Characterization Of Interface Research Articles

Precise Characterization of a Waveguide Fiber Interface in Silicon Carbide

Precise Characterization of a Waveguide Fiber Interface in Silicon Carbide

Hybrid of micro-aramid and nano-alumina prominently enhanced the wear resistance of polytetrafluoroethylene composites

Polymer self-lubricating composites are key in reducing energy consumption from friction, boasting self-lubrication, remarkable wear, and corrosion resistance. This study delves into the unexpected synergy between micro-aramid and nano-Al2O3 in enhancing PTFE’s wear resistance. The results exhibit that the optimal hybrid of 15 vol.% micro-aramid and 1 vol.% nano-Al2O3 particles enhanced the PTFE composites has carried out the best tribological properties, showing synergistic anti-friction and anti-wear effects and obtaining the very low wear rate of 8.73 × 10−7 mm3/Nm, which is decreased by 53% and 98.7% in comparison with separate enhancement of the PTFE composites with 15 vol.% micro-aramid and 1 vol.% nano-Al2O3, respectively. In-depth characterization and analysis of the friction interface are confirmed that PTFE generating carboxylic acid groups during the friction process chelated with the dual steel surface, micro-aramid producing the interaction of the strong polarity with the dual steel, and mechanical stress and high flash temperature promoting friction sintering of nano-Al2O3 to enhance bearing capacity are cooperatively endowed a robustness protective tribofilm with easy shearing and high bearing properties, which effectively enhances the tribological properties of PTFE composites, providing a reference for the research and design of new nano composites with ultra-low wear and self-lubricating properties.

Microstructure evolution and phase interface characterization in anti-ablation (Hf1/4Zr1/4Ta1/4Ti1/4)C-coated C/C composites

Ta and Ti elements are often used as modified components to densify the loose oxide film for HfC/ZrC coatings after long-term ablation, while the synergistic effect among their multi-phase oxides on the ablation resistance of the coatings for C/C composites is still being explored. In this work, a (Hf1/4Zr1/4Ta1/4Ti1/4)C high-entropy carbide ceramic was proposed as an advanced anti-ablation coating for C/C composites and the multicomponent synergistic effect on the ablative behavior was investigated. At the initial ablation, the O atoms first reacted with Hf and Zr elements to form m-(Hf, Zr)O2. The TiO2 was prone to decompose into TiO and then evaporated from the coating during ablation, slowing down the volatilization of Ta2O5. The remaining TiO2 and Ta2O5 diffused to m-(Hf, Zr)O2 and produced a phase transition from Ta/Ti-doped m-(Hf, Zr)O2 to o-(Hf, Zr)6Ta2O17/o-(Hf, Zr)TiO4. The formation of nanotwin between (Hf, Zr)6Ta2O17 and (Hf, Zr)TiO4 enhanced the toughness of the oxide film. Although excessive Ta2O5 broke the stability of the oxide film, the Hf-Zr-rich oxide skeleton (Ta/Ti-doped (Hf, Zr)O2, (Hf, Zr)6Ta2O17 and (Hf, Zr)TiO4)) ensured that C/C substrates were intact after ablation for 180 s, showing superior ablation resistance.

Advancements in semiconductor-based interface engineering strategies and characterization techniques for carrier dynamics in photoelectrochemical water splitting

Advancements in semiconductor-based interface engineering strategies and characterization techniques for carrier dynamics in photoelectrochemical water splitting

A multifunctional tannic acid binder for 5.0 V LiNi0.5Mn1.5O4 electrodes and its interfacial characterization

Due to the higher working voltage of spinel LiNi0.5Mn1.5O4 (LNMO), the electrolyte degrades at high potentials, leading to the generation of numerous alkyl radicals.The transition metals will dissolve under high-voltage reactions, resulting in an unstable LNMO/electrolyte interface, ultimately deteriorating the battery’s cycling performance. In this study, a PAALi-TAc composite binder was obtained through the crosslinking of polyphenolic hydroxides Tannic acid (TAc) with PAALi. The electrode fabricated using this binder achieved a maximum capacity of 132.6 mAh g−1 at a 1 C rate. After 100 cycles, the capacity remained at 130.3 mAh g−1, with a retention rate of 98.2%. Even after 400 cycles, the capacity was maintained at 113.2 mAh g−1, with a retention rate of 85.3%. During the 400 cycles of high-current fast charge and discharge at 5 and 10 C, the capacity retention rates were 89.3% and 88.0%, respectively. The PAALi-TAc binder played a crucial role in establishing a compatible electrolyte interface by terminating the free radical chain reactions and chelating the excess dissolved metals in high-voltage LNMO//Li batteries, and this led to improved cycling and rate performance.

