Surface Film Thickness Research Articles

Evaluation of Scuffing Load Capacity of Helical Gear Based on the Tribo‐Dynamic Model

ABSTRACTThe scuffing load capacity of gear is closely related to the meshing temperature rise of tooth surface. The key to predict the temperature rise is to establish an accurate meshing temperature rise model. In the paper, a tribo‐dynamic model of helical gear is established through coupling of tooth surface lubrication parameters, and the influence of temperature rise on ambient temperature during meshing process is considered. Then, the effects of oil supply temperature, input speed and torque on tooth surface temperature rise, film thickness, friction excitation and gear dynamic characteristics are discussed. The results show that the temperature rise of the gear is higher during the engaging‐in and engaging‐out regions. Meanwhile, there is local high temperature at the end of the contact line due to the end effect. The vibration of gear along the off‐line‐of‐action direction is mainly determined by friction excitation. With the increase of oil supply temperature, input speed and torque, the risk of scuffing failure increases and the influence of oil supply temperature and input load is more significant. The conclusions of this paper may provide some valuable suggestions for the anti‐gluing failure design of gear in engineering.

A time-resolved investigation at multiple-length scales of the structure of liquid foam stabilized by albumins from pea

HypothesisThe structural details of foams made with pea albumins are affected by the pH of the initial solution and followed heat treatment. ExperimentsAn in situ, time-resolved investigation of foams prepared with pea albumins was conducted using small-angle neutron scattering (SANS) in combination with imaging and conductance measurements. Solutions were tested at pH three pH values (3, 4.5, and 8) before and after heating (90 °C for 1 and 5 min). FindingsThe characteristic structures present in the foam from the nano to the meso-scale differed during drainage depending on solution pH. Foams obtained at pH 3, had the largest bubble radius and thinnest plateau border, as well as the highest extent of liquid drainage. At pH 4.5, close to the isoelectric point of the proteins, foams displayed similar bubbles’ behavior to those at pH 8, but with the largest film thickness. In this case, the proteins were extensively aggregated. Heating of the solutions prior to foaming did not significantly affect the foam aging regardless of pH. The quantification of specific surface areas and film thickness over time without sample disruption shows to be a powerful approach to designing foam structures.

On the reconstruction of LEIS spectra after distortion by an electrostatic energy analyzer

The study attempts to reveal the influence of the transmission function of electrostatic deflector analyzers with linear voltage scan on the shape of the LEIS energy spectra and the arising error in surface elemental composition and film thickness analysis. The practical applicability of several analytical and numerical approaches for reconstructing true energy distributions of particles is studied using examples of simulated LEIS spectra. The presented methodology can be extended to a wider range of applications involving electrostatic or magnetic analyzers of charged particles. The study proposesa freely available and ready-to-use tool for simulating distortions of spectra caused by the transmission function of spectrometers and for reconstructing true distributions of arbitrary spectra.

Optimization of automated anodizing plant efficiency and process prediction using Random Forest based Levy flight method

The anodizing process is mainly carried out by industrialists to protect aluminium components from corrosion and strengthen their physical and chemical behavior. The goal of this study is to minimize the total cycle time of aluminum anodizing by optimizing pre-treatment procedures and forecasting the anodization process time. The experiments were carried out at the GOLDEN ANODIZER premises, a local aluminum anodizing industry in Coimbatore, India. The relationship between various anodizing pre-treatment parameters such as Nitric bath pH, Caustic pH, alkaline pH, Mean time duration was optimized to reduce time without affecting output qualities like Surface finish (µm), Film thickness (µm), and correction (%). Also, the anodizing pre-treatment process parameters were predicted using a hybrid machine learning method called the Random Forest Levy Flight Algorithm (RF-LFA). The proposed RF-LFA shows 2–3 times better prediction performance than existing RF and deep neural networks.

