Coatings

11 pages, 3606 KiB

Open AccessEditor’s ChoiceArticle

Influence of Surface Roughness on Nanocrystalline Diamond Films Deposited by Distributed Antenna Array Microwave System on TA6V Substrates

by Azadeh Valinattaj Omran, Chaimaa Mahi, Romain Vayron, Céline Falentin-Daudré and Fabien Bénédic

Coatings 2023, 13(7), 1300; https://doi.org/10.3390/coatings13071300 - 24 Jul 2023

Cited by 1 | Viewed by 2667

Abstract

In this study, the characteristics of nanocrystalline diamond films synthesized at low surface temperature on Ti-6Al-4V (TA6V) substrates using a distributed antenna array microwave reactor aiming at biomedical applications were investigated. The surface roughness of the TA6V substrates is varied by scratching with [...] Read more.

In this study, the characteristics of nanocrystalline diamond films synthesized at low surface temperature on Ti-6Al-4V (TA6V) substrates using a distributed antenna array microwave reactor aiming at biomedical applications were investigated. The surface roughness of the TA6V substrates is varied by scratching with emery paper of 1200, 2400, 4000 polishing grit. Nanocrystalline diamond (NCD) coatings with morphology, purity, and microstructure comparable to those obtained on silicon substrates usually employed in the same reactor and growth conditions are successfully achieved whatever the polishing protocol. However, the latter has a significant effect on the roughness parameters and hardness of the NCD films. The use of the finest polishing grit thus permits us to enhance the hardness value, which can be related to the work-hardening phenomenon arising from the polishing process. Full article

(This article belongs to the Special Issue New Strategies and Recent Advances in Investigations of Micro- and Nano-Coatings for Technological and Biomedical Applications)

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21 pages, 79402 KiB

Open AccessArticle

The Wetting Behavior of Water Droplets on Silane and Silane/GO-Modified Ettringite Surfaces: Insights into Molecular Dynamics Simulations

by Mengmeng Li, Heping Zheng, Yuying Duan, Dongshuai Hou, Pan Wang, Bo Pang, Shaochun Li and Zuquan Jin

Coatings 2023, 13(7), 1299; https://doi.org/10.3390/coatings13071299 - 24 Jul 2023

Cited by 3 | Viewed by 2646

Abstract

The use of rapid-hardening cementitious materials for the emergency repair of critical infrastructure in coastal environments is becoming increasingly widespread, and concrete surface hydrophobic protection treatment is equally necessary to improve the durability of both new and old concrete. Among them, silane-based hydrophobic [...] Read more.

The use of rapid-hardening cementitious materials for the emergency repair of critical infrastructure in coastal environments is becoming increasingly widespread, and concrete surface hydrophobic protection treatment is equally necessary to improve the durability of both new and old concrete. Among them, silane-based hydrophobic materials play an important role in concrete hydrophobic protection. Graphene oxide (GO)-modified silane materials can significantly improve the hydrophobic performance of coatings, but the hydrophobic mechanism of coatings modifying the sulfoaluminate cement’s main hydration product ettringite (AFt) has not yet been explored. In this study, molecular dynamics simulations were conducted to investigate the wetting properties of water droplets on the surface of AFt, isobutyltriethoxy silane (IBTS)-modified AFt, and IBTS/GO-modified AFt. It was found that the AFt substrate had good hydrophilicity, and the droplets could wet the interface through Ca-O ionic bonds and H-bonds. The IBTS coating initially impeded droplet wetting, but the adsorption stability of IBTS on the AFt substrate surface was poor under droplet action, leading to droplet penetration and dispersion of the IBTS coating on the AFt surface. However, the IBTS/GO coating significantly restricted droplet wetting due to the stable adsorption of GO on the AFt surface and the strong stability of hydrogen bonds between IBTS and GO. In conclusion, selecting a suitable bridging material between AFt and silane is crucial for improving the hydrophobic stability of silane coatings on sulfoaluminate cement materials. Full article

(This article belongs to the Special Issue Liquid–Fluid Interfaces and Dynamics)

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19 pages, 6928 KiB

Open AccessEssay

Multi-Method Analysis of Painting Materials in Murals of the North Mosque (Linqing, China)

by Shaohua Dong, Jiankai Xiang, Juan Ji, Yongjin Wang, Gang Zhang, Peng Fu, Jianwu Han and Li Li

Coatings 2023, 13(7), 1298; https://doi.org/10.3390/coatings13071298 - 24 Jul 2023

Cited by 4 | Viewed by 1884

Abstract

The murals of Ming Dynasty North Mosque in Linqing, Shandong Province, Eastern China, are of significant cultural and historical importance. Their final restoration date remains uncertain, making a comprehensive investigation critical before initiating preservation and renovation work. This research project examined the painting [...] Read more.

