Surface Coatings Research Articles

Modeling and analysis of plastic abrasive jet flow characteristics

In this study, the particle velocity and spatial distribution of a plastic abrasive jet were modeled for the removal of surface coatings from a new generation of ship hulls by plastic abrasive jet machining. The particle velocity in the jet has been accurately tested through high-speed photography. It was found that the particle velocity of plastic abrasives with the same particle size was larger than conventional abrasives. Downstream from the nozzle exit axis, the divergence profile of the abrasive jet is approximately linear at distances up to 6.2dN; at distances higher than 6.2dN, the divergence profile line of the abrasive jet is approximately “flared”. The particle velocity of the plastic abrasive increased with increasing jet pressure, and no significant decrease of particle velocity was found in the limited measurement range. The instantaneous velocity distribution of the particles has been discussed in terms of axial and radial directions along the jet. For the radial velocity distribution of the abrasive jet, a relatively steady state is observed in the cross-section of the jet near the nozzle outlet. The results of the model calculations are in accordance with the experimental test data in terms of both tendency and margin of change.

Hard/stiff surface coatings for particle weakening, part I: Methodology

Size-reduction processes are essential for liberating valuable minerals yet energy-inefficient, which needs to be remedied by developing energy-efficient methods. This work is the first part of a wide study that (i) describes a surface coating method, namely, spray coating, and (ii) presents some preliminary results that hard or stiff surface coatings can be used to weaken softer ore particles. The hard surface coatings were achieved with a ceramic spray and two inorganic precipitates (CaCO3 and silica). The fracture energy and/or strength of spray-coated and uncoated particles was measured using the Short Impact Load Cell (SILC). Spray coating can only yield low surface coverage (up to 1–2% of the mass of particles), which is only apparent if particle surfaces are washed before coating. Nevertheless, the preliminary results suggest significant reductions in the fracture force and energy of soft ore particles after they are coated.

Functional biocarbon-based coatings for wood protection and indoor air depollution

Growing concerns about indoor air pollution heighten the need to develop depolluting materials to achieve a healthy built environment. This study developed functional coatings for wooden surfaces using 20 wt% photocatalytic biocarbon particles doped with manganese oxide (BC–MnO2) and two different coating materials (linseed oil and waterborne acrylic). The samples' surface hydrophobicity and color properties were tested before and after accelerated aging. The depolluting potential of the samples was evaluated by formaldehyde removal efficiency test in indoor conditions. Results showed that adding BC-MnO2 particles increased the hydrophobicity regardless of the coating material's type. After accelerated aging, the hydrophobicity of all samples increased, which was attributed to the curing of the oil and acrylic polymers and the increase in surface roughness eventually caused by surface damage. The color change (ΔE) was more intense in the case of uncoated wood and samples without BC-MnO2. However, the BC-MnO2-containing coatings were effective in color preservation (ΔE < 2), which was attributed to the anti-UV property of biocarbon. The BC-MnO2-containing coatings exhibited a promising formaldehyde removal efficiency of up to 24 % and 46 % for oil and acrylic samples, respectively. The combination of BC-MnO2 and acrylic material was more favourable to attracting the formaldehyde molecules, likely due to the similar polarity. The developed functional coatings exhibited an acceptable ability for wood protection and formaldehyde remediation and can be potentially used to enhance indoor air quality.

The Effect of Antibacterial-Osteogenic Surface Modification on the Osseointegration of Titanium Implants: A Static and Dynamic Strategy.

Titanium (Ti) and its alloys are widely used biomaterials in bone repair. Although these biomaterials possess stable properties and good biocompatibility, the high elastic modulus and low surface activity of Ti implants have often been associated with infection, inflammation, and poor osteogenesis. Therefore, there is an urgent need to modify the surface of Ti implants, where changes in surface morphology or coatings loading can confer specific functions to help them adapt to the osseointegration formation phase and resist bacterial infection. This can further ensure a healthy microenvironment for bone regeneration as well as the promotion of immunomodulation, angiogenesis, and osteogenesis. Therefore, in this review, we evaluated various functional Ti implants after surface modification, both in terms of static modifications and dynamic response strategies, mainly focusing on the synergistic effects of antimicrobial activities and functionalized osteogenic. Finally, the current challenges and future perspectives are summarized to provide innovative and effective solutions for osseointegration and bone defect repair.

