Surface Properties Of Substrates Research Articles

Prediction of coating layer thickness and surface hardness in electric discharge coating process using RSM, ANN, and ANFIS with ANOVA optimization

Electric discharge coating (EDC) process is one of the unique and notable surface modification processes that enhance the surface properties of substrates. The coating layer thickness and surface hardness developed by the coating process are the predominant reason for substrate protection and performance enhancement. To enhance the coating efficiency and develop the desired output, optimization of input parameters and forecasting of output parameters was required. In this work, Mg alloy substrates are coated with Cu–Ni green compact electrodes by an EDC process. During the EDC process peak current ( I), pulse duration ( Ton), and compaction load for the electrode ( L) are major influencing parameters of coating layer thickness which are considered as input parameters. The coating layer thickness and surface hardness of the coating substrate were estimated by an optical microscope and Vickers hardness tester, respectively, and also considered as a response. The observed data were analyzed and optimized through analysis of variance (ANOVA) and response surface morphology (RSM) which provides a static relationship between the input parameter and response. Additionally, a prediction model was developed with a machine-learning approach. Two different tools namely artificial neural network (ANN) and, adaptive neuro-fuzzy inference system (ANFIS), were employed for accurate prediction of the model. From the ANN and ANFIS analysis regression coefficient (R) values were 0.97991 and 0.9912, respectively. The present study provides machine-learning capabilities and supports optimizing the input parameter to the target output in the EDC process.

Direct laser writing of planar and stretchable supercapacitors based on a graphene oxide and manganese dioxide nanoparticle composite on a paper substrate

Paper-based supercapacitors (P-SCs) exhibit superior electrochemical performance owing to the flexibility and unique surface properties of paper substrates. Currently, most P-SCs adopt a sandwich structure that is limited by electrode fabrication methods. However, the development of planar paper-based devices is crucial to satisfy the tremendous demand for wearable electronics. Herein, based on the mechanism of interaction between the laser and material, we used direct laser writing (DLW) techniques to fabricate in-plane P-SCs based on graphene oxide (GO) and manganese dioxide (MnO2) composite-covered paper substrates. Owing to the in-plane device structure and pseudocapacitive MnO2, the acquired rGO-MnO2-based planar P-SCs possessed a much higher specific capacitance value (17.7 mF/cm2) than that based on sandwich-structured reduced GO (rGO) (1.71 mF/cm2). In addition, three in-series integrated devices can be easily achieved via the DLW fabrication method, which shows potential for practical applications such as powering a light emitting diode. In addition, by carefully designing the paper substrate structure, the paper-based device exhibited excellent stretching stability. A specific capacitance retention of 86.8% remained after 5000 stretch cycles. Therefore, this study provides valuable insights into the design and fabrication of wearable paper-based electronics.

New Designs and Approaches for Enabling the Large-Scale Fabrication of Gas Diffusion Electrodes

At the heart of the fuel cell resides two electrodes (anode and cathode) sandwiched around a proton exchange membrane. These electrodes are comprised of electrochemically active catalyst, typically platinum based and are either adhered to the membrane electrode assembly (MEA) or directly to the gas diffusion electrodes (GDE). The large-scale fabrication of MEAs or GDEs can help reduce cost and support the viability of mass emergence of fuel cell systems. This study focuses on using a slot die coater to fabricate GDEs using non-supported catalyst inks. It’s worth noting that there are challenges that emerge when using this technique. Some key challenges include ink formulation for proper catalyst suspension, surface properties of the hydrophobic substrate, and maintaining electrode uniformity during deposition. To overcome these challenges, we explore various approaches such as equipment modification, pre-treatment of the substrate, and modifying ink formulations to enhance the reliability of the coating process.

