Interfacial Behavior Research Articles

Reaction behaviors of iron-coke interface during hydrogen-rich smelting in a blast furnace

To further improve the basic theory of blast furnace hydrogen-rich smelting and provide a reference for blast furnace hydrogen-rich production, the influences of different conditions on the contact angle and carburization amount of the iron‒coke interface were measured using iron‒coke interface reaction experiments, and the erosion of the three-dimensional morphology of the coke surface by the iron‒coke interface reaction process was analysed. As the degree of coke dissolution increased, the iron‒coke interface contact angle increased, and the amount of carburization decreased. The change in the interface contact angle and carburization amount between iron and coke after reacting with H2O was greater than that after reacting with CO2, and the interface reaction rate constant and carburization amount were lower for H2O than CO2. When the reaction time increased by 1 min, the differences in the contact angle and carburization amount between the two atmospheres increased by 0.12° and 0.013%, respectively. This improved the permeability of the metal iron for its penetration in the coke layer and was beneficial for stable production. An increase in the reaction temperature and a decrease in the initial carbon mass fraction (w(C)) of metallic iron both increased the carburization rate at the iron‒coke interface, reduced the equilibrium contact angle, improved wettability, and caused severe erosion of the carbon matrix structure on the coke surface. When the temperature exceeded 1673 K, the metal iron could undergo a violent carburization process with coke surface 3, resulting in a wetting phenomenon. The initial w(C) of metallic iron increased by 1%, and the equilibrium contact angle of the iron‒coke interface increased by approximately 3.32°.

A CO2-responsive Janus SiO2 nanofluid: Integration of enhanced oil recovery and demulsification

Aiming to address the issues of limited suitability of conventional chemical oil displacement materials for formation conditions and the serious emulsification of oil and water in the produced liquid, the innovative nano oil-displacing system with CO2-responsive behavior has been developed. This system integrates oil displacement and emulsion breaking. The efficacy of the CO2-response system in creating stable emulsions with a high capacity to decrease interfacial tension has been demonstrated. The interfacial responsive behavior of all active components, including Janus nanoparticles, sodium oleate, gums, and asphaltenes, in the emulsion system was analyzed in terms of interfacial rheology and adsorption. Additionally, the prepared system demonstrated a rapid response to CO2, effectively breaking the emulsion within 5 min. Furthermore, the oil recovery enhancing mechanism of the CO2-response system was investigated using a microscopic visualization model. The system was proved to be efficient in initiating the residual oil within pore channels. Considering the combined effectiveness of the CO2-response system in terms of efficient oil displacement and rapid response, it offers valuable insights for advancing the chemical flooding technology of in enhanced oil recovery.

Oil unsaturation degree dictates emulsion stability through tuning interfacial behaviour of proteins

The unsaturated vegetable oil is commonly incorporated as protein-stabilized emulsion into fat-substituted emulsified meat products (FSEMP), whose quality is closely related with the emulsion stability. Here, we systematically investigated the effects of oil unsaturation degree (UD) on the interfacial properties (structural changes, adsorption dynamics, interfacial rheology, adsorption layer thickness) of proteins and thus the emulsion stability. The oleic acid and linolenic acid were mixed with dodecane as model oils. Three types of proteins were selected as model emulsifiers (fibrous myofibrillar protein, MP; globular whey protein, WP; random-coiled sodium caseinate, SC). The proteins diffused slower to the higher UD interface, resulting in a lower interfacial pressure. This led to a larger droplet size of the higher UD oil emulsion upon emulsification. However, the proteins penetrated and rearranged faster at the higher UD interface ascribed to a more extensive structural unfolding, enabling the formation of stiffer and thicker adsorption layers. This contributed to a stronger short-term stability of MP- and WP-stabilized higher UD oil emulsion; while for the random-coiled SC, the higher UD oil emulsion was less short-term stable, which was primarily determined by the initial (larger) droplet size but not the interfacial layer properties. The stiffer layer at the higher UD interface was on the other hand less stretchable, which tended to yield when subjected to higher strain. This probably accounted for the weaker long-term stability of the higher UD oil emulsion, regardless of protein types. These results highlighted that the oil UD should be elaborately considered for the rational formulation of FSEMP.

