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Volume 15
Issue 7
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Coatings, Volume 15, Issue 7 (July 2025) – 88 articles

Cover Story (view full-size image): Ultraviolet (UV) and visible light contribute significantly to the degradation of many foods by causing detrimental processes such as discoloration, lipid oxidation, generation of off-flavors, and reduced nutritional content. UV radiation, in particular, plays a critical role at the retail level because shelf lighting often emits in the UV-A region. This exposure can ultimately reduce the shelf life of packaged foods. While UV absorbers are commonly used as masterbatch solutions, identifying safer and more effective alternatives remains a priority in the food packaging industry. In this study, we investigate the UV-absorbing capacity of alternative molecules of natural origin incorporated into a biopolymer coating applied to a standard plastic film. View this paper
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14 pages, 4419 KiB  
Article
Slurry Aluminizing Mechanisms of Nickel-Based Superalloy and Applicability for the Manufacturing of Platinum-Modified Aluminide Coatings
by Giulia Pedrizzetti, Virgilio Genova, Erica Scrinzi, Rita Bottacchiari, Marco Conti, Laura Paglia and Cecilia Bartuli
Coatings 2025, 15(7), 822; https://doi.org/10.3390/coatings15070822 (registering DOI) - 14 Jul 2025
Abstract
The slurry aluminizing process is widely employed to enhance the oxidation and corrosion resistance of nickel-based superalloys used in high-temperature environments such as gas turbines and aerospace engines. This study investigates the effects of the concentration of Al vapors in the reactor chamber [...] Read more.
The slurry aluminizing process is widely employed to enhance the oxidation and corrosion resistance of nickel-based superalloys used in high-temperature environments such as gas turbines and aerospace engines. This study investigates the effects of the concentration of Al vapors in the reactor chamber and the initial slurry layer thickness on the microstructure, chemical composition, and phase composition of aluminide coatings. Coatings were manufactured on Ni-based superalloy substrates using CrAl powders as an aluminum source and chloride- and fluoride-based activator salts. The effect of the initial thickness of the slurry layer was studied by varying the amount of deposited slurry in terms of mgslurry/cm2sample (with constant mgslurry/cm3chamber). The microstructure and phase composition of the produced aluminide coatings were evaluated by SEM, EDS, and XRD analysis. Slurry thickness can affect concentration gradients during diffusion, and the best results were obtained with an initial slurry amount of 100 mgslurry/cm2sample. The effect of the Al vapor phase in the reaction chamber was then investigated by varying the mgslurry/cm3chamber ratio while keeping the slurry layer thickness constant at 100 mgslurry/cm2sample. This parameter influences the amount of Al at the substrate surface before the onset of solid-state diffusion, and the best results were obtained for a 6.50 mgslurry/cm3chamber ratio with the formation of 80 µm coatings (excluding the interdiffusion zone) with a β-NiAl phase throughout the thickness. To validate process flexibility, the same parameters were successfully applied to produce platinum-modified aluminides with a bi-phasic ζ-PtAl2 and β-(Ni,Pt)Al microstructure. Full article
(This article belongs to the Special Issue Alloy/Metal/Steel Surface: Fabrication, Structure, Friction and Service Life)
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17 pages, 3865 KiB  
Article
Epoxy Resin/Ionic Liquid Composite as a New Promising Coating Material with Improved Toughness and Antibiofilm Activity
by Sergiy Rogalsky, Olena Moshynets, Oleg Dzhuzha, Yevheniia Lobko, Anastasiia Hubina, Alina Madalina Darabut, Yaroslav Romanenko, Oksana Tarasyuk and Geert Potters
Coatings 2025, 15(7), 821; https://doi.org/10.3390/coatings15070821 (registering DOI) - 14 Jul 2025
Abstract
Long-chain imidazolium-based ionic liquids (ILs) possess a broad-spectrum biological activity and are considered promising antifouling agents for protective coatings. A new hydrophobic IL, 1-dodecyl-3-methylimidazolium dodecylbenzenesulfonate (C12C1IM-DBS), has been synthesized, and a modified epoxy coating material containing 10, 20, and [...] Read more.
Long-chain imidazolium-based ionic liquids (ILs) possess a broad-spectrum biological activity and are considered promising antifouling agents for protective coatings. A new hydrophobic IL, 1-dodecyl-3-methylimidazolium dodecylbenzenesulfonate (C12C1IM-DBS), has been synthesized, and a modified epoxy coating material containing 10, 20, and 30 wt% of this IL was prepared by dissolution of C12C1IM-DBS in commercial DER 331 epoxy resin, followed by a curing phase with diethylenetriamine. Infrared analysis revealed physicochemical interactions between the hydroxyl groups of the resin and the IL. Spectrophotometric studies showed no release of C12C1IM-DBS after 30 days of exposure of the modified coatings to water. The plasticizing effect of the IL on the epoxy resin was established by differential scanning calorimetry analysis. The introduction of 10 and 20% C12C1IM-DBS into DER 331 reduced its glass transition temperature from 122.8 °C to 109.3 and 91.5 °C, respectively. The hardness of epoxy resin decreased by approximately 26% after the introduction of the IL. Moreover, DER 331/C12C1IM-DBS coatings on steel substrates showed significantly improved impact resistance compared to neat resin. The antibiofilm efficiency of DER 331/C12C1IM-DBS coatings was evaluated by assessing the capability of two biofilm-forming model strains, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa PA01, to form attached biofilms on the surface. The IL effectively inhibited S. aureus surface-associated biofilm development even at the lowest content of 10%. On the contrary, an approximately 50% inhibition of biofilm metabolic activity was detected for DER 331/C12C1IM-DBS coatings containing 20% and 30% of the IL. Overall, the results of this study indicate that the hydrophobic IL C12C1IM-DBS is an efficient modifying additive for epoxy resins, which can significantly improve their operational properties for various industrial applications. Full article
(This article belongs to the Special Issue Environmentally-Friendly Coatings towards Biofouling Control and Microbiologically Influenced Corrosion (MIC) Inhibition)
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12 pages, 3535 KiB  
Article
TiN-Ag Multilayer Protective Coatings for Surface Modification of AISI 316 Stainless Steel Medical Implants
by Božana Petrović, Dijana Mitić, Minja Miličić Lazić, Miloš Lazarević, Anka Trajkovska Petkoska, Ilija Nasov, Slavoljub Živković and Vukoman Jokanović
Coatings 2025, 15(7), 820; https://doi.org/10.3390/coatings15070820 (registering DOI) - 14 Jul 2025
Abstract
Stainless steel (SS) is one of the materials most commonly utilized for fabrication of medical implants and its properties are often improved by deposition of protective coatings. This study investigates certain physico-chemical and biological properties of SS substrate coated with multilayer thin film [...] Read more.
