Coatings

12 pages, 1909 KiB

Open AccessArticle

Structure and Properties of Thin Films Prepared on Flexible Substrates from SnCl₄-Derived Solutions

by Elena A. Dmitriyeva, Bedelbek M. Nurbaev, Ekaterina A. Bondar, Anastasiya S. Kovalenko, Anton M. Nikolaev and Olga A. Shilova

Coatings 2024, 14(10), 1343; https://doi.org/10.3390/coatings14101343 - 21 Oct 2024

Viewed by 826

Abstract

Thin transparent films of SnO₂ were obtained from aqueous–alcohol solutions of SnCl₄ on a flexible polyethylene terephthalate (PET) substrate by spray pyrolysis at 100 °C. The influence of the addition of aqueous ammonia to the film-forming solution on the different properties [...] Read more.

Thin transparent films of SnO₂ were obtained from aqueous–alcohol solutions of SnCl₄ on a flexible polyethylene terephthalate (PET) substrate by spray pyrolysis at 100 °C. The influence of the addition of aqueous ammonia to the film-forming solution on the different properties has been studied. Properties studied include surface morphology, phase composition and transparency of the formed films and the crystallization processes and band gap of the film material. It was found that the addition of aqueous ammonia causes the formation of skeletal crystals (NH₄)₂[SnCl₆] with a perovskite structure in the film structure. The resulting films are promising for use in the technology of manufacturing flexible solar cells. Full article

(This article belongs to the Section Thin Films)

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15 pages, 5182 KiB

Open AccessArticle

Mechanical Properties of Spunlace Non-Wovens with a Porous Structure

by Michał Sąsiadek, Anna D. Dobrzańska-Danikiewicz, Maciej Niedziela, Waldemar Woźniak and Michał Szota

Coatings 2024, 14(10), 1342; https://doi.org/10.3390/coatings14101342 - 21 Oct 2024

Viewed by 785

Abstract

The paper describes the influence of the drum system construction of two modern carding machines on the porous structure of spunlace non-wovens composed of polyester and viscose. The non-woven fabric structure, including the number and size of the pores, determines the tensile strength [...] Read more.

The paper describes the influence of the drum system construction of two modern carding machines on the porous structure of spunlace non-wovens composed of polyester and viscose. The non-woven fabric structure, including the number and size of the pores, determines the tensile strength of the composites obtained. The spunlace non-wovens were subjected to tensile strength tests in the machine, and cross-directions and microscopic observations of their structure were made. The results of the experiments were used to determine the relationship between the strength of the material and the porosity of its structure. This knowledge was used to prepare recommendations for the manufacturer of wet wipes in order to enable the selection of a carding machine for the mass production of final products with strength properties that meet market requirements and satisfy the end customer. Full article

(This article belongs to the Special Issue Advances in Coated Fabrics and Textiles)

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21 pages, 6832 KiB

Open AccessReview

Research Progress on Environmental Corrosion Resistance of Thermal Barrier Coatings: A Review

by Xiaoyuan Hu, Ying Xie, Faguo Li and Fucheng Yin

Coatings 2024, 14(10), 1341; https://doi.org/10.3390/coatings14101341 - 21 Oct 2024

Viewed by 943

Abstract

With the development of marine science and technology, marine construction is entering a new period of modern ocean development and utilization. The scale of marine development is expanding constantly. The lifespan of aircraft engines faces new challenges in marine environments. This paper reviews [...] Read more.

With the development of marine science and technology, marine construction is entering a new period of modern ocean development and utilization. The scale of marine development is expanding constantly. The lifespan of aircraft engines faces new challenges in marine environments. This paper reviews recent progress in the development of high-temperature coatings for aero-engines designed to resist marine atmospheric corrosion, with a focus on corrosion mechanisms, detection technologies, current research on marine atmospheric corrosion, standards for evaluating coating resistance, and novel advancements in coating materials. Full article

(This article belongs to the Special Issue Advances of Ceramic and Alloy Coatings, 2nd Edition)

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16 pages, 5483 KiB

Open AccessArticle

Periodically Sinusoidal Magnetic Stray Field and Improved Film Quality of CoMnP Micro-Magnet Arrays for Magnetic Encoders by Electrodeposition with the Assistance of Ultrasound

by Geng-Hua Xu, Jung-Yen Chang, Hsiang-Chun Hsueh and Chiao-Chi Lin

Coatings 2024, 14(10), 1340; https://doi.org/10.3390/coatings14101340 - 21 Oct 2024

Viewed by 2763

Abstract

Magnetic encoders are composed of a magnetic sensor, a hard magnetic recording medium and a signal processing circuit. Electrodeposited micro-magnet arrays produced by micro-fabrication are promising recording media for enhancing encoder performance. However, two major engineering issues have yet to be resolved. One [...] Read more.

Magnetic encoders are composed of a magnetic sensor, a hard magnetic recording medium and a signal processing circuit. Electrodeposited micro-magnet arrays produced by micro-fabrication are promising recording media for enhancing encoder performance. However, two major engineering issues have yet to be resolved. One issue is an unknown relationship between the feature sizes of micro-magnet arrays and their stray field shapes, and another issue is the formation of micro-cracks due to the built-up residual stresses of thick films. In this study, we investigated the effect of feature sizes on the emanating stray field shape at various observation heights. Feature sizes include two height (i.e., film thickness) values of 78 μm and 176 μm, and both width and spacing with three values of 360 μm, 520 μm and 680 μm. Ultrasound-assisted agitation was adopted for investigating the effects of electrodepositing current densities on the film crystalline microstructures and magnetic properties. Narrowing the width of micro-magnets helps the stray field to become a sinusoidal profile. Thinner film, i.e., thickness 78 μm in this study, supports the stray field taking on a sinusoidal profile. Moreover, the spacing between the micro-magnets plays a key factor in determining the shape of the stray field. Under 37 kHz/156 W ultrasound agitation, the optimal hard magnetic properties of electrodeposited CoMnP films are residual magnetization 2329 G and coercivity 968 Oe by a current density of 10.0 mA/cm². Ultrasound-assisted electrodeposition, along with duly designed feature size, facilitates the micro-magnet arrays having a sinusoidal stray field shape using high quality films. Furthermore, for the first time, a systematic understanding of feature-size-dependent stray field evolution and improved polarities quality has been realized for the recording media of sinusoidal magnetic encoders. Full article

(This article belongs to the Special Issue Functional Coatings and Surface Science for Precision Engineering)

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17 pages, 5350 KiB

Open AccessArticle

High-Speed Removal Process for Organic Polymers by Non-Thermal Atmospheric-Pressure Spark Discharge at Room Temperature and Its Mechanism

by Yoshihiro Sakamoto, Takayoshi Tsutsumi, Hiromasa Tanaka, Kenji Ishikawa, Hiroshi Hashizume and Masaru Hori

Coatings 2024, 14(10), 1339; https://doi.org/10.3390/coatings14101339 - 18 Oct 2024

Viewed by 676

Abstract

Heel marks (HMs) are a type of dirt stain consisting of polyester-based urethane rubber on polyvinyl chloride (PVC) floor surfaces. The rapid removal of HMs was achieved by using non-thermal atmospheric-pressure plasma technology. Mimetic HMs were prepared by coating PVC floor samples with [...] Read more.