Plasmonic-mediated S[sbnd]C arylation and S[sbnd]S coupling on nanostructured silver electrodes monitored by in situ surface-enhanced Raman spectroscopy

Plasmon-mediated chemical reaction (PMCR) is a highly attractive field of research. Here we report in situ surface-enhanced Raman spectroscopic (SERS) monitoring of plasmonic-mediated SS bond-forming reaction. The reaction is thought to be a self-coupling reaction proceeding by photoinduced aromatic SC bond arylation. Surprisingly, the SC arylation and SS coupling are found to be occurred on both partially oxidized silver and silver nanoparticles. The results demonstrated that silver oxide or hydroxide and small molecule donor sacrifice agent played a crucial role in the reaction. This work facilitates the in-situ manipulation and characterization of the active silver electrode interface in conjunction with electrochemistry, and also establishes a promising new guideline for surface plasmon resonance photocatalytic reactions on metal nanostructures with high efficiency.

Electronic Interaction of Epoxy Resin with Copper at the Adhered Interface.

A better understanding of the aggregation states of adhesive molecules in the interfacial region with an adherend is crucial for controlling the adhesion strength and is of great inherent academic interest. The adhesion mechanism has been described through four theories: adsorption, mechanical, diffusion, and electronic. While interfacial characterization techniques have been developed to validate the aforementioned theories, that related to the electronic theory has not yet been thoroughly studied. We here directly detected the electronic interaction between a commonly used thermosetting adhesive, cured epoxy of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-diaminodiphenylmethane (DDM), and copper (Cu). This study used a combination of density functional theory (DFT) calculations and femtosecond transient absorption spectroscopic (TAS) measurements as this epoxy adhesive-Cu pairing is extensively used in electronic device packaging. The DFT calculations predicted that π electrons in a DDM molecule adsorbed onto the Cu surface flowed out onto the Cu surface, resulting in a positive charge on the DDM. TAS measurements for the Cu/epoxy multilayer film, a model sample containing many metal/adhesive interfaces, revealed that the electronic states of excited DDM moieties at the Cu interface were different from those in the bulk region. These results were in good accordance with the prediction by DFT calculations. Thus, it can be concluded that TAS is applicable to characterize the electronic interaction of adhesives with metal adherends in a nondestructive manner.

Development and characterization of discontinuous atmospheric pressure interface - Dual pressure chamber miniature mass spectrometer

Miniaturized mass spectrometers have become increasingly prevalent for real-time detection and analysis, owing to their compact size and portability. The pursuit of performance enhancement in these instruments is a pivotal objective within the domain of mass spectrometry miniaturization. This study introduces a novel miniature mass spectrometer featuring a discontinuous atmospheric pressure interface and a dual pressure chamber. Compared to conventional single-chamber, discontinuous sampling interface mass spectrometers, the newly developed instrument demonstrates a more than tenfold improvement in detection efficiency. This significant enhancement is achieved without the need for complex control of switch coupling time series, thereby streamlining the circuit design and improving the instrument's fault tolerance. Furthermore, by capitalizing on the benefits of discontinuous sampling, the instrument reduces the operational pressure relative to traditional continuous sampling in differential pressure vacuum chambers. It accommodates larger inlet capillary (0.38 mm) and skimmer (0.5 mm) diameters, leading to a ninefold increase in response strength for risperidone and lowering the detection limit to 0.5 ppb. The instrument's capacity for rapid drug detection, along with enhanced resolution and detection limits, underscores its potential utility. Additionally, it facilitates the use of smaller mechanical pumps, significantly diminishing both the instrument's volume and power consumption. This presents a promising avenue for further miniaturization of mass spectrometers.

Heterogeneous Coprecipitation of Nanocrystals with Metals on Substrates.