Analytical Analysis of Buckling Of Layered Composite Columns

Abstract: Lightweight composite construction is of great interest in the design and manufacture of spacecraft and marine vehicles because of high specific stiffness and strength. In addition, sandwich construction offers enhanced corrosion resistance, noise suppression and reduction in life-cycle costs. There are several issues and questions related to the use of composite construction that require attention and answers. One of the important issues is the prediction of buckling loads, under either static or sudden load application. For the static case, closed form solutions are derived for a symmetric composite column under axial compression and for various boundary conditions. In this study, improved analytical models are developed to characterize interface behavior of layered composite column-type structures. The mechanics models of the bonded interface with and without adhesive layer are established, from which the interface fracture, delamination buckling, free vibration and stress analysis across the adhesive layer of corresponding interface are studied.

Wettability and infiltration of molten Si on SiO2 substrate containing porous Si3N4 coating: Influence of α-Si3N4 coating and β-Si3N4 coating

Photovoltaic (PV) multicrystalline silicon (Si) is currently grown in SiO2 crucible with porous α-Si3N4 coating, which serves as interfacial releasing agent to avoid sticking. Compared with α-Si3N4, β-Si3N4 should be another potential coating material, due to the same chemical composition and better structural stability. To verify this conception, it's of great importance to ascertain the wetting behavior and infiltration of Si/β-Si3N4/SiO2 ternary system. In this study, the sessile drop technology and micro-structural analysis method were used to investigate interfacial wetting behavior and infiltration of Si drop on different coatings, which are α-Si3N4 coating, β-Si3N4 coating and silica modified β-Si3N4 (β-Si3N4@SiO2) coating. The results show that wettability transformation (from non-wetting to wetting) commonly occurs for all coatings, as well as infiltration. The β-Si3N4 coating displays much shorter non-wetting duration and severer infiltration than α-Si3N4 coating. Compared with β-Si3N4 coating, the β-Si3N4@SiO2 coating exhibits significantly extended non-wetting duration and considerably delayed infiltration. These differences about wettability and infiltration are strongly associated with O content in all coatings and de-oxidation. This work clarify the wettability/infiltration differences between α-Si3N4 coating and β-Si3N4 coating in Si/Si3N4/SiO2 ternary system, and could be used to develop novel β-Si3N4 coating with low cost for PV multicrystalline Si manufacture.

Prediction of the Interface Behavior of a Steel/CFRP Hybrid Part Manufactured by Stamping.

Carbon fiber-reinforced plastic (CFRP) is a lightweight material. The automotive industry has focused on producing a steel/CFRP hybrid part to reduce overall weight. After manufacturing, delamination can occur at the interface between the CFRP and steel owing to the hybrid part constituting dissimilar materials. However, most studies have focused only on designing the manufacturing processes for the hybrid part or evaluating the adhesive used at the interface. Therefore, it is necessary to predict the behavior of the interface after demolding the hybrid part. This study aimed to predict the interface behavior of a steel/CFRP hybrid part by considering its forming and cohesive properties. First, double cantilever beam (DCB) and end-notched flexure (ENF) tests were performed to obtain cohesive parameters, such as energy release rate of modes I and II (GI, GII). The experimentally obtained properties were applied to the bonding area of the hybrid part. Subsequently, a forming simulation was performed to obtain the stress of the steel blank in the hybrid part. The stress distribution after forming was utilized as the initial condition for spring-back simulation. Finally, the interface behavior of the hybrid part was predicted by a spring-back simulation. The simulation was conducted using the residual stress of steel outer and the cohesive properties on the interface, without the application of any external forces. The cases of spring-back simulation were divided as delamination occurrence and attached state. The simulation results for prediction of delamination occurrence and bonding showed good agreement in both cases with experimental ones. The proposed method would contribute to expanding the manufacturing of the hybrid part by stamping and reducing the manufacturing cost by prediction of delamination occurrence.