Stainless steel (SS) is one of the materials most commonly utilized for fabrication of medical implants and its properties are often improved by deposition of protective coatings. This study investigates certain physico-chemical and biological properties of SS substrate coated with multilayer thin film consisting of titanium nitride and silver layers (TiN-Ag film). TiN-Ag films were deposited on the surface of AISI 316 SS substrate by a combination of cathodic arc evaporation and DC magnetron sputtering. SS substrate was analyzed by TEM, while deposited coatings were analyzed by SEM, EDS and wettability measurements. Also, mitochondrial activity assay, and osteogenic and chondrogenic differentiation were performed on dental pulp stem cells (DPSCs). SEM and EDS revealed excellent adhesion between coatings’ layers, with the top layer predominantly composed of Ag, which is responsible for antibacterial properties. TiN-Ag film exhibited moderately hydrophilic behaviour which is desirable for orthopedic implant applications. Biological assays revealed significantly higher mitochondrial activity and enhanced osteogenic and chondrogenic differentiation of DPSC on TiN-Ag films compared to TiN films. The newly designed TiN-Ag coatings showed a great potential for the surface modification of SS implants, and further detailed investigations will explore their suitability for application in clinical practice. Full article
(This article belongs to the Special Issue Recent Advances in Bioceramic Coatings for Medical Implant Applications)
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26 pages, 5588 KiB  
Article
A Methodology for Lacquer Gilding Restoration of Sandstone Sculptures: A Multidisciplinary Approach Combining Material Characterization and Environmental Adaptation
by Haijun Bu and Jianrui Zha
Coatings 2025, 15(7), 819; https://doi.org/10.3390/coatings15070819 (registering DOI) - 14 Jul 2025
Abstract
The restoration of gold leaf on sandstone sculptures requires structural stability, aesthetic considerations, and compliance with the principles of cultural heritage preservation. A primary issue is achieving visual and material compatibility between newly restored and original areas. Based on the “Diagnosis–Analysis–Selection–Restoration” methodology, the [...] Read more.
The restoration of gold leaf on sandstone sculptures requires structural stability, aesthetic considerations, and compliance with the principles of cultural heritage preservation. A primary issue is achieving visual and material compatibility between newly restored and original areas. Based on the “Diagnosis–Analysis–Selection–Restoration” methodology, the research team developed a targeted restoration approach for gilded stone sculptures, using the Shakyamuni sculpture at Erfo Temple in Chongqing as a case study. Assessment of the current situation revealed that over 70% of the sculpture’s surface exhibited gold leaf delamination. The composition and structure of the gold-sizing lacquer, lacquer plaster filler, ground layers, and pigments were investigated using SEM-EDS, XRD, Raman spectroscopy, and THM-Py-GC/MS techniques. The results confirmed that the sculpture featured a typical multilayer gilding structure with clear evidence of historical restorations. Considering both material performance and interfacial compatibility, an NHL2/SiO2/SF016 composite emulsion and traditional lacquer plaster were selected as the optimal materials for reattachment and infill, respectively. A scientific restoration protocol was developed, encompassing gentle cleaning, targeted reattachment and reinforcement, and region-specific repair methods. Principal Component Analysis (PCA) was used to evaluate the influence of temperature and humidity on the curing behavior of lacquer layers. Additionally, a non-invasive gold leaf color-matching technique was developed by controlling the surface roughness of the gold-sizing lacquer, effectively avoiding the damage caused by traditional color-matching methods. Full article
(This article belongs to the Special Issue New Trends in Conservation and Restoration of Cultural Heritage)
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18 pages, 6926 KiB  
Article
Effect of Cerium Nitrate Content on the Performance of Ce(III)/CF/BN/EPN Heat Exchanger Coatings
by Yongbo Yan, Jirong Wu, Mingxing Liu, Qinghua Meng, Jing Zhou, Danyang Feng, Yi Li, Zhijie Xie, Jinyang Li, Xinhui Jiang, Jun Tang, Xuezhi Shi and Jianfeng Zhang
Coatings 2025, 15(7), 818; https://doi.org/10.3390/coatings15070818 (registering DOI) - 13 Jul 2025
Viewed by 91
Abstract
This study investigates the influence of cerium nitrate (Ce(NO3)3·6H2O) content on the performance of Ce(III)/CF/BN/EPN coatings intended for heat exchangers. A series of Ce(III)/carbon fibre (CF)/boron nitride (BN)/epoxy phenolic (EPN) coatings are fabricated with varying concentrations of [...] Read more.
This study investigates the influence of cerium nitrate (Ce(NO3)3·6H2O) content on the performance of Ce(III)/CF/BN/EPN coatings intended for heat exchangers. A series of Ce(III)/carbon fibre (CF)/boron nitride (BN)/epoxy phenolic (EPN) coatings are fabricated with varying concentrations of Ce(NO3)3·6H2O. The results of SEM and EDS show that the dissolution of cerium nitrate in acetone due to the particulate form causes it to be distributed in a diffuse state in the coating. This diffuse distribution does not significantly alter the porosity or structural morphology of the coating. With the increase in cerium nitrate content, both the EIS test results and mechanical damage tests indicate a progressive improvement in the corrosion resistance and self-healing properties of the coatings, while the thermal conductivity (TC) remains largely unaffected. The Ce in the coating reacts with the water molecules penetrating into the coating to generate Ce2O3 and CeO2 with protective properties to fill the permeable pores inside the coating or to form a passivation film at the damaged metal–coating interface, which enhances the anticorrosive and self-repairing properties of the coating. However, the incorporation of Ce(NO3)3·6H2O does not change the distribution structure of the filler inside the coating. As a result, the phonon propagation path, rate, and distance remain unchanged, leading to negligible variation in the thermal conductivity. Therefore, at a cerium nitrate content of 2.5 wt%, the coating exhibits the best overall performance, characterised by a |Z|0.1Hz value of 6.08 × 109 Ω·cm2 and a thermal conductivity of approximately 1.4 W/(m·K). Full article
(This article belongs to the Section Surface Engineering for Energy Harvesting, Conversion, and Storage)
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10 pages, 6843 KiB  
Article
Correlation Between Microstructure and Electric Behavior of (1−x)Ba0.96Ca0.04TiO3-xBa(Mg1/3Nb2/3)O3 Ceramics Prepared via Chemical-Furnace-Assisted Combustion Synthesis
by Haiqin Ding, Jun Wang, Tongchun Qin, Lingling Cui, Guodong Jia, Guang Ji and Zhiwei Li
Coatings 2025, 15(7), 817; https://doi.org/10.3390/coatings15070817 (registering DOI) - 12 Jul 2025
Viewed by 164
Abstract
The (1−x)Ba0.96Ca0.04TiO3-xBa(Mg1/3Nb2/3)O3 (x = 0–0.20) lead-free ceramics were prepared through the chemical-furnace-assisted combustion synthesis (abbreviated as CFACS). The phase structure, microstructure, dielectric, and piezoelectric properties were systematically investigated. Phase analysis revealed the [...] Read more.
The (1−x)Ba0.96Ca0.04TiO3-xBa(Mg1/3Nb2/3)O3 (x = 0–0.20) lead-free ceramics were prepared through the chemical-furnace-assisted combustion synthesis (abbreviated as CFACS). The phase structure, microstructure, dielectric, and piezoelectric properties were systematically investigated. Phase analysis revealed the coexistence of orthorhombic and tetragonal phases in the vicinity of x = 0.07. More importantly, the composition with x = 0.07 exhibited optimal overall electrical properties, including a high piezoelectric coefficient (d33) of 495 pC/N, the planar electromechanical coupling factor (Kp) of 41.9%, and the Curie temperature (Tc) of 123.7 °C. In addition, the average grain size was observed to progressively decrease with increasing x. Full article
(This article belongs to the Section Ceramic Coatings and Engineering Technology)
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14 pages, 3439 KiB  
Article
Superhydrophobic Coating on 6061 Aluminum Alloy Fabricated by Femtosecond Laser Etching and Anodic Oxidation
by Quanlv Liu and Yuxin Wang
Coatings 2025, 15(7), 816; https://doi.org/10.3390/coatings15070816 - 11 Jul 2025
Viewed by 267
Abstract
A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a [...] Read more.