Effects of steaming on physicochemical and emulsification properties of gum arabic

Gum arabic finds extensive application and typically undergoes sterilization prior to utilization in the food industry. This study explored the impact of steam sterilization temperature and duration on the physicochemical and emulsification characteristics of gum arabic, accompanied by proposed mechanisms elucidating observed effects. The results showed that when gum arabic was treated with high temperature sterilization (110 °C ∼ 140 °C), the emulsion prepared turned unstable. The interfacial tension decreased from 8.26 mN/m to 6.77 mN/m after sterilization, while the elastic modulus decreased from 23.65 mN/m to 16.16 mN/m. Moreover, the circular dichroic chromatographic results indicated that the arabinogalactan protein (AGP) structure of gum arabic was more relaxed after high temperature treatment with β-sheets content decreased from 36.2 % to 29.8 % and random coil content increased from 41.3 % to 51.8 %. Quartz crystal microbalance with dissipation (QCM-D) results demonstrated that emulsion surface film thickness and toughness decreased after sterilization treatment of gum arabic. The study indicates that high temperature sterilization may change protein structure in gum arabic and reduce the stability of prepared emulsions.

Silver nanoparticles composited co-dopped polypyrrole/zinc coating for enhancing anti-corrosion and antibacterial properties of ZK60 magnesium alloy in Hank’s solution

For the biodegradable implant applications, silver nanoparticles (Ag NPs) are incorporated in polypyrrole (PPy) co-dopped with tartrate (TA) and salicylate (SA) anions to obtain multi-functional Ag NPs-PPy(TA + SA)/Zn bilayer coating on ZK60 magnesium alloy with high protective and antibacterial properties. The effects of Ag NPs on the composition, structure, and antibacterial and protective properties of Ag NPs-PPy(TA + SA)/Zn bilayer coating are studied. Incorporating Ag NPs influences the electrochemical growth conditions of PPy(TA + SA), possibly increasing the defects in PPy chains. Its surface morphology and film thickness are similar to PPy(TA + SA). However, Ag species (Ag+/Ag0 ≈ 0.1) are only distributed in the PPy surface layer (hundreds of nm), containing some adsorbed and agglomerated Ag NPs on its surface. In Hank’s solution at 37 °C, Ag NPs-PPy(TA + SA) experiences slow degradation, and the Ag content loses slowly to zero. Its protection time is significantly improved to 113 ± 2.6 days, much more prolonged than PPy(TA + SA) (54 ± 1.5 d), suggesting the crucial role of Ag NPs. After Ag NPs-PPy(TA + SA) is broken due to its local destruction, ZK60 displays typical local corrosion. Ag NPs-PPy(TA + SA) exhibited excellent cytocompatibility and antibacterial properties. The corresponding mechanism involved is thoroughly discussed.

Investigation of interfacial properties of Ag–Cu/Si3N4 composite ceramic substrates by interface reaction of Si3N4 and CuO

The surface metallization of Si3N4 ceramics with the Ag–Cu conductive paste containing CuO was systematically investigated. The interfacial reactions between CuO and Si3N4 promoted the surface metallization of the ceramic substrate in an argon atmosphere. The effects of Ag and Cu relative contents on the evolution of the thick film surface morphology were studied. The electrical properties and tensile strength of composite ceramic substrates were enhanced through the generation of Ag–Cu eutectic solution within the thick film layer. The effect of brazing time on the properties of Ag–Cu/Si3N4 composite ceramic substrates was investigated. Mechanical testing and scanning electron microscopy (SEM) were used to analyze the interface tensile strength of the Ag–Cu/Si3N4 composite substrates and the morphology of the Ag–Cu film, and the bonding mechanism of the composite ceramic substrate was studied. When the sample was brazed at 800 °C for 20 min, the maximum tensile strength of 23.6 MPa between the Ag–Cu film and ceramic substrate was obtained, the lowest resistivity of 6.22 μΩ•cm was obtained. The bonding interface between thick film layer and the ceramic substrate formed the Ag–Cu mechanical structure was benefit for improving the comprehensive performance of the Cu/Si3N4 composite ceramic substrate.

