Change In Interfacial Energy Research Articles

Membrane fouling characteristics and mechanisms in coagulation-ultrafiltration process for treating microplastic-containing water

Microplastics (MPs) are recognized as a significant challenge to water treatment processes due to their ability to adsorb or accumulate alginate foulants, impacting the coagulation-ultrafiltration (CUF) process. In this study, the mechanisms of membrane fouling caused by MPs under varying dosages of polymeric aluminum chloride (PAC) coagulant in the CUF process were investigated. It was revealed that MPs contribute to membrane fouling, which initially intensifies and then alleviates as coagulant concentration increases, with a turning point at 0.05 mM PAC dosage. The most significant alleviation of membrane fouling was observed at 0.2 mM PAC dosage. An in-depth analysis of interfacial interaction energy changes during filtration was conducted using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, demonstrating how MPs alter the interaction forces between foulants and the membrane surface, leading to either the exacerbation or mitigation of fouling. Additionally, it was shown that at optimal coagulant concentrations, the presence of MPs promotes the formation of a loose and porous cake layer, disrupting the original structure and creating a more open block structure, thereby alleviating membrane fouling. These findings provide valuable insights for optimizing the CUF process in microplastic-containing water treatment, presenting a novel approach to enhancing efficiency and reducing membrane fouling.

Thermodynamic of solid-state sintering: Contributions of grain boundary energy

This study aimed to highlight the importance of solid-solid interfaces or grain boundaries in the thermodynamics of interfaces during the sintering of materials. Among the three chemical potentials identified in this study, the difference in chemical potential between the grain boundary and the surface emerges as the most critical factor for pore elimination. However, once equilibrium is achieved between the grain boundary and the surface, a second chemical potential associated with the difference in grain size becomes predominant, promoting a new microstructural configuration that reactivates grain boundary formation and perpetuates sintering. A third potential was identified because of the edges, contributing to the rounding of the neck region between grains. The change in interfacial energy resulting from the adsorption or segregation processes plays a pivotal role in pore elimination during sintering. Models attempting to simultaneously predict the stability of grain boundary formation and pore elimination with grain growth were revisited.

Phase-field simulations of the effect of temperature and interface for zirconium δ-hydrides

Hydride precipitation in zirconium cladding materials can damage their integrity and durability. Service temperature and material defects have a significant effect on the dynamic growth of hydrides. In this study, we have developed a phase-field model based on the assumption of elastic behaviour within a specific temperature range (613 K–653 K). This model allows us to study the influence of temperature and interfacial effects on the morphology, stress, and average growth rate of zirconium hydride. The results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride morphology. The ultimate determinant of hydride orientation is the loss of interfacial coherency, primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree q. An escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical, accompanied by the onset of redirection behaviour. Interestingly, redirection occurs at a critical mismatch level, denoted as q c, and remains unaffected by variations in temperature and interfacial energy. However, this redirection leads to an increase in the maximum stress, which may influence the direction of hydride crack propagation. This research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

Phase-field simulation for anisotropic dendrite growth in Mg-3wt.%Zn alloy

The anisotropy interfacial energy changes the growth tendency of dendrites in different directions during solidification, when the growth tendency in a specific direction appears or disappears, the transition of dendrite orientation will happen. In this study, three-dimensional simulations of anisotropic α‐Mg dendrite were conducted by changing the anisotropic interface energy in the phase field model. The variation in the preferred growth direction of equiaxed dendrite in α‐Mg was analyzed by controlling the anisotropic function of the interfaces. The changes in the growth direction of dendrites on different dendrite planes and the distribution of solute were investigated. The dendrites of α‐Mg equiaxed crystals mainly grow in ⟨112‾0⟩ and ⟨112‾3⟩ directions, and the transition of dendrite orientation depends on ⟨112‾0⟩ direction. When ⟨112‾0⟩ direction branching disappears, α‐Mg dendrite is transformed from 18 branches to 12 branches. The solute distribution at the front of the dendrite boundary changes significantly with the growth trend. Differences in the degree of solute distribution affect the solid-liquid interface and change the microstructure of the material.