Corrosion inhibition of Ga-based thermal interface materials with Ni coating on Cu substrate

The gallium (Ga) base liquid metal (LM) with high thermal conductivity and deformability is applied widely in thermal management in electrical systems. However, Ga readily reacts with Cu to form intermetallic compounds (IMCs), which can cause failure in electronic devices. Herein, the thermal interface material (TIM) with Ga and diamond is prepared to analyze the reaction behavior of TIM and Cu/Ni-plated Cu under an aging test at 125 °C. The results show that Ga reacts with Cu substrate and forms CuGa2 bulk. Moreover, Ni coating can inhibit the corrosion of Ga and Cu. However, the as-volcano IMC structures were generated, also. The thermal resistance increased from 2.24 mm2·K·W−1 to 14.47 mm2·K·W−1 from initial time to 200 h. The interfacial corrosion behavior between TIM and Cu substrate is studied by first-principles molecular dynamics simulation. The diffusion coefficient in the z direction of Cu is 0.04 × 10−5 cm2/s. In a word, the work could provide the guidelines for the further design of high-performance corrosion resistance in the region where Ga was used for thermal management on electronic products.

Interfacial bond behavior of steel fibers embedded in manufactured sand-based ultra-high performance concrete

The interfacial bond region between matrix and fibers is a non-negligible weak link that can significantly affect the mechanical properties of manufactured sand-based ultra-high-performance concrete (UHPMC). This study investigates the interfacial bond characteristics between steel fiber-UHPMC matrix using single-fiber pullout tests. Four variable parameters were considered: manufactured sand (MS) replacement ratio, stone powder content, fiber embedment length, and steel fiber geometry. Additionally, the microstructure of the steel fiber-UHPMC matrix interface was evaluated using backscattered electron microscopy (BSEM) and scanning electron microscopy (SEM). The results indicate that two typical failure modes including fiber pullout slip failure (in straight and hooked-end fibers) and fiber rupture failure (in corrugated fibers) were observed. The analysis of interfacial evaluation indicators shows that increasing the MS replacement ratio from 25 % to 100 % results in a decreasing trend in peak load, peak tensile stress, and energy consumption. Peak bond strength decreases with increasing embedment length. With the increase in stone powder content, the peak load, peak bond stress, and energy consumption increase initially and then decrease. Additionally, the interfacial failure mechanisms between straight/hooked-end steel fibers and the UHPMC matrix were further elucidated through bond-slip behavior characterization and microstructure analysis. Finally, a design-oriented bond-slip model was developed to predict the interfacial pull-out behavior of steel fiber -UHPMC matrix, showing favorable agreement between predicted and test results. These findings contribute to understanding the interfacial pullout behavior of steel fibers-UHPMC matrix, providing data reference for the performance optimization of UHPMC.

The wetting of H2O by CO2.

Biphasic interfaces are complex but fascinating regimes that display a number of properties distinct from those of the bulk. The CO2-H2O interface, in particular, has been the subject of a number of studies on account of its importance for the carbon life cycle as well as carbon capture and sequestration schemes. Despite this attention, there remain a number of open questions on the nature of the CO2-H2O interface, particularly concerning the interfacial tension and phase behavior of CO2 at the interface. In this paper, we seek to address these ambiguities using abinitio-quality simulations. Harnessing the benefits of machine-learned potentials and enhanced statistical sampling methods, we present an abinitio-level description of the CO2-H2O interface. Interfacial tensions are predicted from 1 to 500 bars and found to be in close agreement with experiment at pressures for which experimental data are available. Structural analyses indicate the buildup of an adsorbed, saturated CO2 film forming at a low pressure (20 bars) with properties similar to those of the bulk liquid, but preferential perpendicular alignment with respect to the interface. The CO2 monolayer buildup coincides with a reduced structuring of water molecules close to the interface. This study highlights the predictive nature of machine-learned potentials for complex macroscopic properties of biphasic interfaces, and the mechanistic insight obtained into carbon dioxide aggregation at the water interface is of high relevance for geoscience, climate research, and materials science.