The murals of Ming Dynasty North Mosque in Linqing, Shandong Province, Eastern China, are of significant cultural and historical importance. Their final restoration date remains uncertain, making a comprehensive investigation critical before initiating preservation and renovation work. This research project examined the painting materials of the murals using various analytical techniques, including polarized light microscopy (PLM), scanning electron microscopy (SEM), X-ray energy spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), microscopic Raman spectroscopy (M-Raman), X-ray photoelectron spectroscopy (XPS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis. Results indicated that the pigments employed included ultramarine, emerald green, cinnabar, kaolinite, gypsum, and carbon black, while the gum binder used was protein-based adhesive materials. As synthetic ultramarine and emerald green were not introduced to China until the late Qing Dynasty, this suggests that these murals were restored no earlier than this period. The study also revealed that the mural materials used in the North Mosque mural were similar to those found in other architectural murals in China. Thus, the knowledge gained from the conservation and restoration efforts of similar architectural murals can be leveraged to enhance the conservation and restoration efforts of the North Mosque murals. Full article

(This article belongs to the Special Issue Surface and Interface Analysis of Cultural Heritage, 2nd Edition)

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12 pages, 9107 KiB

Open AccessFeature PaperArticle

Self-Assembly and Properties of Elastic Nanocellulose-Carbon Airgel with Ordered Porosity by Template-Free Directional Freezing

by Sihui Wang, Zhengdong Li, Xiaopeng Gong, Feng Hou and Ji Liang

Coatings 2023, 13(7), 1297; https://doi.org/10.3390/coatings13071297 - 24 Jul 2023

Cited by 1 | Viewed by 1545

Abstract

Porous cellulose aerogels with different compositions have been fabricated via three methods, including regular freezing, directional freezing, and hydrothermal treatment, using pure cellulose oxide and cellulose oxide/graphite oxide composites, respectively. The cellulose aerogels are highly elastic and light in weight. The carbon aerogels [...] Read more.

Porous cellulose aerogels with different compositions have been fabricated via three methods, including regular freezing, directional freezing, and hydrothermal treatment, using pure cellulose oxide and cellulose oxide/graphite oxide composites, respectively. The cellulose aerogels are highly elastic and light in weight. The carbon aerogels show an ordered structure through directional freezing with layered skeleton bones and some folds. Unlike low-temperature freezing, the structures can obtain elastic properties. When the deformation is 20%, carbon aerogels can rebound to 95% of their original volume. The cellulose oxide/graphite oxide composite aerogels are synthesized into carbon–aerogel composites, which also have stable and robust structures of bone skeletons due to nanosheets. The carbon–aerogel composites have more than 85% resilience under 40% deformations. Carbon aerogels prepared from nanocelluloses have a novel three-dimensional network structure and have the application of elasticity, which is expected to be applied to metallurgical technology and the aerospace field. Through directional freezing, the carbon aerogels have regular structures of layered skeleton bones with some folds. In contrast to low-temperature freezing, the structures possess excellent elastic properties. Full article

(This article belongs to the Special Issue Synthesis, Properties and Application of Thin Films, Nanofilms and Nanocrystals)

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18 pages, 4059 KiB

Open AccessArticle

Corrosion Behavior of Alkyd-Resin-Coated Carbon Steel under Cathodic Polarization in Both Static and Flowing Seawater

by Hui Guo, Kun Zhou, Zhenliang Feng, Chengjie Li, Jie Xie, Jiyuan Ma, Xinyue Zhang, Xiaohui Wang, Kunshan Xu, Chuanpeng Li and Jie Liu

Coatings 2023, 13(7), 1296; https://doi.org/10.3390/coatings13071296 - 24 Jul 2023

Cited by 3 | Viewed by 1420

Abstract

The effect of cathodic polarization on the corrosion behavior of alkyd-resin-coated carbon steel with an artificial coating defect was researched using a wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) in both static and flowing simulated solutions. The microscopic morphology and chemical [...] Read more.

The effect of cathodic polarization on the corrosion behavior of alkyd-resin-coated carbon steel with an artificial coating defect was researched using a wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) in both static and flowing simulated solutions. The microscopic morphology and chemical structure of the organic coating were characterized by scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR) to reveal the degradation mechanisms of organic coatings under different polarization potentials. The study found that the failure process of the alkyd coating could be accelerated by cathodic polarization. After 312 h of immersion, the impedance under −1100 mV was one order of magnitude lower than that under the open-circuit potential (OCP). The coating delamination became serious with the negative shifting of polarization potential, and the delamination area ratio under −1100 mV in both static and flowing seawater rose to 23% and 14%, respectively. Interestingly, the flowing condition of the immersion solution that combined with cathodic polarization exhibited a synergistic effect, which could accelerate (in the earlier stage) and then alleviate the delamination of the coating. Furthermore, the results showed that both the diffusion of the corrosion particles and the anodic dissolution reaction of the metal could be significantly affected by cathodic polarization and the flowing condition of the solution, which provides a possible approach to gain insight into the delamination of organic coating. Full article

