Coatings

8 pages, 203 KiB

Open AccessCommunication

Coating Quail Eggs with a Bioactive Solution of Corn Starch and Green Propolis Extract

by Gabriel da Silva Oliveira, Igor Rafael Ribeiro Vale, Luana Maria de Jesus, Janaína Dourado Barbosa, Heloisa Alves de Figueiredo Sousa, Concepta McManus, Paula Gabriela da Silva Pires and Vinícius Machado dos Santos

Coatings 2025, 15(5), 573; https://doi.org/10.3390/coatings15050573 (registering DOI) - 10 May 2025

Abstract

Quail eggs are foods that can suffer significant losses in internal quality 14 days after laying and onwards. With the aim of minimizing early quality losses, this study investigated the effect of the combined use of corn starch and green propolis extract (CS+GPE) [...] Read more.

Quail eggs are foods that can suffer significant losses in internal quality 14 days after laying and onwards. With the aim of minimizing early quality losses, this study investigated the effect of the combined use of corn starch and green propolis extract (CS+GPE) on the internal quality attributes of quail eggs, as well as on the bacterial level of their eggshells during storage at room temperature. The Haugh unit remained above 80.00 in eggs coated with CS+GPE at 21 days of storage, which was significantly greater than that of the eggs from the control treatment. On that same day, the bacterial load in the eggshell of the eggs coated with CS+GPE was 34.74% lower than that in eggs from the control treatment. The synergistic use of CS+GPE represents a strategy for preserving quail eggs using bioactive, green, and biodegradable materials. Full article

(This article belongs to the Section Coatings for Food Technology and System)

14 pages, 5368 KiB

Open AccessArticle

Impact of Scanning Speed on Microstructure and Mechanical and Thermal Expansion Properties of Fe-36Ni Alloy Fabricated by Selective Laser Melting

by Zijian Yang, Zhihao Feng, Yufei Di, Tianyu Wang, Kaimin Wei, Zhe Zhang, Junqi Ge, Jiangang Wang, Mingqiang Fan and Jianhui Li

Coatings 2025, 15(5), 572; https://doi.org/10.3390/coatings15050572 (registering DOI) - 10 May 2025

Abstract

The Fe-36Ni alloy, with ultra-low thermal expansion and stable properties, is essential for aerospace remote sensors and aircraft load-bearing structures, widely used in aerospace. Additive Manufacturing, an emerging rapid prototyping technology with short cycles, high efficiency, and flexibility, addresses complex structural fabrication challenges. [...] Read more.

The Fe-36Ni alloy, with ultra-low thermal expansion and stable properties, is essential for aerospace remote sensors and aircraft load-bearing structures, widely used in aerospace. Additive Manufacturing, an emerging rapid prototyping technology with short cycles, high efficiency, and flexibility, addresses complex structural fabrication challenges. While selective laser melting (SLM) enables complex geometry fabrication, post-process treatments (e.g., annealing-induced homogenization, thermal aging for stress relief, surface polishing) remain critical for attaining metallurgical stability in as-built components. The impact of different laser scanning speeds (500 mm/s, 1000 mm/s, 1500 mm/s, 2000 mm/s) on the microstructure and mechanical and thermal expansion properties of the Fe-36Ni alloy fabricated by selective laser melting was studied. The results indicate that all Fe-36Ni alloys predominantly exhibit the γ-phase. Interestingly, a small amount of α precipitates was also observed, which is primarily attributed to the formation of a supercooled region. Notably, at a scanning speed of 1000 mm/s, the Fe-36Ni alloy samples exhibit optimal mechanical properties, with a tensile strength of 439 MPa and an elongation of 49.0%. This improvement is primarily attributed to the enhanced molding quality and grain refinement. The minimum coefficient of thermal expansion occurs at a scanning speed of 2000 mm/s, likely due to the elevated defect density. Full article

(This article belongs to the Special Issue Laser Surface Engineering: Technologies and Applications)

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19 pages, 8676 KiB

Open AccessArticle

Simulation of Internal Environmental Conditions Within Rock Wool Insulation: Implications for Corrosion Under Insulation in Piping Systems

by Jiangshun Wu, Wenchao Li, Feifei Huang, Hongbo Zhang, Bo Zhang, Fuhai Liu and Ying Jin

Coatings 2025, 15(5), 571; https://doi.org/10.3390/coatings15050571 (registering DOI) - 10 May 2025

Abstract

Rock wool is widely used in industrial piping systems for its excellent thermal insulation properties, but its porous structure allows water infiltration that can lead to corrosion under insulation (CUI) on metal pipe surfaces. In order to investigate how water infiltration into the [...] Read more.