Mechanistically Understanding the Correlation Between Dynamic Interface Variation and Stability of Surface Coating on the NMC811 Materials

AbstractLiNi0.8Co0.1‐Mn0.1O2 (NMC811) is widely used in high energy density lithium‐ion batteries, while dynamic variation of liquid‐solid interface induced by oxygen release/evolution results in unexpected performance decay. Surface coating is an effective strategy in promoting the stability of NMC811 materials, and both coating composition and nanostructure arrangement would substantially impact the dynamic variation of liquid‐solid interfaces. To understand such dynamic variation, here evolution and stability of two selected NMC811 materials coated with oxides (the same oxide composition but different nanostructure arrangements) are compared, i.e., concentration uniform core‐shell NMC811 (CUCS811) and concentration gradient core‐shell NMC811 (CGCS811). The gas evolution from the home‐setup operando gas monitors (at 45 and 65 °C) implies that CUCS811 presents more operation and thermal stability because of less amount of CO2 and CH4 along with prolonged interval time in gas production. Composition variation of interfaces indicates that CUCS811 presents more stable interfacial evolution behaviors since more F‐ and P‐rich species for stabilizing the solid‐electrolyte interfaces are detected. The stability analysis suggests that uniform arrangement of Al2O3 and boride in the coating is prone to prevent the interface from degradation upon dynamic interface variation, which is useful in promoting the performance stability of NMC811 positive electrode materials.

Influence of mineral filler characteristics on the filler–asphalt interfacial behavior

The knowledge of mineral filler characteristics and their impacts on filler–asphalt interfacial behavior is not systematic and completed yet. In this paper, eight mineral fillers prepared using the same milling procedure were investigated. The filler–asphalt interfacial behavior was analyzed by differential scanning calorimetric and dynamic shear rheometer tests. Results reveal that in contrast to form factor and specific surface area, particle porosity, particle density, aspect ratio, angularity index, fractal dimension and feature roughness decrease with decreasing particle size. Limestone filler exhibits more regular shape, less significant angularity and richer surface texture than basalt filler. Of all particle characteristics studied, form factor and specific surface area are suggested to be the determining factors affecting filler–asphalt interfacial behavior. Moreover, microscopic morphology analysis provides an insight to interpret the differences explored in mastic interfacial property. The results help employ applicable particle characteristics that fabricate mastic with a stable interface system.

Oil–water interfacial behaviour of different caseins and stability of emulsions: Effect of micelle content and caseins concentrations

This study aimed to investigate the interfacial behaviour of caseins in different micelle content and its effect on the stability of emulsions, including micellar casein concentrate (MCN), calcium caseinate (CaC) and sodium caseinate (NaC). Results revealed that at high protein concentrations (0.5 %–2.5 %), MCN, CaC and NaC exhibited similar interfacial behaviour as well as unfolding rate constants (k1) of 3.11–3.41 × 10−4 (s−1), 2.96–3.35 × 10−4 (s−1) and 2.75–3.27 × 10−4 (s−1), respectively. The interfacial layer formed was dominated by non-micelles, and microscopic images revealed the thickness of the interfacial layer to be 10–20 nm. By contrast, at low concentrations, the differences in the slope of E–π curves and k1 indicated that the micelle content of casein affects protein interfacial behaviour and properties and that micellar casein is involved in the formation of the interfacial layer. The formation of large numbers of droplets during emulsion preparation results in a similar low concentration environment. Cryo-TEM showed adsorption of micellar casein in all three casein-stabilised emulsions, and the amount of adsorption was proportional to the micelle content. NaC has faster adsorption and rearrangement rates due to fewer micelles and more non-micelles, so that NaC forms smaller droplets and more stable emulsions than those formed by MCN and CaC within the range of 0.5 % to 2.0 %.

The interfacial behavior of a liquid crystal elastomer film bonded to an orthotropic substrate under light illumination

Bilayer soft actuators composed of a liquid crystal elastomer (LCE) film and a soft substrate have been widely used in soft robotics, bioengineering, and other fields. The existence of stress concentration at the interface edge easily leads to delamination damage of layered structures. Therefore, this article focuses on the distribution of interfacial stresses of the light-driven LCE film/orthotropic substrate system. The governing equations of the LCE film/substrate system are derived. The distributions of peeling and shear stresses on the interface are given and validated by using the finite element method (FEM). The effects of light illumination intensity, light attenuation distance and the director direction on the distribution of interfacial stresses are comprehensively analyzed. It is found that the signs of the shear stress and peeling stress depend on the director direction. This indicates that aligning the director in a certain direction may enhance the interface strength. The results may be useful for designing light-responsive LCE bilayer drivers.