ConspectusThe heterogeneous coprecipitation of nanocrystals with metals on substrates plays a significant role in both natural and engineered systems. Due to the small dimensions and thereby the large specific surface area, nanocrystal coprecipitation with metals, which is ubiquitous in natural settings, exerts drastic effects on the biogeochemical cycling of metals on the earth's crust. Meanwhile, the controlled synthesis of nanocrystals with metal doping to achieve tunable size/composition enables their broad applications as adsorbents and catalysts in many engineered settings. Despite their importance, complex interactions among aqueous ions/polymers, nanocrystals, substrates, and metals are far from being well-understood, leaving the controlling mechanisms for nanocrystal formation with metals on substrates uncovered.In this Account, we discuss our systematic investigation over the past 10 years of the heterogeneous formation of representative nanocrystals with metals on typical substrates. We chose Fe(OH)3 and BaSO4 as representative nanocrystals. Mechanisms for varied metal coprecipitation were also investigated for both types of nanocrystals (i.e., Fe, Al, Cr, Cu, and Pb)(OH)3 and (Ba, Sr)(SO4, SeO4, and SeO3)). Bare SiO2 and Al2O3, as well as those coated with varied organics, were selected as geologically or synthetically representative substrates. Through the integration of state-of-the-art nanoscale interfacial characterization techniques with theoretical calculations, the complex interactions during nanocrystal formation at interfaces were probed and the controlling mechanisms were identified.For BaSO4 and Fe(OH)3 formation on substrates, the local supersaturation levels near substrates were controlled by Ba2+ adsorption and the electrostatic attraction of Fe(OH)3 monomer/polymer to substrates, respectively. Meanwhile, substrate hydrophobicity controlled the interfacial energy for the nucleation of both nanocrystals on (in)organic substrates. Metal ions' (i.e., Cr/Al/Cu/Pb) hydrolysis constants and substrates' dielectric constants controlled metal ion adsorption onto substrates, which altered the surface charges of substrates, thus controlling heterogeneous Fe(OH)3 nanocrystal formation on substrates by electrostatic interactions. The sizes and compositions of heterogeneous (Fe, Cr)(OH)3 and (Ba, Sr)(SO4, SeO4, SeO3) formed on substrates were found to be distinct from those of homogeneous precipitates formed in solution. The substrate (de)protonation could alter the local solution's pH and the substrates' surface charge; substrates could also adsorb cations, affecting local Fe/Cr/Ba/Sr ion concentrations at solid-water interfaces, thus controlling the amount/size/composition of nanocrystals by tuning their nucleation/growth/deposition on substrates. From slightly supersaturated solution, homogeneous coprecipitates of microsized (Ba, Sr)(SO4, SeO4, SeO3) formed through growth, with little Sr/Se(VI) incorporation due to higher solubilities of SrSO4 and BaSeO4 over BaSO4. While cation enrichment near substrates made the local solution highly supersaturated, nanosized coprecipitates formed on substrates through nucleation, with more Sr/Se(VI) incorporation due to lower interfacial energies of SrSO4 and BaSeO4 over BaSO4. The new insights gained advanced our understanding of the biogeochemical cycling of varied elements at solid-water interfaces and of the controlled synthesis of functional nanocrystals.

Interfacial Characterization and Mechanical Properties of Friction Stir Welding Dissimilar Joint Between Al Alloy and Advanced Ultrahigh-Strength Steel

Interfacial Characterization and Mechanical Properties of Friction Stir Welding Dissimilar Joint Between Al Alloy and Advanced Ultrahigh-Strength Steel

Solid-lubrication performance of Ti3C2Tx - Effect of tribo-chemistry and exfoliation