Rock wool is widely used in industrial piping systems for its excellent thermal insulation properties, but its porous structure allows water infiltration that can lead to corrosion under insulation (CUI) on metal pipe surfaces. In order to investigate how water infiltration into the insulated pipeline system creates a corrosive environment, a study on the flow behavior of fluids in porous media was conducted. Experiments were performed to measure the flow velocity and pressure drop along three principal directions—axial, radial, and circumferential. These measurements enabled the derivation of specific viscous and inertial resistance coefficients, which characterize the flow through the rock wool structure. The results indicated that the flow parameters of rock wool change over time and with repeated use, particularly after dry–wet cycles. The experimentally derived parameters were incorporated into both small-scale and large-scale three-dimensional computational fluid dynamics (CFD) models to simulate water transport within the rock wool insulation layer. Validation experiments performed on a real rock wool-insulated pipeline system confirmed the predictive accuracy of the CFD simulations in capturing water movement through the insulation. The large-scale model further analyzed the influence of inlet velocity, rock wool aging, and pipeline inclination on the development of environmental conditions for CUI. Full article

(This article belongs to the Special Issue Alloy/Metal/Steel Surface: Fabrication, Structure, Friction and Service Life)

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15 pages, 1998 KiB

Open AccessArticle

DFT-Based Investigation of Pd-Modified WO₃/Porous Silicon Composites for NO₂ Gas Sensors: Enhanced Synergistic Effect and High-Performance Sensing

by Xiaoyong Qiang, Zhipeng Wang, Yongliang Guo and Weibin Zhou

Coatings 2025, 15(5), 570; https://doi.org/10.3390/coatings15050570 - 9 May 2025

Abstract

Pd-WO₃ coatings on porous silicon (PSi) substrates are engineered to enhance interfacial charge transfer and surface reactivity through atomic-scale structural tailoring. This study combines first-principles calculations and experimental characterization to elucidate how Pd nanoparticles (NPs) optimize the coating’s electronic structure and environmental [...] Read more.

Pd-WO₃ coatings on porous silicon (PSi) substrates are engineered to enhance interfacial charge transfer and surface reactivity through atomic-scale structural tailoring. This study combines first-principles calculations and experimental characterization to elucidate how Pd nanoparticles (NPs) optimize the coating’s electronic structure and environmental stability. The hierarchical PSi framework with uniform nanopores (200–500 nm) serves as a robust substrate for WO₃ nanorod growth (50–100 nm diameter), while Pd decoration (15%–20% surface coverage) strengthens Pd–O–W interfacial bonds, amplifying electron density at the Fermi level by 2.22-fold. Systematic computational analysis reveals that Pd-induced d-p orbital hybridization near the Fermi level (−2 to +1 eV) enhances charge delocalization, optimizing interfacial charge transfer. Experimentally, these modifications enhance the coating’s response to environmental degradation, showing less than 3% performance decay over 30 days under cyclic humidity (45 ± 3% RH). Although designed for gas sensing, the coating’s high surface-to-volume ratio and delocalized charge transport channels demonstrate broader applicability in catalytic and high-stress environments. This work provides a paradigm for designing multifunctional coatings through synergistic interface engineering. Full article

15 pages, 13589 KiB

Open AccessArticle

Fabrication and Mechanism Investigation of High-Porosity Micro-Arc Oxidation Functional Coating on Aluminum Foam Substrate

by Xianyin Chen, Tao Li, Yu Zhu, Mengzhen Tian and Tiantian Jia

Coatings 2025, 15(5), 569; https://doi.org/10.3390/coatings15050569 - 9 May 2025

Abstract

A high-porosity micro-arc oxidation (MAO) functional coating was fabricated on aluminum foam substrate through micro-arc oxidation technology, developing a structurally and functionally integrated bulk catalyst support material. Orthogonal experiments were employed to determine the optimal electrical parameters for achieving maximum coating porosity, with [...] Read more.

A high-porosity micro-arc oxidation (MAO) functional coating was fabricated on aluminum foam substrate through micro-arc oxidation technology, developing a structurally and functionally integrated bulk catalyst support material. Orthogonal experiments were employed to determine the optimal electrical parameters for achieving maximum coating porosity, with systematic investigations into the effects of electrolyte temperature and sodium tetraborate additives on pore characteristics. The phase composition, surface morphology, and elemental distribution of the porous coating were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Mercury intrusion porosimetry was applied to quantify the total pore area and pore size distribution. By means of secondary micro-arc oxidation, the catalyst was distributed in a gradient on the coating cross-section, which greatly improved the utilization rate of the catalyst. The formation mechanism of the porous coating was discussed, and the specific surface area of the fabricated catalyst-loaded materials was as high as (1.4~6.3) × 10⁴ m²/m³, which provided a large number of attachment sites for catalyst particles. Full article