Heel marks (HMs) are a type of dirt stain consisting of polyester-based urethane rubber on polyvinyl chloride (PVC) floor surfaces. The rapid removal of HMs was achieved by using non-thermal atmospheric-pressure plasma technology. Mimetic HMs were prepared by coating PVC floor samples with HMs to a thickness of 13.9 μm. The removal area, thickness, and volume were measured after applying spark discharges at high voltage and a repetition rate of 50 kHz. The treated surfaces were analyzed by using X-ray photoelectron spectroscopy (XPS) and pyrolysis–gas chromatography with time-of-flight mass spectrometry (Py-GC/TOFMS). Removal rates of 20 mm²/min in area, 52 mm³/min in volume, and 7 μm/min in depth were achieved with an inter-electrode distance of 10.0 mm and an air flow rate of 20 standard liters per minute. A removal depth of 10 μm/min was achieved without air supply. The mechanism of stain removal by spark discharge was modeled by decomposing the original high-molecular-weight molecules in polyester-based urethane rubber into low-molecular-weight molecules, such as methylene diisocyanate (MDI) components. The results of this study may facilitate the development of a novel electric vacuum cleaner capable of removing floor stains. Full article

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27 pages, 1969 KiB

Open AccessReview

Research Progress on Polysaccharide Composite Films and Coatings with Antioxidant and Antibacterial Ingredients to Extend the Shelf Life of Animal-Derived Meat

by Ming Yuan, Jun Mei and Jing Xie

Coatings 2024, 14(10), 1338; https://doi.org/10.3390/coatings14101338 - 18 Oct 2024

Viewed by 1051

Abstract

Animal-derived meat is rich in proteins and other nutrients, but is prone to spoilage during storage, including microbial contamination and fat oxidation. Therefore, there is an urgent need to find effective solutions to extend the shelf life of animal-derived meat. Polysaccharides are natural [...] Read more.

Animal-derived meat is rich in proteins and other nutrients, but is prone to spoilage during storage, including microbial contamination and fat oxidation. Therefore, there is an urgent need to find effective solutions to extend the shelf life of animal-derived meat. Polysaccharides are natural macromolecules containing multi-hydroxyl structures and functional groups, which have good solubility, film-forming properties, etc., and can form edible films. Polysaccharide films can be combined with biopolymers, nanoparticles, and natural active agents to improve their properties and enhance the antioxidant and antimicrobial activities of the films. This review summarizes the various sources of polysaccharides, such as chitosan, hyaluronic acid, sodium alginate, carrageenan, starch, and pullulan polysaccharides and their combination with different substances to extend the shelf life of animal-derived meat. This review may serve as a reference for further development of polysaccharides in animal-derived meat preservation. Full article

(This article belongs to the Special Issue Advanced Coatings and Films for Food Packing and Storage, 2nd Edition)

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20 pages, 7384 KiB

Open AccessArticle

Evolutionary Mechanism of Solidification Behavior in the Melt Pool During Disk Laser Cladding with 316L Alloy

by Chang Li, Jiabo Liu, Shuchao Li, Fanhong Kong, Xuan Wang, Han Sun and Yichang Sun

Coatings 2024, 14(10), 1337; https://doi.org/10.3390/coatings14101337 - 18 Oct 2024

Viewed by 661

Abstract

Laser cladding is an emerging environmentally friendly surface-strengthening technology. During the cladding process, the changes in molten pool temperature and velocity directly affect the solidification process and element distribution. The quantitative revelation of the directional solidification mechanism in the molten pool during the [...] Read more.

Laser cladding is an emerging environmentally friendly surface-strengthening technology. During the cladding process, the changes in molten pool temperature and velocity directly affect the solidification process and element distribution. The quantitative revelation of the directional solidification mechanism in the molten pool during the cladding process is crucial for enhancing the quality of the cladding layer. In this study, a multi-field coupling numerical model was developed to simulate the coating process of 316L powder on 45 steel matrices using a disk laser. The instantaneous evolution law of the temperature and flow fields was derived, providing input conditions for simulating microstructure evolution in the molten pool’s paste zone. The behavior characteristics of the molten pool were predicted through numerical simulation, and the microstructure evolution was simulated using the phase field method. The phase field model reveals that dendrite formation in the molten pool follows a sequence of plane crystal growth, cell crystal growth, and columnar crystal growth. The dendrites can undergo splitting to form algal structures under conditions of higher cooling rates and lower temperature gradients. The scanning speed of laser cladding (6 mm/s) has minimal impact on dendrite growth; instead, convection within the molten pool primarily influences dendrite growth and tilt and solute distribution. Full article

(This article belongs to the Special Issue Effects of Laser Treatment on Surface Characterization and Mechanical Properties of Alloys)

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2 pages, 135 KiB

Open AccessRetraction

RETRACTED: Chupradit et al. Ultra-Sensitive Biosensor with Simultaneous Detection (of Cancer and Diabetes) and Analysis of Deformation Effects on Dielectric Rods in Optical Microstructure. Coatings 2021, 11, 1564

by Supat Chupradit, Shameen Ashfaq, Dmitry Bokov, Wanich Suksatan, Abduladheem Turki Jalil, Amer M. Alanazi and Mika Sillanpaa

Coatings 2024, 14(10), 1336; https://doi.org/10.3390/coatings14101336 - 18 Oct 2024

Viewed by 668

Abstract

The journal retracts the article, “Ultra-Sensitive Biosensor with Simultaneous Detection (of Cancer and Diabetes) and Analysis of Deformation Effects on Dielectric Rods in Optical Microstructure” [...] Full article

(This article belongs to the Special Issue Strengthening, Corrosion and Protection of High Temperature Structural Materials)