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

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23 pages, 10400 KiB

Open AccessReview

Inclusions and Segregations in the Selective Laser-Melted Alloys: A Review

by Mahdi Yeganeh, Zahra Shahryari, Ali Talib Khanjar, Zeinab Hajizadeh and Fatemeh Shabani

Coatings 2023, 13(7), 1295; https://doi.org/10.3390/coatings13071295 - 24 Jul 2023

Cited by 13 | Viewed by 2372

Abstract

This paper aims to review some important microstructural defects arising in the alloys manufactured by selective laser melting (SLM) or laser powder bed fusion (LPBF). During the manufacturing process, various defects can occur in metals, which can negatively impact their mechanical properties and [...] Read more.

This paper aims to review some important microstructural defects arising in the alloys manufactured by selective laser melting (SLM) or laser powder bed fusion (LPBF). During the manufacturing process, various defects can occur in metals, which can negatively impact their mechanical properties and structural integrities. These defects include gas pores, lack of fusions, keyholes, melt pools, cracks, inclusions, and segregations. In this review, heterogeneities such as inclusion and segregation defects are discussed. Other types of defects have been comprehensively discussed in other reviews. Inclusions refer to foreign ceramic particles that are present within the metal, whereas segregations refer to the uneven distribution of alloying elements within the microstructure of the metal. The cause of appearance, effect of different parameters, and methods to reduce them in the final part are also reviewed. The effects of these defects on the integrity of the produced parts are discussed. Solutions for the elimination or minimization of these defects are also suggested. Post treatments and modifications of an alloy’s composition can also help to improve its material properties and reduce its defect concentration. Full article

(This article belongs to the Special Issue Advances in Metal Additive Manufacturing Technique: Processes and Novel Materials)

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19 pages, 4248 KiB

Open AccessArticle

Multi-Scale Analysis of Terahertz Time-Domain Spectroscopy for Inversion of Thermal Growth Oxide Thickness in Thermal Barrier Coatings

by Rui Li, Dongdong Ye, Jianfei Xu and Jiabao Pan

Coatings 2023, 13(7), 1294; https://doi.org/10.3390/coatings13071294 - 24 Jul 2023

Cited by 2 | Viewed by 1609

Abstract

To address the inverse problem of thermal growth oxide (TGO) thickness in thermal barrier coatings (TBCs), a novel multi-scale analysis (MSA) method based on terahertz time-domain spectroscopy (THz-TDS) is introduced. The proposed method involves a MSA technique based on four wavelet basis functions [...] Read more.

To address the inverse problem of thermal growth oxide (TGO) thickness in thermal barrier coatings (TBCs), a novel multi-scale analysis (MSA) method based on terahertz time-domain spectroscopy (THz-TDS) is introduced. The proposed method involves a MSA technique based on four wavelet basis functions (db4, sym3, haar, coif3). Informative feature parameters characterizing the TGO thickness were extracted by performing continuous wavelet transform (CWT) and max-pooling operations on representative wavelet coefficients. Subsequently, multi-linear regression and machine learning regression models were employed to predict and assess the wavelet feature parameters. Experimental results revealed a discernible trend in the wavelet feature parameters obtained through CWT and max-pooling in the MSA, wherein the visual representation of TGO thickness initially increases and then gradually decreases. Significant variations in these feature parameters with changes in both thickness and scale enabled the effective inversion of TGO thickness. Building upon this, multi-linear regression and machine learning regression prediction were performed using multi-scale data based on four wavelet basis functions. Partial-scale data were selected for multi-linear regression, while full-scale data were selected for machine learning regression. Both methods demonstrated high accuracy prediction performance. In particular, the haar wavelet basis function exhibited excellent predictive performance, as evidenced by regression coefficients of 0.9763 and 0.9840, further confirming the validity of MSA. Hence, this study effectively presents a feasible method for the inversion problem of TGO thickness, and the analysis confirms the promising application potential of terahertz time-domain spectroscopy’s multi-scale analysis in the field of TBCs evaluation. These findings provide valuable insights for further reference. Full article

(This article belongs to the Special Issue Nondestructive Evaluation of Material Surfaces: Theory, Techniques and Applications)

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12 pages, 1913 KiB

Open AccessFeature PaperArticle

Optimization of Bulk Heterojunction Organic Photovoltaics

by Alaa Y. Ali, Natalie P. Holmes, Nathan Cooling, John Holdsworth, Warwick Belcher, Paul Dastoor and Xiaojing Zhou

Coatings 2023, 13(7), 1293; https://doi.org/10.3390/coatings13071293 - 24 Jul 2023

Viewed by 1762

Abstract

The performance of poly(3-hexylthiophene) (P3HT): phenyl-C₆₁-butyric acid methyl ester (PCBM) organic photovoltaic (OPV) devices was found to be strongly influenced by environmental during preparation, thermal annealing conditions, and the material blend composition. We optimized laboratory fabricated devices for these variables. Humidity [...] Read more.

