Film Formation Research Articles

Avaliação do comportamento reológico de argamassas de revestimento por meio do método do Squeeze-Flow com base no empacotamento de partículas e o teor de água da mistura

Abstract Mortars’ workability results from other properties, such as consistency, plasticity, cohesion, water retention, exudation, initial adhesion and density. A workable mortar distributes itself in application, doesn’t segregate during transport, and remains plastic during the application time. This property depends on several application factors, together with the constituent materials. Therefore, this study aims to assess the influence of the formulation, aggregate type and water content on rheological behavior of rendering mortars, combined with particle packing studies. For this purpose, three usual mortar formulations were chosen. The minimum water content was calculated through the concepts of particle packing and the squeeze flow test. As a result, the influence of each constituent on the workability of the mortar was determined, together with the formulations optimized by the aggregate type. The water content analysis revealed the wet packing density and minimum value required for the formation of the water film around the particles.

Tribo-oxidation mechanism of gradient nanostructured Inconel 625 alloy during high-temperature wear

The tribo-oxidation layer is typically formed at the contact interface of high temperature wear, which exhibits a significant effect on the friction behavior of gradient nanostructured (GNS) materials. This study systematically investigated the wear resistance, near-surface microstructure, and compositional changes of ultra-thick GNS Inconel 625 alloy subjected to surface mechanical rolling treatment (SMRT) under high-temperature sliding wear conditions. The experimental results indicated that as the temperature increased to 500 °C, a tribo-oxidation layer was formed on the surface of the GNS sample, thereby resulting in an abnormal increase in the coefficient of friction (COF) and a rapid decrease in the wear rate. The gradient nanostructures facilitated oxidation diffusion channels, promoting the formation of a protective Cr2O3 film and spinel oxides, reducing the wear rate. At lower temperatures, a rapidly formed Cr2O3 film shielded the matrix, forming a tribo-oxidation layer composed of Cr2O3 and nickel. At 800 °C, the tribo-oxidation layer exhibited complex structures, including glaze, spinel oxide, Cr2O3, and Cr2O3/Ni mixed layers. This complexity was attributable to the oxidation diffusion rate of the gradient nanostructures and tribo-oxide layers. The findings not only elucidated the tribo-oxidation mechanism of GNS nickel-based superalloys but also offered valuable insights for designing wear-resistant materials.

Modulation of Al-Zn-0.5Sn-0.5Mn anode properties by trace Sb

In aluminum-air batteries, hydrogen precipitation corrosion is a difficult problem for aluminum anodes in alkaline electrolytes, which causes a decrease in the efficiency and shortens the service life of aluminum anodes. Under the condition of 4 mol·L-1 NaOH alkaline solution, the addition of trace Sb (0.04 wt%) to Al-Zn-0.5Sn-0.5Mn resulted in an increase of 88.64% in energy density and 74.03% in the specific capacity of the aluminum anode, and a constant current discharge at a current density of 10 mA·cm-2, with a discharge voltage as high as 1.43 V and the discharge process is stable, the anode efficiency reaches 90.90% and the energy density reaches 2526 Wh·kg-1. The improvement in the performance of the aluminum anode is mainly due to the precipitation of the AlSb phase, which activates the grain boundaries, improves the electrochemical activity of the aluminum anode, and forms Sb-containing membranes to inhibit the formation of surface passivation films. Efficient discharge in alkaline solution and long battery life.

High-yield hydrogen peroxide treatment of refined softwood in recyclable deep eutectic solvent to produce moisture-tolerant wood nanofiber films