1 pages, 122 KiB

Open AccessCorrection

Correction: Chen et al. Preparation of Pie-Shaped CoMoO₄ with High Capacitive and Photocatalytic Properties by a Solvothermal Method. Coatings 2022, 12, 1771

by Shuoyan Chen, Juan Wu, Gang Wang, Jing Wang, Licai Fan, Jian Hao, Shen Wang, Yang Liu, Hongyu Wu, Yang Li, Jing Gao and Mingli Yang

Coatings 2024, 14(10), 1335; https://doi.org/10.3390/coatings14101335 - 18 Oct 2024

Viewed by 431

Abstract

Following publication, concerns were raised regarding the peer-review process related to the publication of this article [...] Full article

12 pages, 6333 KiB

Open AccessArticle

Tribological and Corrosion Properties of Al₂O₃@Y₂O₃-Reinforced Ni60A Composite Coatings Deposited Using Laser Cladding

by Yu Yin, Xing-Hua Ma, Jingwei Li, Shuling Zhang, Zihao Yin, Minghao Ma and Feng Guo

Coatings 2024, 14(10), 1334; https://doi.org/10.3390/coatings14101334 - 18 Oct 2024

Viewed by 671

Abstract

Since rare earth oxides and hard ceramic particles improve coating quality, a novel Al₂O₃@Y₂O₃ core–shell structure was prepared. Then, Ni60A coatings with different amounts (2~6 wt.%) of Al₂O₃@Y₂O₃ core–shell [...] Read more.

Since rare earth oxides and hard ceramic particles improve coating quality, a novel Al₂O₃@Y₂O₃ core–shell structure was prepared. Then, Ni60A coatings with different amounts (2~6 wt.%) of Al₂O₃@Y₂O₃ core–shell structures were prepared using laser cladding technology on an H13 steel surface. To demonstrate the unique effect of the core–shell structure on the performance of the coatings, a set of controlled experiments was also conducted with different proportions of Al₂O₃-Y₂O₃ mechanically mixed powders. The effect of Al₂O₃@Y₂O₃ addition on the phase composition, element distribution, microstructure, wear, and corrosion resistance of the coatings was characterized and tested thoroughly. By comparing the forming quality, hardness, wear, and corrosion resistance of the different coatings, 2 wt.% was confirmed as the optimal concentration of Al₂O₃@Y₂O₃, and its corresponding friction coefficient was about 0.44. The wear rate was approximately 4.15 × 10⁻³ mm³·(N·m)⁻¹, the self-corrosion potential was around −0.3659 V, and the self-corrosion current density was about 1.248 × 10⁻⁶ A·cm⁻². Full article

(This article belongs to the Section Laser Coatings)

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15 pages, 2719 KiB

Open AccessArticle

Physical-Vapor-Deposition-Coated Natural Rocks as Sustainable Cutting Material: First Insights into the Effect of Substrate Integrity on Properties of TiN Thin Film

by Hilke Petersen, Dominic Graf, Nelson Filipe Lopes Dias, Wolfgang Tillmann, Philipp Dan Hendrik Wolters, Benjamin Bergmann and Bernd Breidenstein

Coatings 2024, 14(10), 1333; https://doi.org/10.3390/coatings14101333 - 17 Oct 2024

Viewed by 664

Abstract

The most important cutting materials for machining are carbides. Their production requires both tungsten and cobalt; however, these materials are becoming increasingly difficult to obtain and are sometimes mined under ethically questionable conditions. As a result, increasing efforts are being made to expand [...] Read more.

The most important cutting materials for machining are carbides. Their production requires both tungsten and cobalt; however, these materials are becoming increasingly difficult to obtain and are sometimes mined under ethically questionable conditions. As a result, increasing efforts are being made to expand the range of cutting materials. The basic suitability of natural rocks for cutting tools in less demanding processes has already been demonstrated. PVD coating of the natural rocks could improve their performance. The adhesion mechanisms in TiN-coated natural rock samples are discussed below. The TiN thin film is characterized in depth. Full article

(This article belongs to the Special Issue Modern Methods of Shaping the Structure and Properties of Coatings)

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21 pages, 11497 KiB

Open AccessArticle

Enhancing Passivation Behaviors and Wear Resistance of Biomedical Ti-15Mo Alloy via {332} Twinning Pre-Tension and Aging

by Shanshan Zhang, Fazhan Yang, Wei Sun, Ning Cui and Tiewei Xu

Coatings 2024, 14(10), 1332; https://doi.org/10.3390/coatings14101332 - 17 Oct 2024

Viewed by 713

Abstract

The purpose of this investigation was to determine the extent to which a combination of pre-deformation and aging procedures could enhance the corrosion and wear resistance of the Ti-15Mo alloy for biomedical materials. The initial grains were refined with {332} twins and other [...] Read more.

The purpose of this investigation was to determine the extent to which a combination of pre-deformation and aging procedures could enhance the corrosion and wear resistance of the Ti-15Mo alloy for biomedical materials. The initial grains were refined with {332} twins and other defects after the pre-deformation, increasing the amount of precipitation nucleation and forming finer α phases during aging. The finer precipitates with numerous boundaries are beneficial in forming a thicker passivation film in phosphate-buffered saline (PBS) solution, and the corrosion resistance of the 20% pre-deform plus aged alloy is improved by 4.23 times. The result indicates that the corrosion passivation behavior and film structure of the biomedical Ti-15Mo alloy are significantly influenced by its microstructure. The worn track and debris of the alloy after pre-tension and aging gradually decreases with the increase in pre-deformation rates, caused by the increase in the hardness and wear resistance. The mechanism of corrosion and wear resistance in PBS solution were revealed, which showed the pre-tension and aging processes that were performed on the Ti-15Mo alloy. This study proposes that pre-tension with {332} twins contributed to precipitation refinement, which would enhance the passivation behaviors and wear resistance of the biomedical β titanium alloy. Full article

(This article belongs to the Special Issue Advances in Surface Engineering and Biocompatible Coatings for Biomedical Applications, 2nd Edition)

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15 pages, 3195 KiB

Open AccessArticle

Sodium Alginate–Montmorillonite Composite Film Coatings for Strawberry Preservation

by Xiaoping Yan, Zuolong Yu, Yao Chen, Chao Han, Yunxiao Wei, Fan Yang, Yan Qian and Yong Wang

Coatings 2024, 14(10), 1331; https://doi.org/10.3390/coatings14101331 - 17 Oct 2024

Viewed by 801

Abstract

In this study, we prepared sodium alginate (SA) and montmorillonite (MMT) composite films for application in coatings for strawberry preservation. SA and MMT were used as the matrix and glycerol was used as a plasticizer. Six types of composite films with different MMT [...] Read more.