Multi-layer Ti3C2Tx coatings have demonstrated an outstanding wear performance with excellent durability due to beneficial tribo-layers formed. However, the involved formation processes dependent on the tribological conditions and coating thickness are yet to be fully explored. Therefore, we spray-coated Ti3C2Tx multi-layer particles onto stainless steel substrates to create coatings with two different thicknesses and tested their solid lubrication performance with different normal loads (100 and 200 mN) and sliding frequencies (1 and 2.4 Hz) using linear-reciprocating ball-on-disk tribometry. We demonstrate that MXenes’ tribological performance depends on their initial state (delaminated few-layer vs. multi-layer particles), coating thickness, applied load and sliding frequency. Specifically, the best behavior is observed for thinner multi-layer coatings tested at the lower frequency. In contrast, coatings made of delaminated few-layer MXene are not as effective as their multi-layer counterparts. Our high-resolution interface characterization by transmission electron microscopy revealed unambiguous differences regarding the uniformity and chemistry of the formed tribo-layers as well as the degree of tribo-induced MXenes’ exfoliation. Atomistic insights into the exfoliation process and molecular dynamic simulations quantitatively backed up our experimental results regarding coating thickness and velocity dependency. This ultimately demonstrates that MXenes’ tribological performance is governed by the underlying tribo-chemistry and their exfoliation ability during rubbing.

A comprehensive dimensional analysis of waste‐derived reinforcements in interface interactions with semi‐bio‐based PA6,10 composites

AbstractThis study elucidates interfacial interactions in semi‐synthetic polyamides by applying dimensional analysis to graphene derived from waste sources like coffee, tires, and chopped carbon fiber resulting in lightweight and high‐performance composites. Graphene from tires in platelet form (GNP), graphene from coffee in spherical form (CWC), and carbon fiber bundles (CF) were incorporated into Polyamide 6,10 (PA6,10) with high‐shear mixer by examining the optimum loading ratio for each reinforcement through interface characterization. At the same loading ratios, specific flexural properties are significantly enhanced when employing high aspect ratio CF reinforcement, while the platelet structure of GNP is more effective in improving specific tensile properties. Additionally, the spherical graphene of CWC exhibited the highest crystallinity, along with CF. In addition, sustainable PA6,10‐based compounds reinforced with waste‐derived materials were compared to commercial synthetic PA6‐based compounds with similar thermal and mechanical characteristics. The research revealed that the addition of 20 wt% CWC to the PA6,10 matrix outperforms commercial synthetic compounds by providing lightweight in terms of specific tensile. The findings of this study demonstrate that effectively incorporating waste‐derived reinforcing materials into semi‐synthetic composites presents a promising strategy to improve performance and serve as viable alternatives to commercial products through tailored waste‐derived reinforcement, particularly in applications that require lightweight and robust load‐bearing capabilities.Highlights Waste‐based reinforcements are sustainable alternatives to synthetic materials Size and aspect ratio of reinforcements give varying strengthening mechanisms Tailorable mechanical performance through different waste‐based reinforcements Waste‐based reinforcements offer lightweight for automotive composites Lightweight and sustainable composites can replace commercial products

Highly Ordered Co-Assembly of Bisurea Functionalized Molecular Switches at the Solid-Liquid Interface.

Immobilization of stimulus-responsive systems on solid surfaces is beneficial for controlled signal transmission and adaptive behavior while allowing the characterization of the functional interface with high sensitivity and high spatial resolution. Positioning of the stimuli-responsive units with nanometer-scale precision across the adaptive surface remains one of the bottlenecks in the extraction of cooperative function. Nanoscale organization, cooperativity, and amplification remain key challenges in bridging the molecular and the macroscopic worlds. Here we report on the design, synthesis, and scanning tunneling microscopy (STM) characterization of overcrowded alkene photoswitches merged in self-assembled networks physisorbed at the solid-liquid interface. A detailed anchoring strategy that ensures appropriate orientation of the switches with respect to the solid surface through the use of bis-urea groups is presented. We implement a co-assembly strategy that enables the merging of the photoswitches within physisorbed monolayers of structurally similar 'spacer' molecules. The self-assembly of the individual components and the co-assemblies was examined in detail using (sub)molecular resolution STM which confirms the robust immobilization and controlled orientation of the photoswitches within the spacer monolayers. The experimental STM data is supported by detailed molecular mechanics (MM) simulations. Different designs of the switches and the spacers were investigated which allowed us to formulate guidelines that enable the precise organization of the photoswitches in crystalline physisorbed self-assembled molecular networks.