In this study, a novel hydrogen peroxide treatment of refined softwood (thermomechanical pulp) in urea-LiCl-based deep eutectic solvent with negligible material loss (<2 %) was studied as a pre-treatment in the production of wood nanofibers (WNF). A short treatment time (2 min) was shown to slightly alter the structure of wood by increasing the oxygen content at the surface of the fibers and increasing the fine fiber fraction content due to the mild oxidation of surface of fibers potentially via hydrogen peroxide mediated formation of lithium hypochlorite. The mild alteration of the fiber structure resulted in the formation of a WNF film with 33 % higher tensile index compared to films obtained from WNF produced without hydrogen peroxide treatment. Furthermore, deep eutectic solvent recyclability was successfully demonstrated for five consequent treatments. In addition, hot pressing of the WNF films was investigated to improve the water tolerance (wet tensile strength) of the films. By studying various pressing conditions (time, temperature, and pressure), the wet tensile strength of films was increased from 1.0 kNm/kg to almost 20 kNm/kg with only ten minutes pressing time. The increase in wet tensile strength was effectively correlated to a decrease in the water uptake of the films during submersion in water. Simultaneously to the increased water tolerance, the dry tensile properties of the films decreased, but always remained above 40 kNm/kg.

Colorimetric ammonia-sensing nanocomposite films based on starch/sodium alginate and Cu-Phe nanorods for smart packaging application

The development of colorimetric ammonia-sensing smart packaging materials with real-time freshness detection ability are crucial for ensuring food safe. This research involved the construction of Cu-based framework (Cu-Phe) nanorods with colorimetric ammonia-sensing ability through an easy-to-perform aqueous solution method, and their subsequent utilization as nano inclusions in starch/sodium alginate (ST/SA) substrate to foster the creation of high-performance smart packaging materials. Research findings revealed that the addition of Cu-Phe nanorods (3, 6, 9 wt%) within ST/SA substrate led to the formation of compatible nanocomposite films with significantly augmented physical performance and functionality. Especially, the film containing 9 wt% Cu-Phe presented the highest tensile strength (30.32 MPa), elongation at break (19.12 %), UV-shielding efficacy (blocking >99 % of UV passage), water vapor barrier effectiveness (1.90 × 10−6 g/m·h·Pa) and oxygen barrier ability (2.26 × 10−3 g/m2·s). In addition, the developed ST/SA/Cu-Phe nanocomposite film possessed excellent antibacterial activity (over 99.9 %) against Escherichia coli and Staphylococcus aureus, superior colorimetric ammonia-sensing ability, and long-term colour stability. Also of note, the Cu-Phe added ST/SA nanocomposite film allowed for detecting prawn and pork freshness reduction in real-time via discernible colour transition, suggesting its extensive promise for smart packaging applications.

Nickel oxide films with the zinc blende-type structure – A re-evaluation of X-ray diffraction data

The previously unobserved formation of zinc blende-type structured nickel oxide films (NiO1.2) was discovered by the re-evaluation of X-ray powder diffraction data. Nickel oxide films were synthesized by deposition of nickel together with activated oxygen at substrate temperatures of 83K and 298K. At 83K, amorphous NiO films are formed, which crystallize at around 473K forming the rock salt-type structure. In contrast, films deposited at 298K are polycrystalline and form the zinc blende-type structure. Both structures have largely identical lattice parameters with the same nickel fcc sublattice, but with either tetrahedral or octahedral sites filled with oxygen atoms. The only difference observed between the X-ray powder patterns is the intensity of the reflections. The calculation of X-ray difference maps was decisive in distinguishing between the two structures. The Ni-O distances in the zinc blende structure are 181pm, confirming the presence of NiIII in the NiO1.2 film.

Effect of Ti addition on the microstructure and corrosion behavior of laser cladding AlCoCrFeNi high-entropy alloy coatings

AlCoCrFeNi high-entropy alloys (HEAs) has higher strength and wear resistance but poorer corrosion resistance. In the present investigation, the AlCoCrFeNi HEAs containing titanium(Ti) were fabricated via laser cladding to enhance the corrosion resistance properties of the coating and the influence of the Ti content on the microstructure of the coatings was investigated. The results show that the microstructure of the coating changed from a single BCC phase to a BCC+B2 phase with the addition of Ti. The Laves phases appeared within the coating when the Ti content was beyond 0.5 mol ratio. As an excellent corrosion-resistant element, Ti promoted the formation of a passive film and enhanced the corrosion resistance of the HEAs coating. The corrosion resistance of the coating first increased and then decreased with the addition of Ti, and the AlCoCrFeNiTi0.5 coating exhibited optimal corrosion resistance.