Is the Interfacial Electrochemical Behavior of Quercetin the Same as That of Catechol Plus Resorcinol?

Background: Electrodeposition of functional films from polyphenol-containing solutions has emerged as a new field of surface functionalization from bio-sourced molecules. There is, however, almost no knowledge about the chemical structure of such complex films. It is the aim of this research to use the known electrodeposition of films made from catechol and resorcinol, two isomers of dihydroxybenzene, to understand the electrodeposition of a more complex polyphenol, quercetin, which is constituted from a fused catechol and resorcinol moiety. The aim of this article is hence to introduce some methodology in the interpretation of the electrochemical behavior of complex polyphenols starting from their building blocks. Methods: Cyclic voltammetry (CV) is used to deposit films from quercetin and from equimolar blends of catechol and resorcinol on amorphous carbon and gold working electrodes. The main experimental parameter was the potential sweep rate used during the CVs. Results: The CV of quercetin is not the exact sum of the CV of the catechol + resorcinol blends, but the major features are conserved, namely the presence of two main oxidation peaks affiliated to those of catechol and resorcinol but shifted to less anodic potentials. In addition, the anodic electron transfer coefficients of the two oxidation waves of quercetin are higher than those measured in the catechol resorcinol blend. However, film deposition ability is reduced with quercetin compared to catechol + resorcinol blend in probable relationship to steric hindrance occurring during the non-electrochemical crosslinking of the deposit. The quercetin-based films deposited at 10 mV·s−1 on gold electrodes are conformal and display some antioxidant activity.

Incorporating interface effects into multi-material topology optimization by improving interface configuration: An energy-based approach

Interfaces between structural multi-materials generally exhibit asymmetric resistance to tension and compression. Given this interface behavior, this work suggests an energy-based approach to improve the interface configuration for multi-material topology optimization. Based on the strain spectral decomposition, we decompose the structural elastic strain energy into tensile and compressive portions. In the density-based topology optimization framework, we use the gradient-based method to track the interface between multiple materials. Then, we construct an interface-associated scalar field to penalize the tensile portion of the strain energy, causing a pseudo-degradation of the strain energy at the interface region. Finally, within limited material usages and by minimizing the linear weighted structural strain energy and its pseudo-degradation, multi-material topology optimization with improved interface configuration is achieved. Several 2D and 3D numerical examples are investigated, by which the effectiveness and robustness of the suggested approach are fairly validated.

Molecular dynamics characterization of the interfacial structure and forces of the methane-ethane sII gas hydrate interface

The nucleation of gas hydrates is of great interest in flow assurance, global energy demand, and carbon capture and storage. A complex molecular understanding is critical to control hydrate nucleation and growth in potential applications. Molecular dynamics is employed combined with the mechanical definition of surface tension to assess the surface stresses controlling interfacial behavior. We characterize the interfacial tension for sII methane/ethane hydrate and gas mixtures for different temperatures and pressures. We find that the surface tension trends positively with temperature in a balance of water-solid and water-gas interactions. The molecular dipole shows the complexities of water molecule behavior in small, compressed pre-melting layer that emerges as a quasi-liquid. These behaviors contribute to the developing knowledge base surrounding practical applications of this interface.

Liberalizing the effects of Al and Cr in coatings for enhanced interface stability with Mo-rich Ni3Al-based superalloys

The interfacial behaviors between protective coatings and substrate single-crystal superalloys significantly impact their service performances. This work focuses on the elements interdiffusion and microstructural evolution at the interface between a NiCrAlY coating and a series of high-Mo Ni3Al-based single-crystal superalloys, through the coupled phase-field simulations and DICTRA kinetics calculations of their model systems. The critical roles of Al and Cr played in the microstructural evolution at coating/superalloy interface have been confirmed, which requires the appropriate content decreases of Al and Cr in the coating at 1100 °C. However, the addition of Mo reduces the driving force of element diffusion from coating to substrate by increasing the activities of Al and Cr in superalloy. Moreover, increasing the Mo content in superalloy from 8 wt% to 10 wt% could also counteract the promoting effect of Al on Ni mobility and mitigate the γ′ coarsening and detrimental TCP precipitation. Therefore, the effects of Mo enable the reasonable increase of Al content in coating to better balance the interfacial stability and oxidation resistance of coated superalloy, besides its advantage in reducing the anisotropy of TCP precipitate. The obtained interfacial evolution mechanisms resulting from the phase transformation thermodynamics and element interdiffusion kinetics are expected to aid the coating design for advanced single-crystal superalloys servicing at ultra-high temperature.

