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Adhesion between graphene and polymers: A surface analysis perspective
摘要： Efficient adhesion between polymers and two-dimensional materials, such as graphene, is fundamental and crucial for the development of flexible devices or special coating materials as well as defining the quality of the transfer processes for these materials. Here, contact angle (CA) measurements of four distinct polymers, low-density polyethylene – LDPE, polypropylene – PP, poly (butylene adipate-co-terephthalate) – PBAT and poly (vinylidene-fluoride-co-trifluoroethylene) – PVDF-TrFE, and graphene achieved by chemical vapor deposition (CVD) were used to understand the adhesion phenomena between such materials. The CA measurements were carried out at specific thermal conditions mimicking a transfer process that is based on direct contact of CVD graphene and polymers above their melting temperature (Direct Dry Transfer – DDT). Surface analysis allowed the efficiency of such transfer method to be pre-estimated owing to an understanding of the adhesion properties of both materials by comparing their polar and dispersive components values. However, rheological properties and chemical structures seemed to be equally important in this evaluation, either by molecular weight modification or introduction of chemical groups onto the surface of polymer films. The results allowed for an understanding of the role of the main factors in adhesion phenomena between graphene and polymers and how they can be used to improve graphene coating during transfer processes.
关键词： graphene,coatings,adhesion,nanomaterials,polymers
更新于2025-09-10 09:29:36
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FeSiAl/ZnO-filled resin composite coatings with enhanced dielectric and microwave absorption properties
摘要： Composite coatings with resin matrix and hybrid fillers of FeSiAl and ZnO powders have been developed for their potential application as microwave absorbing coatings. The effects of FeSiAl and ZnO content on the complex permittivity, complex permeability and reflection loss (RL) of such composite coatings were studied in the frequency range of 8.2–12.4 GHz (X-band). Compared with the complex permeability, the complex permittivity showed more dependence on the absorbent content and the permittivity values increase notably with increasing FeSiAl or ZnO content. Owing to the best impedance matching and appropriate electromagnetic attenuation, the composite coating filled with 35 wt% FeSiAl and 20 wt% ZnO powders exhibits the most desirable microwave absorption properties with the effective absorption bandwidth (< ?10 dB, > 90% absorption) 3.5 GHz in 8.6–12.1 GHz and the strong absorption peak ?40.5 dB at 10.4 GHz, when the thickness is 2.2 mm. The results suggest that FeSiAl/ZnO-filled resin composite coatings could be qualified as good candidates for highly efficient and strong microwave absorbing coatings.
关键词： FeSiAl,dielectric properties,resin composite coatings,microwave absorption,ZnO
更新于2025-09-10 09:29:36
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Cathode plasma electrolytic deposition of Al2O3 coatings doped with SiC particles
摘要： Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7 μm and 40 nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5 g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5 g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings.
关键词： Cathode plasma electrolytic deposition,Surface roughness,Al2O3 coatings,SiC particles
更新于2025-09-10 09:29:36
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High-rate deposition of silicon films in a magnetron discharge with liquid target
摘要： Silicon coatings have been deposited on substrates made of low-carbon and high-carbon steels and tungsten in a magnetron discharge with liquid target at substrate bias voltages ranging from +100 V to -600 V. The structure of obtained coatings was examined by a scanning electron microscopy. The strong influence of substrate bias voltage on the coating structure was observed. The corrosion resistance of coated steel samples was examined in concentrated sulphuric, hydrochloric and nitric acids and their solutions. The resistance of coated tungsten samples against high-temperature oxidation was examined by their exposure to O2 gas at a pressure of 0.2 Pa and a temperature of 1073 K. The coatings deposited under bias voltages of +100 V and -600 V had dense structures and showed the best protective properties among all deposited coatings.