In this study, we prepared sodium alginate (SA) and montmorillonite (MMT) composite films for application in coatings for strawberry preservation. SA and MMT were used as the matrix and glycerol was used as a plasticizer. Six types of composite films with different MMT contents were compared by analyzing their mechanical properties, permeability, and preservation effects. The results show that the mechanical properties of the 10 and 20% MMT composite films were superior, with tensile strength and fracture elongation values reaching 63.09 and 48.06 MPa and 5.75 and 6.47%, respectively. Increased MMT content caused the water vapor permeability to decrease, while the effect on oil permeability was the opposite. A comparison of the preservation effect provided by the coatings showed that, on day 12, the weight loss, malondialdehyde content, and respiratory intensity of strawberries treated with the 20% MMT coating liquid decreased by 43.3, 25.8, and 57.1%, respectively, compared with the control. The contents of titratable acid, soluble sugar, total phenols, and soluble solids decreased by 25.8, 37.7, 25.9, and 14.5%, respectively. The results provide data support for the application of these new composite films as edible coatings for fruit preservation. Full article

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18 pages, 32353 KiB

Open AccessArticle

Numerical Simulation and Experimental Study of Deposition Behavior for Cold Sprayed Dual Nano HA/30 wt.% Ti Composite Particle

by Miao Sun, Xiao Chen, Zecheng Wu, Chengdi Li and Xianfeng Deng

Coatings 2024, 14(10), 1330; https://doi.org/10.3390/coatings14101330 - 17 Oct 2024

Viewed by 591

Abstract

Hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) composite coatings added in the second phase could improve the mechanical properties and bonding strength. The cold spraying technique, as a technology for the deposition of solid particles at low temperatures, is [...] Read more.

Hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) composite coatings added in the second phase could improve the mechanical properties and bonding strength. The cold spraying technique, as a technology for the deposition of solid particles at low temperatures, is employed to deposit HA ceramic composite coatings. The nano HA material possesses characteristics that enhance properties and promote interface bonding. Due to the exceptional mechanical properties of Ti material, adding Ti particles could improve the mechanical properties of nano HA/Ti composite coatings. In order to explore the deposition deformation mechanism of composite particles under different cold spraying conditions, numerical simulation and experimental testing of deposition behaviors of dual nano HA/Ti composite particles were analyzed. As the particle velocity increased from 400 m/s to 800 m/s in the numerical simulation analysis, the more serious the deposition deformation. Meanwhile, more cracking and splashing phenomena occurred on the surface of the particle. By analyzing the stress value curve of Ti and HA units under different particle velocities, it was found that the adiabatic shear instability phenomenon occurred during the particle deposition on the substrate. In addition, the degree of particle deformation increased with the decrease in the particle size. The results of the experimental investigation were consistent with that of the numerical simulation. Full article

(This article belongs to the Special Issue Functional Coatings: Microstructure, Mechanical Properties, and Wear Behaviour)

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15 pages, 9405 KiB

Open AccessArticle

Study on the Synergistic Effect of Several Sulfur Compounds to the Corrosion Attack of Copper in Liquefied Petroleum Gas

by Chaoben Wang, Yuan Lu, Jinghui Ma and Hu Wang

Coatings 2024, 14(10), 1329; https://doi.org/10.3390/coatings14101329 - 17 Oct 2024

Viewed by 626

Abstract

During the process of liquefied petroleum gas (LPG) exploitation, various sulfide-containing gases are produced, which significantly bring about corrosion attacks to copper equipment and facilities. Investigations on the effects of sulfides, hydrogen sulfide (H₂S), carbonyl sulfide (COS), and ethanethiol (C₂ [...] Read more.

During the process of liquefied petroleum gas (LPG) exploitation, various sulfide-containing gases are produced, which significantly bring about corrosion attacks to copper equipment and facilities. Investigations on the effects of sulfides, hydrogen sulfide (H₂S), carbonyl sulfide (COS), and ethanethiol (C₂H₆S) on copper corrosion and synergistic mechanisms are of great significance for LPG production. This paper studied the synergistic corrosion effects of mixed sulfide-containing gases in LPG on copper plates, including the influence of H₂S + COS, H₂S + C₂H₆S, as well as H₂S + COS + C₂H₆S. The results showed that there exists an apparent synergistic effect between different sulfide-containing gases, which decreased the critical point of corrosion and enhanced the severity of copper corrosion. SEM observation on corrosion products with the addition of different sulfide-containing gases demonstrated that the microstructures of corrosion products are significantly different, which reveals different corrosion mechanisms. By characterizing the corrosion products on copper surfaces, corresponding corrosion mechanisms were proposed. Individual H₂S reacts with copper directly as chemical corrosion. The presence of water leads to the dissolution of H₂S into water film at the copper surface and results in electrochemical corrosion in nature. COS tends to decompose into acidic gas H₂S and CO₂, which accelerates the electrochemical corrosion at the copper surface. C₂H₆S can react with copper directly as chemical corrosion. A mixture of different sulfur-containing gases enhanced the corrosion attack by synergistic effect. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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17 pages, 4305 KiB

Open AccessArticle

Asymmetric Supercapacitor Performance Enhancement Through Fe-Doped MoS₂ Nanosheets Synthesized via Hydrothermal Method

by Pritam J. Morankar, Thupakula V. M. Sreekanth, Rutuja U. Amate, Manesh A. Yewale, Aviraj M. Teli, Sonali A. Beknalkar and Chan-Wook Jeon

Coatings 2024, 14(10), 1328; https://doi.org/10.3390/coatings14101328 - 17 Oct 2024

Viewed by 725

Abstract

As modern civilization’s energy demands continue to rise, the need for efficient renewable energy solutions becomes increasingly critical. In addressing this challenge, our research explores the potential of newly developed iron (Fe)-doped molybdenum disulfide (MoS₂) thin-film electrodes, synthesized through a simple [...] Read more.