(This article belongs to the Special Issue Advanced Thin Films, Surface and Interface in Photocatalytic Applications)

11 pages, 4951 KiB

Open AccessArticle

Improvement in the Polarization Fatigue Properties of PbZr_0.50Ti_0.50O₃ Thick Film Using a Ba_0.3Sr_0.7Zr_0.18Ti_0.82O₃ Buffer Layer

by Kefan Wu, Junxi Zhang, Zhiyang Fan and Ping Yu

Coatings 2025, 15(5), 568; https://doi.org/10.3390/coatings15050568 - 9 May 2025

Abstract

The polarization fatigue of PbZr_1−xTi_xO₃ (PZT) films is one of the most serious failure issues in their practical application. In the present work, Ba_0.3Sr_0.7Zr_0.18Ti_0.82O₃ (BSZT) was used as an [...] Read more.

The polarization fatigue of PbZr_1−xTi_xO₃ (PZT) films is one of the most serious failure issues in their practical application. In the present work, Ba_0.3Sr_0.7Zr_0.18Ti_0.82O₃ (BSZT) was used as an inserting layer to improve the polarization fatigue of PbZr_0.50Ti_0.50O₃ thick film. PZT thick films and BSZT layers were deposited via magnetron sputtering technology. The effects of BSZT layer on the dielectric response, remanent polarization, and fatigue resistance of PZT thick films were investigated experimentally. The results showed that the dielectric constant increased from 457 to 880 (1 MHz), and the reversible/irreversible Rayleigh coefficients were also enhanced. The remanent polarization P_r of the PZT thick films increased from 37 μC/cm² to 42.4 μC/cm². After a 1.08 × 10⁹ cycles polarization fatigue test, the ferroelectric polarization loss was 9% for the PZT thick film at 368 kV/cm. The reversible/irreversible Rayleigh coefficients had a very small decline, of only 5% and 2%, respectively. This demonstrates that, different from the previously reported buffer layers, BSZT buffer layers can simultaneously enhance the dielectric and ferroelectric properties and improve the polarization fatigue of PZT thick films. Full article

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28 pages, 4467 KiB

Open AccessReview

Review of Laser Texturing Technology for Surface Protection and Functional Regulation of Aluminum Alloys: Wettability, Anti-Icing, Corrosion Resistance, and Wear Resistance

by Jinxia Zhou, Jianmei Wu, Shanshan Tang and Yanzhou Li

Coatings 2025, 15(5), 567; https://doi.org/10.3390/coatings15050567 - 9 May 2025

Abstract

Laser surface texturing (LST) is a versatile method for enhancing material surface properties, offering high precision and flexibility for surface modification. This review comprehensively examines the application of laser texturing technology for surface protection and functional regulation of aluminum alloys, focusing on wettability, [...] Read more.

Laser surface texturing (LST) is a versatile method for enhancing material surface properties, offering high precision and flexibility for surface modification. This review comprehensively examines the application of laser texturing technology for surface protection and functional regulation of aluminum alloys, focusing on wettability, anti-icing, corrosion resistance, and wear resistance. It highlights recent progress in laser surface patterning techniques, describing the principles and attributes of methods such as direct laser writing, laser interference patterning, and laser shock treatment. The influence of laser intensity, scanning velocity, and texture spacing on surface topography is discussed thoroughly. Mechanisms of wettability control via laser surface texturing are summarized, emphasizing the key factors required to achieve superhydrophobic or hydrophilic properties through texture design. Advancements in enhancing anti-icing, anti-frost, anti-fouling, and anti-corrosion properties through multi-scale textures and their synergistic effects with functional coatings are analyzed. Additionally, the enhancement of wear resistance and friction performance under both dry and lubricated conditions is reviewed, with a focus on how the geometry and arrangement of textures affect the coefficient of friction and wear rate. Finally, the paper addresses challenges and future directions, including process optimization, scalability, and the integration of LST with advanced coatings to maximize its potential in aluminum alloy applications. Full article

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15 pages, 1857 KiB

Open AccessArticle

Prediction of Surface Roughness in Milling Additively Manufactured High-Strength Maraging Steel Using Broad Learning System

by Cuiling Zhao, Wenwen Tian, Qi Yan and Yuchao Bai

Coatings 2025, 15(5), 566; https://doi.org/10.3390/coatings15050566 - 9 May 2025

Abstract

Additive manufacturing (AM) provides a promising method to fabricate advanced functional parts with different mechanical and material performances from their traditional counterparts. However, the poor surface quality makes the subsequent post-processing necessary for precision application. Hybrid manufacturing combining additive and subtractive manufacturing processes [...] Read more.