Electrochemically Induced Deposition (ECiD): A Versatile Method that Greatly Extends the Portfolio of Surface Coatings and Materials Fabricated by Electrochemical Deposition

Electrochemically induced deposition or ECiD can be defined as the deposition of compound films on a surface, as the result of chemical reactions in the near surface region between a precursor present in the bulk solution and an electrochemically generated precursor, mediator, or catalyst near that surface. The ECiD process has evolved from an odd curiosity into a thriving new branch in electrodeposition science. The library of materials synthesized by ECiD has been greatly expanded, along with the number of precipitation triggering knobs or tricks. Together with the breadth of possibilities and applications, the science behind the process has also accelerated. This article introduces the principle of the ECiD process for the electrodeposition of oxides, hydroxides, and compounds such as metal phosphates and metal-organic frameworks. The article discusses the mechanisms of these electrochemically induced deposition reactions as well as the pro-bases used to trigger the deposition.

Fatigue and tensile behaviour of Ti+TiN+Ti+TiVN multilayer nitride films coated on AZ91 magnesium alloy by closed field unbalanced magnetron sputtering

Despite their extensive use in the automotive and aerospace industries, Mg and Mg alloys, which are light metals, exhibit low fatigue and tensile strength. In this study, transition metal-nitride (TMN) multilayer coatings (Ti+TiN+Ti+TiVN) were coated twice on AZ91 Mg alloy using a Confined Field Unbalanced Magnetron Sputtering (CFUBMS) system to increase fatigue and tensile strength. The structural properties of the films were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS) methods, and the mechanical properties were analyzed by rotating bending fatigue and tensile testing machines. Ti+TiN+Ti+TiVN multilayer nitride surface coatings on AZ91 Mg alloys showed a dense and columnar microstructure and according to XRD results (111) was the preferred orientation with the dominant peak. The fatigue limit value of the AZ91 base material was fixed at 60.46 MPa, while it increased to 68.48 MPa after being coated with multilayer nitride. Along with the multilayer nitride coating, the tensile strength increased from 169.98 MPa to 175.43 MPa. As a result, the multilayer hard nitride coating with low surface roughness, which fills the defects, notches, and voids on the surface of the AZ91 base material, increased the fatigue and tensile strength in parallel. Based on the outcomes of the research, the literature has been enriched with an innovative approach through the enhancement of fatigue and tensile strengths by applying a CFUBMS coating to lightweight metals and alloys, such as AZ91, especially in the transportation industry where lightness and dynamic load resistance are essential.

Surface Coating Enabling Sulfide Solid Electrolytes with Excellent Air Stability and Lithium Compatibility

All‐solid‐state lithium metal batteries (ASSLMBs) featuring sulfide solid electrolytes (SEs) are recognized as the most promising next‐generation energy storage technology because of their exceptional safety and much‐improved energy density. However, lithium dendrite growth in sulfide SEs and their poor air stability have posed significant obstacles to the advancement of sulfide‐based ASSLMBs. Here, a thin layer (approximately 5 nm) of g‐C3N4 is coated on the surface of a sulfide SE (Li6PS5Cl), which not only lowers the electronic conductivity of Li6PS5Cl but also achieves remarkable interface stability by facilitating the in situ formation of ion‐conductive Li3N at the Li/Li6PS5Cl interface. Additionally, the g‐C3N4 coating on the surface can substantially reduce the formation of H2S when Li6PS5Cl is exposed to humid air. As a result, Li–Li symmetrical cells using g‐C3N4‐coated Li6PS5Cl stably cycle for 1000 h with a current density of 0.2 mA cm−2. ASSLMBs paired with LiNbO3‐coated LiNi0.6Mn0.2Co0.2O2 exhibit a capacity of 132.8 mAh g−1 at 0.1 C and a high‐capacity retention of 99.1% after 200 cycles. Furthermore, g‐C3N4‐coated Li6PS5Cl effectively mitigates the self‐discharge behavior observed in ASSLMBs. This surface‐coating approach for sulfide solid electrolytes opens the door to the practical implementation of sulfide‐based ASSLMBs.