High-refractive-index glass device fabricated by room temperature bonding

Abstract Wafer bonding is an essential technology for attaching various materials, including glass. Glass-glass bonding has been applied to fabricate glass micro/nanofluidic devices that work as analytical tools for chemical and biological research. Here, we report the fabrication of micro/nanofluidic devices consisting of a high refractive index (HRI) glass as a component of the device for the first time. Although HRI glass has been used for high-sensitivity and high-resolution imaging in microscopy, it has not been used for glass fluidic devices due to the lack of bonding method for HRI glass. The glass fluidic devices were made through glass-glass bonding at room temperature, which could avoid severe damage to bonded substrates of two glass types due to different rates of thermal expansion. The pressure endurance of these devices was measured to find the correlation with the surface properties of glass substrates. The measured results indicated that chemical groups other than SiOH enhanced the pressure endurance of the devices. Thus, these chemical groups helped to form the fluidic devices consisting of HRI glass and another glass type, borosilicate or fused silica, to achieve practical pressure endurance up to 270 kPa. The HRI glass-incorporating device showed 8-fold higher sensitivity and 30 % narrower spatial resolution of fluorescence signals than the other devices with non-HRI glass.

Achieving enhanced electroless Ni-P plating on 6H-SiC substrate through optimization of plasma activation durations

This study explores the impact of plasma activation on the surface properties of 6H-SiC substrates and the subsequent characteristics of electroless nickel‑phosphorus (NiP) plating. The research investigates how varying plasma activation durations influence surface roughness, chemical composition, and plating adhesion. Plasma activation significantly increased surface roughness from 592 nm to 772 nm and the oxidation layer thickness from 5.76 nm to 32.2 nm. These changes were accompanied by corresponding decreases in water and NiP solution contact angles, indicating enhanced surface wettability. The electroless NiP plating demonstrated a progressive increase in surface roughness, and the Ra roughness reached 1319 nm. X-ray diffraction (XRD) analysis revealed a reduction in the crystallinity of the NiP layer, alongside the emergence of new phases such as Ni2P and Ni8P3, indicating alterations in the structural and chemical composition of the plating. The average thickness of the NiP plating decreased from 39.70 μm at 10 min of plasma activation to 36.12 μm at 30 min, suggesting a potential reduction in deposition efficiency with prolonged activation times. Additionally, the hardness of the NiP layer exhibited a decline from 525 HV to 502 HV, attributed to increased surface oxidation and defect formation. The adhesion quality of the plating also deteriorated with increased plasma activation time, as evidenced by significant peeling and cracking, as observed in the scratch test.

The Mechanism of Aluminum Deposition and Dendrite Growth on a Copper Substrate in Anode-Free Aluminum Batteries.

Given the critical demand for batteries with a high energy density and the global scarcity of lithium, anode-free aluminum batteries (AFABs) have attracted significant attention. AFABs utilize collectors instead of traditional anode metal foils, eliminating the need for anode materials and significantly enhancing the energy density of the batteries. However, the proliferation of aluminum dendrites might cause safety risks and reduce Coulombic efficiency, possibly impeding commercialization. This study employs molecular dynamics (MD) simulations to explore the deposition mechanisms of aluminum (Al) on copper (Cu) collectors and the dynamics of aluminum dendrite growth under nonhomogeneous deposition conditions. The results indicate that the surface properties of the Cu substrate significantly affect aluminum deposition, leading to more homogeneous and amorphous deposition on Cu(110) surfaces. However, the FCC structure of Al atoms on the Cu(111) surfaces exhibited the largest number. Strategically increasing the temperature and pressure can effectively prevent the formation of aluminum dendrites. The results are helpful for enhancing the battery cycle stability and the application of novel AFABs.

Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates.

Sublimation methods utilizing the surface properties of substrates can address the challenge of controlling hollow morphologies in rod crystals. Spherulites were formed on the hydrophilic surface of the (0001) planes of α-quartz and sapphire substrates by sublimation of 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1a). Various types of hollow morphologies, distinguished by the size and shape of their cross sections and by the presence or absence of branching structures, were formed separately on α-quartz and sapphire substrates. Such precise control of the hollow morphologies was attributed to the wettability of each substrate, leading to the formation of spherulites of 1a. In addition, it was indicated that the formation process of the surface morphologies of spherulites was associated with the hollow morphologies of rod crystals of 1a.

