angle, and improves surface wettability. Moreover, chemical elements or functional groups that enhance adhesion are introduced on the surface, improving the bonding capability between the adhesive and the substrate. Compared to single‐surface treatment methods, hybrid treatment methods significantly enhance the surface characteristics of aluminum alloys and are expected to become a primary focus for future research on bonded joint performance.

Sub-ambient water wettability of hydrophilic and hydrophobic SiO2 surfaces.

The wettability of SiO2 surfaces, crucial for understanding the phase transition processes of water, remains a topic of significant controversy in the literature due to uncertainties in experiments. Molecular dynamics (MD) simulations offer a promising avenue for elucidating these complexities, yet studies specifically addressing water contact angles on hydrophilic and hydrophobic SiO2 surfaces at sub-ambient temperatures are notably absent. In this study, we experimentally measured water contact angles of hydrophilic and hydrophobic SiO2 surfaces at ambient temperature and employed MD to investigate water contact angles on Q3, Q3/Q4, and Q4 SiO2 surfaces across temperatures ranging from 220 to 300K. We investigated the effects of the distribution of hydroxyl groups, droplet size, and hydroxyl density and found that the hydroxyl density had the largest impact on contact angle. Moreover, hydrogen bond analysis uncovered enhanced water affinities of Q3 and Q3/Q4 SiO2 surfaces at lower temperatures, and the spreading rate of precursor films reduced with decreasing temperature. This comprehensive study sheds light on the intricate interaction between surface properties and water behavior, promoting our understanding of the wettability of SiO2 surfaces.