关键词： high-temperature oxidation,silicon coatings,liquid target,corrosion resistance,magnetron discharge
更新于2025-09-10 09:29:36
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Application of coatings on silver studied with punctual and imaging techniques: from specimens to real cases
摘要： The protection of silver artifacts with a coating of organic material isolating the surface from oxygen and S-bearing gases is still one of the most used techniques for the preservation of silver surfaces. A variety of materials suitable to this purpose are being used in the conservation practice. Among them there are acrylic polymers, nitrocellulose lacquer, microcrystalline wax and combination of them in superimposing layers. They are applied either by brush or, in some cases, by spraying. The first stage in a conservation project is often the cleaning of residuals of old protectives, aimed at making the silver surface free from remnants of yellowish materials and enabling the application of new coatings. Unfortunately, removing aged coatings and applying new ones are “blind” processes, since the techniques available for not invasively monitoring the surface of silver artifacts are punctual and do not allow an overall overview of the surface. This is the case of reflectance FTIR and thickness measurement with the Eddy Current technique, which, apart from being punctual, are tricky to apply to uneven surfaces. In this paper, we aim to show the benefits of using an imaging technique, UV induced VIS luminescence, for monitoring the presence and the distribution of protective coatings on silver surfaces and of combining it with reflectance FTIR and thickness gauge. At first, our study was focused on specimens treated with nitrocellulose, acrylic emulsion and microcrystalline wax. The application of the treatments was studied with UV-induced VIS luminescence as well as with the abovementioned punctual techniques to cross-validate the outcome of each method and to assess their suitability for application on organic protective layers on silver artifacts. In a further stage, UV induced VIS luminescence was applied to a real case, a silver chalice that was treated with nitrocellulose lacquer after cleaning.
关键词： reflectance FTIR,UV-induced VIS luminescence,silver artifacts,protective coatings,Eddy Current technique
更新于2025-09-10 09:29:36
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Nonvacuum Surfacing of Protective Coatings Using a Low-Energy Electron Beam
摘要： The results of electron-beam surfacing in air of protective coatings by a low-energy (120 keV) electron beam produced by an electron gun with a plasma emitter are presented. The gun is mounted on an industrial robotic manipulator KUKA, which allows the electron beam to be moved to the atmosphere along a given path without electromagnetic sweep. The combined (self-propagating high-temperature synthesis and electron-beam surfacing) method for obtaining coatings from reaction mixtures of TiO2 : 2.1C and TiO2 : 0.3Cr2O3 : 3.3С is implemented using this setup. The optimum composition of the reaction mixtures and the deposition regimes are determined by thermodynamic modeling using the TERRA program. The obtained coatings with a thickness of 120–200 μ m have a microhardness of 12 GPa. The coatings and the transition layer are established to have good heat resistance up to 900°C. Noticeable changes in the weight characteristics of coatings occur at above 1000°C.
关键词： electron beam surfacing at atmospheric pressure,microhardness,plasma emitter,electron beam,differential pumping system,carbide coatings,self-propagating high-temperature synthesis (SHS),electron gun,gas discharge
更新于2025-09-10 09:29:36
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Zinc Electrochemical Deposition from Ionic Liquids and Aqueous Solutions Onto indium tin oxide.
摘要： Ionic Liquids (ILs) are classified as green solvents and in this context, ILs offer the possibility to improve the electrodeposition processes of several metals or alloys, without involve the use of hazardous chemicals. In this work, we study the electrodeposition process of metallic zinc from the protic ionic liquid 2-hydroxyethyl ammonium propionate (2-HEAP) and from acidic aqueous solutions on indium tin oxide (ITO) as substrate. Electrodeposits obtained from 2-HEAP by using different zinc salts as a source of metallic ions are compared with electrodeposits obtained from aqueous solutions. Results show the influence of zinc salt and of the reaction media (2-HEAP or aqueous solutions) on the electrochemical reduction process and on the morphological properties of the deposits.