Investigation on nanofiltration membrane fouling behaviour of cation-induced apam in strontium-bearing mine water

This paper investigates the effect of sodium, calcium and strontium ions interacting with APAM on the fouling behavior of nanofiltration membranes during mine water treatment. The membrane fouling behavior was assessed qualitatively and quantitatively by processing experimental data, characterization of fouled membranes and analysis of interfacial thermodynamic energy changes. The results show that the membrane fouling composition is mainly dominated by SrSO4, and the LW and EL interfacial interaction energies between APAM and cations during fouling formation are characterized by attractive forces, while the AB interaction energies are of the opposite nature, and it is mainly the AB interaction energy that affects the total interaction of the fouling surface thermodynamics. When Sr2+ is present, the AB interaction energy decreases significantly and the composite foulant adheres to the fouling membrane more easily. The addition of Ca2+ increases the repulsive forces and energy barriers, alleviating the degree of membrane fouling.

Three-dimensional shape and stress field of a deformation twin in magnesium

While the three-dimensional (3D) shape and stress field of a twin in hexagonal close-packed (HCP) metals have attracted considerable interest in recent years due to their substantial impact on internal stress and mechanical properties, a detailed understanding of their variation with twin size is still lacking. An analytical model that is not restricted by spatial scale is developed in this work by considering the effects of anisotropic twin boundary energy, elastic strain energy and plastic relaxation to predict the 3D shape with the minimum energy, and the stress field, of an isolated ellipsoidal twin of different sizes. The model is applied to Mg with a focus on the {101¯2} twin type. The analytical calculation results show that the nucleation of the nano-sized twin embryos is facilitated by the stress field near structural defects such as dislocations. During the expansion of this nano-sized twin embryo, the interplay between the elastic strain energy and interfacial energy changes the length of the twin along the twin shear (forward) direction from being shorter to longer than that along the lateral direction. In contrast to the current understandings, the maximum shear stress on the twin plane along the twin shear direction occurs at the lateral, rather than the forward, side of the twin. At the forward side, the maximum shear stress occurs at a distance ahead of the twin tip and this distance increases with increasing twin thickness.

Interaction between nucleant particles and a solid-liquid interface in Al-4.5Cu alloy

Al3Ti and TiB2 particles were made in-situ from adding halide salts in molten Al-4.5 wt % Cu alloys. The molten halide salts also dissolved the oxide in the molten metal to ensure that the newly formed Al3Ti and TiB2 particles had intimate interfaces with the molten metal. Excess amounts of titanium were added into the melt to ensure that the wetting angles between the particles and the molten alloy were small and the particles were able to significantly reduce the grain sizes of the aluminum alloy. Such particle/matrix systems should have a negative total interfacial energy change when a particle is engulfed into the solid by an advancing solid-liquid interface, resulting in particles being engulfed by an advancing solid-liquid interface according to widely accepted theories on particle pushing. Experimental results indicate that these particles are actually pushed by the growing dendrites into the interdendritic regions, regardless of the growth rates being positive, close to nil, or even negative. It seems that the particle pushing mechanisms based on interfacial energy interactions are not applicable for these particle/matrix systems under experimental conditions of this study. Analytical analysis suggests that these particles are pushed by the growing dendrites due to fluid flow before they could get into close contact with the solid-liquid interface within a several interatomic layers where the van der Waals forces become significant. The shrinkage driven flow in the liquid of the mushy zone is sufficient to dislodge a particle from a depression and rolls the particle on the solid-liquid interface.

Wetting behavior and mechanism between hot metal and carbon brick

Wetting behavior between hot metal and carbon brick is the first step to explore the erosion of carbon brick. In order to investigate the wetting behavior, wetting experiments between hot metal (with carbon content 2.87, 3.47, 4.12, 4.51, and 4.96 mass%) and carbon brick were carried out. The wetting angle under different conditions was measured, the reaction interface morphology and carbon structure were analyzed, the mechanism of hot metal wetting carbon brick was clarified based on interfacial energy and scaling law. The results show that: The wetting angle decreased gradually with the increase of wetting time for all initial carbon content experiments, the wetting angle increased with the increase of initial carbon content in hot metal. The dissolution of carbon occurred during the wetting process, which left a concave on carbon brick. The graphitization degree of carbon in carbon brick increased after the wetting behavior. In the initial stage of the wetting reaction, the change of interfacial energy caused by carbon dissolution reaction was the essential reason for the change of wetting angle. In the final stage of the wetting reaction, the wetting angle mainly depended on the concave shape after the concave was formed. The wetting model was established to explore the wetting behavior with dissolution reaction, the scaling relationship between the spreading radius of iron drop and time was obtained, which was convenient to evaluate the wetting behavior between hot metal and carbon brick.