The performance of poly(3-hexylthiophene) (P3HT): phenyl-C₆₁-butyric acid methyl ester (PCBM) organic photovoltaic (OPV) devices was found to be strongly influenced by environmental during preparation, thermal annealing conditions, and the material blend composition. We optimized laboratory fabricated devices for these variables. Humidity during the fabrication process can cause electrode oxidation and photo-oxidation in the active layer of the OPV. Thermal annealing of the device structure modifies the morphology of the active layer, resulting in changes in material domain sizes and percolation pathways which can enhance the performance of devices. Thermal annealing of the blended organic materials in the active layer also leads to the growth of crystalline for P3HT domains due to a more arrangement packing of chains in the polymer. Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) acts as a hole transport layer in these P3HT:PCBM devices. Two commercially materials of PEDOT:PSS were utilizing in the optimization of the OPV in this research; high conductivity PEDOT:PSS-PH1000 and PEDOT:PSS-Al4083, which is specifically designed for OPV interfaces. It was demonstrated that OPVs were prepared with PEDOT:PSS-PH1000 have a less than the average performance of PEDOT:PSS-Al4083. The power conversion efficiency (PCE) decreased clearly with a reducing in masking area devices from 5 mm² to 3.8 mm² for OPVs based on PH1000 almost absolutely due to the reduced short circuit current (J_sc). This work provides a roadmap to understanding P3HT:PCBM OPV performance and outlines the preparation issues which need to be resolved for efficient device fabrication Full article

(This article belongs to the Special Issue Advanced Polymer and Thin Film for Sustainable Energy Harvesting)

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14 pages, 4051 KiB

Open AccessArticle

Enhanced Electrochromic Properties of Nanocrystalline Molybdenum Oxide Films Modified by Dopamine

by Dan Zhou and Liping Yang

Coatings 2023, 13(7), 1292; https://doi.org/10.3390/coatings13071292 - 24 Jul 2023

Cited by 4 | Viewed by 1438

Abstract

Molybdenum oxide (MoO₃) electrochromic (EC) materials have not been widely used at present due to relatively poor performance and inadequate research. In order to enhance the EC properties of the MoO₃ to achieve the purpose of practical use, the modified [...] Read more.

Molybdenum oxide (MoO₃) electrochromic (EC) materials have not been widely used at present due to relatively poor performance and inadequate research. In order to enhance the EC properties of the MoO₃ to achieve the purpose of practical use, the modified nanocrystalline MoO₃ films were fabricated by a cheap and simple complexation-assisted sol–gel method followed by annealing at 300 °C. In this method, dopamine (DA) is used as a structure-directing agent and the added amount of DA has a great influence on the structure and morphology and, thus, electrochemical and EC properties of the MoO₃ films. Different from the pure MoO₃ polycrystalline film, the film modified with a suitable amount of DA possesses a distinctive nanocrystal-embedded amorphous structure, and, thus, can achieve synergy effects of EC properties through combining the advantages of both amorphous phases and nanocrystalline. Therefore, compared with the pure MoO₃ film, the modified MoO₃ film shows much higher EC properties in terms of optical contrast, coloration efficiency, switching speed, and cycling stability. Moreover, a complementary type EC device with dual active layers (the modified MoO₃ film and polyaniline) was fabricated and tested, and the results demonstrate the potential application of the modified MoO₃ film. Full article

(This article belongs to the Special Issue Recent Advances in Metallic and Metal Oxide Thin Films)

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11 pages, 5501 KiB

Open AccessArticle

Effect of Polyethylene-Grafted Maleic Anhydride on the Properties of Flue-Gas Desulfurized Gypsum/Epoxy Resin Composites

by Fei Li, Hai Li, Juncheng Die, Yafeng Zhang, Yi Li, Mingyu Wang, Yang Cao, Kexi Zhang and Jinchun Tu

Coatings 2023, 13(7), 1291; https://doi.org/10.3390/coatings13071291 - 23 Jul 2023

Cited by 1 | Viewed by 1711

Abstract

Waste resource utilization can save energy, reduce costs, and is one of the important means to protect the environment. Flue-gas desulphurized (FGD) gypsum is a common industrial by-product. These by-products are not only difficult to use, but also have serious impacts on the [...] Read more.