A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a fluorosilane ethanol solution, the surface exhibited superhydrophobicity with a contact angle of 154°. Subsequently, the anodic oxidation process formed an anodic oxide film dominated by an array of aluminum oxide (Al2O3) nanopores at the submicron scale. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the nanopore structures uniformly and continuously covered the laser-ablated layer. This hierarchical structure significantly increased the surface water contact angle to 162°. Wettability analysis showed that the prepared composite coating formed an air layer accounting for 91% of the surface area. Compared with the sample only treated by femtosecond laser etching, the presence of the Al2O3 nanopore structure significantly enhanced the mechanical durability, superhydrophobic durability, and corrosion resistance of the superhydrophobic surface. The proposed multi-step fabrication strategy offers an innovative method for creating multifunctional, durable superhydrophobic coatings and has important implications for their large-scale industrial use. Full article
(This article belongs to the Special Issue Superhydrophobic Coatings, 2nd Edition)
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48 pages, 7567 KiB  
Review
Research Progress on Microstructure, Mechanical Properties, and Strengthening Mechanisms of In Situ-Synthesized Ceramic-Reinforced Titanium Matrix Composite Coatings via Laser Cladding
by Min Wen, Boqiang Jiang, Xianyin Duan and Dingding Xiang
Coatings 2025, 15(7), 815; https://doi.org/10.3390/coatings15070815 - 11 Jul 2025
Viewed by 277
Abstract
The laser cladding (LC) of titanium matrix composite coatings (TMCCs) on titanium components not only effectively enhances the wear resistance, fatigue resistance, corrosion resistance, and biocompatibility of titanium and its alloys, but also circumvents the incompatibility and low bonding strength issues associated with [...] Read more.
The laser cladding (LC) of titanium matrix composite coatings (TMCCs) on titanium components not only effectively enhances the wear resistance, fatigue resistance, corrosion resistance, and biocompatibility of titanium and its alloys, but also circumvents the incompatibility and low bonding strength issues associated with other metallic composite coatings. While the incorporation of ceramic particles is a critical strategy for improving the coating performance, the limited interfacial bonding strength between ceramic particles and the matrix has historically constrained its advancement. To further elevate its performance and meet the demands of components operating in harsh environments, researchers worldwide have employed LC to synthesize in situ hard ceramic reinforcements such as TiC, TiB, TiN, and others within TMCCs on titanium substrates. This approach successfully addresses the aforementioned challenges, achieving coatings that combine a high interfacial bonding strength with superior mechanical properties. This paper provides a comprehensive review of the processing techniques, phase composition, microstructure, and mechanical properties of in situ-synthesized ceramic-reinforced TMCCs via LC on titanium components, with a focused summary of their strengthening mechanisms. Furthermore, it critically discusses the challenges and future prospects for advancing this technology. Full article
(This article belongs to the Topic Advanced Manufacturing and Surface Technology, 2nd Edition)
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19 pages, 2215 KiB  
Article
Ni-Co Electrodeposition Improvement Using Phenylsalicylimine Derivatives as Additives in Ethaline-Based Deep Eutectic Solvents (DES)
by Enrique Ordaz-Romero, Paola Roncagliolo-Barrera, Ricardo Ballinas-Indili, Oscar González-Antonio and Norberto Farfán
Coatings 2025, 15(7), 814; https://doi.org/10.3390/coatings15070814 - 11 Jul 2025
Viewed by 248
Abstract
The development of metallic coatings as Ni-Co alloys, with particular emphasis on their homogeneity, processability, and sustainability, is of the utmost significance. To address these challenges, the utilization of phenylsalicylimines (PSIs) as additives within deep eutectic solvents (DES) was investigated, assessing their influence [...] Read more.
The development of metallic coatings as Ni-Co alloys, with particular emphasis on their homogeneity, processability, and sustainability, is of the utmost significance. To address these challenges, the utilization of phenylsalicylimines (PSIs) as additives within deep eutectic solvents (DES) was investigated, assessing their influence on the electrodeposition process of these metals at an intermediate temperature of 60 °C, while circumventing aqueous reaction conditions. The findings demonstrated that the incorporation of PSIs markedly enhances coating uniformity, resulting in an optimal cobalt content of 37% and an average thickness of 24 µm. Electrochemical evaluations revealed improvements in charge and mass transfer, thereby optimizing process efficiency. Moreover, computational studies confirmed that PSIs form stable complexes with Co (II), modulating the electrochemical characteristics of the system through the introduction of the diethylamino electron-donating group, which significantly stabilizes the coordinated forms with both components of the DES. Additionally, the coatings displayed exceptional corrosion resistance, with a rate of 0.781 µm per year, and achieved an optimal hardness of 38 N HRC, conforming to ASTM B994 standards. This research contributes to the development of electroplating bath designs for metallic coating deposition and lays the groundwork for the advancement of sophisticated technologies in functional coatings that augment corrosion resistance and mechanical properties. Full article
(This article belongs to the Special Issue Electrochemistry and Corrosion Science for Coatings)
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20 pages, 4664 KiB  
Article
Evaluation of the Selected Surface Properties of European Oak and Norway Maple Wood Sanded with Aluminum Oxide Sandpapers of Different Grits
by Agnieszka Laskowska, Anna Piwek, Karolina Lipska, Teresa Kłosińska, Katarzyna Rybak and Piotr Boruszewski
Coatings 2025, 15(7), 813; https://doi.org/10.3390/coatings15070813 - 11 Jul 2025
Viewed by 222
Abstract
The aim of the study was to determine the relationship between selected features of wood and the surface properties after sanding operations. Woods presenting different anatomical structures, i.e., ring-porous hardwood (European oak) and diffuse-porous hardwood (Norway maple), were used in the study. The [...] Read more.
The aim of the study was to determine the relationship between selected features of wood and the surface properties after sanding operations. Woods presenting different anatomical structures, i.e., ring-porous hardwood (European oak) and diffuse-porous hardwood (Norway maple), were used in the study. The wood surfaces were finished by sanding with aluminum oxide sandpapers of different grits: P60, P120, P180, and P240. It was shown that among the analyzed factors (wood species, anatomical section, measurement direction, and sandpaper grit size) and the interactions between them, the direction of measurement had the greatest influence (47%) on the Ra parameter values for oak wood. The sandpaper grit determined 22% of the Ra parameter variability. The measurement direction and the grit size of the sandpaper were identified as the most influential factors affecting the Rsm parameter values. Comparable patterns were observed in the case of Norway maple wood. Due to its diffuse-porous structure, the roughness of maple wood was less affected by the sandpaper grit compared to that of oak wood. Wood species had the greatest influence, increased from 41% to 71% when examining the contact angle at phase boundary wood-water after 3 s and 30 s. Sandpaper grit showed the greatest impact on the contact angles at the wood–diiodomethane phase boundary. This impact was practically at the same level after testing the contact angles after 3 s (27%) and after 30 s (28%). Wood species determined the color parameters, being responsible for 93% of the L* parameter, 50% of parameter a*, and 78% of parameter b*. The influence of sandpaper grit on the a* and b* parameter values was at a low level, i.e., 4%. SEM micrographs revealed the diverse structural characteristics of the wood following the sanding process. Full article
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18 pages, 1467 KiB  
Article
Effect of a Protein–Polysaccharide Coating on the Physicochemical Properties of Banana (Musa paradisiaca) During Storage
by Maritza D. Ruiz Medina, Yadira Quimbita Yupangui and Jenny Ruales
Coatings 2025, 15(7), 812; https://doi.org/10.3390/coatings15070812 - 11 Jul 2025
Viewed by 212
Abstract
Banana (Musa paradisiaca) is a climacteric fruit with high postharvest perishability, limiting its export potential. This study evaluated the effectiveness of a natural protein–polysaccharide edible coating—comprising whey, agar, cassava starch, and glycerol—on maintaining the physicochemical quality of green bananas during 28 [...] Read more.