A machine learning-driven approach to predicting thermo-elasto-hydrodynamic lubrication in journal bearings

Traditional methods of evaluating the performance of journal bearings, for example thermal-elastic-hydrodynamic- lubrication theory, are limited to simplified conditions that often fail to accurately model real-world components. Numerical models that include additional phenomena such as cavitation and fully coupled effects like deformation, temperature, pressure and viscosity can be more accurate but require a large amount of computational overhead, making analysis slower and more costly. To address this limitation, a novel machine learning-driven approach is developed to predict the 2D distribution of surface deformation, film thickness, temperature, and pressure across the bearing surface as a function of design variables such as load and speed. The training dataset, generated using a fully coupled Reynolds’ Equation solver implemented in OpenFOAM, contains a significantly extended range of conditions than in previous studies with approximately 39000000 points encompassing 4925 different test cases. Modelled bearing speeds range from 2000 to 10000rpm, while load values are varied between 1 and 30kN. Predicting surface deformation, film thickness, temperature and pressure across the bearing surface results in a mean absolute percentage error below 0.4% or better. The work also demonstrates that the trained models have a strong ability to generalise the prediction beyond the original training data range with only a 1% error at up to 200% of the highest trained speed. This work also demonstrates that machine learning-based processes are a practical alternative to physics-based numerical modelling, especially in cases where rapid performance evaluation is desired as real-time calculation is possible with significantly reduced computational cost. This has the potential to enable development of rapid design optimisation tools and real-time performance monitoring at high resolution and with low latency. Using consumer hardware, it is found that the neural network-based approach is faster than the existing numerical modelling technique by a factor of over 10000, enabling real-time predictions of lubrication systems.

Contacts at the Nanoscale and for Nanomaterials.

Contact scaling is a major challenge in nano complementary metal-oxide-semiconductor (CMOS) technology, as the surface roughness, contact size, film thicknesses, and undoped substrate become more problematic as the technology shrinks to the nanometer range. These factors increase the contact resistance and the nonlinearity of the current-voltage characteristics, which could limit the benefits of the further downsizing of CMOS devices. This review discusses issues related to the contact size reduction of nano CMOS technology and the validity of the Schottky junction model at the nanoscale. The difficulties, such as the limited doping level and choices of metal for band alignment, Fermi-level pinning, and van der Waals gap, in achieving transparent ohmic contacts with emerging two-dimensional materials are also examined. Finally, various methods for improving ohmic contacts' characteristics, such as two-dimensional/metal van der Waals contacts and hybrid contacts, junction doping technology, phase and bandgap modification effects, buffer layers, are highlighted.

Tuning the crystalline orientation of quasi 1D anisotropic Sb2Se3 as a function of growth temperature for thin film photovoltaic applications

Antimony selenide (Sb2Se3) shows excellent photon absorption in the visible region and hence gaining tremendous attention from the last decade for thin film photovoltaics. Also, it has unique one-dimensional crystal structure and simple binary composition. However, the growth of Sb2Se3 thin films with its predominant orientation along [hk1] to make use of easy electrical charge transport seems challenging due to various governing growth parameters. In this work, we have studied the role of growth temperature (between 200 ℃ and 320 ℃) in the crystalline orientation of Sb2Se3 thin films on glass substrates via close-space thermal evaporation. In addition to growth orientation, we have investigated the effect of growth temperature on the surface morphology, elemental composition, film thickness, and optical properties of Sb2Se3 thin films. Electrical properties and photoresponse were measured on [hkl] and [hk0] oriented films to understand the effect of anisotropy and it is inferred that [hk1] oriented film as a favorable one for the charge transport. Also, the photoresponse results showed fair photoconductance under white light illumination and zero applied bias.

Analyzing the corrosion and tribocorrosion performances of monolayer TiO2 and bilayer TiO2-SiO2 coatings at different SBF temperatures

In this study, monolayer TiO2 coating was formed by the anodization method and bilayer TiO2-SiO2 coating was formed by the spin-coating method on commercially pure titanium (Cp-Ti) samples. The aim of this work compare the effects of monolayer and bilayer coatings at 37 °C and 60 °C in simulated body fluid (SBF) on the corrosion and tribocorrosion behaviors of Cp-Ti material. XRD and SEM were used for structural characterization of the coatings. Afterward, the adhesion strength of monolayer and bilayer coatings was investigated. The bilayer film began to separate from the Cp-Ti surface at higher forces, which was associated with energy dissipation between the layers, increased load-carrying capacity, and increased surface hardness. The best resistance was achieved from the bilayer film in tribocorrosion experiment at both 37 °C and 60 °C SBF temperatures; the result was attributed to higher surface hardness and film thickness. Consequently, untreated, monolayer, and bilayer Cp-Ti samples were tested for adhesion strength, corrosion, and tribocorrosion and bilayer samples exhibited the highest performance.