Waste resource utilization can save energy, reduce costs, and is one of the important means to protect the environment. Flue-gas desulphurized (FGD) gypsum is a common industrial by-product. These by-products are not only difficult to use, but also have serious impacts on the ecological environment. The conventional process of the industrial utilization of the calcium sulfate whisker pretreatment process leads to a low utilization rate of FGD gypsum, further increasing the consumption of resources and leading to secondary pollution. This study presents a method of preparing composites by adding FGD gypsum directly into epoxy resin with polyethylene-grafted maleic (PGM) anhydride as a compatibilizer of FGD gypsum/epoxy resin composites. Results showed weak tensile properties and impact properties of the composites when only FGD gypsum was added. When the amount of PGM added was 6 wt%, the tensile properties and impact properties of FGD gypsum/epoxy resin composites improved by 75% and 63%, and compared with the neat epoxy resin, the tensile properties and impact properties of FGD gypsum/epoxy resin composites, respectively, improved by 30% and 57%. Additionally, laser particle size analysis, X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), a thermogravimetric analyzer (TGA), and a Differential scanning calorimeter (DSC) were used to examine the effects of PGM on the mechanical properties of FGD gypsum/epoxy resin composites and its mechanism of action. The recycling of FGD gypsum in resin materials has been extended in this study. Full article

(This article belongs to the Special Issue Functionalities of Polymer-Based Nanocomposite Films and Coatings)

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21 pages, 8410 KiB

Open AccessArticle

A Study on the Adsorption Mechanism and Compactness of the TFS Coating Interfacial Layer

by Yafei Xie, Tong Zhao and Kai Liu

Coatings 2023, 13(7), 1290; https://doi.org/10.3390/coatings13071290 - 23 Jul 2023

Cited by 3 | Viewed by 1145

Abstract

Chrome-plated plates, also known as tin-free plates (TFS), are the latest substrates for coating plates. The coating plate cannot be separated from the TFS during the stamping and extension process, and the interface layer of the TFS coating plate cannot produce pores to [...] Read more.

Chrome-plated plates, also known as tin-free plates (TFS), are the latest substrates for coating plates. The coating plate cannot be separated from the TFS during the stamping and extension process, and the interface layer of the TFS coating plate cannot produce pores to ensure good corrosion resistance and the appearance of the metal packaging cans. This requires the TFS coating plate interfacial layer to have good adsorption and compactness. In this paper, the molecular simulation model of the interfacial layer interaction of the TFS coating plate was established by using molecular mechanics simulation, Monte Carlo simulation, and molecular dynamics simulation, and the influential rules of chromium oxide crystalline structure, coating functional group type, and coating pressure on the adsorption and compactness of interfacial layer were analyzed and verified by experiments. The results show that the adsorption is stronger when the surface of the TFS is a chromium oxide (110) crystalline surface and contains hydroxide ions. The adsorption of polyester polyurethane coating and polyether polyurethane coating for and the adsorption of polyester polyurethane coating functional groups is stronger than polyether functional groups, and the adsorption of other functional groups is ranked by the same method. The interfacial layer compactness increases with an increase in coating pressure. For this experimental sample, the value of the film pressure sensor is 18,940 g when meeting the requirements of adsorption and compactness of the interfacial layer of the TFS coating plate, which can be extended for other coating plates. Full article

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11 pages, 18606 KiB

Open AccessArticle

Influence of Laser Power on Microstructure and Properties of Al-Si+Y₂O₃ Coating

by Yali Gao, Pengyong Lu, Sicheng Bai, Baolong Qin and Dongdong Zhang

Coatings 2023, 13(7), 1289; https://doi.org/10.3390/coatings13071289 - 23 Jul 2023

Cited by 6 | Viewed by 1338

Abstract

Al-Si/7.5 wt.%Y₂O₃ coatings were prepared on Mg alloy with laser cladding to enhance the wear and corrosion resistance of substrate. The influence of laser power on the microstructure and properties of the coating were discussed. The results uncovered that the [...] Read more.

Al-Si/7.5 wt.%Y₂O₃ coatings were prepared on Mg alloy with laser cladding to enhance the wear and corrosion resistance of substrate. The influence of laser power on the microstructure and properties of the coating were discussed. The results uncovered that the coatings consisted primarily of Mg₂Si, Mg₁₇Al₁₂, Mg₂Al₃, Al₄MgY, and α-Mg phases. Through calculation, it was observed that the crystal size decreased with the decrease in the laser power. Y₂O₃ gave the coating a better strengthening effect due to the fine-grain strengthening and hard-phase strengthening. The average hardness of the coating with laser power of 1100 W achieved 312 HV, which was approximately 4.2 times that of the substrate. The wear volume of the coating was 22.2% that of the substrate. Compared with Mg alloy, the self-corrosion potential of the coating increased by 1.09 V, and the self-corrosion current density decreased by three orders of magnitude. Full article

(This article belongs to the Special Issue Microstructure, Friction and Wear, Hardness Properties and Numerical Simulation of Coatings)

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22 pages, 10268 KiB

Open AccessArticle

Synthesis and Characterization of Cadmium Ion-Imprinted/Natural Sand Composite and Research on Its Adsorption Properties

by Aray Murat, Shuaibing Gao, Lingling Wang, Linlin Chai, Shawket Abliz and Abliz Yimit

Coatings 2023, 13(7), 1288; https://doi.org/10.3390/coatings13071288 - 23 Jul 2023

Cited by 1 | Viewed by 1316

Abstract

Cadmium is a common heavy metal that can cause serious harm to human health, even in trace amounts. Therefore, it is of great significance to develop environmentally friendly, inexpensive, and readily available adsorbent materials with high selectivity. By preparing ion-imprinted composites on the [...] Read more.