Phosphatidylcholine Surface Hydration-Dependent Adsorption to Mucin Enhances Intestinal Mucus Barrier Function.

The crucial role of zwitterionic phosphatidylcholines (PC) within mucus gel is essential for maintaining intestinal homeostasis, while the underlying mechanism remains incompletely understood. Herein, we compared the dynamic interfacial adsorption behavior of saturated dipalmitoylphosphatidylcholine (DPPC) and unsaturated dioleoylphosphatidylcholine (DOPC) to intestinal mucin and their impact on the intestinal mucus barrier function. Results of quartz crystal microbalance with dissipation showed that the highly surface-hydrated DPPC vesicles exhibited significantly faster and more extensive adsorption to purified intestinal mucin than the slightly surface-hydrated DOPC vesicles. Utilizing an intestinal Caco-2/HT29-MTX coculture model, we observed that DPPC vesicles adsorbed much more to the mucus gel compared to DOPC vesicles. Additionally, DPPC vesicle adsorption displayed increased wetting, and converse for DOPC vesicles. Interestingly, both of them exhibited nearly the same protective effects against cell injury induced by peptic-tryptic digests of gliadin (PTG). The partial mechanism involved the binding of PTG to DPPC and DOPC within the mucus gel, thereby restricting PTG contact with the underlying epithelial cells. These findings shed light on the intricate interfacial dynamics of PC adsorption to mucin and their implications for maintaining the integrity of the intestinal mucus barrier.

Surfactant-interlayer assisted interfacial polymerization for constructing Janus nanofiltration membranes: Enhanced Li+/Mg2+ separation efficiency

Nanofiltration (NF) technology shows significant potential for lithium extraction, but the limited Mg2+ rejection of conventional negatively charged NF membranes constrains Li+/Mg2+ selectivity. This work proposed a surfactant-interlayer assisted interfacial polymerization (SIAIP) methodology to convert a traditional NF membrane into a Janus membrane featuring dual-electrical properties. Sodium dodecyl sulfate (SDS) restricted the IP reaction region and modulated the interfacial diffusion behavior of amine monomers. The hydrophilic and negatively charged hyaluronic acid (HA) interlayer modified the substrate, enhancing membrane permeability. Under the combined influence of SDS and HA, more amine monomers were stored and diffused to the reaction interface, transforming the membrane surface into a positively charged region and forming a Janus structure with the negatively charged interlayer. The optimal SIAIP membranes possessed a homogeneous pore size distribution, with a high selectivity (S Li, Mg) of 42.15 and superb permeability of 11.06 L m−2 h−1 bar−1. This investigation furnishes an innovative approach for developing high-efficiency Li+/Mg2+ separating NF membranes.

Ultra-short running-in period and robust lubricity constructed by dynamic disulfide and hydrogen bonds from ionic liquid polyethylene glycol lubrication

Polyethylene glycol (PEG) system behave the characteristics of non-toxic, non-irritating and good compatibility with various substances, so the improvement and stability of lubrication property and comprehensive performance is vital for PEG system under harsh working conditions. Here, highly reactive ionic liquids (ILs) are designed and introduced with a specifically designed molecular structure, the ultra-short running-in period and robust lubricity can be obtained by dynamic disulfide and hydrogen bonds from the constructed IL-PEG200 lubrication system. Combined with analytical techniques (XPS, FIB-TEM, Nanoindentation, Raman, TOF-SIMS), their interaction was explored to further clarify the interfacial self-assembly behavior. The superior bearing capacity is mainly ascribed to the synergistic effect of carbon-like film, dynamic disulfide bond, hydrogen bonding and interfacial tribochemical reaction.