Understanding visible light and microbe-driven degradation mechanisms of polyurethane plastics: Pathways, property changes, and product analysis

The accumulation of polyurethane plastics (PU-PS) in the environment is on the rise, posing potential risks to the health and function of ecosystems. However, little is known about the degradation behavior of PU-PS in the environment, especially water environment. To address this knowledge gap, we investigated and isolated a degrading strain of Streptomyces sp. B2 from the surface of polyurethane coatings. Subsequently, a photoreactor was employed to simulate the degradation process of bio-based polyurethane (BPU) and petroleum-based polyurethane (PPU) under three conditions, including single microorganism (SM), single light exposure (SL), and combined light exposure/microorganism action (ML) in aqueous solution. The results indicated that PU-PS mainly relies on biodegradation, with the highest degradation rate observed after 28 d under SM condition (BPU 5.69 %; PPU 5.25 %). SL inhibited microbial growth and degradation, with the least impact on plastic degradation. Microorganisms colonized the plastic surface, secreting relevant hydrolytic enzymes and organic acids into the culture medium, providing a negative charge. The carbon chains were broken and aged through hydrogen peroxide induction or attack by oxygen free radicals. This process promoted the formation of oxidized functional groups such as OH and CO, disrupting the polymer's structure. Consequently, localized fragmentation and erosion of the microstructure occurred, resulting in the generation of secondary microplastic (MPs) particles, weight loss of the original plastic, increased surface roughness, and enhanced hydrophilicity. Additionally, BPU exhibited greater degradability than PPU, as microorganisms could utilize the produced fatty acids, which promoted their reproduction. In contrast, PPU degradation generated a large amount of isocyanate, potentially toxic to cells and inhibiting biodegradation. This study unveils the significant role of microorganisms in plastic degradation and the underlying degradation mechanisms of BPU, providing a novel strategy for polyurethane degradation and valuable information for comprehensive assessment of the behavior and fate of MPs in the environment.

Stealth and Biocompatible Gold Nanoparticles through Surface Coating with a Zwitterionic Derivative of Glutathione.

Gold nanoparticles (AuNPs) hold promise in biomedicine, but challenges like aggregation, protein corona formation, and insufficient biocompatibility must be thoroughly addressed before advancing their clinical applications. Designing AuNPs with specific protein corona compositions is challenging, and strategies for corona elimination, such as coating with polyethylene glycol (PEG), have limitations. In this study, we introduce a commercially available zwitterionic derivative of glutathione, glutathione monoethyl ester (GSHzwt), for the surface coating of colloidal AuNPs. Particles coated with GSHzwt were investigated alongside four other AuNPs coated with various ligands, including citrate ions, tiopronin, glutathione, cysteine, and PEG. We then undertook a head-to-head comparison of these AuNPs to assess their behavior in biological fluid. GSHzwt-coated AuNPs exhibited exceptional resistance to aggregation and protein adsorption. The particles could also be readily functionalized with biotin and interact with streptavidin receptors in human plasma. Additionally, they exhibited significant blood compatibility and noncytotoxicity. In conclusion, GSHzwt provides a practical and easy method for the surface passivation of AuNPs, creating "stealth" particles for potential clinical applications.

Cell-Specific Impacts of Surface Coating Composition on Extracellular Vesicle Secretion.