Cadmium is a common heavy metal that can cause serious harm to human health, even in trace amounts. Therefore, it is of great significance to develop environmentally friendly, inexpensive, and readily available adsorbent materials with high selectivity. By preparing ion-imprinted composites on the surface of a suitable carrier through surface imprinting, the number of effective adsorption sites can be increased, and target ions can be more quickly identified. In this study, we synthesized a cadmium ion-imprinted/natural sand composite material (NS/Cd-IIP) using natural sand as the carrier, Cd(II) as the template ion, and acrylamide as the functional monomer. A series of characterization techniques were employed to confirm the composite. Static and dynamic adsorption experiments were conducted to investigate various factors affecting its adsorption performance. The optimum adsorption pH was found to be 7, and the adsorption equilibrium time was determined to be 105 min. The imprinted composites exhibited a static adsorption saturation capacity of 33.84 mg·g⁻¹, which was significantly higher than that of the non-imprinted composites. The adsorption behavior of composites followed Langmuir isotherm and quasi-second-order kinetic. Thermodynamic parameters indicated that the adsorption process of NS/Cd-IIP for Cd(II) was exothermic, entropic, and spontaneous. The selectivity of NS/Cd-IIP towards Cd(II) was significantly higher than that towards other ions. By optimizing the dynamic adsorption conditions, the maximum adsorption capacity of NS/Cd-IIP was determined to be 3.77 mg·g⁻¹, and the adsorption behavior conformed to the Thomas model. NS/Cd-IIP was used as a solid-phase extractant for trace determination of Cd(II) in tap water, achieving a recovery rate exceeding 101%. Full article

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19 pages, 3551 KiB

Open AccessArticle

Enhanced Adsorption of Methylene Blue Using Phosphoric Acid-Activated Hydrothermal Carbon Microspheres Synthesized from a Variety of Palm-Based Biowastes

by Saeed Alhawtali, Mohanad El-Harbawi, Abdulrhman S. Al-Awadi, Lahssen El Blidi, Maher M. Alrashed and Chun-Yang Yin

Coatings 2023, 13(7), 1287; https://doi.org/10.3390/coatings13071287 - 22 Jul 2023

Cited by 6 | Viewed by 2174

Abstract

In the present study, the ability for novel carbon microspheres (CMs) derived from date palm (Phoenix dactylifera) biomass using a hydrothermal carbonization (HTC) process and activated using phosphoric acid to remove methylene blue dye was investigated. Three types of palm-based wastes [...] Read more.

In the present study, the ability for novel carbon microspheres (CMs) derived from date palm (Phoenix dactylifera) biomass using a hydrothermal carbonization (HTC) process and activated using phosphoric acid to remove methylene blue dye was investigated. Three types of palm-based wastes (seeds, leaflet, and inedible crystallized date palm molasses) were used and converted to CMs via the HTC process. The prepared samples were then activated using phosphoric acid via the incipient wetness impregnation method. The CMs samples before and after activation were analyzed using scanning electron microscopy (SEM), elemental analysis and scanning (CHNS), and the Fourier transform infrared (FTIR) and Brunauer–Emmet–Teller (BET) methods. The samples exhibited high BET surface areas after activation (1584 m²/g). The methylene blue adsorption results showed good fitting to the Langmuir, Fruendlich, and Temkin isotherm models for all activated samples. The maximum adsorption capacity achieved was 409.84 mg/g for activated CM obtained from the palm date molasses, indicating its high potential for application as a dye-based adsorption material. Full article

(This article belongs to the Special Issue Advanced Technology in Environmental Remediation and Resource Utilization)

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14 pages, 2822 KiB

Open AccessArticle

Enhanced Adsorption of Azoxystrobin from Water by As-Prepared Silica Nanoparticles

by Farag Malhat, Osama I. Abdallah, Mohamed Hussien, Ahmed M. Youssef, Fahad M. Alminderej and Sayed M. Saleh

Coatings 2023, 13(7), 1286; https://doi.org/10.3390/coatings13071286 - 22 Jul 2023

Cited by 3 | Viewed by 1703

Abstract

Nanoparticles are of great interest for water treatment as they remove a significant portion of water contaminants. In analogy to these emerging practices, the present work investigated the feasibility of using silica nanoparticles (SiO₂-NPs) to remove azoxystrobin from an aqueous solution. [...] Read more.