Use of Wheat Fiber and Nanobentonite to Stabilize Clay Subgrades

Since clayey soils naturally present low mechanical strength, they pose direct challenges for engineering applications. Finding appropriate soil stabilizers to address the challenges posed by clayey soils is crucial for ensuring that the soil meets the necessary geotechnical requirements and fulfills economic and environmental issues. To this end, this research uses several stabilizers and techniques in clayey soils to improve their suitability for construction. The main objective of this study is to assess the use of wheat fiber and nanobentonite (NB) in soil stabilization, estimate their behavior in practices, outline their obstacles and potential for soil improvement, and consider their ecological and financial effects. This research also evaluates the behavior of the soil by incorporating NB (0.4, 0.8, and 1.2%) as a stabilizing agent. For this purpose, the randomly dispersed wheat fibers as a reinforcing agent at different dosages and lengths (0.3, 0.6, 0.9%, and 5, 10, and 15 mm) were combined to the soil matrix. The soil was characterized by conducting compaction, unconfined compressive strength (UCS), direct shear (DS), California bearing ratio (CBR), indirect tensile strength (ITS), freezing-thawing (F-T) tests, and microstructural analysis. The data were used to assess the effect of wheat fiber and NB on the soil’s geotechnical properties. The results revealed that incorporating 0.8% NB into the soil led to the best enhancement in compressive strength. This improvement is attributed to the dehydration and formation of a viscous-like film between the soil particles. In addition, 0.6% fibers with a length of 15mm increased the interaction and bonding forces between the particles of soil, resulting in a maximum increase in compressive strength. Combining fibers and NB improved the shear strength, tensile strength, and bearing capacity. Besides, the stabilized soil exhibited superior resistance to freezing-thawing cycles compared to the unreinforced clay. Overall, the results indicate that using wheat fibers and NB is a cost-effective and eco-friendly solution for stabilizing clay subgrades.

Effects of magnetic field on the anodic dissolution of alloy 690 in NaCl + Na2S2O3 solution

Purpose The purpose of this paper is to study the anodic dissolution processes of alloy 690 in NaCl + Na2S2O3 solutions by using digital holography. Design/methodology/approach The digital holography technique was used to in situ observe the dynamic processes occurring at the electrode|electrolyte interface during the anodic dissolution of alloy 690 in NaCl + Na2S2O3 solutions, both in the presence and absence of a magnetic field (MF). Findings In 3.5% NaCl + 0.01 M Na2S2O3 solutions, MF inhibited intergranular corrosion (IGC) because it increased the defects in the oxide film and facilitated the uniform adsorption of low concentration of S on these defects due to its stirring effects, which resulted in a weakened adsorption of S at the grain boundaries. Conversely, in 3.5% NaCl + 0.1 M Na2S2O3 solutions, MF promoted IGC by increasing the number of defects in the oxide film, with lots of S species preferentially adsorbing at the grain boundaries. The resultant salt films formed more readily, inhibiting the formation of the oxide film at the grain boundaries. Originality/value Through the use of digital holography, it was possible to in situ observe the initiation of IGC at a single grain boundary and its progression to adjacent grain boundaries, regardless of the presence or absence of MF.

Rapid Prototyping for Accelerated Establishment of Film Processing‐Performance Relationships in Silicon Phthalocyanine OFETs