Biomaterial properties have recently been shown to modulate extracellular vesicle (EV) secretion and cargo; however, the effects of substrate composition on EV production remain underexplored. This study investigates the impacts of surface coatings composed of collagen I (COLI), fibronectin (FN), and poly l-lysine (PLL) on EV secretion for applications in therapeutic EV production and to further understanding of how changes in the extracellular matrix microenvironment affect EVs. EV secretion from primary bone marrow-derived mesenchymal stromal cells (BMSCs), primary adipose-derived stem cells (ASCs), HEK293 cells, NIH3T3 cells, and RAW264.7 cells was characterized on the different coatings. Expression of EV biogenesis genes and cellular adhesion genes was also analyzed. COLI coatings significantly decreased EV secretion in RAW264.7 cells, with associated decreases in cell viability and changes in EV biogenesis-related and cell adhesion genes at day 4. FN coatings increased EV secretion in NIH3T3 cells, while PLL coatings increased EV secretion in ASCs. Surface coatings had significant effects on the capacity of EVs derived from RAW264.7 and NIH3T3 cells to impact in vitro macrophage proliferation. Overall, surface coatings had different cell-specific effects on EV secretion and in vitro functional capacity, thus highlighting the potential of substrate coatings to further the development of clinical EV production systems.

Selection of optimal strategy for managing decentralized solar PV systems considering uncertain weather conditions

Solar power is a promising source of energy that is environmentally friendly, sustainable, and renewable. Solar photovoltaic (PV) panels are the most common and mature technology used to harness solar energy. Unfortunately, these panels are prone to dust accumulation, which can have a significant impact on their efficiency. To maintain their effectiveness, solar photovoltaics s must be cleaned regularly. Eight main techniques are used to clean solar panels: natural, manual, mechanical, robotic, drone, coating, electrical, and acoustic. This study aims to identify the best cleaning method using multiple criteria decision-making (MCDM) techniques. Using the Analytical Hierarchy Process (AHP), Quality Function Deployment (QFD), Fuzzy Technique for Order of Preference by Similarities to Ideal Solution (FTOPSIS), and Preference Selection Index (PSI), this research evaluates all eight cleaning methods based on several criteria that are categorized under cost, performance, resource requirement, and safety in Abu Dhabi. The data are collected from surveys completed by experts in solar and sustainable energy. The AHP, QFD, and PSI results identified natural, manual, and surface coating as the best and most effective cleaning methods. Natural cleaning involves using rainwater primarily to remove dirt and dust; manual cleaning requires cleaning agents and wiping clothes; and surface coatings involve applying a layer of hydrophobic material to the panels to repel dust. Identifying the most effective cleaning method for dust removal from solar panels can ensure optimal efficiency recovery at minimal costs and resources.

Synergistic effect of ZnO Thin Films with Gold as Antifungal Coatings

Microbial contamination on surfaces is a problem worldwide, affecting public health and industry. The increasing prevalence and severity of microbial infection outbreaks across various environments have highlighted the urgent need to develop antimicrobial coatings/surfaces to mitigate the risk of disease transmission through high‐touched surfaces. This work focuses on assessing the antifungal activity of thin films based on zinc oxide (ZnO), produced by reactive magnetron sputtering with varying thicknesses, and evaluating the impact of varying gold concentrations within the ZnO matrix on both microstructure and antifungal activity. The developed thin films exhibit noteworthy antifungal activity against the fungus Candida albicans, achieving 80% reduction in cell viability, regardless of thickness and gold concentration (up to 15.4 at%). Annealing treatment at 600 °C induces the formation of large and irregular gold nanostructures (sizes from 39 to 260 nm), enhancing the antifungal activity compared to the as‐deposited samples. This highlights the surface‐dependent antifungal efficacy of ZnO‐based thin films and a synergistic effect when combined with gold. Additionally, the thin films not only exhibit antifungal activity but also demonstrate potential for localized surface plasmon resonance applications. Overall, ZnO‐based thin films hold promise as antifungal coatings for diverse surfaces, offering a preventive measure against microbial contamination.

Development of the Instrumental Indentation Method in Diagnostics of Physical and Mechanical Properties of Hardened Surface Layers and Coatings of Materials in Engineering Products

Development of the Instrumental Indentation Method in Diagnostics of Physical and Mechanical Properties of Hardened Surface Layers and Coatings of Materials in Engineering Products

Development of a tomato xylem-mimicking microfluidic system to study Ralstonia pseudosolanacearum biofilm formation.