Banana (Musa paradisiaca) is a climacteric fruit with high postharvest perishability, limiting its export potential. This study evaluated the effectiveness of a natural protein–polysaccharide edible coating—comprising whey, agar, cassava starch, and glycerol—on maintaining the physicochemical quality of green bananas during 28 days of refrigerated storage (13 °C, 95% RH). Seven formulations were tested, including an uncoated control. Physicochemical parameters such as weight loss, firmness, fruit dimensions, peel color, titratable acidity, pH, and soluble solids (°Brix) were systematically monitored. Significant differences were observed among treatments (ANOVA, p < 0.001). The most effective coating (T5), composed of 16.7% whey, 16.7% agar, 33.3% cassava starch, and 33.3% glycerol (based on 30 g/L solids), reduced weight loss by 58.8%, improved firmness retention by 48.4%, and limited sugar accumulation by 17.0% compared to the control. It also stabilized pH and acidity, preserved peel thickness and color parameters (L*, a*, b*), and delayed ripening. These findings confirm the coating’s capacity to form a cohesive semipermeable barrier that modulates moisture loss and respiration, making it a functional and sustainable alternative for extending banana shelf life in tropical supply chains. Full article
(This article belongs to the Special Issue Mitigating Environmental and Health Risks of Coatings: Advances in Safer Formulation, Use, and Disposal)
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19 pages, 1241 KiB  
Article
ThermalInsulation Dry Construction Mixture Based on Diatomite
by Ruslan E. Nurlybayev, Erzhan I. Kuldeyev, Axaya S. Yestemessova, Zaure N. Altayeva, Yelzhan S. Orynbekov, Aktota A. Murzagulova, Alinur A. Iskakov, Gaukhar K. Abisheva and Yerlan Y. Khamza
Coatings 2025, 15(7), 811; https://doi.org/10.3390/coatings15070811 - 11 Jul 2025
Viewed by 229
Abstract
In the context of intensified construction and stricter requirements for the energy efficiency of buildings, the use of thermal insulation materials and technologies is becoming particularly important. One promising area in this field is the use of thermal insulation mixtures, which are versatile, [...] Read more.
In the context of intensified construction and stricter requirements for the energy efficiency of buildings, the use of thermal insulation materials and technologies is becoming particularly important. One promising area in this field is the use of thermal insulation mixtures, which are versatile, adaptable, and highly reliable in operation. Mixtures based on fillers with a porous structure and materials that impart thermal insulation properties, which provide higher thermal insulation properties, are of great interest. However, the development of dry thermal insulation mixtures is hampered by insufficient study of their physical, mechanical, and operational characteristics. This article presents the results of research work on the development and study of dry building thermal insulation mixtures. A distinctive feature of the work is the creation of a composition of dry building thermal insulation mixtures based on local raw materials, such as diatomite, its thermal modification at a temperature of 900 °C, the use of expanded perlite sand, lime, and Portland cement. Research into the properties of modified diatomite has shown that its surface after thermal treatment differs from the surface of unburned diatomite in that it becomes more active and has a 3–4 times higher increase in strength. Modified diatomite and expanded perlite sand have low thermal conductivity, and this property was used in the creation of building thermal insulation mixtures, which was confirmed by research, as the thermal conductivity coefficient ranged from 0.128 to 0.152 W/m °C. The developed dry thermal insulation lime–cement mixture is intended for both interior and exterior finishing works, which is confirmed by the results obtained for determining the frost resistance of the solution and the frost resistance of the contact zone, and corresponds to the F35 grade and has a strength of up to 3.59 MPa. Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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13 pages, 939 KiB  
Article
Composite Coating Enriched with Lemon Peel Extract for Enhancing the Postharvest Quality of Cherry Tomatoes
by Rafael González-Cuello, Joaquín Hernández-Fernández and Rodrigo Ortega-Toro
Coatings 2025, 15(7), 810; https://doi.org/10.3390/coatings15070810 - 10 Jul 2025
Viewed by 171
Abstract
The present study investigated the efficacy of edible coatings formulated with gellan gum and lemon peel extract (LPE) in preserving the postharvest quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). Selected fruits exhibiting uniform ripeness and free from defects were sanitized [...] Read more.
The present study investigated the efficacy of edible coatings formulated with gellan gum and lemon peel extract (LPE) in preserving the postharvest quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). Selected fruits exhibiting uniform ripeness and free from defects were sanitized and coated with solutions containing different HAG/LAG (high- and low-acyl gellan gum) ratios, incorporating 4.0% (w/v) LPE. Physicochemical and physiological parameters, including soluble solids content, weight loss, pH, titratable acidity, oxygen consumption, carbon dioxide and ethylene production, skin redness (a*/b* ratio), and decay incidence, were systematically assessed under storage conditions of 25 °C and 70% relative humidity. HAG-coated fruits showed the lowest weight loss (1.08%), higher soluble solids (7.11 °Brix), and greater firmness (3.11 N/mm2) compared to uncoated controls. Moreover, they exhibited reduced oxygen consumption (0.06 mg·kg−1·h−1), ethylene production (3.10 mg·kg−1·h−1), and decay rate (2%). Redness was better preserved, and decay rates were substantially (p < 0.05) reduced throughout the storage period. These findings highlight the potential of HAG-based edible coatings enriched with LPE as an innovative postharvest technology to extend shelf life, maintain quality attributes, and reduce postharvest losses in cherry tomatoes. Full article
(This article belongs to the Section Coatings for Food Technology and System)
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15 pages, 5168 KiB  
Article
Effects of Pulse Ion Source Arc Voltage on the Structure and Friction Properties of Ta-C Thin Films on NBR Surface
by Sen Feng, Wenzhuang Lu, Fei Guo, Can Wang and Liang Zou
Coatings 2025, 15(7), 809; https://doi.org/10.3390/coatings15070809 - 10 Jul 2025
Viewed by 193
Abstract
Nitrile rubber (NBR) is prone to adhesion and hysteresis deformation when in contact with hard materials, leading to wear failure. To mitigate this issue, the deposition of diamond-like carbon (DLC) films onto the rubber surface is a commonly employed method. By utilizing pulsed [...] Read more.