Segregation of alloying elements at the bcc-Fe/B2–NiAl interface and the corresponding effects on the interfacial energy

The distribution tendency of the alloying elements in the body-centered cubic (bcc) Fe/B2–NiAl interface is of fundamental importance for understanding the nucleation and morphology of NiAl precipitates during the aging process of the B2–NiAl precipitation strengthened maraging steels. In the present work, the first-principles density functional calculations have been used to perform an extensive investigation on the segregation tendency of the common alloying elements in the bcc-Fe/NiAl interface and the resulting effects on the interfacial energy and the nucleation parameters of NiAl nuclei in the dilute solid solution FenNiAl. It was found that the coherency strain energy for forming coherent bcc-Fe/NiAl interfaces accounts for approximately 11% of the total nucleation free energy of NiAl phase, and the interfacial energies of bcc-Fe/NiAl at 0 K are 33 mJ/m2, 53 mJ/m2 and 37 mJ/m2 for (100), (110) and (111) planes, respectively. Based on the investigations of the sublattice site preference of the solute atoms in NiAl bulk, the segregation energies of the alloying elements in the interface were calculated and the results indicate that Si, Ti, V, Mn, Nb, Y, La, Cr, Co, Cu and Mo energetically prefer to segregate to the interface, and the segregations result in the corresponding changes of interfacial energy. Among these segregation solutes, La, Cr and Mo decrease both critical nucleation radius and the nucleation barrier of NiAl nuclei in the dilute solid solution FenNiAl, and the other alloying elements exhibit the inverse effects.

A study on the interfacial adhesion energy between capping layer and dielectric for cu interconnects

Recently, Cu interconnect and low-k materials have been applied to reduce the interconnect resistive-capacitive delay issue. However, as the process node size is reduced to a few nanometers, high leakage currents appear through the dielectric under high electric fields. Therefore, issues of Cu diffusion at the interface between the dielectric and the capping layer have been reported. This study investigated interfacial adhesion energy change at the film level between dielectric (low-k, tetraethyl orthosilicate (TEOS)) and capping layer (SiCN, SiN) taking into account the correlation between interfacial adhesion energy and interconnect reliability. In the capping layer/low-k interface, when low-k is applied to the top layer, it shows high interfacial adhesion energy (> 34.31 ± 3.49 J/m2) due to the presence of an O-rich thin layer. But when low-k is applied to the bottom layer, due to the SiC bond, it shows low interfacial adhesion energy (< 5.60 ± 2.46 J/m2). The interface between TEOS and SiN has high interfacial adhesion energy (> 32.54 ± 1.97 J/m2) regardless of the stacking order and CMP process. It clearly shows that low-k dielectrics will affect the deterioration of the interfacial adhesion energy and O-rich layer will greatly improve the interfacial adhesion energy in dielectric/capping layers.

Coplanar Electrowetting-Induced Droplet Detachment from Radially Symmetric Electrodes.

This work demonstrates electrowetting-induced droplet detachment in air from coplanar electrodes using a single voltage pulse. It also presents two models to predict when this detachment will occur. Previous works approximated the minimum energy for detachment based on (i) adhesion work at the solid-liquid interface and (ii) interfacial energy changes along all three interfaces in the system. This investigation updates those models to include changes in gravitational potential energy during detachment and provides validation by testing predicted detachment thresholds against experimental observations. Droplets of varying volume were ejected from electrowetting devices with (i) radially symmetric four-part coplanar electrodes and (ii) single electrodes with a ground wire inserted directly into the droplet. All experiments were performed in air. Incorporation of gravitational potential energy improves predictions for critical electrowetting number and captures the observed increase in applied voltage required with increased droplet volume. These new models will be of particular benefit in three-dimensional digital microfluidics applications that manipulate droplets in air.

The effects of introducing elasticity using different interpolation schemes to the grand potential phase field model

Introducing elastic energy in the phase field method has been shown to influence interfacial energy, depending on the elastic interpolation scheme. This study investigates the impact of the elastic energy when using a grand potential-based phase field method, comparing the result of Khachaturyan’s strain interpolation scheme (KHS) and Voight-Taylor’s elastic energy interpolation scheme (VTS). The KHS model leads to a decrease in the interfacial energy, while the VTS model leads to an increase. The change in interfacial energy is greater with the VTS model than the KHS model, which suggests that the KHS model is more appropriate to limit the artificial impact of the elastic energy on the interfacial energy. When the contribution at the interface is not negligible, it is shown that both the microstructure evolution kinetics and the equilibrium microstructure can be influenced by the choice of the elastic scheme being used. In addition, this paper shows that the grand potential model might not be appropriate when the system requires the introduction of a composition-dependent term in the elastic energy contribution. This limitation is due to the need for an explicit and invertible relation between the total potential and the composition.