Preparation and characterization of highly CO2 permeable and selective graphene oxide membranes by introducing gutter layers into porous substrates

Here, we present graphene oxide (GO)-based thin-film composite (TFC) membranes with enhanced CO2 separation performance using a surface-modified substrate for uniform GO depositions. We extensively characterized the surface properties of porous substrates to identify optimal conditions for universal and uniform GO selective layer. Our results reveal that incorporating polyvinylpyrrolidone (PVP) as a gutter layer is essential for achieving consistent and regular GO layer coating. As a result, the developed GO membranes demonstrate a CO2 permeance of 350 GPU, which is a ∼350 % improvement over the GO membranes without gutter layer, coupled with a higher selectivity for CO2/N2 and CO2/CH4 pairs. The results indicate the excellent potential for significantly enhanced CO2 separation performances with the development of suitable support membranes.

Effects of Time-Elapsed Bleaching on the Surface and Mechanical Properties of Dentin Substrate Using Hydrogen Peroxide-Free Nanohydroxyapatite Gel.

There is a critical need to address concerns surrounding the potential impact of bleaching gels specifically on the tooth substrate. Therefore, this laboratory investigation aimed to assess the impact of a hydrogen peroxide (HP)-free bleaching (HiSmileTM) in comparison to an HP-based bleaching (Opalescence RegularTM) on the surface and mechanical characteristics of tooth substrate. Sixty sound human premolar teeth were sectioned to produce dentin fragments and divided into two primary groups based on the bleaching agent used. Each group was subdivided into three subgroups (n = 10) per distinct bleaching regimens: (T1) fragments underwent a 7-day immersion in distilled water at 37°C without any bleaching treatment, (T2) fragments underwent a 7-day immersion in distilled water at 37°C, with the application of bleaching gel occurring on the seventh day for 10minutes, and (T3) fragments underwent a bleaching regimen for seven consecutive days, each session lasting for 10minutes. The initial and final evaluations of surface roughness, nano-hardness, and elastic modulus were performed. Following the bleaching regimens of T3, a composite stub was fabricated on the dentin fragments for the shear bond strength (SBS) test. Statistical testing was accomplished using the analysis of variance (P < 0.05). HP-based bleaching gel showed significant differences between measurement intervals in surface roughness, elastic modulus, and SBS parameters (P < 0.05). In contrast, HP-free bleaching gel showed insignificant differences within the group (P > 0.05). The SBS between dentin-composite was significantly affected with the use of HP-based bleaching gel, while HP-free bleaching gel showed insignificant difference between measurement intervals. The qualitative validation of the treatment's impact was further demonstrated using the scanning electron microscopy. The findings suggest that the bonding stability of composite restorations to dentin may be compromised after bleaching with an HP-based gel, whereas immediate bonding procedures can be safely conducted following the application of an HP-free bleaching gel.

Efficient perovskite light-emitting diodes on a flexible substrate.

The surface properties of target substrates are crucial for the in situ crystallization and growth of metal halide perovskite films fabricated by the anti-solvent method. In this work, a high-quality quasi-2D perovskite film with various-n phases is fabricated on the commonly used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) by introducing a branched polyethylenimine (PEI) modifying layer. PEI suppresses the influence of acidic surface of the PEDOT:PSS and regulates the components of the perovskite film, increasing the proportion of large-n phases. Additionally, PEI reduces the formation of defects in perovskite films, leading to higher photoluminescence quantum efficiency and longer photoluminescence lifetime. Based on this high-quality perovskite film, a flexible light-emitting diode with an ultimate current efficiency of 63.2 cd/A is achieved, nearly twofold higher than that of the device (35.1 cd/A) without a PEI modifying layer.

Analysis of vibrational dynamics in cell-substrate interactions using nanopipette electrochemical sensors

Cell-substrate interaction plays a critical role in determining the mechanical status of living cell membrane. Changes of substrate surface properties can significantly alter the cell mechanical microenvironment, leading to mechanical changes of cell membrane. However, it is still difficult to accurately quantify the influence of the substrate surface properties on the mechanical status of living cell membrane without damage. This study addresses the challenge by using an electrochemical sensor made from an ultrasmall quartz nanopipette. With the tip diameter less than 100 nm, the nanopipette-based sensor achieves highly sensitive, noninvasive and label-free monitoring of the mechanical status of single living cells by collecting stable cyclic membrane oscillatory signals from continuous current versus time traces. The electrochemical signals collected from PC12 cells cultured on three different substrates (bare ITO (indium tin oxides) glass, hydroxyl modified ITO glass, amino modified ITO glass) indicate that the microenvironment more favorable for cell adhesion can increase the membrane stiffness. This work provides a label-free electrochemical approach to accurately quantify the mechanical status of single living cells in real-time, which may help to better understand the relationship between the cell membrane and the extra cellular matrix.