Nitrile rubber (NBR) is prone to adhesion and hysteresis deformation when in contact with hard materials, leading to wear failure. To mitigate this issue, the deposition of diamond-like carbon (DLC) films onto the rubber surface is a commonly employed method. By utilizing pulsed arc ion plating technology and adjusting the arc voltage of the pulsed arc ion source, tetrahedral amorphous carbon (ta-C) films with varying sp3 content were prepared on the surface of NBR. The effects of arc voltage on the structural composition and friction performance of NBR/ta-C materials were examined. A scanning electron microscopy analysis revealed that the ta-C film applied to the surface of NBR was uniform and dense, exhibiting typical network crack characteristics. The results of Raman spectroscopy and X-ray photoelectron spectroscopy indicated that as the arc voltage increased, the sp3 content in the film initially rose before declining, reaching a maximum of 72.28% at 300 V. Mechanical tests demonstrated that the bonding strength and friction performance of the film are primarily influenced by the percentage of sp3 content. Notably, the ta-C film with lower sp3 content demonstrates enhanced wear resistance. At 200 V, the sp3 content of the film is 58.16%, resulting in optimal friction performance characterized by a stable friction coefficient of 0.38 and minimal wear weight loss. This performance is attributed to the protective qualities of the ta-C film and the formation of a graphitized transfer film. These results provide valuable insights for the design and development of wear-resistant rubber materials. Full article
(This article belongs to the Section Thin Films)
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14 pages, 3012 KiB  
Article
Deep Learning-Based Automated Detection of Welding Defects in Pressure Pipeline Radiograph
by Wenpin Zhang, Wangwang Liu, Xinghua Yu, Dugang Kang, Zhi Xiong, Xiao Lv, Song Huang and Yan Li
Coatings 2025, 15(7), 808; https://doi.org/10.3390/coatings15070808 - 10 Jul 2025
Viewed by 220
Abstract
This study applies deep learning-based object detection technology to defect detection in weld radiographs, proposing a technical solution for accurately identifying the types and locations of defects in weld X-ray radiographs. The research encompasses the construction of a defect dataset, the design of [...] Read more.
This study applies deep learning-based object detection technology to defect detection in weld radiographs, proposing a technical solution for accurately identifying the types and locations of defects in weld X-ray radiographs. The research encompasses the construction of a defect dataset, the design of a multi-model object detection network, and the development of an automated film evaluation algorithm. This technology significantly enhances the efficiency and accuracy of detecting and identifying harmful defects on weld radiographs, providing critical technical support for ensuring the safe operation and efficient maintenance of pipelines of pressure equipment. Full article
(This article belongs to the Special Issue Advances in Protective Coatings for Metallic Surfaces)
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20 pages, 1363 KiB  
Article
A Three-Dimensional Optimization Framework for Asphalt Mixture Design: Balancing Skeleton Stability, Segregation Control, and Mechanical Strength
by Jinfei Su, Linhao Fan, Lei Zhang, Shenduo Hu, Jicong Xu, Guanxian Li and Shihao Dong
Coatings 2025, 15(7), 807; https://doi.org/10.3390/coatings15070807 - 9 Jul 2025
Viewed by 235
Abstract
The composition design of asphalt mixtures plays a pivotal role in determining pavement performance and durability. To improve skeleton stability, paving uniformity, and mechanical strength, this research proposes a three-dimensional optimization framework for asphalt mixture design, focusing on aggregate gradation and optimum asphalt [...] Read more.
The composition design of asphalt mixtures plays a pivotal role in determining pavement performance and durability. To improve skeleton stability, paving uniformity, and mechanical strength, this research proposes a three-dimensional optimization framework for asphalt mixture design, focusing on aggregate gradation and optimum asphalt content. A skeleton-dense and anti-segregation gradation optimization method was developed by integrating a previously established skeleton-dense model with a segregation tendency prediction approach. In parallel, a mechanically driven method for determining optimum asphalt content was proposed by introducing the maximum migration shear stress as a performance-based alternative to the conventional Marshall stability parameter. Research results show that asphalt mixtures designed and compacted with the optimized gradation exhibit significantly enhanced high-temperature stability, while maintaining satisfactory low-temperature cracking resistance and moisture susceptibility. Field validation was conducted through the construction of a trial pavement section using the optimized gradation under recommended mixing and compaction temperatures. The resulting pavement demonstrated excellent compaction, strong resistance to segregation, and a highly stable spatial structure. These findings confirm the effectiveness of the proposed methodology in enhancing the high-temperature deformation resistance and overall structural integrity of asphalt mixtures. Full article
(This article belongs to the Special Issue Surface and Interface Characteristics of Pavements: New Perspectives and Applications)
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26 pages, 3081 KiB  
Article
Numerical Evaluation of Modified Mortar Coatings for Thermal Protection of Reinforced Concrete and Steel Structures Under Standardized Fire Exposure
by Fabrício Longhi Bolina, Arthur S. Henn, Débora Bretas Silva and Eduardo Cesar Pachla
Coatings 2025, 15(7), 806; https://doi.org/10.3390/coatings15070806 - 9 Jul 2025
Viewed by 170
Abstract
This study investigates the thermal performance of 23 different mortar types, each containing different mixes, properties, and additives. A comprehensive literature review was conducted to collect experimental data on the thermal properties of these mortars, which were then used in a numerical analysis [...] Read more.
This study investigates the thermal performance of 23 different mortar types, each containing different mixes, properties, and additives. A comprehensive literature review was conducted to collect experimental data on the thermal properties of these mortars, which were then used in a numerical analysis through thermal finite element modeling. The results showed that all mortar types contributed to reducing the internal temperature of structural steel and reinforced concrete elements, with performance primarily influenced by key factors such as the mortar’s thermal conductivity, specific heat capacity, thermal diffusivity, and coating thickness. In particular, the mortar with glass fiber reinforced polymer (GFRP) as a slag substitute and the mortar with expanded perlite replacing sand showed the highest thermal protection and achieved a temperature reduction on the order of 100%. In contrast, mortars containing 30% vermiculite or 15% light expanded polyvinyl chloride (PVC) as a sand substitute showed the lowest thermal performance. Full article
(This article belongs to the Special Issue Surface Treatments and Coatings for Asphalt and Concrete)
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20 pages, 4718 KiB  
Article
Shear Performance of New-to-Old Concrete Under Different Interface Treatments
by Shoukun Shi, Da Wang, Zhiyun Li, Yan Jiang, Jinchao Yue and Yibin Huang
Coatings 2025, 15(7), 805; https://doi.org/10.3390/coatings15070805 - 9 Jul 2025
Viewed by 220
Abstract
In shield tunneling, ensuring bonding performance at new-to-old concrete interfaces between segments and linings is crucial for composite lining stability. While extensive research exists on the mechanical bonding behavior of such interfaces, comparative studies on two prevalent treatment methods—scabbling and grooving—remain limited. This [...] Read more.
In shield tunneling, ensuring bonding performance at new-to-old concrete interfaces between segments and linings is crucial for composite lining stability. While extensive research exists on the mechanical bonding behavior of such interfaces, comparative studies on two prevalent treatment methods—scabbling and grooving—remain limited. This study systematically evaluates these techniques’ effects on interfacial bonding via direct shear tests, benchmarking against smooth-interface specimens. Complementary cohesive zone modeling simulations further analyze stress distribution and damage evolution during shear failure. The results demonstrate that scabbled specimens exhibit 10.5%~18.2% higher shear strength than grooved counterparts under increasing normal stress, with both treatments significantly enhancing load–transfer synergy through mechanical interlocking. Furthermore, the energy-based bilinear cohesive model accurately predicts full-interface behavior, providing practical guidance for interface treatment selection in tunneling engineering. Full article
(This article belongs to the Special Issue Innovative Coatings for Enhancing the Corrosion Resistance and Durability of Reinforced Concrete Structures)
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16 pages, 13999 KiB  
Article
The Influence of Ni Incorporation on the Surface Porosity and Corrosion Resistance of CrBN Coatings on 45 Steel in Seawater
by Zhidong Zhou, Xue Wu, Qianzhi Wang, Gai Zhao and Zhifeng Zhou
Coatings 2025, 15(7), 804; https://doi.org/10.3390/coatings15070804 - 9 Jul 2025
Viewed by 222
Abstract
By adjusting NiCr target power, five CrNiBN coatings with different Ni contents were fabricated on 45 steel by magnetron sputtering with the aim of improving corrosion resistance of CrBN coatings in seawater. The structure and morphology of CrNiBN coatings were characterized by X-ray [...] Read more.