As modern civilization’s energy demands continue to rise, the need for efficient renewable energy solutions becomes increasingly critical. In addressing this challenge, our research explores the potential of newly developed iron (Fe)-doped molybdenum disulfide (MoS₂) thin-film electrodes, synthesized through a simple hydrothermal method, as a promising energy storage device. By systematically varying the Fe doping levels, we aim to elucidate the relationship between Fe content and the structural, morphological, and electrochemical properties of the MoS₂ electrodes. The optimized FM-3 electrode exhibited a remarkable areal capacitance of 8.25 F/cm² at a current density of 10 mA/cm² with an energy density of 0.22 mWh/cm² and a power density of 2.2 mW/cm². Furthermore, the FM-3 demonstrated impressive long-term cycling stability, retaining 85.58% of its initial capacitance after 10,000 charge–discharge cycles. To further explore practical applicability, an asymmetric pouch-type supercapacitor device was assembled using an FM-3 electrode and activated carbon. The device achieved an impressive areal capacitance of 0.43 F/cm² at a current density of 20 mA/cm², delivering an energy density of 0.133 mWh/cm² and a power density of 7.5 mW/cm². The exceptional performance of the FM-3 electrode can be attributed to the enhanced diffusion rate, charge transfer efficiency, and better carrier mobility induced by Fe doping. This work not only highlights the significant electrochemical performance improvements of Fe-doped MoS₂ electrodes but also demonstrates their potential for scalable energy storage solutions, making a valuable contribution to the field of next-generation energy storage technologies. Full article

(This article belongs to the Special Issue Energy Storage and Conversion: From Materials, Devices to Applications)

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17 pages, 4527 KiB

Open AccessArticle

Performance of Cobalt-Doped C₃N₅ Electrocatalysis Nitrate in Ammonia Production

by Boyu Liang, Yueqi Wu, Jing Han, Wenqiang Deng, Xinyao Zhang, Runrun Li, Yan Hong, Jie Du, Lichun Fu and Runhua Liao

Coatings 2024, 14(10), 1327; https://doi.org/10.3390/coatings14101327 - 16 Oct 2024

Viewed by 819

Abstract

In this experiment, C₃N₅ was synthesized by pyrolysis of 3-amino-1,2,4 triazole material, and then 1% Co-C₃N₅, 3% Co-C₃N₅, 5% Co-C₃N₅, 7% Co-C₃N₅, and 9% [...] Read more.

In this experiment, C₃N₅ was synthesized by pyrolysis of 3-amino-1,2,4 triazole material, and then 1% Co-C₃N₅, 3% Co-C₃N₅, 5% Co-C₃N₅, 7% Co-C₃N₅, and 9% Co-C₃N₅ were synthesized by varying the mass ratio of cobalt chloride to C₃N₅ by stirring and ultrasonic shaking. SEM, XPS, and XRD tests were performed on the synthesized materials. The experimental results showed that Co atoms were successfully doped into C₃N₅. The electrocatalytic reduction experiments were performed to evaluate their NH₃ yields and electrochemical properties. The results showed that the ammonia yield obtained by the electrolysis of the 9% Co-C₃N₅ catalyst as the working electrode in a mixed electrolytic solution of 0.1 mol/L KNO₃ and 0.1 mol/L KOH for 1 h at a potential of −1.0 V vs. RHE was 0.633 ± 0.02 mmol∙h⁻¹∙mg_cat⁻¹, and the Faraday efficiency was 65.98 ± 2.14%; under the same experimental conditions, the ammonia production rate and Faraday efficiency of the C₃N₅ catalyst were 0.049 mmol∙h⁻¹∙mg_cat⁻¹ and 16.41%, respectively, and the ammonia production rate of the C₃N₅ catalyst was nearly 13-fold worse than the 9% Co-C₃N₅, which suggests that Co can improve the Faraday efficiency and ammonia yield of the electrocatalytic reduction of NO₃⁻. This is due to the strong synergistic effect between the cobalt and C₃N₅ components, with C₃N₅ providing abundant and homogeneous sites for nitrogen coordination and the Co-N species present in the material being highly efficient active sites. The slight change in current density after five trials of 9% Co-C₃N₅ and the decrease in ammonia yield by about 12% in five repetitions of the experiment indicate that 9% Co-C₃N₅ can be recycled and work stably in electrocatalytic reactions and has good application prospects. Full article

(This article belongs to the Special Issue Advanced Materials for Electrocatalysis and Energy Storage)

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16 pages, 10438 KiB

Open AccessArticle

Assessing the Fire Properties of Various Surface Treatments on Timber Components in Ancient Chinese Buildings: A Case Study from the Xianqing Temple in Changzhi, Shanxi, China

by Yupeng Li, Sokyee Yeo, Weihan Zou and Shibing Dai

Coatings 2024, 14(10), 1326; https://doi.org/10.3390/coatings14101326 - 16 Oct 2024

Viewed by 765

Abstract

Traditional and modern coatings play a key role in enhancing the fire resistance of ancient Chinese buildings. However, further comparative analysis is needed on the fire properties of the two coatings and their effects on different timber structural components. This study focuses on [...] Read more.

Traditional and modern coatings play a key role in enhancing the fire resistance of ancient Chinese buildings. However, further comparative analysis is needed on the fire properties of the two coatings and their effects on different timber structural components. This study focuses on the main hall of the Shanxi Changzhi Xianqing Temple, a typical traditional column and beam construction built between the Song and Jin periods. Firstly, the combustion characteristics of various timber structural component samples with different surface treatments (traditional “Yi-ma-wu-hui” and modern flame retardants) were analyzed using cone calorimeter. Secondly, the fire development process of the Xianqing Temple building model was analyzed by a fire dynamics simulator (FDS), and the effect mechanism of different surface treatments on the burning process was further studied. The results show that the fire resistance of timber structural components is significantly improved after modern and traditional surface treatments. The traditional method is more effective in delaying the peak heat release rate and reducing the surface temperature during combustion, while the modern surface treatment significantly prolongs the ignition time of the timber structural components. The FDS results confirm that modern and traditional surface treatments significantly improve the fire resistance of the building, delaying the flashover time by about 300 s, with no collapse occurring within 800 s. In addition, the fire resistance of buildings after traditional surface treatment is better compared to traditional methods. The above research results can provide direct data support for the selection and optimization of fireproof coatings and treatment methods for ancient buildings. Full article

(This article belongs to the Special Issue Coatings for Cultural Heritage: Cleaning, Protection and Restoration)

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13 pages, 4630 KiB

Open AccessArticle

Effect of Rare Earth Y on the Microstructure, Mechanical Properties and Friction of Sn-Babbitt Alloy

by Xiaoyan Ren, Yuan Chang, Shengsheng Chen, Ningning Chen, Zhenghua Shi, Yougui Zhang, Huimin Chen, Zhiming Guo, Jinzhi Hu, Guowei Zhang and Hong Xu

Coatings 2024, 14(10), 1325; https://doi.org/10.3390/coatings14101325 - 16 Oct 2024

Viewed by 810

Abstract

Babbitt alloy is a bearing material with excellent properties, including good anti-friction wear resistance, embeddedness, corrosion, and compliance, as well as sufficient bearing capacity. However, with the development of engines to have high speed and heavy load, the use of Babbitt alloy as [...] Read more.