Effect of nanobubbles on the mobilization of microplastics in shorelines subject to seawater infiltration

The widespread presence of microplastics (MPs) in the ocean has varying degrees of impact on ecosystems and even human health. Coastal tidal zones are crucial in controlling the movement of MPs, which are influenced by waves and tidal forces. Meanwhile, natural nanobubbles (NBs) in the ocean can affect the hydrodynamic properties of the tidal zone. The mobilization of MPs in coastal tidal zones under the effect of NBs has been less studied. In this study, we explored natural NBs' influence on the mobilization of MPs in shorelines subject to seawater infiltration. Using glass beads as a substrate, a coastal porous environment was constructed through column experiments, and the pump-controlled water flow was used to study the transport of MPs subject to seawater movement within the substrate. The infiltration of MPs under continuous and transient conditions, as well as the upward transport induced by flood tide, were considered. The role of salinity in the interactions between NBs, MPs, and substrates was evaluated. Salinity altered the energy barriers between particles, which in turn affected the movement of MPs within the substrate. In addition, hydrophilic MPs were more likely to infiltrate within the substrate and had different movement patterns under continuous and transient flow conditions. The motion of the MPs within the substrate varied with flow rate, and NBs limited the vertical movement of MPs in the tidal zone. It was also observed that NBs adsorbed readily onto substrates, altering the surface properties of substrates, particularly their ability to attach and detach from other substances.

Design of fluorine-free superhydrophobic coating for fibred architectonic concrete

In outdoor environment, the exterior walls surface of buildings always suffers from damages caused by ultraviolet radiations, temperature variation, abrasion and erosion phenomenon, dust pollution, and microbial adhesion: Thereby reducing their durability over time. In order to overcome these obstacles, the superhydrophobic coatings can be an advantageous solution to ensure long-term stable use by improving the exterior concrete walls durability. In this line, a fluorine-free water-repellent coating was developed through sol-gel method and successfully applied to concrete substrates by dip-coating technique. The coating was formulated with low surface energy polydimethylsiloxane (PDMS) and polymeric silica (PS) to simultaneously modify the microstructure and chemical properties of concrete substrate surface. The coated concrete substrate showed super-hydrophobicity with high water contact angle (WCA) over than 150°. Besides, the self-cleaning property, mechanical robustness, stability under UV irradiations, resistance to temperature and humidity were investigated. The results indicated that the coated concrete substrate cannot be soiled by dust and can resist over than 300 cycles of abrasion test. It also presents resistance to temperature of 45°C associated with a humidity of 80% during 720 hours and showed excellent resistance to prolonged exposure to UV irradiations during 1440 hours. Natural out-door aging tests have shown that the superhydrophobic coating is weather resistant.

Mechanisms of colloid removal from polydimethylsiloxane (PDMS) surfaces during washing: Implications for enhanced produce decontamination

Microbial contamination of fresh produce poses significant challenges to food safety and public health. Postharvest washing is a common practice in the fresh produce industry to reduce microbial load. This study aimed to elucidate the mechanisms involved in bacterial removal from produce surfaces during washing, using model colloids as bacterial surrogates and polydimethylsiloxane (PDMS) replicas of tomato, lettuce, and spinach as model produce surfaces. Colloids were deposited onto the PDMS surfaces and subsequently washed using different solutions (DI water, NaCl, and surfactants Tween 80 and sodium dodecyl sulfate) at varying concentrations. The PDMS surfaces were then withdrawn from the solutions at two distinct velocities. Colloid removal efficacy and the associated physicochemical interactions between colloids and substrate surfaces under various washing conditions were quantified. The results revealed that colloid removal was controlled by the residual amount of washing solution retained and contact line action. These factors, in turn, were influenced by the sample-withdrawal velocity and physicochemical properties of substrate surfaces, colloids, and washing solutions. Specifically, SDS at 2 mol/m3 combined with a slow withdrawal velocity significantly optimized colloid removal, achieving up to 79.0% efficiency. Conversely, using Tween 80 at 0.08 mol/m3 concentration significantly impeded removal efficiency. Understanding these dynamics to minimize residual solution retention and optimize colloid/bacteria movement with the contact line upon washing can significantly enhance the cleaning efficacy of fresh produce. The findings of this study provide an improved understanding on the key factors governing the retention and removal of colloidal particles (including microorganisms) that can guide the development of effective decontamination strategies.