Additive manufacturing (AM) provides a promising method to fabricate advanced functional parts with different mechanical and material performances from their traditional counterparts. However, the poor surface quality makes the subsequent post-processing necessary for precision application. Hybrid manufacturing combining additive and subtractive manufacturing processes is an effective method to improve the surface quality of additive manufacturing (AMed) metal parts rapidly by using a subtractive process, in which surface roughness is an important technical indicator. Therefore, accurate surface roughness prediction is crucial for process and quality control in the subtractive machining of additively manufactured parts. In this study, a prediction method utilizing a broad learning system (BLS) is developed to predict the surface roughness of machined AMed maraging steel parts considering aging heat treatment. First, feature extraction was performed on the force signal during the cutting process in the time domain, frequency domain, and time–frequency domain. Then, the maximum information coefficient was used to select important features from high to low feature by feature. Furthermore, the important features and cutting parameters were fused as the input of BLS. Finally, the corresponding prediction results were compared with those based only on cutting parameters. The results show that the prediction accuracy of machined surface roughness is higher when fusing force signal features and cutting parameters. The prediction errors (mean absolute percentage error) were reduced by 67.28% and 16.39% to 0.53% and 0.51%, respectively, for the AMed maraging steels with and without heat treatment. Full article

(This article belongs to the Special Issue Recent Development in Post-processing for Additive Manufacturing)

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29 pages, 6857 KiB

Open AccessArticle

Physicochemical and Preliminary Biological Properties of Thin Films Based on Fluoride-Doped Hydroxyapatite in a Dextran Matrix for Biomedical Applications

by Liliana Ghegoiu, Daniela Predoi, Simona Liliana Iconaru, Carmen Steluta Ciobanu, Krzysztof Rokosz, Steinar Raaen, Monica Luminita Badea and Mihai Valentin Predoi

Coatings 2025, 15(5), 565; https://doi.org/10.3390/coatings15050565 - 9 May 2025

Abstract

A spin-coating technique was used to produce new thin films of fluoride-doped hydroxyapatite (HApF) and fluoride-doped hydroxyapatite in a dextran matrix (HApF-Dx) with the potential to be used as nanocoatings for various biomedical implants. The stability of the suspensions used in obtaining the [...] Read more.

A spin-coating technique was used to produce new thin films of fluoride-doped hydroxyapatite (HApF) and fluoride-doped hydroxyapatite in a dextran matrix (HApF-Dx) with the potential to be used as nanocoatings for various biomedical implants. The stability of the suspensions used in obtaining the thin films was confirmed by ultrasonic measurements with double-distilled water as a reference. The HApF and HApF-Dx thin films obtained by spin-coating showed diffraction patterns corresponding to hexagonal hydroxyapatite. The X-ray photoelectron spectroscopy studies confirmed the partial substitution of hydroxyl groups (-OH) by fluoride ions. The FTIR studies were conducted in order to highlight the presence of the functional group specific for the HAp in the samples and the influence of the dextran addition on the vibrational characteristics. The surface morphologies of the HApF and HApF-Dx thin films were explored using scanning electron microscopy (SEM), atomic force microscopy (AFM), and metallographic microscopy (MM). The surfaces of the HApF and HApF-Dx thin films were found to be smooth, homogenous, and nanostructured. The biocompatibility assays on HGF-1 cells confirmed that both coatings exhibited good cell viability for all the tested time intervals (24 and 48 h). The findings highlighted the potential of HApF and HApF-Dx coatings for biomedical applications. Additional information about the HGF-1 adherence and development on the surface of the HApF and HApF-Dx coatings was obtained using metallographic microscopy, scanning electron microscopy, and atomic force microscopy techniques. This research demonstrates that the spin-coating method can be successfully used to fabricate HApF and HApF-Dx nanocoatings for potential biomedical applications. Full article

(This article belongs to the Special Issue Films and Coatings with Biomedical Applications)

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21 pages, 6803 KiB

Open AccessArticle

Optimized Data Preprocessing and Model Selection for TBM Cutter Wear Prediction

by Liping Bai, Deyun Mo, Hongshu Li, Weiran Huang and Zelun Cai

Coatings 2025, 15(5), 564; https://doi.org/10.3390/coatings15050564 - 9 May 2025

Abstract

The estimation of disc cutter life is important due to the high equipment replacement cost in tunnel boring machines (TBMs). In this paper, we propose a comprehensive method for predicting disc cutter wear, integrating dimensionality reduction in shield tunneling parameters, data input preprocessing, [...] Read more.