Babbitt alloy is a bearing material with excellent properties, including good anti-friction wear resistance, embeddedness, corrosion, and compliance, as well as sufficient bearing capacity. However, with the development of engines to have high speed and heavy load, the use of Babbitt alloy as a bearing material exposes its weaknesses of low bearing capacity, insufficient fatigue strength and a sharp decline in mechanical properties with an increase in working temperature. Therefore, its application scope is gradually narrowed and subject to certain limitations. Improving the tensile strength and wear resistance of tin-based Babbitt alloy is of great significance to expanding its application. In this study, tin-based Babbitt alloy was taken as the main research object; the particle size, microstructure, mechanical properties, and friction were systematically studied after the single addition of Y-Cu composite in tin-based Babbitt alloy liquid. The wear performance and the strengthening, toughening and wear mechanisms of tin-based Babbitt alloy were investigated under the action of Y in order to prepare a high-performance tin-based Babbitt alloy for bimetallic bearing. It was found that when rare-earth Y was added to the Babbitt alloy body, the wear properties were greatly improved. Full article

(This article belongs to the Special Issue Advances in Wear-Resistant Coatings)

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12 pages, 6738 KiB

Open AccessArticle

The Utilization of Central Composite Design for the Production of Hydrogel Blends for 3D Printing

by Thalita Fonseca Araujo and Luciano Paulino Silva

Coatings 2024, 14(10), 1324; https://doi.org/10.3390/coatings14101324 - 16 Oct 2024

Viewed by 969

Abstract

Central composite design (CCD) is a statistical experimental design technique that utilizes a combination of factorial and axial points to study the effects of multiple variables on a response. This study focused on optimizing hydrogel formulations for 3D printing using CCD. Three biopolymers [...] Read more.

Central composite design (CCD) is a statistical experimental design technique that utilizes a combination of factorial and axial points to study the effects of multiple variables on a response. This study focused on optimizing hydrogel formulations for 3D printing using CCD. Three biopolymers were selected: sodium alginate (SA), gelatin (GEL), and carboxymethyl cellulose (CMC). The maximum and minimum concentrations of each polymer were established using a Google Scholar search, and CCD was employed to generate various combinations for hydrogel preparation. The hydrogels were characterized in accordance with their swelling degree (SD) in phosphate-buffered saline (PBS) and Dulbecco’s Modified Eagle Medium (DMEM), as well as their printability in 2D and 3D assays. The formulation consisting of 7.5% SA, 7.5% GEL, and 2.5% CMC exhibited the best swelling properties and exceptional printability, surpassing all other tested formulations. This study highlights the effectiveness of design of experiment methodologies in accelerating the development of optimized hydrogel formulations for various applications in 3D printing and suggests avenues for future research to explore their performance in specific biological contexts. Full article

(This article belongs to the Special Issue Recent Advances in Multifunctional Hydrogel and Its Application)

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4 pages, 182 KiB

Open AccessEditorial

Trends in Coatings and Surface Technology

by Pooja Sharma and Fábio Ferreira

Coatings 2024, 14(10), 1323; https://doi.org/10.3390/coatings14101323 - 16 Oct 2024

Viewed by 1359

Abstract

The advancement in material science, industrial evolution, and growing environmental concerns make it essential for continuous updates in coating and surface technology [...] Full article

(This article belongs to the Special Issue Trends in Coatings and Surface Technology)

18 pages, 4583 KiB

Open AccessReview

Ni Catalysts for Thermochemical CO₂ Methanation: A Review

by Jungpil Kim

Coatings 2024, 14(10), 1322; https://doi.org/10.3390/coatings14101322 - 16 Oct 2024

Viewed by 1629

Abstract

This review underscores the pivotal role that nickel-based catalysts play in advancing CO₂ methanation technologies, which are integral to achieving carbon neutrality. This study meticulously examines various aspects of catalyst design, including the significance of support materials and co-catalysts in enhancing catalytic [...] Read more.

This review underscores the pivotal role that nickel-based catalysts play in advancing CO₂ methanation technologies, which are integral to achieving carbon neutrality. This study meticulously examines various aspects of catalyst design, including the significance of support materials and co-catalysts in enhancing catalytic activity and selectivity. This discussion reveals that while nickel catalysts offer a cost-effective solution due to their availability and high performance, challenges such as sintering and carbon deposition at high temperatures remain. These issues necessitate the development of catalysts with superior thermal stability or those capable of maintaining high activity at lower temperatures. This review also highlights the innovative use of three-dimensional fiber deposition technology in fabricating catalysts, which has shown promising results in improving reaction efficiency and stability over prolonged operation. Moving forward, this research emphasizes the importance of optimizing catalyst structure and fabrication techniques to overcome existing limitations. The ongoing development in this field holds great promise for the industrial application of CO₂ methanation, contributing significantly to global efforts in reducing greenhouse gas emissions and promoting sustainable energy use. Full article

(This article belongs to the Special Issue Advanced Research on Energy Storage Materials and Devices)

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17 pages, 20073 KiB

Open AccessArticle

Effect of Zinc Powder Reduced Graphene Oxide on the Corrosion Resistance of Waterborne Inorganic Zinc-Rich Coatings

by Xuefei Fang, Yuchun Yuan, Qiuyue Wang, Chengwei Ji, Yuna Wu, Huan Liu, Jinghua Jiang and Aibin Ma

Coatings 2024, 14(10), 1321; https://doi.org/10.3390/coatings14101321 - 16 Oct 2024

Cited by 1 | Viewed by 940

Abstract

Graphene oxide (GO) is considered an ideal material for applications involving corrosion resistance due to its excellent properties. However, the structure, surface functional groups, and distribution of GO in zinc-rich coatings (ZRCs) have a remarkable influence on coating properties. GO was reduced in [...] Read more.