AbstractUnderstanding the complex relationships underlying the performance of organic electronic devices, such as organic field‐effect transistors (OFETs), requires researchers to navigate a multi‐dimensional parameter space that includes material design, solution formulation, fabrication parameters, and device geometry. Herein, a recently developed materials acceleration platform is demonstrated, named the RoboMapper, to perform direct on‐chip fabrication of OFETs by ultrasonic meniscus printing using silicon phthalocyanine (SiPc) derivatives as the semiconductor. OFETs using bis(tri‐n‐butylsilyl oxide) SiPc ((3BS)2‐SiPc) exhibited the best device performance characterized by the highest electron field‐effect mobility (µe). Through optical microscopy and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS), the favorable performance of (3BS)2‐SiPc is attributed to the specific film morphology and molecular packing achieved with optimal print conditions. Investigating the impact of deposition parameters reveals the crucial role of solvent evaporation rate and print speed in achieving high‐quality film formation. Overall, optimal fabrication conditions for (3BS)2‐SiPc devices include slow print speeds and fast evaporating solutions achieved by using a mixture of co‐solvents and an elevated substrate temperature. The results of this work reveal distinct relationships between deposition conditions, film properties, and device performance for each SiPc derivative and emphasize the necessity of high throughput experimentation to comprehensively understand process‐performance relationships in organic semiconductors.

Effect of bionic shield texture on friction behavior of silicon carbide under water lubrication condition

Abstract Reasonable texture parameters can effectively generate local dynamic pressure effects and promote the formation of lubrication film. The synergistic friction reduction mechanism of the shield-shaped texture on the Silicon Carbide (SiC) surface under water-based lubrication conditions between the flow pressure effect and the ‘rolling ball’ effect is investigated by combining simulation analysis and friction experiments. The effects of shield textured surface on the friction and wear characteristics of SiC surface and the characteristics of interfacial polarization electric field under different rotational speeds and different load conditions were analyzed. The results display that synergistic texture lubrication has a beneficial effect on improving tribological properties. The surface with 6% texture area occupancy showed the best tribological characteristics. The surface with a textured area occupancy of 6% displays the optimal tribological properties. Moreover, the friction reduction mechanisms under different working conditions are discussed, with the textured uniformly arranged surfaces being more suitable for high-speed and heavy load (140 N, 2000 rpm) conditions and the textured non-uniformly arranged surfaces being more suitable for low-speed and light load (40 N, 400 rpm) conditions.

Freestanding Phosphonium Covalent Organic Frameworks with Efficient Hydroxide Conduction for Zinc–Air Batteries

Owing to their well‐defined crystalline pore structures and ordered functional ionic groups along the skeleton, ionic covalent organic frameworks (iCOFs) exhibit excellent performance and have significant potential for use in energy storage and conversion devices. Herein, we for the first time developed cationic phosphonium COFs with high hydroxide conduction even with low ion exchange capacity (IEC). Specifically, we synthesized COFs containing quaternary phosphonium groups as excellent ion transport moieties. Then, we fabricated freestanding phosphonium membranes through a vapor‐assisted method, which exhibited high hydroxide conductivity of 126 mS cm–1 at 80 °C from a minimal IEC of 1.17 mmol g–1. The resulting film was successfully applied to zinc–air batteries, demonstrating energy density of 96.1 mW cm–2, specific capacity of 95.0 mAh cm–2, and stable operation over 2,300 min. Overall, in addition to investigating a novel cationic functional group, we demonstrated a freestanding film formation method of COF‐based materials. The findings can provide a solid foundation for advancing the field of iCOFs to ion transport and promoting electrochemical applications.

Identification of Cause–Effect Relationships between Process Parameters and the Film Formation in the Semidry Electrode Production for Lithium‐Ion Batteries

Conventional electrode production for lithium‐ion batteries has high energy and plant space demand, due to the high solvent content of the slurry to be processed by slot die or doctor blade coating. By using the semidry electrode production, the solvent content is reduced by more than 50% compared to the conventional electrode production, decreasing energy demand and drying length. Regarding technology readiness level, the semidry electrode production is on the pilot scale, as the basic principles have been shown. However, many unknown cause–effect correlations exist between the process parameters and the product properties. This study aims to analyze process parameter variations and their influence on the geometric, electrochemical, and mechanical properties of the electrode. An experimental design is utilized to obtain statistically relevant conclusions. It is found that the first calender gap and the roller speed influence the mass loading and the porosity of the electrode. The roller speed significantly influences the ionic resistance within the electrode, which may be attributed to the used release foil.

