Journal of Coatings Technology and Research最新文献

Hydroxyl acrylate emulsion was prepared firstly by the semicontinuous seeded emulsion polymerization, and then adding polyaniline (PANI)/Cu/ZrO₂ ternary nanocomposites, two-component waterborne polyurethane (2 K WPU) composite coatings with antistatic and antibacterial properties were obtained by mixing the emulsion with hydrophilic modified polyisocyanate. The structure and morphology of the PANI/Cu/ZrO₂ were observed by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffractometer. The thermal, antistatic, antibacterial, anticorrosion, and mechanical properties of the 2 K WPU composite coatings were determined. The results showed that the addition of the ternary nanocomposites increased the antistatic, antibacterial, anticorrosion, and mechanical properties of the 2 K WPU coating. The initial decomposition temperature increased from 200 to 225°C, and the tensile strength increased by 44.4%. The coatings still maintained good impact strength of 50/50 kg cm, adhesion of grade 2, flexibility of 1 mm, pendulum hardness of 293 s, and the gloss (60°) of 119.4.

In this work, flatbed screen printing is evaluated regarding its capability to produce catalyst layers of PEM fuel cells. In the field of printed electronics, screen printing is regarded as robust and high-throughput coating technology. The possibility of in-plane structuring could be an additional degree of freedom, enabling more complex designs of catalyst layers in the future. In this study, process parameters are varied to investigate their effect on resulting layer thickness, homogeneity, and Pt-loading. With the usage of different screens, the Pt-loading can be adjusted. Additionally, two different pastes with and without water content are investigated. The catalyst paste without water showed a better process stability during printing and performed best under dry conditions (RH = 40%) and worst under wet conditions (RH = 100%) during electrochemical in-situ testing. Overall, the reproducibility of the CCM production process was verified. The viscosity of the catalyst paste with 19.55 wt% water in solvent was higher compared to the paste without water. Furthermore, a carbon paste (Pt-free) is developed in a similar viscosity range as the catalyst pastes. The main challenge of screen printing process development lies in the paste optimization to prevent evaporation effects over time, ensuring sufficient wetting of the paste on the substrate and sufficient fuel cell performance.

Erosion equations were developed to predict the material removal of polyurethane coatings on carbon fiber reinforced plastic (CFRP) surfaces and validated through experimental data. The effects of abrasive properties, process parameters, and organic coating properties (such as fracture toughness and hardness) were considered in the equations. As the erosion angle increased, elastoplastic deformation in the oblique direction and repeated "deformation" in the normal direction were the main reasons for material removal. The ductile erosion behavior was confirmed by experimental data because the maximum erosion rate occurred at an incident angle of 30°. The coefficient and index in the equations were determined by experimental data, and the equations were verified. The developed equations could accurately predict the quantity loss of organic coatings under different particle sizes and particle velocities, and the erosion equations were in good agreement with the experimental data.

The digitization of a society has tremendously influenced the social, economic, and organizational activities of human beings. Internet of things (IoT) will be the next norm to ensure well-being, protection, and comfort of the human beings. Owing to the crisis in energy and consumption of fuel, the research in energy harvesters and autonomous sensors has been focused to develop self-powered wearable devices. The stand-alone energy devices are not suitable to fulfill the requirement of supplying power to the various wearable devices because of higher weight, large volume, frequent recharging, and replacement. The integration of wearable devices into textile materials has recently fostered the emergence of textile-based piezoelectric energy harvesters and sensors. A critical review has been presented on the current status of the textile-based piezosensors and energy harvesters, covering fundamental aspects like probable piezocoatings, fabrication strategies, material choices, working principles, theory behind piezoelectric energy harvesting devices and possible potential applications.

We use deep learning (DL) algorithms for the phenomenological classification of Saffman-Taylor-instability-driven spontaneous pattern formation at the liquid meniscus in the fluid splitting in a gravure printing press. The DL algorithms are applied to high-speed video recordings of the fluid splitting process between the rotating gravure cylinder and the co-moving planar target substrate. Depending on rotation velocity or printing velocity and gravure raster of the engraved printing cylinder, a variety of transient liquid wetting patterns, e.g., a raster of separate drops, viscous fingers, or more complex, branched liquid bridges appear in the printing nip. We discuss how these patterns are classified with DL methods, and how this could serve the identification of different hydrodynamic flow regimes in the nip, e.g., point or lamella splitting.