Interface characterization of Mg-7Al-1Ca alloy reinforced by integrated 3D[sbnd]Cu open-cell foam

In this study, a 3DCu open-cell metal foam has produced through investment casting, then molten Mg-7Al-1Ca has penetrated through the 3DCu open-cell foam to produce the composite. The composites were heat treated at 290 °C and 480 °C for 1 h to find the adhesion mechanism at the interface of Mg-7Al-1Ca/3D-Cu open-cell foam. Then, the microstructural and mechanical properties of the Mg-7Al-1Ca/3D-Cu open-cell foam interface were investigated by metallography, micro-hardness, and punch-out test. The results indicate that the shear strength of the Mg-7Al-1Ca/3D-Cu interface is a function of the diffusion bond thickness and types of intermetallic phases. The as-cast sample tolerated 98.5 MPa shear stress. However, the 480 °C heat-treated sample has the most fracture toughness compared to the 290 °C heat-treated and the as-cast samples, 84.7, 75.6, and 35.1 J/mm3, respectively. Therefore, the heat-treatment cycle, T = 480 °C, t = 1 h, with decreasing 9.5% (98.5 to 89 MPa) of the shear strength led to an 140% (35.1 to 84.7 J/mm3) increase in energy absorption density of the interface of the composite.

Functional grading of low alloy steel to 316 L by wire arc additive manufacturing – Microstructural and mechanical characterization of bi-metal interface

This study examines the interface layer between a high-strength low-alloy steel and an overlaying austenitic stainless steel as deposited through wire arc additive manufacturing in a bi-metal block. By utilizing optical and electron microscopy techniques, and accompanied by phenomenological and thermodynamic modeling, the work elucidates on the nature of the distinct microstructural features at a new level of detail. Results showcase martensite in the form of a band along the fusion line of the first dissimilar layer, as well as in segregated islands. Within the same bead, yet away from the fusion line, an austenite matrix is identified alongside a large phase fraction of primary ferrite and sparse bainite. These findings enhance our understanding of the nature of the heterogeneous microstructure at the interface of a bi-metal build and establish empirical evidence for future modeling of microstructural development. Supplementary characterization reveals the impact of these microstructural heterogeneities on bulk mechanical performance. Hardness indents exhibit varied results along the interface, peaking at martensite islands with values up to 370HV0.2, surpassing the neighboring matrix by 50%. Under quasi-static tensile loading, bi-metallic specimens display strain partitioning along the fusion boundary, as confirmed by Digital Image Correlation. When compared to the adjoining stainless steel, the diluted interface layer exhibits superior strength (σy: 411 MPa) and comparable ductility (24%), leading to necking and failure away from this region. These results help predict the structural performance of bi-metal parts, and build a base for further research in more intricate loading scenarios, such as crack propagation processes.

Adhesion evaluation and interface characterization of 3D printed concrete for automatic repair

3D concrete printing can be used for automatic repair, aiming at increasing efficiency and reducing the use of manpower, as compared to conventional manual repair. Ensuring strong adhesion of the 3D printed materials and characterizing the interface is crucial for the success of this approach. To this end, we first evaluated the adhesion performance of 3D printed concrete based on a low-carbon binder, i.e., calcium sulfoaluminate (CSA) cement. CSA cement pastes with different re-dispersible polymer powder substitution rates were used as coating before 3D printing. We used two approaches, X-ray computed tomography (CT) and scanning electron microscopy (SEM), to characterize the interface region. Results indicate that the yield stress of the 3D printing material and the coating material plays an important role in the adhesion in both the fresh and hardened state. Moreover, the limited adhesion at the overlay interface can be due to the limited contact at the centimeter and micro scale, as reflected by CT and SEM, respectively. Applying a coating can fill the air voids at the interface, while the placement of a coating may not improve the bond strength and can even have a negative impact due to the limited liquid medium at the interface.