The bacterial wilt pathogen Ralstonia pseudosolanacearum (Rps) colonizes plant xylem vessels and blocks the flow of xylem sap by its biofilm (comprising of bacterial cells and extracellular material), resulting in devastating wilt disease across many economically important host plants including tomatoes. The technical challenges of imaging the xylem environment, along with the use of artificial cell culture plates and media in existing in vitro systems, limit the understanding of Rps biofilm formation and its infection dynamics. In this study, we designed and built a microfluidic system that mimicked the physical and chemical conditions of the tomato xylem vessels, and allowed us to dissect Rps responses to different xylem-like conditions. The system, incorporating functional surface coatings of carboxymethyl cellulose-dopamine, provided a bioactive environment that significantly enhanced Rps attachment and biofilm formation in the presence of tomato xylem sap. Using computational approaches, we confirmed that Rps experienced linear increasing drag forces in xylem-mimicking channels at higher flow rates. Consistently, attachment and biofilm assays conducted in our microfluidic system revealed that both seeding time and flow rates were critical for bacterial adhesion to surface and biofilm formation inside the channels. These findings provided insights into the Rps attachment and biofilm formation processes, contributing to a better understanding of plant-pathogen interactions during wilt disease development.

Silver and Copper Nanoparticle-Loaded Self-Assembled Pseudo-Peptide Thiourea-Based Organic-Inorganic Hybrid Gel with Antibacterial and Superhydrophobic Properties for Antifouling Surfaces.

The escalating threat of antimicrobial resistance has become a global health crisis. Therefore, there is a rising momentum in developing biomaterials with self-sanitizing capabilities and inherent antibacterial properties. Despite their promising antimicrobial properties, metal nanoparticles (MNPs) have several disadvantages, including increased toxicity as the particle size decreases, leading to oxidative stress and DNA damage that need consideration. One solution is surface functionalization with biocompatible organic ligands, which can improve nanoparticle dispersibility, reduce aggregation, and enable targeted delivery to microbial cells. The existing research predominantly concentrates on the advancement of peptide-based hydrogels for coating materials to prevent bacterial infection, with limited exploration of developing surface coatings using organogels. Herein, we have synthesized organogel-based coatings doped with MNPs that can offer superior hydrophobicity, oleophobicity, and high stability that are not easily achievable with hydrogels. The self-assembled gels displayed distinct morphologies, as revealed by scanning electron microscopy and atomic force microscopy. The cross-linked matrix helps in the controlled and sustained release of MNPs at the site of bacterial infection. The synthesized self-assembled gel@MNPs exhibited excellent antibacterial properties against harmful bacteria such as Escherichia coli and Staphylococcus aureus and reduced bacterial viability up to 95% within 4 h. Cytotoxicity testing against metazoan cells demonstrated that the gels doped with MNPs were nontoxic (IC50 > 100 μM) to mammalian cells. Furthermore, in this study, we coated the organogel@MNPs on cotton fabric and tested it against Gram +ve and Gram -ve bacteria. Additionally, the developed cotton fabric exhibited superhydrophobic properties and developed a barrier that limits the interaction between bacteria and the surface, making it difficult for bacteria to adhere and colonize, which holds potential as a valuable resource for self-cleaning coatings.

Selection of Surface Coating Materials for Ni-Rich NCM in All-Solid-State Batteries through Electronic Band Structure Analysis Using UPS/LEIPS

Selection of Surface Coating Materials for Ni-Rich NCM in All-Solid-State Batteries through Electronic Band Structure Analysis Using UPS/LEIPS

Depth-resolved elemental and molecular analysis of polymeric multilayers with EI-MS and ICP-OES using chemometric evaluation

Polymeric composite materials with layered structures have increasingly gained importance as, for specific applications, the required properties cannot be achieved with one single material; thus, for example, multi-layer polymers or special surface coatings are employed.None of the conventionally available techniques enables a comprehensive characterization of composite materials, including depth-resolved information about their organic and elemental constituents.In this work, a previously introduced approach enabling the direct characterization of the organic and inorganic constituents of solid polymer samples was further developed and optimized for depth profiling analysis of stacked layer polymers. For this purpose, the ablation chamber’s washout behavior and transfer line’s transport efficiency were improved. Chemometric methods were applied for the data analysis to gain greater insight and enable more precise differentiation, comparison and classification.The work investigates the feasibility of the developed approach by analyzing a multi-layer stacked polymer sample created from nail polishes and using cluster analysis on the data collected with the bimodal detection. The layers of the sample could be differentiated by their organic and elemental constituents’ fingerprints, achieving a depth resolution of 7 µm.