By adjusting NiCr target power, five CrNiBN coatings with different Ni contents were fabricated on 45 steel by magnetron sputtering with the aim of improving corrosion resistance of CrBN coatings in seawater. The structure and morphology of CrNiBN coatings were characterized by X-ray diffraction and scanning electron microscope, while its electrochemical properties were evaluated by open circuit potential, electrochemical impedance spectroscopy, and potential dynamic polarization. The results demonstrated that Ni incorporation could reduce the surface porosity of CrBN coatings from 16.8% to 7.7% as Ni content increased from 4.35 at% to 19.62 at%. On this basis, when Ni increased from 4.35 at% to 7.28 at%, self-corrosion potential gradually increased, which prompted the CrNiBN coating with 7.28 at% Ni to present the highest charge transfer resistance Rct of 1.965 × 104 Ω·cm2 and the highest polarization resistance Rp of 74.9 kΩ·cm2. However, more Ni doping from 12.54 at% to 19.62 at% would decrease self-corrosion potential and trigger oxidation. Consequently, the CrNiBN coatings with Ni content from 12.54 at% to 19.62 at% presented decreasing Rct and Rp. Even so, the corrosion resistance of the CrNiBN coating was still better than that of CrBN coating indicating an improved corrosion inhibition efficiency by 12.53 times. Full article
(This article belongs to the Special Issue Tribological and Corrosion Characterisation in Advanced Materials and Coatings)
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13 pages, 2285 KiB  
Article
Effect of Buffer Layer Type on the Mechanical Properties and Corrosion Resistance of Magnetron Sputtered Cr Coatings on 7050 Al Alloy
by Yang Ding, Tao He, Xiangyang Du, Alexey Vereschaka, Catherine Sotova, Kang Chen, Jian Li, Yuqi Wang and Peiyu He
Coatings 2025, 15(7), 803; https://doi.org/10.3390/coatings15070803 - 9 Jul 2025
Viewed by 196
Abstract
Limited hardness and corrosion resistance restrict 7050 aluminum alloys in aggressive environments. Cr coatings, applied as single layers or over Ti, Al, or Ni buffer layers, were deposited onto 7050 aluminum alloy by direct-current magnetron sputtering; their microstructure, adhesion, mechanical properties, and corrosion [...] Read more.
Limited hardness and corrosion resistance restrict 7050 aluminum alloys in aggressive environments. Cr coatings, applied as single layers or over Ti, Al, or Ni buffer layers, were deposited onto 7050 aluminum alloy by direct-current magnetron sputtering; their microstructure, adhesion, mechanical properties, and corrosion behavior were examined. The results indicate that introducing a buffer layer significantly enhances the bonding strength between a Cr coating and an aluminum alloy substrate, with the Ni buffer layer exhibiting the highest bonding strength, nearly three times that of the Cr coating alone. Furthermore, the buffer layer influences the mechanical properties of the Cr coatings, with Ni/Cr and Al/Cr coatings demonstrating increased hardness and elastic modulus. The Ni/Cr coating achieved the highest values of 3.95 GPa and 62.09 GPa, respectively. Regarding corrosion performance, The Cr coatings containing buffer layers showed markedly better corrosion resistance than the bare 7050 Al alloy. A compact Cr2O3 passive film formed on their surfaces, cutting the corrosion current density by roughly two orders of magnitude. Among all samples, the Ti/Cr coating performed best, registering the lowest current density (1.687 × 10−6 A cm−2) and the highest charge-transfer resistance (6090 Ω cm2). Full article
(This article belongs to the Special Issue Advanced Surface Engineering of Alloys: Coatings and Thin Films)
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18 pages, 3853 KiB  
Article
Investigation on the Deviation and Thermal Damage Effects in Laser-Induced Lateral Crack Propagation of Soda–Lime Glass
by Huaye Kong, Xijing Zhu, Yao Liu, Dekang Zhang and Xingqi Du
Coatings 2025, 15(7), 802; https://doi.org/10.3390/coatings15070802 - 9 Jul 2025
Viewed by 255
Abstract
This study is based on the laser-induced thermal-crack propagation (LITP) technology, focusing on the issues of deviation and thermal damage during the transverse crack propagation process, with the aim of achieving high-purity, non-destructive, and high-precision cutting of glass. A 50 W, 1064 nm [...] Read more.
This study is based on the laser-induced thermal-crack propagation (LITP) technology, focusing on the issues of deviation and thermal damage during the transverse crack propagation process, with the aim of achieving high-purity, non-destructive, and high-precision cutting of glass. A 50 W, 1064 nm fiber laser is used for S-pattern scanning cutting of soda–lime glass. A moving heat source model is established and analyzed via MATLAB R2022a numerical simulation. Combined with the ABAQUS 2019 software, the relationships among temperature field, stress field, crack propagation, and deviation during laser-induced thermal crack cutting are deeply explored. Meanwhile, laser thermal fracture experiments are also carried out. A confocal microscope detects glass surface morphology, cross-sectional roughness and hardness under different heat flux densities (HFLs), determining the heat flux density threshold affecting the glass surface quality. Through a comprehensive study of theory, simulation, and experiments, it is found that with an increase in the HFL value of the material, the laser-induced thermal crack propagation can be divided into four stages. When the heat flux density value is in the range of 47.2 to 472 W/m2, the glass substrate has good cross-sectional characteristics. There is no ablation phenomenon, and the surface roughness of the cross-section is lower than 0.15 mm. The hardness decreases by 9.19% compared with the reference value. Full article
(This article belongs to the Special Issue Laser Additive Manufacturing: Materials, Technologies, and Applications)
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23 pages, 5228 KiB  
Article
From Conventional to Electrified Pavements: A Structural Modeling Approach for Spanish Roads
by Gustavo Boada-Parra, Ronny Romero, Federico Gulisano, Freddy Apaza-Apaza, Damaris Cubilla, Andrea Serpi, Rafael Jurado-Piña and Juan Gallego
Coatings 2025, 15(7), 801; https://doi.org/10.3390/coatings15070801 - 9 Jul 2025
Viewed by 239
Abstract
The accelerated growth of the transport sector has increased oil consumption and greenhouse gas (GHG) emissions, intensifying global environmental challenges. The electrification of transportation has emerged as a key strategy to achieve sustainability targets, with electric vehicles (EVs) expected to account for 50% [...] Read more.