Reducing Energy Losses at the Organic–anode-buffer Interface of Organic Photovoltaics

Understanding the sources of energy loss in organic photovoltaic cells can ultimately lead to increasing their power-conversion efficiency. Here we explore energy losses at the interface between an archetype structure comprising a vacuum-deposited tetraphenyldibenzoperiflanthene/${\mathrm{C}}_{70}$ bulk-heterojunction active layer and several anode buffer layers (ABLs) using a combination of experimental and computational tools. The composition of the active organic region adjacent to the ABL interface is controlled independently from that in the bulk to determine energy losses that are attributed to charge transfer between the organic active region and the ABL. The open-circuit voltage (${V}_{\mathrm{OC}}$) can be varied over a range of 120 meV without affecting the short-circuit current and fill factor by growing an interface layer whose composition ranges from 100% ${\mathrm{C}}_{70}$ to 0% ${\mathrm{C}}_{70}$ in tetraphenyldibenzoperiflanthene at the active-region--ABL interface. Kinetic Monte Carlo simulations are used to quantitatively evaluate the magnitude of the interfacial energy loss and change in ${V}_{\mathrm{OC}}$ with various interface-layer compositions. When the interface layer consists of neat ${\mathrm{C}}_{70}$ that permits nondissipative hole tunneling into the ABL, the interfacial energy loss is reduced and ${V}_{\mathrm{OC}}$ increases by 20--40 mV compared with conventional devices with a homogenous mixed active region.

Experimental evidence on the effect of substrate roughness on segmental dynamics of confined polymer films

Understanding the properties of thin films remains an unresolved issue even after decades of scientific research. In this article, we investigate the role of surface roughness, one of the various factors that affect the dynamics of polymer films. The tested sample is poly-(4-chlorostyrene) coated onto silicon substrates treated with plasma for different amounts of time. By using dielectric spectroscopy, we provide experimental evidence that as substrate roughness increases (i) the segmental mobility slows down, and (ii) the distribution of the α-relaxation time becomes narrower. Ultimately, the confinement effect vanishes, and the polymer film recovers its bulk-like behavior for sufficiently rough surfaces. Further studies that employ AFM, ellipsometry, and contact angle measurements allowed us to conclude that the deviation in segmental dynamics as a function of surface roughness is due to the changes in interfacial energy that affects the number of chains irreversibly absorbed to the substrate which in turn improve packing density near the substrate. Therefore, the surface roughness is an inevitable factor to consider when designing numerous devices which rely on supported polymer films.

Two-Dimensional Stationary Thermocapillary Flow of Two Liquids in a Plane Channel

The problem of two-dimensional stationary flow of two immiscible liquids in a plane channel with rigid walls is studied. On the one of walls a temperature distribution is imposed and the another wall is heat-insulated. On the common interface the interfacial energy change is taken into account. The temperature in the liquids is distributed according to a quadratic law. It agrees with velocities field of the Hiemenz type. The conjugate boundary value problem is nonlinear and inverse for pressure gradients along the channel. The tau-method is used for the solution of problem. Three different solutions are obtained in results. It is established numerically that the obtained solutions converge to the solutions of the slowly flow problem with a decrease the Marangoni number. For each of the solutions the characteristic flow structures are constructed.

Effect of the Third Element Ni on the Solidification Microstructure of Undercooled Cu-40 wt.% Pb Monotectic Alloy Melt

In this paper, the evolution of solidification microstructure of Cu-40 wt.% Pb monotectic alloy of the third element Ni pair under deep undercooling conditions was studied. By comparing the phenomena of liquid phase separation during deep undercooling and rapid solidification of Cu-40 wt.% Pb monotectic alloy, the melt of the alloy increases with the undercooling, and the solidification structure appears uneven or even stratified. With the addition of the third element Ni, the liquid phase separation can be effectively inhibited by the change of interfacial energy. The solidified structure undergoes the transformation from coarse dendrite to the first kind of granular and refined dendrite in a wide undercooling range. When the undercooling reaches 143 K, the structure begins to show an inhomogeneous trend.