Graphene oxide (GO) is considered an ideal material for applications involving corrosion resistance due to its excellent properties. However, the structure, surface functional groups, and distribution of GO in zinc-rich coatings (ZRCs) have a remarkable influence on coating properties. GO was reduced in a hydrochloric acid environment using spherical zinc powder, and the resulting products were subsequently dried and incorporated into waterborne inorganic ZRCs. Results show that zinc powder effectively reduces oxygen-containing functional groups on the GO surface, and reduced GO (rGO) is deposited on the surface of zinc powder. This improves the electron migration efficiency of rGO and decreases its surface energy. The electrochemical impedance spectroscopy (EIS) and salt spray test results demonstrate that among the coatings, the ZRC containing 0.2 wt.% rGO (40Zn–0.2rGO) exhibits the highest impedance modulus at the low frequency end. Its impedance modulus reaches 1 × 10⁴ Ω∙cm² after 216 h immersion. Furthermore, 40Zn–0.2rGO exhibits no signs of corrosion at the marked areas even after 216 h of the salt spray test. The good dispersion effect of the added 0.2 wt.% rGO in the coating, coupled with its exceptional electrical conductivity, facilitates the enhanced contribution of zinc powder to cathodic protection, thereby mitigating the matrix erosion caused by corrosive media. Following zinc powder corrosion, the surface of the coating can still be adorned with insoluble corrosion products such as ZnO or Zn₅(OH)₈Cl₂, thereby offering shielding protection to the substrate. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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29 pages, 15808 KiB

Open AccessArticle

Optimization of Pavement Structure Using High-Modulus Asphalt Coating Considering the Effects of Base-Course Combinations

by Hao Wang, Jincheng Wei, Jianmin Guo, Xizhong Xu, Chengji Sun and Jiabao Hu

Coatings 2024, 14(10), 1320; https://doi.org/10.3390/coatings14101320 - 16 Oct 2024

Viewed by 733

Abstract

High-modulus asphalt concrete (HMAC) has been widely used in the surface coating of high-grade pavement. Due to HMAC’s modulus being significantly higher than traditional asphalt concrete, the mechanical responses of a pavement structure using an HMAC coating must be notably different from those [...] Read more.

High-modulus asphalt concrete (HMAC) has been widely used in the surface coating of high-grade pavement. Due to HMAC’s modulus being significantly higher than traditional asphalt concrete, the mechanical responses of a pavement structure using an HMAC coating must be notably different from those of a traditional asphalt pavement structure. Moreover, when asphalt surface coating is fixed, the selection of base-course combinations will determine the mechanical response of the whole pavement structure. However, previous studies usually analyzed the mechanical response of pavement structures at limited combinations of base-courses, resulting in difficulties comprehensively understanding the laws of mechanics and effectively optimizing the HMAC pavement structure. Hence, in this study, a total of 108 groups of numerical experiments under six working conditions of base-course combinations are carried out using orthogonal experimental design to investigate the mechanical response of pavement structures using HMAC coatings using the PR MODULE high-modulus additive. The effects of pavement thickness, material modulus, and structural combination on mechanical responses are analyzed for the 108 groups to determine the optimal pavement combinations based on the balance of mechanical response and economic efficiency. The results show the following: The effect of the base layer type on mechanical response is more significant than that of the subbase layer type. Surface and undersurface layer thickness for the granular material base layer; surface and base layer thickness for the asphalt mixture base layer; and base layer thickness, subbase layer modulus, and base layer modulus for the inorganic binder mixture base layer are the key factors for mechanical response. Finally, six recommended HMAC pavement structure configurations for various base-courses are proposed. Full article

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19 pages, 10073 KiB

Open AccessArticle

Predictive Modeling and Optimization of Layer-Cladded Ti-Al-Nb-Zr High-Entropy Alloys Using Machine Learning

by Ruirui Dai, Hua Guo, Jianying Liu, Marco Alfano, Junfeng Yuan and Zhiqiang Zhao

Coatings 2024, 14(10), 1319; https://doi.org/10.3390/coatings14101319 - 16 Oct 2024

Viewed by 819

Abstract

In this work, the influence of laser power (LP), scanning speed (SS), and powder feeding speed (PF) on the porosity, dilution, and microhardness of lightweight refractory high-entropy alloy (RHEA) coatings produced via laser cladding (LC) was investigated. Variance analysis (ANOVA) was deployed to [...] Read more.

In this work, the influence of laser power (LP), scanning speed (SS), and powder feeding speed (PF) on the porosity, dilution, and microhardness of lightweight refractory high-entropy alloy (RHEA) coatings produced via laser cladding (LC) was investigated. Variance analysis (ANOVA) was deployed to ascertain the effect of LP, SS, and PF on performance metrics such as porosity, dilution, and microhardness. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) was then applied to optimize these processing parameters to minimize porosity, achieve suitable dilution, and maximize microhardness, enhancing the mechanical properties of RHEA coatings. Finally, machine learning models—Random Forest (RF), Gradient Boosting Decision Tree (GBDT), and Genetic Algorithm-enhanced GBDT (GA-GBDT)—were developed using orthogonal experimental data, with GA-GBDT demonstrating superior predictive accuracy. The proposed approach integrates statistical analysis and advanced ML techniques, providing a better understanding into optimizing LP, SS, and PF for improved RHEA coatings performance in industrial applications, thereby advancing laser cladding technology. Full article

(This article belongs to the Special Issue High-Temperature Protective Coatings)

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24 pages, 26404 KiB

Open AccessArticle

Effects of Different Surface Treatment Methods on Laser Welding of Aluminum Alloy and Glass

by Changjun Chen, Lei Li, Min Zhang and Wei Zhang

Coatings 2024, 14(10), 1318; https://doi.org/10.3390/coatings14101318 - 15 Oct 2024

Viewed by 994

Abstract

Hermetic glass-to-metal sealing (GMTS) technology combines metal and glass and can be used to construct vacuum tubes; electric discharge tubes; semiconductor diodes; reed switches; and pressure-tight glass-to-metal windows, optical windows, and lenses in electronics or electronic systems. The hermetic and mechanically strong seals [...] Read more.

Hermetic glass-to-metal sealing (GMTS) technology combines metal and glass and can be used to construct vacuum tubes; electric discharge tubes; semiconductor diodes; reed switches; and pressure-tight glass-to-metal windows, optical windows, and lenses in electronics or electronic systems. The hermetic and mechanically strong seals engineered using GTMS are highly reliable, making them suitable for deployment in harsh environments and for applications requiring high performance. However, it has always been challenging to precisely and robustly join glass and metal due to the significant disparities in their properties. In this study, the laser transmission welding of borosilicate glass and aluminum alloy using a pulsed Nd:YAG laser to achieve hermetic glass–metal seals was experimentally investigated. This research focused on various processing parameters and the influence of surface conditions on bonding quality. Three different types of surfaces—a polished surface, a surface subjected to preoxidation, and a laser-modified surface—were compared. To evaluate the weld strength, shear-tensile separation forces were measured. The analysis of fracture and separation encompassed detailed examinations of the weld morphology, microstructure, and elemental composition. The results revealed that increasing the laser welding energy initially enhanced the weld strength until a saturation point was reached. Among the three different surface treatments tested, the laser surface modification of aluminum alloy yielded the highest weld strength. The maximum achieved bond force exceeded 35.38 N, demonstrating the feasibility of using cost-effective pulsed laser welding for glass-to-metal sealing. The results were significantly better than those from previous research in which aluminum alloy surfaces were pretreated using microarc oxidation. Full article