The accelerated growth of the transport sector has increased oil consumption and greenhouse gas (GHG) emissions, intensifying global environmental challenges. The electrification of transportation has emerged as a key strategy to achieve sustainability targets, with electric vehicles (EVs) expected to account for 50% of global car sales by 2035. However, widespread adoption requires smart infrastructure capable of enabling dynamic in-motion charging. In this context, Electric Road Systems (ERSs), particularly those based on Wireless Power Transfer (WPT) technologies, offer a promising solution by transferring energy between road-embedded transmitters and vehicle-mounted receivers. This study assesses the structural response and service life of conventional and electrified asphalt pavement sections representative of the Spanish road network. Several standard pavement configurations were analyzed under heavy traffic (dual axles, 13 tons) using a hybrid approach combining mechanistic–empirical multilayer modeling and three-dimensional Finite Element Method (FEM) simulations. The electrified designs integrate prefabricated charging units (CUs) placed at a 9 cm depth, disrupting the structural continuity of the pavement. The results reveal stress concentrations at the CU–asphalt interface and service life reductions of up to 50% in semiflexible pavements. Semirigid sections performed better, with average reductions close to 40%. These findings are based on numerical simulations of standard Spanish sections and do not include experimental validation. Full article
(This article belongs to the Special Issue Recent Research in Asphalt and Pavement Materials)
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17 pages, 4520 KiB  
Article
An Analysis of the Tribological and Thermal Performance of PVDF Gears in Correlation with Wear Mechanisms and Failure Modes Under Different Load Conditions
by Enis Muratović, Adis J. Muminović, Łukasz Gierz, Ilyas Smailov, Maciej Sydor and Muamer Delić
Coatings 2025, 15(7), 800; https://doi.org/10.3390/coatings15070800 - 9 Jul 2025
Viewed by 274
Abstract
With engineering plastics increasingly replacing traditional materials in various drive and control gear systems across numerous industrial sectors, material selection for any gearwheel critically impacts its mechanical and thermal properties. This paper investigates the engagement of steel and Polyvinylidene Fluoride (PVDF) gear pairs [...] Read more.
With engineering plastics increasingly replacing traditional materials in various drive and control gear systems across numerous industrial sectors, material selection for any gearwheel critically impacts its mechanical and thermal properties. This paper investigates the engagement of steel and Polyvinylidene Fluoride (PVDF) gear pairs tested under several load conditions to determine polymer gears’ characteristic service life and failure modes. Furthermore, recognizing that the application of polymer gears is limited by insufficient data on their temperature-dependent mechanical properties, this study establishes a correlation between the tribological contact, meshing temperatures, and wear coefficients of PVDF gears. The results demonstrate that the flank surface wear of the PVDF gears is directly proportional to the temperature and load level of the tested gears. Several distinct load-induced failure modes have been detected and categorized into three groups: abrasive wear resulting from the hardness disparity between the engaging surfaces, thermal failure caused by heat accumulation at higher load levels, and tooth fracture occurring due to stiffness changes induced by the compromised tooth cross-section after numerous operating cycles at a specific wear rate. Full article
(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)
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18 pages, 12442 KiB  
Article
Properties of Diamond-like Coatings in Tribological Systems Lubricated with Ionic Liquid
by Krystyna Radoń-Kobus and Monika Madej
Coatings 2025, 15(7), 799; https://doi.org/10.3390/coatings15070799 - 8 Jul 2025
Viewed by 259
Abstract
The paper shows the effect of using a lubricant in the form of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), on the tribological properties of a hydrogenated diamond-like coating (DLC) doped with tungsten a-C:H:W. The coatings were deposited on 100Cr6 steel by [...] Read more.
The paper shows the effect of using a lubricant in the form of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), on the tribological properties of a hydrogenated diamond-like coating (DLC) doped with tungsten a-C:H:W. The coatings were deposited on 100Cr6 steel by plasma-enhanced chemical vapor deposition PECVD. Tribological tests were carried out on a TRB3 tribometer in a rotary motion in a ball–disc combination. 100Cr6 steel balls were used as a counter-sample. Friction and wear tests were carried out for discs made of 100Cr6 steel and 100Cr6 steel discs with a DLC coating. They were performed under friction conditions with and without lubrication under 10 N and 15 N loads. The ionic liquid BMIM-PF6 was used as a lubricant. Coating thickness was observed on a scanning microscope, and the linear analysis of chemical composition on the cross-section was analyzed using the EDS analyzer. The confocal microscope with an interferometric mode was used for analysis of the geometric structure of the surface before and after the tribological tests. The contact angle of the samples for distilled water, diiodomethane and ionic liquid was tested on an optical tensiometer. The test results showed good cooperation of the DLC coating with the lubricant. It lowered the coefficient of friction in comparison to steel about 20%. This indicates the synergistic nature of the interaction: DLC coating–BMIM-PF6 lubricant–100Cr6 steel. Full article
(This article belongs to the Special Issue Tribological and Mechanical Properties of Coatings)
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17 pages, 1027 KiB  
Review
Photon Detector Technology for Laser Ranging: A Review of Recent Developments
by Zhihui Li, Xin Jin, Changfu Yuan and Kai Wang
Coatings 2025, 15(7), 798; https://doi.org/10.3390/coatings15070798 - 8 Jul 2025
Viewed by 319
Abstract
Laser ranging technology holds a key position in the military, aerospace, and industrial fields due to its high precision and non-contact measurement characteristics. As a core component, the performance of the photon detector directly determines the ranging accuracy and range. This paper systematically [...] Read more.
Laser ranging technology holds a key position in the military, aerospace, and industrial fields due to its high precision and non-contact measurement characteristics. As a core component, the performance of the photon detector directly determines the ranging accuracy and range. This paper systematically reviews the technological development of photonic detectors for laser ranging, with a focus on analyzing the working principles and performance differences of traditional photodiodes [PN (P-N junction photodiode), PIN (P-intrinsic-N photodiode), and APD (avalanche photodiode)] (such as the high-frequency response characteristics of PIN and the internal gain mechanism of APD), as well as their applications in short- and medium-range scenarios. Additionally, this paper discusses the unique advantages of special structures such as transmitting junction-type and Schottky-type detectors in applications like ultraviolet light detection. This article focuses on photon counting technology, reviewing the technological evolution of photomultiplier tubes (PMTs), single-photon avalanche diodes (SPADs), and superconducting nanowire single-photon detectors (SNSPDs). PMT achieves single-photon detection based on the external photoelectric effect but is limited by volume and anti-interference capability. SPAD achieves sub-decimeter accuracy in 100 km lidars through Geiger mode avalanche doubling, but it faces challenges in dark counting and temperature control. SNSPD, relying on the characteristics of superconducting materials, achieves a detection efficiency of 95% and a dark count rate of less than 1 cps in the 1550 nm band. It has been successfully applied in cutting-edge fields such as 3000 km satellite ranging (with an accuracy of 8 mm) and has broken through the near-infrared bottleneck. This study compares the differences among various detectors in core indicators such as ranging error and spectral response, and looks forward to the future technical paths aimed at improving the resolution of photon numbers and expanding the full-spectrum detection capabilities. It points out that the new generation of detectors represented by SNSPD, through material and process innovations, is promoting laser ranging to leap towards longer distances, higher precision, and wider spectral bands. It has significant application potential in fields such as space debris monitoring. Full article
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1 pages, 123 KiB  
Retraction
RETRACTED: Cui et al. Effects of Cr2O3 Content on Microstructure and Mechanical Properties of Al2O3 Matrix Composites. Coatings 2021, 11, 234
by Kunkun Cui, Yingyi Zhang, Tao Fu, Shahid Hussain, Tahani Saad Algarni, Jie Wang, Xu Zhang and Shafaqat Ali
Coatings 2025, 15(7), 797; https://doi.org/10.3390/coatings15070797 - 8 Jul 2025
Viewed by 161
Abstract
This journal retracts the article titled “Effects of Cr2O3 Content on Microstructure and Mechanical Properties of Al2O3 Matrix Composites” [...] Full article
18 pages, 6590 KiB  
Article
Synthesis of ZnS Nano-Powders and Fabrication of ZnS Thin Films via Electron-Beam Evaporation: Structural and Optical Characterization
by Ahmed Al-Mobydeen, Ehab AlShamaileh, Bashar Lahlouh, Mariam Al-Qderat, Ahmed N. AL-Masri, Wadah Mahmoud, Imad Hamadneh, Muayad Esaifan and Iessa Sabbe Moosa
Coatings 2025, 15(7), 796; https://doi.org/10.3390/coatings15070796 - 7 Jul 2025
Viewed by 333
Abstract
Nanoscale zinc sulfide (ZnS) powders have attracted considerable interest due to their unique properties and diverse applications in various fields, including wastewater treatment, optics, electronics, photocatalysis, and solar systems. In this study, nano-powder ZnS was chemically synthetized starting from Zn powder, diluted HCl, [...] Read more.