(Invited) Mesoporous Metallic Materials Electrodeposited from Polymeric Micelle Assemblies for Energy Applications

The surfactant-assisted electrodeposition is an effective means to obtain high-quality mesoporous materials in a rather simple synthesis approach. Commercial or home-made block copolymers can be dissolved in aqueous media above their critical micelle concentration to serve as a soft template in the so-called electrodeposition from polymeric micelle assemblies or micelle-assisted electrodeposition in short [1]. The nanoscale porosity of the resulting films, which extends throughout the whole surface and entire film thickness, endow them with large surface-to-volume (S/V) ratios. Such large S/V ratios are particularly amenable for (electro)catalytic applications and, whenever the alloy presents ferromagnetic properties, for magnetoelectric purposes. In our group, mesoporous Cu-Ni, Co-Pt, Ni-Pt and Fe-Pt alloys with pore size around 10 nm have been electrodeposited from Pluronic P-123 containing solutions [2-4]. Similarly, mesoporous Ni films with larger pore diameters (25 - 600 nm) have been deposited using custom-made PS-b-P4VP block copolymer micelles [5]. Even, the double template approach can be utilized to obtain, for example, matrices of mesoporous Co-Pt microdisks when the micelle-assisted electrodeposition is performed on optically lithographed substrates [6], or nanoporous Fe-Pd nanowires using anodized alumina and P-123 as hard and soft templates, respectively [7]. The introduction of an equilibration time between electrolyte preparation and deposition has been determined key in some cases to consistently reproduce the films mesoporosity [8].The electrodeposited mesoporous metallic materials exhibit higher electrocatalytic activity towards hydrogen evolution reaction (HER) in either acid or alkaline media compared to their dense counterparts [3]. In addition, their durability is not severely compromised in spite of the much larger surface exposed to the media. On the other hand, modulation of their magnetic properties with voltage is also possible when these films are electrolyte-gated in aprotic polar solvents like propylene carbonate. The intense electric field strength created at the film / electrolyte interface thanks to the built-in electric double layer allows for tuning of the coercivity (HC) or the saturation magnetization upon voltage application by virtue of different, but often concomitant, mechanisms taking place, like charge carrier accumulation and oxygen migration [6,9]. Variations greater than 30% in HC have been achieved.In this talk I will summarize the main synthesis-wise milestones achieved during the research in the field and the benefits brought by mesoporous alloys to electrocatalysis and magnetoelectricity.[1] C. Li et al. Acc. Chem. Res. 51 (2018) 1764[2] J. Zhang et al. ACS Appl. Mater. Interfaces 10 (2018) 14877[3] K. Eiler et al. Appl. Cat. B 265 (2020) 118597[4] E. Isarain‐Chávez et al. ChemSusChem 11 (2018) 367[5] R. Fagotto Clavijo et al. Cat. Today, in press.[6] C. Navarro-Senent et al. ACS Appl. Mater. Interfaces 10 (2018) 44897[7] D. Raj et al. Nanomaterials 13 (2023) 403[8] C. Navarro-Senent et al. Electrochim. Acta 358 (2020) 136940[9] C. Navarro-Senent et al. APL Materials 7 (2019) 030701

Effect of tin inclusion on zinc sulfide thin films properties for photocatalytic applications

Tin doped zinc sulfide (Sn:ZnS) thin films are synthesized by chemical bath deposition (CBD) technique. Tin concentration is varied from 0 to 12 at.-% by a step of 3 at.-%. Structural investigation by X-ray diffraction (XRD) analysis shows the crystallization of the material along the cubic structure as well as an improvement of the crystallinity after Sn inclusion. The surface morphology and film thickness are examined by scanning electron microscopy (SEM) revealing some surface modifications after tin incorporation. Also, some microstructures are observed for the sample elaborated with 9 at.-% Sn. These new microstructures are due to the segregation of tin in the film. Collected optical data show high transmittance in the visible range. The band gap energy is estimated to be about 3.8 eV. Impedance spectra show single semi-circle indicating a single relaxation process. Photocatalytic activity is evaluated and an increment of the degradation efficiency is remarked with the increase of the irradiation time.