关键词： Zinc electrodeposition,Zn coatings,ITO,protic ionic liquids
更新于2025-09-10 09:29:36
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Recovery of scratch deformation formed on crosslinked polyorganosiloxane films
摘要： As consumers generally desire longer lasting scratch-free coatings, scratch resistance has become one of the most important properties of automotive coatings. Surface scratches that deform a coating but do not break it can recover over time, eventually even becoming invisible to the human eye. This phenomenon arises from elastic-plastic behavior and is called "self-recovery". This paper mainly focuses on the recovery of scratch deformations. Conventional coatings with low glass transition temperature (Tg) have fast recovery characteristics, like rubbers, but cannot attain sufficient hardness. Therefore, it is difficult to simultaneously improve both scratch recovery characteristics and hardness in conventional coatings such as 2 K urethane coatings consisting of acrylic polyols because both arise from the same causes as the mobility of the main chain of the coating. Herein, we explore the remarkable improvement of scratch recovery characteristics without sacrificing hardness by using a base resin with a siloxane main chain instead of a carbon-carbon main chain such as that of an acrylic polyol. We demonstrate that crosslinked polyorganosilsesquioxane coatings (Si-films) achieve both hardness suitable for automobile coatings and improved scratch recovery characteristics superior to those of conventional coatings (C-films). Si-films demonstrated 20% better elastic recovery index than C-films, and the Si-films recovered about twice as fast as the C-films. Scratch deformations on the Si-films almost disappeared after 15 min, even at room temperature, while C-films were needed over 24 days. Thus, coatings based on a siloxane main chain may offer dramatically improved self-recovery.
关键词： Scratch resistance,Coatings,Scratch deformation,Recovery,Polyorganosiloxane,Automotive
更新于2025-09-10 09:29:36
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Solar Energy Absorbing Materials that are Capable of Withstanding Long-Term Exposure at 600 °C: Research Strategy
摘要： Pipes for parabolic-trough solar energy collectors (PTSC) must be able to operate and withstand high temperatures in corrosive environments for a long time without changing its microstructure and losing its original properties. The stages of development of a new material and technology for solar energy collectors that allows the production of a PTSC solar energy-absorbing material that is capable of withstanding temperatures ≥ 600 °C for at least 250 days are described. This material is a glass-crystalline enamel coating that is adhered to tubular stainless steel pipes. Such enamel coatings have high coefficients of thermal expansion (CTE) that are similar to the metal surface. These matching CTEs allow the enamel coatings to resist flaking during the heating at 900 °C. The high-temperature resistance of the developed coating was ensured not only by specific additives added to the frit of the coating but also by an additional nanosized sol-gel coating over the enamelled metal substrate.
关键词： thermal properties,enamel coatings for steel,anti-reflective coatings,sol-gel coatings
更新于2025-09-09 09:28:46
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Organic-inorganic composite nanocoatings with superhydrophobicity and thermal stability
摘要： Purpose – This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles. Design/methodology/approach – Sol-gel methods have been used to design superhydrophobic glass substrates through surface modi?cation by using low-surface-energy Isooctyl trimethoxysilane (ITMS) and Ethyl trimethoxysilane (ETMS) solution. Hierarchical double-rough scale solid surface was built by Si micro- and nanoparticles to enhance the surface roughness. The prepared sol was applied onto glass substrate using dip-coating method and was dried at control temperature of 400°C inside the tube furnace. Findings – The glass substrate achieved the water contact angle as high as 154 6 2° and 150.4 6 2° for Si/ITMS and Si/ETMS ?lms, respectively. The Si/ITMS and Si/ETMS also were equipped with low sliding angle as low as 3° and 5°, respectively. The Si micro- and nanoparticles in the coating system have created nanopillars between them, which will suspend the water droplets. Both superhydrophobic coatings have showed good stability against high temperature up to 200°C as there are no changes in WCA shown by both coatings. Si/ITMS ?lm sustains its superhydrophobicity after impacting with further temperature up to 400°C and turns hydrophobic state at 450°C. Research limitations/implications – Findings will be useful to develop superhydrophobic coatings with high thermal stability. Practical implications – Sol method provides a suitable medium for the combination of organic-inorganic network to achieve high hydrophobicity with optimum surface roughness. Originality/value – Application of different alkyl chain groups of silane resin blending with micro- and nanoparticles of Si pigments develops superhydrophobic coatings with high thermal stability.
关键词： Superhydrophobic,Organic coatings,Thermal stability,Coatings,Hierarchical roughness
更新于2025-09-09 09:28:46