Nanoparticles are of great interest for water treatment as they remove a significant portion of water contaminants. In analogy to these emerging practices, the present work investigated the feasibility of using silica nanoparticles (SiO₂-NPs) to remove azoxystrobin from an aqueous solution. We investigated the effects of experimental parameters, such as solution temperature, adsorbent dosage, contact time, and initial azoxystrobin concentration, on the removal efficiency of azoxystrobin. Structural and chemical analysis of the synthesized nanoparticles was performing using X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and surface studies. The percentage of azoxystrobin removal efficiency was 92.8 at an initial azoxystrobin concentration of 10 mg/L. The result showed that by increasing the adsorbent dosage from 0.005 to 0.1 mg, the percentage removal efficiency of azoxystrobin from aqueous solution increased significantly from 59.72% to 95.21%. At the same time, the adsorption amount of azoxystrobin in equilibrium decreased with increasing temperature. It was found that the optimum temperature for removing azoxystrobin was 20 °C. Although the study was conducted under well-controlled laboratory conditions, the silica nanoparticle system showed excellent performance in removing a significant amount of azoxystrobin, making it a potential alternative/cooperator in water treatment for removing pesticides from aqueous solutions. Full article

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27 pages, 10706 KiB

Open AccessArticle

Incorporating Physics-Based Models into Equivalent Circuit Analysis of EIS Data from Organic Coatings

by Steven A. Policastro, Rachel M. Anderson, Carlos M. Hangarter, Attilio Arcari and Erick B. Iezzi

Coatings 2023, 13(7), 1285; https://doi.org/10.3390/coatings13071285 - 22 Jul 2023

Cited by 8 | Viewed by 2048

Abstract

Electrochemical impedance spectroscopy (EIS) is a widely used method for monitoring coatings because it can be done in situ and causes little damage to the coating. However, interpreting the impedance data from coatings in order to determine the state of the coating and [...] Read more.

Electrochemical impedance spectroscopy (EIS) is a widely used method for monitoring coatings because it can be done in situ and causes little damage to the coating. However, interpreting the impedance data from coatings in order to determine the state of the coating and its protective abilities is challenging. A modified version of the rapid electrochemical assessment of paint (REAP) equivalent circuit is developed here, along with a method to calculate the impedance of a circuit using matrix algebra. This new equivalent circuit and the calculation method are used to analyze EIS data obtained from a two-layer commercial organic coating system immersed in NaCl solutions with different concentrations and at different temperatures. The matrix calculation method is validated by comparing results obtained from commercial analysis software to this method for two different equivalent circuits, and the parameter values are nearly equal. Physics-based models of the equivalent circuit elements are derived and used to obtain both initial estimates for the regressions and physics-based constraints on the model parameters. These models are integrated into the regression procedure, and the corrected Akaike information criterion (AICc) is used to compare fits between the new circuit and classic equivalent circuits. The AICc values indicate the new circuit results in better fits than classic equivalent circuits used for coatings analysis. Full article

(This article belongs to the Special Issue Research Progress on Coatings Degradation and Atmospheric Corrosion of Metal Surfaces)

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12 pages, 2845 KiB

Open AccessArticle

Effect of Bath Composition on Titanium Anodization Using the Constant-Current Approach: A Crystallographic and Morphological Study

by Lapo Gabellini, Nicola Calisi, Stefano Mauro Martinuzzi, Rosa Taurino, Massimo Innocenti, Tiberio Bacci, Francesca Borgioli, Emanuele Galvanetto and Stefano Caporali

Coatings 2023, 13(7), 1284; https://doi.org/10.3390/coatings13071284 - 21 Jul 2023

Cited by 1 | Viewed by 1616

Abstract

Porous TiO₂ thin films were prepared via electrochemical anodization of commercial-grade titanium foils in baths containing variable amounts of ethylene glycol. X-Ray diffraction, scanning electron microscopy, and UV/visible spectroscopy were employed to assess the effect of ethylene glycol on the nature of [...] Read more.

Porous TiO₂ thin films were prepared via electrochemical anodization of commercial-grade titanium foils in baths containing variable amounts of ethylene glycol. X-Ray diffraction, scanning electron microscopy, and UV/visible spectroscopy were employed to assess the effect of ethylene glycol on the nature of TiO₂ layers. Emphasis is given to the modification of pore size and anatase-to-rutile ratio since these characteristics strongly affect the catalytic performance of TiO₂. To simplify the scaling up of the process, a single-step anodization process was employed on a commercial grade 2 titanium foil in constant-current mode without the use of fluorides—conditions that are easily replicable on an industrial scale. We point out some interesting relationships among operating parameters, such as bath composition and current densities, and the characteristics of the anodization layers evidence that the pore size and anatase-to-rutile ratio can be strictly controlled. Increasing the amount of ethylene glycol stimulated the formation of a thinner and less porous TiO₂ layer, richer in rutile phase, and characterized by reduced-diameter pores. These results demonstrate the effectiveness and, to some extent, the tunability of the morphology and mineralogic composition of titanium anodization in fluoride-free and ethylene-glycol-bearing acidic solutions. Full article