“Bobbit Worm”‐Inspired Soft Adaptive Grasper with Self‐Generated Triboelectric Force Sensor

AbstractSoft actuators can realize delicate adaptive grasping of fragile and irregularly shaped objects, which are essential in biological and engineering systems. Yet, critical concerns in the frontier soft graspers are insufficient grasping ability and functional limitations. Here, we propose a Bobbit worm‐inspired multimodal‐sensing adaptive soft grasper (MSASG) enabled by harnessing the Miura‐origami skeleton integrated with self‐generated triboelectric force sensors (TFSs). The Miura‐origami skeleton endows the soft grasper a high grasping force while provides an energy‐efficient way to passively embrace an object without extra energy input. A multimodal TFSs with tactile sensing (TFS‐1) and pressure‐feedback (TFS‐2) functions is constructed by directly packaging a pyramid‐pattern elastic film on the Miura‐origami skeleton. The MSASG implement fast grasping or releasing action by evaluating pressures of various approaching prey, including hermit crabs, crickets, and beetle, etc. And its sensitivity greater than 0.18 V mN−1. In particular, the grasping performances and triboelectric sensing capacity can be optimized by modulating topological parameters (crease length, and surface film thickness, etc.), using a combination of theoretical modeling, finite element simulations, and experiments. The bionic design of soft graspers broadens the future applications for versatile human‐robot‐environment interaction scenarios, such as adaptive robots, reconfigurable architectures, medical devices, and deep‐sea explorations.

‘Newton’ fast shutter system for neutron scattering instruments at the ESS and ISIS neutron sources

Interfacial processes are involved in many areas of chemistry, physics and biochemistry, but following the structural changes of surfaces and thin films at relevant timescales remains challenging. Time-of flight neutron reflectometry can determine changes in surface composition and film thickness, but the speed of these measurements is typically limited by the neutron flux over the range of wavelengths available at existing instrumentation. This necessarily means that, even using the time-of-flight method, measurements over several angles of incidence are required to cover the full Q-range important for structural determination. The very high intensity of the ESS pulsed source makes such configuration changes very inefficient, as the measurements can potentially be recorded in seconds or even milliseconds. Here, we present a conceptual design and some preliminary results from a new type of fast beam shutter system that will allow efficient measurement of broad angular ranges at sub-second timescales. The shutter system is conceptually also potentially useful for a fast aperture application on the ZOOM instrument at the ISIS Target station 2. By using two perpendicular shutters with slits cut into them, it is possible to create a square aperture within the beam as the neutron pulse passes. We believe that the flexibility demonstrated will mean that this system has the potential to be generally useful in many neutron instrumentation applications.

Physicochemical, Biological, and Antibacterial Properties of Four Bioactive Calcium Silicate-Based Cements.

Calcium silicate-based cement (CSC) is a pharmaceutical agent that is widely used in dentistry. This bioactive material is used for vital pulp treatment due to its excellent biocompatibility, sealing ability, and antibacterial activity. Its drawbacks include a long setting time and poor maneuverability. Hence, the clinical properties of CSC have recently been improved to decrease its setting time. Despite the widespread clinical usage of CSC, there is no research comparing recently developed CSCs. Therefore, the purpose of this study is to compare the physicochemical, biological, and antibacterial properties of four commercial CSCs: two powder-liquid mix types (RetroMTA® [RETM]; Endocem® MTA Zr [ECZR]) and two premixed types (Well-Root™ PT [WRPT]; Endocem® MTA premixed [ECPR]). Each sample was prepared using circular Teflon molds, and tests were conducted after 24 h of setting. The premixed CSCs exhibited a more uniform and less rough surface, higher flowability, and lower film thickness than the powder-liquid mix CSCs. In the pH test, all CSCs showed values between 11.5 and 12.5. In the biological test, cells exposed to ECZR at a concentration of 25% showed greater cell viability, but none of the samples showed a significant difference at low concentration (p > 0.05). Alkaline phosphatase staining revealed that cells exposed to ECZR underwent more odontoblast differentiation than the cells exposed to the other materials; however, no significant difference was observed at a concentration of 12.5% (p > 0.05). In the antibacterial test, the premixed CSCs showed better results than the powder-liquid mix CSCs, and ECPR yielded the best results, followed by WRPT. In conclusion, the premixed CSCs showed improved physical properties, and of the premixed types, ECPR exhibited the highest antibacterial properties. For biological properties, none of these materials showed significant differences at 12.5% dilution. Therefore, ECPR may be a promising material with high antibacterial activity among the four CSCs, but further investigation is needed for clinical situations.