Critical role of the composition of the cell culture medium on cell attachment and viability on PLA biocomposite scaffolds under in vitro assay conditions

In tissue engineering applications 3D scaffolds undertake the function of the native extracellular matrix (ECM) for cell attachment, survival, proliferation, and differentiation. For successful long-term implementation scaffolds need to mimic the ECM in vitro and in vivo. Many studies have focused on protein adsorption as the most critical factor for cell attachment. To improve protein adsorption on polymeric scaffolds various physical and chemical surface modification techniques, such as changing surface porosity, surface energy, and introducing various functional surface chemical groups have been investigated. It is well studied and documented that complex interactions between the biomaterial surface and the cell culture components in in vitro assay conditions define the scaffold performance. In this study influence of in vitro assay components on HepG2 liver cell attachment and proliferation on 3D printed poly(lactic acid) (PLA) scaffolds coated with various polymeric electrospun webs were investigated. MTT assays were performed on the scaffolds by using 3 different cell culture media; (i) basal cell culture medium (DMEM), (ii) DMEM supplemented with 10% albumin, and (iii) DMEM supplemented with 10% fetal bovine serum (FBS). Results obtained have shown dramatic improvement in cell attachment and proliferation in DMEM supplemented with 10% FBS when compared with DMEM and DMEM containing 10% albumin. Our findings clearly demonstrate synergistic effects of all bioactive components present in the FBS medium in significantly improving the HepG2 cell attachment and proliferation on polymeric scaffolds under in vitro conditions, regardless of the substrate structure, composition, and surface properties.

Tuning and optimization of structure and surface properties of thin and fine hydrophilic nanofibrous substrates through low‐pressure heat‐press treatment

AbstractThe properties of electrospun nanofibrous membranes (ENMs), including pore size, surface roughness, and hydrophilicity, significantly affect crosslinking, thickness, and morphology of the polyamide selective layer formed on top of ENM substrate in thin film composite membranes, and, ultimately the performance of membranes. We produced polyamide 66 nanofiber layers with a thickness of 10 μm and a fiber diameter of 55 nm, considerably thinner and finer than usual ENM substrates. We then subjected this thin layer to post‐production treatment using the efficient low‐pressure heat‐press (LPHP) method at a pressure of 3 kPa at three different temperatures and two different time intervals. It was found that the morphology of the nanofiber layer was preserved, and its structural characteristics, including pore structure, surface roughness, wettability, crystallinity, and specific surface area, were favorable with LPHP treatment. The optimal conditions were obtained with treatment at 190°C for 3600 s, in which the roughness of the nanofiber substrate decreased from 64 to 25 nm. Using these substrates offers new, less‐explored opportunities for optimizing the LPHP treatment of the substrate. These substrates are proposed for a new generation of TFC membranes in a continuous production line, with the possibility of scaling up for pressure‐ and osmosis‐driven membranes.

Advancements in Laser Cladding and Iron based Alloys- A Review

This study briefs about the latest developments in Laser Cladding and alloying process which helps improving the surface properties of substrate. Laser cladding is one of the material deposition technique which helps in lengthening the surface life of Base materials in power generation industries. A thick layer of materials which helps in improving the substrate properties deposited. It helps in enhancing the mechanical properties like wear, corrosion resistance, hardness. Laser cladding in comparison to other deposition techniques provides better powder efficiency, low distortion due to low power requirement, good surface uniformity, better binding property. Independent metal alloys, ceramics, composites are used to enhance the surface of the material used. Iron based alloys are the most common alloy with better mechanical properties, other independent metal alloys like aluminum alloy, nickel alloy, tungsten alloy can be used. In this review, the study of iron based alloys for laser cladding has been explained. Also, the effecting laser parameters on microstructure, material composition, mechanical properties and thermal properties are considered. The material characterization techniques like XRD, SEM, XPS, DSC, scratch test, corrosion &amp; erosion test are discussed. The issue emerges and the possibilities in Laser cladding for Iron based alloyed are briefed.