The estimation of disc cutter life is important due to the high equipment replacement cost in tunnel boring machines (TBMs). In this paper, we propose a comprehensive method for predicting disc cutter wear, integrating dimensionality reduction in shield tunneling parameters, data input preprocessing, and optimized model selection. First, we select core TBM operation parameters as model inputs through principal component analysis (PCA) and PCA directly. And, then, based on the characteristics of the operation parameters, we propose a data preprocessing method for time series models. This method uses excavation rings as units, providing a more accurate representation of the actual shield excavation process. Furthermore, by evaluating the prediction accuracy, training efficiency, and inference efficiency of various models, we demonstrate that the combined PCA data + Min Max Scaler + gated recurrent unit (GRU) method achieves the most accurate prediction results while offering real-time prediction capabilities. Full article

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13 pages, 7814 KiB

Open AccessArticle

Understanding the Chamber Wall-Deposited Thin Film of Plasma Deposition Equipment for the Efficiency of In Situ Dry-Cleaning

by Jiseok Lee, Jiwon Jang and Sang Jeen Hong

Coatings 2025, 15(5), 563; https://doi.org/10.3390/coatings15050563 - 8 May 2025

Abstract

In plasma-enhanced chemical vapor deposition (PECVD) processes, thin films can accumulate on the inner chamber walls, resulting in particle contamination and process drift. In this study, we investigate the physical and chemical properties of these wall-deposited films to understand their spatial variation and [...] Read more.

In plasma-enhanced chemical vapor deposition (PECVD) processes, thin films can accumulate on the inner chamber walls, resulting in particle contamination and process drift. In this study, we investigate the physical and chemical properties of these wall-deposited films to understand their spatial variation and impact on chamber maintenance. A 6-inch capacitively coupled plasma (CCP)-type PECVD system was used to deposit SiO₂ films, whilst long silicon coupons were attached vertically to the chamber side walls to collect contamination samples. The collected contamination samples were comparatively analyzed in terms of their chemical properties and surface morphology. The results reveal significant differences in hydrogen content and Si–O bonding configurations compared to reference films deposited on wafers. The top chamber wall, located near the plasma region, exhibited higher hydrogen incorporation and larger Si–O–Si bonding angles, while the bottom wall exhibited rougher surfaces with larger particulate agglomerates. These variations were closely linked to differences in gas flow dynamics, precursor distribution, and the energy state of the plasma species at different chamber heights. The findings indicate that top-wall contaminants are more readily cleaned due to their high hydrogen content, while bottom-wall residues may be more persistent and pose higher risks for particle generation. This study provides insights into wall contamination behavior in PECVD systems and suggests strategies for spatially optimized chamber cleaning and conditioning in high-throughput semiconductor processes. Full article

(This article belongs to the Special Issue Advanced Plasma Surface Treatments and Their Applications in Coating Technologies)

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20 pages, 2162 KiB

Open AccessArticle

Evaluation of Pectin-Based Coatings, Olive Leaf Extract, and Chitosan Nanoparticles for Acrylamide and Hydroxymethylfurfural Mitigation in French Fries: A Comparative Study of the Deep Frying and Air Frying Methods

by Asmaa Abu-Thabet, Asmaa Al-Asmar, Mohammed Sabbah, Abdallatif Mayyala and Loredana Mariniello

Coatings 2025, 15(5), 562; https://doi.org/10.3390/coatings15050562 - 8 May 2025

Abstract

This study evaluated the potential of pectin (PEC)-based coatings, enhanced with olive leaf extract (OLE) and chitosan nanoparticles (CH-NPs), to mitigate the formation of harmful compounds during the frying of French fries. The research compared deep fat and hot air frying methods. Initial [...] Read more.

This study evaluated the potential of pectin (PEC)-based coatings, enhanced with olive leaf extract (OLE) and chitosan nanoparticles (CH-NPs), to mitigate the formation of harmful compounds during the frying of French fries. The research compared deep fat and hot air frying methods. Initial characterization of the coating solutions included assessing zeta potential, Z-Average, polydispersity index, and antioxidant capacity. The inclusion of OLE and CH-NPs significantly boosted antioxidant activity, reaching 78.9%, without substantially altering zeta potential or Z-Average characteristics. Notably, hot air frying induced significantly higher levels of acrylamide (ACR) and hydroxymethylfurfural (HMF) compared to deep fat frying. However, the application of the developed coatings demonstrated a marked reduction in both ACR and HMF across both frying techniques. Furthermore, the coatings, particularly PEC with OLE and CH-NPs, effectively decreased oil absorption by 55% while simultaneously increasing moisture content. The sensory evaluation indicated that the panelists liked the deep-fat-fried fries significantly more compared to hot air frying. Deep-fat frying led to an elevated browning index, which was significantly counteracted by the application of the coatings. These findings underscore the importance of informing consumers about the potential for increased ACR and HMF formation during hot air frying, despite its advantages in reducing fat content, to ensure informed dietary choices. Full article