Decoupling bulk and surface characteristics with a bare tilted fiber Bragg grating.

The tilted fiber Bragg grating (TFBG) with dense comb-like resonances offers a promising fiber-optic sensing platform but could suffer from cross sensitivity dependent on bulk and surface environment. In this work, the decoupling of bulk and surface characteristics (indicated by bulk refractive index (RI) and surface-localized binding film) from each other is attained theoretically with a bare TFBG sensor. This is realized with the proposed decoupling approach based on differential spectral responses of cut-off mode resonance and mode dispersion represented as wavelength interval between P- and S-polarized resonances of the TFBG to the bulk RI and surface film thickness. The results demonstrate that with this method the sensing performance for decoupling bulk RI and surface film thickness is comparative to the cases in which either the bulk or surface environment of the TFBG sensor changes, with the bulk and surface sensitivities over 540 nm/RIU and 12 pm/nm, respectively.

Modeling and Control of SiNx Film Growth using the Kinetic Monte Carlo Method: Impact of Gas Flow Rate on Surface Roughness and Film Thickness

Modeling and Control of SiNx Film Growth using the Kinetic Monte Carlo Method: Impact of Gas Flow Rate on Surface Roughness and Film Thickness

Developing digital twin design for enhanced productivity of an automated anodizing industry and process prediction using hybrid deep neural network

Automation is beneficial when implemented in challenging environments requiring less human effort or reducing human effort. Employee safety is a concern to increase productivity, delivery and achieve the required quality. The present research investigates the possibility of installing an automation procedure in an anodizing industry called GOLDEN ANODIZER, which is situated in Coimbatore, India. During the preliminary analysis at the specified industry premises, there was a reduction in productivity, quality and customer delivery due to manual operations, including some health issues were identified. And hence the present investigation analyses the possibility of installation of an automation system for the anodizing process. For such reason, the digital twin of an automation system is first designed, developed and tested using Siemens NX software. The anodizing factors such as Anodizing medium temperature (K), Acid Concentration (wt%), applied voltage (V) and Responses Surface Finish (Ra), Film Thickness (tf) and Time Duration (T) were optimized for improved productivity and quality. Prediction results and RMSE analysis show that the proposed hybrid PSO-LFA algorithm has outperformed all modern algorithms. The proposed algorithm optimized the anodizing parameters and suggested 3650.7 s as a new cycle time. Also, the improved cycle time can boost the plant outcome by 182% and reduce the manpower by 46% through the proposed Automation system.

Nanostructured nickel films by supersonic cluster beam deposition: Morphology, oxidation, and clues of hollow structures by Kirkendall effect at room temperature

Supersonic Cluster Beam Deposition was exploited to study morphology, nanostructure and room temperature spontaneous oxidation of Nickel films obtained by cluster assembling in high-vacuum conditions. Size analysis shows the dominant presence of particles with dimensions below 10 nm, while the lognormal profile of the size distribution confirms that gas-phase homogeneous nucleation and aggregation prior to deposition is at the base of the mechanism governing clusters formation. The relationship between surface roughness and film thickness is found to follow a power law, suggesting a growth process ascribable to ballistic deposition model. Although ultrafine dimensions, clusters oxidation is not complete as residual metallic Nickel, beside NiO and Ni(OH)2, is detected by Electron Spectroscopy and observed by Transmission Electron Microscopy and Electron Diffraction, within core-shell structures. Cubic symmetry is identified in both metallic and NiO phases, while hydroxide phase appears as amorphous. The presence of hollow particles is also unveiled, which may represent a first clue of room temperature Kirkendall effect in ultrafine Nickel particles produced by Supersonic Cluster Beam Deposition. The coexistence of core-shell and hollow structures of the same size suggests that particle dimension per-se is not enough to define unambiguously the outcomes of room temperature oxidation process.