Nanoscale zinc sulfide (ZnS) powders have attracted considerable interest due to their unique properties and diverse applications in various fields, including wastewater treatment, optics, electronics, photocatalysis, and solar systems. In this study, nano-powder ZnS was chemically synthetized starting from Zn powder, diluted HCl, and laboratory-prepared Na2S. The obtained ZnS was studied using an SEM coupled with EDS, XRD analysis, UV–Visible spectroscopy, and FTIR techniques. The XRD results showed that the synthesized nanoscale ZnS powder was approximately 2.26 nm. Meanwhile, the EDS and XRD patterns confirmed the high purity of the obtained ZnS powder. In addition, the ZnS powder was compacted and sintered in an argon atmosphere at 400 °C for 8 h to prepare the required pellets for thin-film deposition via E-beam evaporation. The microscopic structure of the sintered pellets was investigated using the SEM/EDS. Furthermore, the optical properties of the deposited thin films were studied using UV–Visible spectroscopy in the wavelength range of 190–1100 nm and the FTIR technique. The bandgap energies of the deposited thin films with thicknesses of 111 nm and 40 nm were determined to be around 4.72 eV and 5.82 eV, respectively. This article offers a facile production route of high-purity ZnS powder, which can be compacted and sintered as a suitable source for thin-film deposition. Full article
(This article belongs to the Special Issue Trends in Coatings and Surface Technology, 2nd Edition)
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20 pages, 2705 KiB  
Article
Temperature and Depth Sensor Based on Fiber Bragg Gratings with Temperature-Compensated Structure in Marine Environment
by Xinyu Zhao, Chenxi Wei, Lina Zeng, Lu Li, Shengjie Liu, Li Sun, Zaijin Li, Hao Chen, Guojun Liu, Yi Qu, Zichun Le, Yingchao Li, Lianhe Li and Lin Li
Coatings 2025, 15(7), 795; https://doi.org/10.3390/coatings15070795 - 6 Jul 2025
Viewed by 374
Abstract
A fiber Bragg grating (FBG)-based ocean temperature and depth sensor structure is proposed. The pressure sensing section employs a secondary sensitization design comprising a piston and the polycarbonate buffer, while the temperature sensing section utilizes an FBG encapsulated within a metal silver tube, [...] Read more.
A fiber Bragg grating (FBG)-based ocean temperature and depth sensor structure is proposed. The pressure sensing section employs a secondary sensitization design comprising a piston and the polycarbonate buffer, while the temperature sensing section utilizes an FBG encapsulated within a metal silver tube, accompanied by a temperature compensation structure. Simulation analyses verify the enhanced sensitivity of the proposed configuration. By selecting suitable materials for the piston, metal tube, and polymer, and optimizing the dimensions of key components, the sensitivity of the bare FBG sensor is significantly improved through the combined effects of the piston, polymer, and metal tube. After optimization, the sensor exhibits a pressure sensitivity of 1.33 nm/MPa and a temperature sensitivity of 102.77 pm/°C, meeting the high-precision detection requirements for ocean temperature and depth sensing. The experimental results show that the temperature sensitivity is 109.9 pm/°C within the temperature range of −5~35 °C, and that the pressure sensitivity is 1.63 nm/MPa within the pressure range of 1~10 MPa. These results confirm that the sensor is well-suited for high-precision ocean temperature and depth measurements. Full article
(This article belongs to the Section Laser Coatings)
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31 pages, 6707 KiB  
Review
A Comprehensive Review of Hot In-Place Recycling Technology: Classification, Factors Affecting Performance of Asphalt Mixtures, and Benefits Analysis
by Chengwei Xing, Haozongyang Li, Zhibin Chang, Huailei Cheng, Hengji Zhang, Shixian Tang and Bohan Zhu
Coatings 2025, 15(7), 794; https://doi.org/10.3390/coatings15070794 - 6 Jul 2025
Viewed by 327
Abstract
The application of hot in-place recycling asphalt mixtures (HIRAMs) is gaining increasing attention in highway maintenance due to its environmental and economic benefits. This paper comprehensively reviews and discusses the state-of-the-art studies in the field of hot in-place recycling (HIR). Firstly, different HIR [...] Read more.
The application of hot in-place recycling asphalt mixtures (HIRAMs) is gaining increasing attention in highway maintenance due to its environmental and economic benefits. This paper comprehensively reviews and discusses the state-of-the-art studies in the field of hot in-place recycling (HIR). Firstly, different HIR technologies are introduced, including surface recycling, remixing, and repaving. Then, this paper provides a detailed description of the key factors influencing the road performance of HIRAMs in terms of both materials and production, such as reclaimed asphalt pavement (RAP), rejuvenators, virgin asphalt, virgin asphalt mixtures, preheating temperature, and mixing time. Furthermore, the environmental and economic benefits of HIR are compared with other preventative maintenance and recycling technologies. Finally, some challenges for the investigation of HIR are further discussed, and the corresponding suggestions are recommended for future investigation. Full article
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17 pages, 11614 KiB  
Article
Influence of Si Content on the Microstructure and Properties of Hydrogenated Amorphous Carbon Films Deposited by Magnetron Sputtering Technique
by Zhen Yu, Jiale Shang, Qingye Wang, Haoxiang Zheng, Haijuan Mei, Dongcai Zhao, Xingguang Liu, Jicheng Ding and Jun Zheng
Coatings 2025, 15(7), 793; https://doi.org/10.3390/coatings15070793 - 6 Jul 2025
Viewed by 292
Abstract
Hydrogenated amorphous carbon (a-C:H) films are widely valued for their excellent mechanical strength and low friction, but their performance significantly degrades at elevated temperatures, limiting practical applications in aerospace environments. In this work, we aimed to enhance the high-temperature tribological behavior of a-C:H [...] Read more.
Hydrogenated amorphous carbon (a-C:H) films are widely valued for their excellent mechanical strength and low friction, but their performance significantly degrades at elevated temperatures, limiting practical applications in aerospace environments. In this work, we aimed to enhance the high-temperature tribological behavior of a-C:H films through controlled silicon (Si) doping. A series of a-C:H:Si films with varying Si contents were fabricated via direct current magnetron sputtering, and their microstructure, mechanical properties, and friction behavior were systematically evaluated from room temperature up to 400 °C. Results show that moderate Si doping (8.3 at.%) substantially enhances hardness and wear resistance, while enabling ultralow friction (as low as 0.0034) at 400 °C. This superior performance is attributed to the synergistic effects of transfer layer formation, preferential Si oxidation, and tribo-induced graphitization. This study provides new insights into the high-temperature lubrication mechanisms of Si-doped a-C:H films and demonstrates the critical role of Si content optimization, highlighting a viable strategy for extending the thermal stability and lifespan of solid-lubricating films. Full article
(This article belongs to the Special Issue Sputtering Deposition for Advanced Materials and Interfaces)
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