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

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18 pages, 6738 KiB

Open AccessArticle

Development of Zn-Reinforced Mg Matrix Composites via High Energy Ball Milling Duration: Impact on Mechanical Properties and Biodegradability

by S. Bilal Çetinkal, Emin Salur, Gökhan Arıcı, Ahmed Degnah, Sayan Sarkar and Halit Sübütay

Coatings 2025, 15(5), 561; https://doi.org/10.3390/coatings15050561 - 8 May 2025

Abstract

In this study, Zn-reinforced Mg matrix composite materials were produced via powder metallurgy by exposing them to ball milling at varying mechanical milling times. Following ball milling, the powders were cold-pressed under 600 MPa to obtain green compacts. The sintering process was carried [...] Read more.

In this study, Zn-reinforced Mg matrix composite materials were produced via powder metallurgy by exposing them to ball milling at varying mechanical milling times. Following ball milling, the powders were cold-pressed under 600 MPa to obtain green compacts. The sintering process was carried out in a tube furnace under an argon atmosphere at 500 °C for 120 min. The effects of different milling times (2 h, 4 h, and 8 h) on particle and grain size, as well as the influence of sintering temperature and time on the microstructure, were investigated through SEM analysis. Phase evolution and changes in crystal planes occurring after ball milling were revealed by XRD analysis. SEM images show that Zn particles were homogeneously distributed within the matrix after 8 h of milling. Furthermore, it can be clearly stated that the highest hardness values were obtained from the samples produced after 8 h of milling. The sample group with the highest density, least mass loss, and lowest degradation rate was obtained from materials produced from 4 h ball milled powders. The intermetallic phase formed in the powder structure after 8 h of milling tends to reduce density and corrosion properties. The findings reveal that the addition of these alloys to pure Mg clearly enhances its hardness and density, while also imparting superior corrosion resistance. These combined improvements suggest that the developed materials hold strong potential for application in biomedical and clinical environments, where both mechanical strength and corrosion resistance are critical. Full article

(This article belongs to the Special Issue Advanced High Entropy Alloy Materials and Films: Properties and Applications)

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13 pages, 4024 KiB

Open AccessArticle

A Preparation Method for Improving the Thermal Conductivity of Graphene Film

by Xia Zhao and Xin Jia

Coatings 2025, 15(5), 560; https://doi.org/10.3390/coatings15050560 - 8 May 2025

Abstract

Graphene films are widely used in thermal management of electronic devices due to their excellent properties such as high flexibility, high thermal conductivity and light weight. However, in the traditional preparation process, some structural defects are introduced, which will lead to an increase [...] Read more.

Graphene films are widely used in thermal management of electronic devices due to their excellent properties such as high flexibility, high thermal conductivity and light weight. However, in the traditional preparation process, some structural defects are introduced, which will lead to an increase in phonon scattering, thereby reducing the thermal conductivity of graphene. Therefore, a new method for preparing graphene thin films is proposed by using the evaporation method; the graphene oxide composite film is prepared by adding carbon-rich molecules (CRMs) to the graphene oxide dispersion liquid. The experimental results show that the addition of a mass fraction of 0.15% CRMs helps to form continuous strips and channels, which are beneficial to the construction of the internal aromatic structure of graphene and improve the crystallinity of graphene film. The in-plane thermal conductivity of the composite film increased from 598.74 W/(m·K) to 704.27 W/(m·K) after adding carbon-rich molecules. However, excess CRMs can lead to the formation of disordered structures during graphitization, which will reduce the thermal conductivity of the film to a certain extent. The radiation properties of graphene films are also proposed to verify the validity of the above conclusions, and the results show that the graphene film with a mass fraction of 0.24% CRMs has better heat dissipation performance, which can be reduced by 5 °C compared with that of pure graphene film. Through the application of graphene in new energy car seats, it is proved that compared with the resistance wire seats, graphene seats have better performance in terms of a fast heating speed and uniform heating. Full article

(This article belongs to the Special Issue Electrochemical Properties and Applications of Thin Films)

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14 pages, 4838 KiB

Open AccessArticle

Antibacterial and Film Characteristics of Copper-Doped Diamond-like Carbon Films via Sputtering Using a Mixed Target of Copper and Graphite

by Kazuya Kanasugi, Takayoshi Nakajima and Kenji Hirakuri

Coatings 2025, 15(5), 559; https://doi.org/10.3390/coatings15050559 - 7 May 2025

Abstract

Copper-doped diamond-like carbon films (Cu-DLC) are effective antibacterial materials and are fabricated using different techniques. By controlling the ratio of the graphite and diamond structures as well as the hydrogen bonds, the biocompatibility, chemical stability, wear resistance, and high hardness of Cu-DLC can [...] Read more.