Insights Into Pool Boiling Heat Transfer on Minichannel Surfaces Through Point and Field Measurements

Abstract In this study, saturated pool boiling experiments were conducted on copper minichannel and flat surfaces at atmospheric pressure using water as the working fluid. The heat transfer performance was assessed through point measurements with a heater block, cartridge heaters, and thermocouples, as well as field measurements using a thin-foil heater and infrared thermography. Two copper minichannel surfaces with square cross sections of 1 mm (minichannel-1) and 2 mm (minichannel-2) side lengths were tested and compared to a flat surface. Minichannel-1 and minichannel-2 enhanced the critical heat flux (CHF) by 17% and 45%, respectively, and improved the heat transfer coefficient by 24–40% and 51–75%, respectively, compared to the flat surface. Minichannel-2 exhibited the lowest and most uniform boiling surface temperature, making it the best performer among the three. There was no significant change in departure frequency among the surfaces, and no significant change in departure diameter for the flat surface and minichannel-1. However, minichannel-2 had lower departure diameters due to its deeper channels, which prevented bubble coalescence and maintained low departure diameters. Additionally, minichannel-2 delayed vapor film formation by breaking it with its deeper fins, thereby improving CHF and slightly enhancing bubble dynamics. The enhancement in boiling heat transfer is primarily attributed to the increased surface area provided by the minichannels, with a minor contribution from improved bubble dynamics. However, the dominant factor in enhancing pool boiling heat transfer on minichannel surfaces is the increase in surface area.

The Interaction Between Fluorinated Additives and Imidazolyl Ionic Liquid Electrolytes in Lithium Metal Batteries: A First‐Principles Study

ABSTRACTThis investigation employs first‐principles calculations to explore the interaction between imidazolium ionic liquids (ILs) and fluoride additives on lithium metal surface. Our focus lies in the comprehensive analysis of three distinct categories of fluorinated additives, each differing in their degree of fluorination. The computations reveal that fluorination plays a significant role in determining both the ionic conductivity and the formation of the solid–electrolyte interphase (SEI) film. Specifically, heightened fluorination enhances the oxidative stability of the system but diminishes the strength of solvent binding, resulting in the formation of larger salt/anion clusters and a decrease in ionic conductivity. Conversely, increased fluorination facilitates the interaction between fluorinated additives and the lithium metal surface, thereby aiding in the formation of a stable SEI film characterized by an abundance of inorganic LiF components. This is important as it serves to suppress dendrite growth and mitigate interface side reactions. Considering the combined influences of ionic conductivity and film formation, 1FP is suggested as the optimal candidate for pyridine‐based additive systems, with FEC preferred for cyclic ester‐based additive systems and BC for chain ester‐based additive systems. This study provides theoretical references for the design of ionic liquid‐fluorinated additive electrolyte systems that can protect the lithium metal anode.

Biobased hydrophobic liquid mulch film from soybean oil and starch for enhanced terraced field cultivation.

Terraced agriculture faces soil loss during rainstorms leading to natural disasters and crop growth impediments. This study describes a novel biobased hydrophobic liquid mulch film comprised of waste soybean oil, starch, and acrylate monomers that can be used to enhance terraced field cultivation. The novel film, optimized at a 3:7 soybean oil to acrylate monomers ratio, exhibited superior spray ability, reduced wicking, and excellent film formation, which are crucial for its effectiveness as a water erosion barrier. The wet state of the SOSA film demonstrated optimal impact resistance, with increased elongation at break and reduced breaking strength compared to its dry state, facilitating seedling emergence. It significantly improved soil moisture retention (4.8-5.7 %) and temperature (0.9-5.6 °C) and boosted maize seed germination by 28 %. Under extreme conditions of a 24° slope and 90 mm/h rainfall, the SOSA film achieved an 80.6 % reduction in soil loss and a 57.4 % increase in pakchoi yield over bare soil. This study's comprehensive analyses confirmed the film's formation mechanism and provided a scientific basis for its practical application performance, highlighting the film's unprecedented success in using waste materials for sustainable terrace farming and its potential as a transformative approach to soil conservation and crop productivity.