(This article belongs to the Special Issue Laser-Assisted Processes and Thermal Treatments of Materials)

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12 pages, 2861 KiB

Open AccessArticle

Morphological and Corrosion Characterization of Electroless Ni-P Coatings Deposited on Ductile Iron

by Nicolás Ortiz, Jesús Rafael González-Parra, Jairo Olaya, Dayi Agredo, Raul Valdez, Helgi Waage, Ana María Bolarín, Félix Sánchez and Arturo Barba-Pingarrón

Coatings 2024, 14(10), 1317; https://doi.org/10.3390/coatings14101317 - 15 Oct 2024

Viewed by 747

Abstract

Ductile iron is distinguished by its balance of mechanical properties and other advantageous characteristics, including its capacity to absorb energy. This makes it suitable for applications requiring high strength. However, its performance is impaired by its low corrosion resistance. In this study, a [...] Read more.

Ductile iron is distinguished by its balance of mechanical properties and other advantageous characteristics, including its capacity to absorb energy. This makes it suitable for applications requiring high strength. However, its performance is impaired by its low corrosion resistance. In this study, a Ni-P coating was applied to the surface of ductile cast iron using electroless nickel plating to increase its corrosion resistance in 0.1 M NaCl. The characterization of the substrate and the coated materials was conducted using scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and electrochemical noise. The results show that the coating deposited on a ductile iron is amorphous, compact, homogeneous, and well-adhered. The surface hardness is increased by 53%. Also, a notable increase in corrosion resistance is evidenced by the blocking effect of the coating that delimits the access of the electrolyte to the ductile iron coating. The corrosion mechanism is related to the mixed and localized corrosion phenomena for the different evaluation times. Full article

(This article belongs to the Special Issue Corrosion Resistance of Innovative Composite Coatings Based on Nanoparticles)

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17 pages, 3688 KiB

Open AccessArticle

Investigating the Inhibitory Effect of Sargassum natans and Sargassum fluitans Extracts on Iron Corrosion in 1.00 mol L⁻¹ HCl Solution

by Stacy Melyon, Pau Reig Rodrigo, Manon Sénard, Laura Brelle, Muriel Sylvestre, Sarra Gaspard, Drochss Pettry Valencia and Gerardo Cebrian-Torrejon

Coatings 2024, 14(10), 1316; https://doi.org/10.3390/coatings14101316 - 15 Oct 2024

Viewed by 1125

Abstract

This study deals with the efficacy of extracts of Sargassum natans and Sargassum fluitans, an invasive brown algae present in Guadeloupe, as novel and environmentally friendly corrosion inhibitors for iron in 1 mol L⁻¹ hydrochloric acid solutions. Six different Sargassum extracts (SE) were [...] Read more.

This study deals with the efficacy of extracts of Sargassum natans and Sargassum fluitans, an invasive brown algae present in Guadeloupe, as novel and environmentally friendly corrosion inhibitors for iron in 1 mol L⁻¹ hydrochloric acid solutions. Six different Sargassum extracts (SE) were obtained using Soxhlet extraction with ethyl acetate, acetone, and ethanol, respectively, as solvents; cold successive maceration with chloroform and methanol, respectively; and microwave-assisted extraction with water. Subsequent electrochemical analysis showed that extracts from ethanol and ethyl acetate exhibited remarkable inhibition efficiencies of, respectively, 72.6% and 70.2%, but the better one was the extract of the cold maceration from chloroform with an inhibition efficiency of 92.0%. These findings allow us to focus on the chloroform extract (SEd) in order to see the change happening during the corrosion process via SEM and EDX analyses. Also, NMR analysis was conducted to identify the main chemicals responsible for the anticorrosion effect. The successful demonstration of the corrosion inhibitor effectiveness of extracts of Sargassum natans and fluitans suggests a potentially valuable use for this invasive biomass. These encouraging results warrant further investigation to identify and elucidate the active inhibitors in these extracts to deepen our understanding of their mechanisms for corrosion prevention and potentially expand their utility as an environmentally conscious approach to corrosion control. Full article

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17 pages, 9928 KiB

Open AccessArticle

Anti-Corrosion and Wave-Absorbing Properties of Epoxy-Based Coatings on Q235 Steel

by Rehan Zhang, Kai Yang, Bo Dang, Mengling Zhan, Pingze Zhang and Shuqin Li

Coatings 2024, 14(10), 1315; https://doi.org/10.3390/coatings14101315 - 15 Oct 2024

Viewed by 918

Abstract

Carbon nanotube/epoxy resin (CNE) coatings and carbon nanotube/carboxy iron powder/epoxy resin (CIE) coatings were applied on the surface of Q235 steel, and their corrosion, absorption properties and other characteristics were measured in this work. The results indicate that the average thickness of a [...] Read more.

Carbon nanotube/epoxy resin (CNE) coatings and carbon nanotube/carboxy iron powder/epoxy resin (CIE) coatings were applied on the surface of Q235 steel, and their corrosion, absorption properties and other characteristics were measured in this work. The results indicate that the average thickness of a single application was approximately 400 μm, and the surface of the CNE coating was still smooth and intact after a 3000 h copper ion accelerated salt spray test without bubbles, falling off or other corrosion phenomena. The same was true for 28 days of full immersion in solutions of 10% hydrochloric acid (HCl) and 10% sodium hydroxide (NaOH) of the coating. The electrochemical testing exhibited the corrosion current of the CNE coating as being markedly lower than that of Q235 steel, with a protection efficiency of 81.68% for the Q235 steel. The CNE-0.6 coating had the maximum corrosion voltage (−0.390 V), and the CNE-0.3 coating had the minimum corrosion current of 2.07 × 10⁻⁶ A·cm². The adhesion between the coating and Q235 could reach level 0, and the tensile strength of the coating was up to 18.75 MPa. The coating was observed to remain intact and free from detachment upon undergoing a drop test from a height of 50 cm. In addition, the CIE-0.6 coating exhibited an effective absorption band of 9.1 GHz, covering the range from 8.2 to 13.7 GHz, and it achieved a maximum reflection loss of −15.1 dB at a frequency of 8.6 GHz. Full article

(This article belongs to the Special Issue Oxidation, Wear, Corrosion Behaviors and Activated Bonding Properties of Coatings Deposited on Metals)

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