Copper-doped diamond-like carbon films (Cu-DLC) are effective antibacterial materials and are fabricated using different techniques. By controlling the ratio of the graphite and diamond structures as well as the hydrogen bonds, the biocompatibility, chemical stability, wear resistance, and high hardness of Cu-DLC can be regulated. In this study, three types of Cu-DLC films were deposited on SUS304 substrates using Ar-sputtering with mixed targets comprising different C/Cu ratios. The films’ structures, surface, and antibacterial properties were investigated using electron probe microanalysis, Raman and X-ray photoelectron spectroscopy, atomic force microscopy, and ball-on-disk tests. The Cu concentration in the Cu-DLC films increased with an increase in its content in the target; however, no significant differences were observed in the Raman spectra. The surface composition, roughness, and dynamic friction coefficients were similar across all Cu-DLC films, which displayed smoothness and friction properties similar to those of standard DLC films without Cu. The antibacterial activity (R value) was evaluated as per ISO 22196. Although DLC films exhibited no antibacterial activity (R < 2), all the prepared Cu-DLC films displayed good antibacterial activity (R ≥ 2). The proposed deposition process facilitated Cu-DLC coating, thus promoting its use in the healthcare fields. Full article

(This article belongs to the Special Issue Electrochemical Properties and Applications of Thin Films)

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20 pages, 4439 KiB

Open AccessArticle

Predicting UV-Vis Spectra of Benzothio/Dithiophene Polymers for Photodetectors by Machine-Learning-Assisted Computational Studies

by Abrar U. Hassan and Mamduh J. Aljaafreh

Coatings 2025, 15(5), 558; https://doi.org/10.3390/coatings15050558 - 7 May 2025

Abstract

The current study represents a machine-learning (ML)-assisted reverse polymer engineering for the rational design of high-performance benzothiophene (BT) benzodithiophene (BDT) polymers for photodetector applications. By integrating their 5617 units with various acceptor moieties, a total of 72,976 unique polymer combinations are generated. The [...] Read more.

The current study represents a machine-learning (ML)-assisted reverse polymer engineering for the rational design of high-performance benzothiophene (BT) benzodithiophene (BDT) polymers for photodetector applications. By integrating their 5617 units with various acceptor moieties, a total of 72,976 unique polymer combinations are generated. The optical properties of these polymers are predicted with high accuracy (R² = 0.86) using a Gradient-Boosting Regression (GBR) model. The SHAP value-based feature importance analysis indicates that Chi0 is the most influential factor in predicting the absorption maxima (λ_max) of polymers, followed by LabuteASA, Chi0V, Chi1, SlogP_VSA12, and other molecular descriptors. The robustness of the employed model is further validated through K-Fold cross-validation, with the highest mean squared error (MSE) observed at 2.02 in the fold-2 subset. The designed polymers exhibit λ_max within the range of 400–750 nm, demonstrating their suitability for photodetector applications. Moreover, a Transformer-Assisted Orientation (TAO) approach is employed to optimize polymer design, successfully achieving bandgaps as low as 0.42 eV. This approach facilitates the rapid design and optimization of high-performance polymers with tailored electronic properties, effectively addressing the limitations of conventional trial-and-error methods. The current ML-assisted approach presents a promising strategy for expediting the development of high-performance photodetectors and other advanced optoelectronic devices. Full article

(This article belongs to the Special Issue Advances in Polymer Composites, Coatings and Adhesive Materials)

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14 pages, 3257 KiB

Open AccessArticle

Phosphorylated Cellulose-Based Porous Monoliths for Efficient and Eco-Friendly Heavy Metal Ion Adsorption

by Yuhang Shu, Guangyu Zhang, Zhipeng Liao, Yao Liang, Qidong Wang, Yu Ren and Zhaohang Yang

Coatings 2025, 15(5), 557; https://doi.org/10.3390/coatings15050557 - 7 May 2025

Abstract

Heavy metal ion contamination in aquatic systems presents substantial environmental and public health challenges, demanding innovative remediation solutions. This study reports the synthesis of phosphorylated cellulose (PC) monoliths via thermally induced phase separation (TIPS) as a sustainable solution for heavy metal removal. Through [...] Read more.