Ultrathin Al2O3 film modification on waterborne epoxy coatings by atomic layer deposition for augmenting the corrosion resistance

The polar channels formed by the curing of waterborne anticorrosive coatings compromise their water resistance, leading to coating degradation and metal corrosion. To enhance the anticorrosive performance of waterborne coatings, this study proposed a novel method of depositing ultrathin Al2O3 films on the surface of waterborne epoxy coatings by atomic layer deposition, a technique that can modify the surface properties of polymer materials by depositing functional films. The Al2O3-modified coatings exhibited improved sealing and barrier properties by closing the polar channels and surface defects and cracks. The surface structure and morphology of the modified coatings were characterized by x-ray photoelectron spectroscopy and scanning electron microscopy. The hydrophilicity and corrosion resistance of the modified coatings were evaluated by water contact angle measurement, Tafel polarization curve, and electrochemical impedance spectroscopy. The results indicated that the water contact angle of the Al2O3-modified coating increased by 48° compared to the unmodified coating, and the protection efficiency of the modified coating reached 99.81%. The Al2O3-modified coating demonstrated high anticorrosive efficiency and potential applications for metal anticorrosion in harsh marine environments.

Investigation on tribological properties of high-velocity air fuel spraying WC–Cr3C2–Ni coating on the surface of continuous casting crystallization rollers

To overcome the wear problem of the substrate of thin-strip continuous casting crystallization rollers and improve economic efficiency, high-velocity air fuel (HVAF) technology was used to deposit WC–Cr3C2–Ni wear-resistant coatings on the surface of the crystallization rollers. The existing performance and wear condition of curved WC–Cr3C2–Ni coatings during continuous casting were investigated by the ring-block wear system. The experimental results showed that the WC–Cr3C2–Ni coating with a thickness of 300 μm effectively reduced the coefficient of friction (by 16.4 %) and the wear rate (by 82.5 %) on the surface of the crystallization roller and significantly reduced the roughness of the wear interface (by 71.2 %), which provided reliable protection for the substrate. The results of high-temperature (200 °C) wear tests showed that the WC–Cr3C2–Ni coating deposited via HVAF protected the substrate in actual long-cycle production and exhibited an excellent resistance to the emergence and expansion of failure cracks. This study provided a theoretical basis for the selection and preparation of surface coatings for thin strip continuous casting crystallization rollers.

Biosynthesized silver nanoparticles prevent bacterial infection in chicken egg model and mitigate biofilm formation on medical catheters.

Investigating the application of innovative antimicrobial surface coatings on medical devices is an important field of research. Many of these coatings have significant drawbacks, including biocompatibility, coating stability and the inability to effectively combat multiple drug-resistant bacteria. In this research, we developed an antibiofilm surface coating for medical catheters using biosynthesized silver nanoparticles (b-Cs-AgNPs) developed using leaves extract of Calliandra surinamensis. Various characterization techniques were employed to thoroughly characterize the synthesized b-Cs-AgNPs and c-AgNPs. b-Cs-AgNPs were compatible with human normal kidney cells and chicken embryos. It did not trigger any skin inflammatory response in in vivo rat model. b-Cs-AgNPs demonstrated potent zone of inhibition of 19.09mm when subjected to the disc diffusion method in E. coli confirming strong antibacterial property. Different anti-bacterial assays including liquid growth curve, colony counting assay, biofilm formation assay supported the potent antimicrobial efficacy of b-Cs-AgNPs alone and when coated to medical grade catheters. Mechanistic studies reveal the presence of ferulic acid, that was important for the synthesis of b-AgNPs along with enhanced antibacterial effects of b-Cs-AgNPs compared to c-AgNPs, supported by molecular docking analysis. These results together demonstrated the effective role b-Cs-AgNPs in combating infections and mitigating biofilm formations, highlighting their need for further study in the field of biomedical applications.