Single-Component Hydrophilic Terpolymer Thin Film Systems for Imparting Surface Chemical Versatility on Various Substrates.

We demonstrate a single-component hydrophilic photocrosslinkable copolymer system that incorporates all critical functionalities into one chain. This design allows for the creation of uniform functional organic coatings on a variety of substrates. The copolymers were composed of a poly(ethylene oxide)-containing monomer, a monomer that can release a primary amine upon UV light, and a monomer with reactive epoxide or cyclic dithiocarbonate with a primary amine. These copolymers are easily incorporated into the solution-casting process using polar solvents. Furthermore, the resulting coating can be readily stabilized through UV light-induced crosslinking, providing an advantage for controlling the surface properties of various substrates. The photocrosslinking capability further enables us to photolithographically define stable polymer domains in a desirable region. The resulting copolymer coatings were chemically versatile in immobilizing complex molecules by (i) post-crosslinking functionalization with the reactive groups on the surface and (ii) the formation of a composite coating by mixing varying amounts of a protein of interest, i.e., fish skin gelatin, which can form a uniform dual crosslinked network. The number of functionalization sites in a thin film could be controlled by tuning the composition of the copolymers. In photocrosslinking and subsequent functionalizations, we assessed the reactivity of the epoxide and cyclic dithiocarbonate with the generated primary amine. Moreover, the orthogonality of the possible reactions of the presented reactive functionalities in the crosslinked thin films with complex molecules is assessed. The resulting copolymer coatings were further utilized to define a hydrophobic surface or an active surface for the adhesion of biological objects.

Research and Development Status of Laser Cladding on Stainless Steel Alloys: A Review

Stainless steels as one of the most appealing structural material in many fields of industries because of its resistance to corrosion, high tensile strength, durability, temperature resistant etc. To improve its surface properties and overcome issues like large heat affected zones, poor surface quality, and limited dissolvability, researchers have explored surface modifications through laser cladding. This paper gives a detailed review about the work done in recent years, in the region of laser cladding of different grades of stainless-steel alloys with different coating materials highlighting on feeding ways of cladding material, laser cladding process parameters, types of lasers employed, types of coating &amp; composite coating materials in enhancing the surface properties of the stainless-steel substrate and their relevant applications.

Highly Efficient Light-Emitting Diodes based on Self-Assembled Colloidal Quantum Wells.

Nanocrystal-based light-emitting diodes (Nc-LEDs) have immense potential for next-generation high-definition displays and lighting applications. They offer numerous advantages, such as low cost, high luminous efficiency, narrow emission, and long lifetime. However, the external quantum efficiency (EQE) of Nc-LEDs, typically employing isotropic nanocrystals, has been limited by the out-coupling factor. Here we demonstrate efficient, bright, and long lifetime red Nc-LEDs based on anisotropic nanocrystals of colloidal quantum wells (CQWs). Through modification of the substrate's surface properties and control of the interactions among CQWs, we successfully spin-coated a self-assembled layer with an exceptionally high distribution of in-plane transitions dipole moment (TDM) of 95%, resulting in an out-coupling factor of 37%. Our devices exhibit a remarkable peak external quantum efficiency (EQE) of 26.9%, accompanied by a maximum brightness of 55,754cd m-2 and a long operational lifetime (T95 @100cd m-2 ) over 15,000h. These achievements represent a significant advancement compared to previous studies on Nc-LEDs incorporating anisotropic nanocrystals. We expect our work to provide a general self-assembly strategy for enhancing the light extraction efficiency of Nc-LEDs based on anisotropic nanocrystals. This article is protected by copyright. All rights reserved.