Heavy metal ion contamination in aquatic systems presents substantial environmental and public health challenges, demanding innovative remediation solutions. This study reports the synthesis of phosphorylated cellulose (PC) monoliths via thermally induced phase separation (TIPS) as a sustainable solution for heavy metal removal. Through systematic optimization of phosphorylation degree (ranging from 16.3% to 49.5%) and pore architecture, we developed materials with exceptional adsorption capacity and flow characteristics. Comprehensive characterization (SEM, FTIR, and elemental analysis) confirmed the successful incorporation of the phosphate group while revealing tunable three-dimensional porous structures controlled by cellulose acetate concentration (80–120 mg mL⁻¹) and phosphorylation parameters. Optimal Cu²⁺ adsorption occurs at 43.9% phosphorylation, coupled with stable permeability, under continuous flow conditions. The monolith effectively removes heavy metal ions (e.g., Cu²⁺, Ni²⁺, Cd²⁺) across a wide pH range, driven by electrostatic and hard-soft acid-base interactions. Additionally, the material maintains an absorption capacity of over 90% after multiple regeneration cycles. These findings highlight the potential of PC monoliths as cost-effective, scalable, and environmentally friendly adsorbents for heavy metal ion removal in water treatment applications. Full article

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14 pages, 7058 KiB

Open AccessArticle

Manufacturing Process and Characteristics of Silica Nanostructures for Anti-Reflection at 355 nm

by Anne Gärtner, Mihai-George Mureșan, Christian Mühlig, Tobias Herffurth, Nadja Felde, Hanjörg Wagner, Ulrike Schulz, Astrid Bingel, Sven Schröder, Tomáš Mocek and Andreas Tünnermann

Coatings 2025, 15(5), 556; https://doi.org/10.3390/coatings15050556 - 6 May 2025

Abstract

Recent advancements in photonics have intensified the performance requirements for optical systems and present significant challenges for optical coating technologies. Conventional interference coating systems often prove to be insufficient, especially in applications requiring large angles of light incidence or a wide wavelength range. [...] Read more.

Recent advancements in photonics have intensified the performance requirements for optical systems and present significant challenges for optical coating technologies. Conventional interference coating systems often prove to be insufficient, especially in applications requiring large angles of light incidence or a wide wavelength range. Nanostructures, which consist of an air material mixture, offer promising alternatives. In this work, silica nanostructures are manufactured by the AR-plas2 method, in which first an organic layer is evaporated onto a substrate. This organic layer forms self-organizing nanostructures by a plasma etching step, which are subsequently coated with silica. Finally, the organic residues are removed by additional plasma etching and heat treatment steps, which results in hollow silica structures. The work examines the optical and functional properties of these structures designed for 355 nm to demonstrate their use as anti-reflective coatings for advanced optical systems. Full article

(This article belongs to the Special Issue New Functional Coatings and Thin Films for Sensor and Green Energy Technologies)

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14 pages, 4721 KiB

Open AccessArticle

Tuning Fillers via Multidimensional Synergistic Optimization for High-Temperature Capacitive Energy Storage

by Linfei Lu, Yipeng Tan, Hang Gao, Chiung Kuei Fu, Lingmin Yao and Qinglin Deng

Coatings 2025, 15(5), 555; https://doi.org/10.3390/coatings15050555 - 6 May 2025

Abstract

High-temperature performance is crucial for dielectric capacitors, especially in military and aerospace applications, as they offer superior charge–discharge rates and power density compared to supercapacitors and batteries. However, the stability of polymers based on commercial dielectric capacitors under extreme environmental conditions (i.e., ≥100 [...] Read more.

High-temperature performance is crucial for dielectric capacitors, especially in military and aerospace applications, as they offer superior charge–discharge rates and power density compared to supercapacitors and batteries. However, the stability of polymers based on commercial dielectric capacitors under extreme environmental conditions (i.e., ≥100 °C) presents significant challenges. Herein, with polyimide (PI) as the matrix, a middle layer is produced that is rich in zero-dimensional nanoparticles, BaTiO₃ (0DBTO@PI), to enhance dielectric polarization. The upper and lower layers integrate two-dimensional laminated Al₂O₃ (2DAO@PI) as thermal conductive and insulating layers to improve heat dissipation and electrical insulation. The composites combine polarization enhancement and thermal management to synergistically improve high-temperature capacitive energy storage. As a result, the designed composite capacitors maintain good performance at temperatures > 150 °C. Even at 200 °C, it retains 2.36 J cm⁻³ (a 203% increase over pure PI), demonstrating unprecedented stability under extreme temperatures. Layer-specific functionalization provides a new and significant paradigm for designing high-temperature polymer-based energy storage films. Full article

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

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