Pyridine derivatives are prepared and evaluated before being incorporated into polyurethane coating formulations to create antifungal and insecticidal coating compositions. Different analyses, including Fourier transform infrared (FTIR), mass, proton nuclear magnetic resonance (¹HNMR), and carbon-13 nuclear magnetic resonance (¹³C NMR) spectra, were used to confirm the synthesized compounds. The material has been coated using a polyurethane coating mixture. Gloss, scratch resistance, flexibility, and adhesion are some of the coating attributes investigated; mechanical capabilities include impact resistance and shore hardness, and physicochemical properties such as chemical resistance of coated polyurethane (PU) samples are also investigated. PU coatings were applied to substrates to measure coating properties. The mechanical properties of the PU cast films were measured. The results of the experiments revealed that all PU coatings based on dihydropyridine derivatives had good scratch resistance which varied from > 1.5 to > 2 kg. While reducing gloss value varied from 65 to 85, there is no effect of the prepared compounds in the other mechanical test. These PU coatings have excellent chemical resistance except the alkali resistance as evidenced by their physicochemical properties. The observed antifungal and insecticide activities indicated that dry wood coated with PU based on dihydropyridine derivatives is promising for resistance to these insects and fungi, in comparison with the paint as blank. The results revealed that the inhibition zones diameter by compound 2 were 25.1 ± 0.69, 23.2 ± 0.94, 20.16 ± 0.62, 20 ± 0.80, and 18 ± 0.81 mm against A. terreus, A. niger, A. flavus, C. albicans, and A. fumigatus, respectively, whereas the inhibition zones (IZ) diameter by compound 3 were 22.56 ± 0.30, 21.03 ± 0.49, 21.03 ± 0.61, 21 ± 0.66, and 20 ± 0.78 mm versus A. niger, A. fumigatus A. flavus, C. albicans, and A. terreus, respectively. The ordering activity against insects increased as the dose concentration of the pyridine derivatives was increased.

The current review explicitly describes the phosphorus-based flame-retardant (FR) coating materials derived from the bio-resources. It segregates the coatings according to their polymeric backbone type and correlates their structure with the end-application properties. The review will provide a readership to understand different chemistries of FR systems and implement similar in developing the bio-based FR systems for coatings. Furthermore, the review targets to brief the various mechanisms of phosphorus-based FR coating systems depending upon the resin type, such as epoxy, phenolic, polyurethane. The synergistic effects of phosphorus and other FR moieties are also discussed, along with their synthesis chemistries and the structural impact on the properties.

Many sites with high solar radiation like MENA regions face high dust loads that reduce the efficiency generation of solar plants. In this context, this paper provides an overview of dust adhesion mechanism on the surfaces of concentrated solar power (CSP) mirrors. The assessment of dust adhesion was performed on the hydrophilic/hydrophobic glasses at two representative CSP locations in Morocco (Ouarzazate and Midelt). Two types of reflecting mirrors are examined. The first one is based on superhydrophilic TiO₂ protective coating, and the second one is the reflector mirror based on hydrophobic Al₂O₃ protective coating. The research shows that for particle radius of 2 µm, the Van der Waals force dominates for hydrophobic coating for Midelt with high humidity. In contrast, the capillary forces are prominent on the superhydrophilic TiO₂ coating for Ouarzazate with low humidity. The results show good agreement with the X-ray diffraction results. However, as compared to Midelt dust, the dust particles from Midelt are formed of Smectites for the clay fractions. Smectite is highly swelling clay in water compared with Illite, Kaolinite, and Vermiculites types of clay minerals (low swelling clay in water). This work provided a facile method for the calculus of adhesion forces on the surfaces of CSP mirrors and as result helps us to select the best types of anti-soiling coating for reflector mirrors.

Since ice formation on surfaces at subzero temperatures leads to accidents, increased equipment maintenance costs, and reduced performance, multiple strategies, including superhydrophobic surfaces and coatings, have been explored as means to reduce ice adhesion to solid surfaces. Previous work has correlated the effect of topography of regularly patterned superhydrophobic surfaces with ice adhesion. This work, however, investigated the effect of filtered topography on ice adhesion for random superhydrophobic surfaces. The ice adhesion behavior of superhydrophobic composite coatings, prepared from a mixture of silica nanoparticles and polymer binder and sprayed on glass slides, was determined using a shear strength measurement. The ice adhesion significantly decreased with an increase in particle content up to 40 wt.%, after which the ice adhesion became nearly constant. The present study focuses on the use of a novel filtering method for coating topography evaluation which isolated the asperities contributing to the interface from the roughness profile in the superhydrophobic coating. It showed that the ice adhesion correlated with the filtered asperity height and spacing for these random hydrophobic surfaces. Higher particle contents led to larger asperity distances, smaller solid fractions, and lower ice adhesion. The results and conclusions are based on a static ice adhesion test using still water. In this work, it is demonstrated that ice adhesion can be predicted based on the solid–water–air interface, a correlation that could guide future superhydrophobic coating fabrication to create surfaces with greater reduction in ice adhesion.