Interfacial quantum chemical characterization of aromatic organic matter adsorption on oxidized microplastic surfaces

Examining the adsorption efficiency of individual contaminants on microplastics (MPs) is resource-intensive and time-consuming. To address this challenge, combined laboratory adsorption experiments with model simulations were performed to investigate the adsorption capacities and mechanisms of MPs before and after aging. Our adsorption experiments revealed that aged polyethylene (PE) and polyvinyl chloride (PVC) MPs exhibited increased adsorption capacity for benzene, phenol, and naphthalene. Additionally, density functional theory (DFT) simulations provided insights into changes in adsorption sites, adsorption energy, and charge density on MPs. The π bond of the benzene ring emerged as a pivotal factor in the adsorption process, with van der Waals forces exerting dominant influence. For instance, the adsorption energy of benzene on pristine PE was −0.01879 eV. When oxidized groups, such as hydroxyl, carbonyl, and carboxyl, on the surface of aged PE became the adsorption sites, the adsorption energy increased to −0.06976, −0.04781, and −0.04903 eV, respectively. Regions with unoxidized functional groups also exhibited higher adsorption energies than pristine PE. These results indicated that aged PE had a stronger affinity for benzene compared to pristine PE, enhancing its adsorption. Charge density difference and energy density of states corroborated this observation, revealing larger π-bond charge accumulation areas for benzene on aged PE, suggesting stronger dipole interactions and enhanced adsorption. Similar trends were observed for phenol and naphthalene. In summary, the DFT calculations aligned with the adsorption experiment findings, confirming the effectiveness of simulation methods in predicting changes in the adsorption performance of aged MPs.

Direct Characterization of Buried Interfaces in 2D/3D Heterostructures Enabled by GeO2 Release Layer.

Inconsistent interface control in devices based on two-dimensional materials (2DMs) has limited technological maturation. Astounding variability of 2D/three-dimensional (2D/3D) interface properties has been reported, which has been exacerbated by the lack of direct investigations of buried interfaces commonly found in devices. Herein, we demonstrate a new process that enables the assembly and isolation of device-relevant heterostructures for buried interface characterization. This is achieved by implementing a water-soluble substrate (GeO2), which enables deposition of many materials onto the 2DM and subsequent heterostructure release by dissolving the GeO2 substrate. Here, we utilize this novel approach to compare how the chemistry, doping, and strain in monolayer MoS2 heterostructures fabricated by direct deposition vary from those fabricated by transfer techniques to show how interface properties differ with the heterostructure fabrication method. Direct deposition of thick Ni and Ti films is found to react with the monolayer MoS2. These interface reactions convert 50% of MoS2 into intermetallic species, which greatly exceeds the 10% conversion reported previously and 0% observed in transfer-fabricated heterostructures. We also measure notable differences in MoS2 carrier concentration depending on the heterostructure fabrication method. Direct deposition of thick Au, Ni, and Al2O3 films onto MoS2 increases the hole concentration by >1012 cm-2 compared to heterostructures fabricated by transferring MoS2 onto these materials. Thus, we demonstrate a universal method to fabricate 2D/3D heterostructures and expose buried interfaces for direct characterization.

A guide to troubleshooting metal sacrificial anodes for organic electrosynthesis.

The development of reductive electrosynthetic reactions is often enabled by the oxidation of a sacrificial metal anode, which charge-balances the reductive reaction of interest occurring at the cathode. The metal oxidation is frequently assumed to be straightforward and innocent relative to the chemistry of interest, but several processes can interfere with ideal sacrificial anode behavior, thereby limiting the success of reductive electrosynthetic reactions. These issues are compounded by a lack of reported observations and characterization of the anodes themselves, even when a failure at the anode is observed. Here, we weave lessons from electrochemistry, interfacial characterization, and organic synthesis to share strategies for overcoming issues related to sacrificial anodes in electrosynthesis. We highlight common but underexplored challenges with sacrificial anodes that cause reactions to fail, including detrimental side reactions between the anode or its cations and the components of the organic reaction, passivation of the anode surface by an insulating native surface film, accumulation of insulating byproducts at the anode surface during the reaction, and competitive reduction of sacrificial metal cations at the cathode. For each case, we propose experiments to diagnose and characterize the anode and explore troubleshooting strategies to overcome the challenge. We conclude by highlighting open questions in the field of sacrificial-anode-driven electrosynthesis and by indicating alternatives to traditional sacrificial anodes that could streamline reaction optimization.

In Situ Interface Characterization of Arcing Electrode Materials and Evolution in Electrical Endurance Experiments

In Situ Interface Characterization of Arcing Electrode Materials and Evolution in Electrical Endurance Experiments