A novel multicomponent micro-alloyed magnesium for orthopaedic applications: a microstructural, mechanical, degradation and bioactivity study

ABSTRACT The current study focuses on development of magnesium based micro-alloy with the composition of Mg–0.5Zn–0.15Ca–0.1Mn–0.1Sn–0.1Ag–0.2Ce–0.2Sr using casting method. Microstructural examinations conducted using optical microscopy and scanning electron microscopy (SEM) unveiled a uniform grain distribution in the alloy with minimal intermetallic content, corroborated by X-ray diffraction (XRD) analysis matching the magnesium peak precisely. Tensile testing indicated that the solution strengthening process boosted the alloy’s required yield strength and stiffness, while enhancing magnesium’s ductility up to 19.07% elongation. Electrochemical tests demonstrated an outstanding corrosion resistance rate of 0.91 mm/year, supported by Nyquist plots indicating passivation behaviour and film formation. The pH variations revealed an initial spike to 8.13 within the first 24 hours, gradually declining thereafter. The bioactivity assessment of the developed alloy showcased the formation of near-stoichiometric apatite layers on the alloy surface, confirming its potential as a suitable orthopaedic implant material.

Developing Hydration Maps of Polymer Latex Film Formation Using Terahertz Time-Domain Spectroscopy.

The dynamics of the drying process of polymer latexes after casting as a wet film onto a substrate are important to track as they influence the physical and mechanical properties and performance of the dried polymer films. Current methods used to follow this drying process include gravimetric analysis, coupled with advanced techniques like GARField-NMR or optical coherence tomography. The latter two methods provide height and spatial information in the z-direction, normal to the substrate, and occasionally in the xz- or yz-planes. Terahertz time-domain spectroscopy (THz-TDS) is a welcome addition as it provides both the structural and spectroscopic information in the parallel xy-plane, filling the geometric gap. Herein, we utilize THz-TDS to study the drying and film formation process of various polymer latexes with a broad range of glass transition temperatures. We showcase the applicability of this technique in obtaining 2D parallel hydration maps of the drying dispersions, in the form of droplets, using latex-dependent calibration lines. Our findings display known phenomena arising from the drying of the colloidal dispersions.

Evaluation of the optical and electrical properties of (C8BTBT)(F4TCNQ) charge-transfer complexes according to film formation temperatures during solution-coating

Abstract This study focused on (C8BTBT)(F4TCNQ) charge-transfer complexes, where C8BTBT is 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and F4TCNQ represents fluorinated derivatives of 7,7,8,8,-tetracyanoquinodimethane. These complexes exhibit excellent thermal and atmospheric stability and near-infrared absorption, serving as transparent thin films for photoelectric conversion. Here, we sought to improve the photoelectric conversion efficiency (and thus the quantum efficiency, QE) of (C8BTBT)(F4TCNQ) thin films by altering the film formation temperatures during solution-coating; we evaluated optical and electrical properties of the films. We found that increased film coverage of a substrate surface (leading to continuous film formation) enhanced optical absorption and improved the photocurrent extraction efficiency when such films were incorporated into devices. C8BTBT and its components, when present alone, negatively affected both the device fabrication yield and photocurrent extraction. It is thus important to maximize (C8BTBT)(F4TCNQ) formation when seeking to improve the QE.

On the interaction between a rising bubble and a settling particle

This study investigates the interaction between a freely rising, deformable bubble and a freely settling particle of the same size due to gravity. Initially, an in-line configuration is considered while varying the Bond, Galilei and Archimedes numbers. The study shows that as the bubble and particle approach each other, a liquid film forms between them that undergoes drainage. The formation of the liquid film leads to dissipation of kinetic energy, and for sufficiently large bubble velocities, particle flotation takes place. Increasing the Bond number causes the bubble to deform more severely, which may allow the particle to pass through the bubble as it ruptures. This work also considers an offset configuration, which shows that the bubble slides away from the particle, affecting its settling trajectory.