A Novel Method to Measure the Effective Change of the Interfacial Energy due to Kinetic Self-Assembly of Amyloid Fibrils.

Adsorbates growing a self-assembled layer on a solid-liquid interface can significantly change the effective interfacial energy at the solid surface. However, measuring the changes in the effective surface energy while these adsorbates accumulate is challenging, as static contact angle measurements can be affected by the motion and accumulation of these adsorbates at the droplet's boundary (coffee stain effects). In this report, we utilize a novel method that takes advantage of spin-induced dewetting to measure the change in the effective surface energy as the self-assembly progresses. We use a previously well-studied model system of self-assembled fibrils of amyloid-β (Aβ) peptides on the mica substrate to demonstrate the feasibility of this method. Using variations of terminal spin speeds and acceleration rates, we measure the terminal spin speed at which a wetting-dewetting transition (WDT) occurs on a surface that hosts self-assembled Aβ12-28 fibrils. By comparing this speed with the WDT speed on the bare mica substrate, we can quantify the spreading coefficient and thus the effective change of the substrate's interfacial energy due to the adsorption of mobile peptides at various stages of the self-assembly. These measurements show that the surface becomes more hydrophilic as the self-assembly progresses and thus can explain previous observations that the self-assembly of this particular peptide system is self-limiting and stops before full surface coverage.

Two-dimensional Plane Thermocapillary Flow of Two Immiscible Liquids

The problem of two-dimensional stationary flow of two immiscible liquids in a plane channel with rigid walls is considered. A temperature distribution is specified on one of the walls and another wall is heat- insulated. The interfacial energy change is taken into account on the common interface. The temperature in liquids is distributed according to a quadratic law. It agrees with velocities field of the Hiemenz type. The corresponding conjugate boundary value problem is nonlinear and inverse with respect to pressure gradients along the channel. The Tau method is used for the solution of the problem . Three different solutions are obtained. It is established numerically that obtained solutions converge to the solutions of the slow flow problem with decreasing the Marangoni number. For each of the solutions the characteristic flow structures are constructed.

Swelling effects on localized adhesion of an elastic ribbon.

We investigate the adhesion mechanism between an elastic strip of vinylpolysiloxane bent in a racquet-like shape, and a thick elastomeric substrate with the aim to understand how local swelling modifies adhesion. Using a modified loop-tack adhesion test, we place a droplet of silicone oil in between the two materials, vary the dwell time and measure the force required to separate the two interfaces. The experiments are then compared with an analytical model that describes how the critical peel force is modified as the interfacial surface energy changes over time. Our study reveals that in certain circumstances swelling can enhance adhesion. More specifically, strong adhesion is obtained when most of the droplet is absorbed by the solid. By contrast, when the droplet remains at the interface a small adhesive force is measured.

Crystallization kinetics of the Fe40Ni40P14B6 metallic glass in an extended range of heating rates

The effect of heating rate (in the range of 0.083–3.333 K s−1) on the parameters of thermal stability and crystallization kinetics of the Fe40Ni40P14B6 metallic glass has been investigated by differential scanning calorimetry and X-ray diffraction. An analytical model of glass crystallization describing the homogeneous nucleation rate, the velocity of interface-limited growth, the number of crystal volume density in crystallized samples as well as the crystallization kinetics at constant rate heating is presented. A modified procedure of estimation of thermodynamic and kinetic parameters governing the rate of crystal nucleation and growth based on the use of the measured heating rate-dependent variations of the volume fraction crystallized and the average grain size is proposed. The values of the effective diffusivity have been estimated by the Kissinger-like isoconversional method accounting the contribution of both the free energy difference and the specific interfacial nucleus-melt energy changes estimated from the structural data. It has been shown for the first time that the shapes of the non-isothermal experimental kinetic crystallization curves measured at the heating rates ≤ 1.333 K s−1 are well described by the approximate analytical equation and the values of the Avrami exponent lowering from 5.5 to 2.3 with the heating rates increasing have been estimated. The evaluated ranges of the nucleation rate (1.4 × 1016–2.5 × 1017 m−3 s−1) and growth velocity of crystals (2.05 × 10−9–3.0 × 10−7 m s−1) in Fe40Ni40P14B6 glass at temperatures from 653 to 714 K are in reasonable agreement with the experimental data. Possible variations of the established eutectic crystallization mechanism revealed by changes of the Avrami exponent with the heating rate increasing are discussed.