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16 pages, 3757 KiB

Open AccessFeature PaperArticle

Influence of TiO₂ on the Microstructure, Mechanical Properties and Corrosion Resistance of Hydroxyapatite HaP + TiO₂ Nanocomposites Deposited Using Spray Pyrolysis

by Hafedh Dhiflaoui, Sarra Ben Salem, Mohamed Salah, Youssef Dabaki, Slah Chayoukhi, Bilel Gassoumi, Anouar Hajjaji, Ahmed Ben Cheikh Larbi, Mosbah Amlouk and Hicham Benhayoune

Coatings 2023, 13(7), 1283; https://doi.org/10.3390/coatings13071283 - 21 Jul 2023

Cited by 5 | Viewed by 1627

Abstract

Titanium oxides and their alloys are widely used in medical applications because of their biocompatibility. However, they are characterized by their low resistance to corrosion. The HaP + TiO₂ nanocomposites’ coating was applied in different experiments, especially on a Ti-6Al-4V substrate with [...] Read more.

Titanium oxides and their alloys are widely used in medical applications because of their biocompatibility. However, they are characterized by their low resistance to corrosion. The HaP + TiO₂ nanocomposites’ coating was applied in different experiments, especially on a Ti-6Al-4V substrate with the spray pyrolysis process to deal with such weakness. The TiO₂ content effects on the surface morphology and the phase composition were investigated using a scanning electron microscopy, X-ray microanalysis (SEM-EDXS) and X-ray diffraction (XRD). The mechanical properties were determined with nanoindentation. The potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and simulated body fluid (SBF) solution environment tests were carried out to investigate the corrosion resistance of HaP + TiO₂/Ti6Al4V systems. The experimental findings revealed that sprayed thin films possessed uniform morphology. The coatings’ nanoindentations proved that the HaP + 20% TiO₂ coating hardness (252.77 MPa) and the elastic modulus (52.48 GPa) overtopped those of the pure hydroxyapatite coatings. The corrosion test demonstrated that the corrosion current density of about 36.1 µA cm⁻² and the corrosion potential of the order of −392.7 mV of HaP + 20% TiO₂ was lower compared to the pure HaP coating. Full article

(This article belongs to the Special Issue Advanced Biomaterials and Coatings)

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16 pages, 1435 KiB

Open AccessFeature PaperArticle

Self-Healing Redox-Active Coatings Based on Ferrocenyl-Containing Polysiloxanes

by Artem A. Rashevskii, Konstantin V. Deriabin, Elizaveta K. Parshina and Regina M. Islamova

Coatings 2023, 13(7), 1282; https://doi.org/10.3390/coatings13071282 - 21 Jul 2023

Cited by 6 | Viewed by 1420

Abstract

The known ferrocenyl-containing silicone materials have redox activity and electrical conductivity at the level of antistatic materials, but they are incapable of self-healing due to their irreversible cross-linking, which significantly reduces their application area. The development of novel self-healing ferrocenyl-containing silicone rubbers (FSRs) [...] Read more.

The known ferrocenyl-containing silicone materials have redox activity and electrical conductivity at the level of antistatic materials, but they are incapable of self-healing due to their irreversible cross-linking, which significantly reduces their application area. The development of novel self-healing ferrocenyl-containing silicone rubbers (FSRs) is a promising area of research that extends the possibilities of their application as protective coatings. In this work, a new method was developed to synthesize FSRs with different ferrocenyl unit content (25 and 50 mol.%) by anionic copolymerization of cyclic octamethylcyclotetrasiloxane (D₄), cyclic tetraferrocenyl-substituted 1,3,5,7-tetramethyltetrasiloxane (Fc₄D₄), and bicyclic cross-linking agent (bis-D₄). The optimal concentrations of the cross-linking agent and ferrocenyl-substituted unit content for FSRs are 5 wt.% and 25 mol.%, respectively. The FSRs exhibit tensile strength and elongation at break up to 0.1 MPa and 215%. The FSRs possess both self-healing at room and/or elevated temperatures (100 °C) and redox activity (Fc/Fc⁺ transformations at E⁰ = 0.43 V) and conductivity at the antistatic level (ca. 10⁻¹⁰–10⁻¹¹ S·cm⁻¹). The thermal properties of the FSRs were studied. The proposed approach is relevant for the creation of new functional silicone materials as flexible, self-healing, and antistatic protective coatings. Full article

(This article belongs to the Special Issue Functionalities of Polymer-Based Nanocomposite Films and Coatings)

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13 pages, 5547 KiB

Open AccessArticle

Chemical Composition, Structure, and Physical Properties of AlN Films Produced via Pulsed DC Reactive Magnetron Sputtering

by Vladimir R. Shayapov, Alena L. Bogoslovtseva, Sergey Yu. Chepkasov, Igor P. Asanov, Evgeny A. Maksimovskiy, Aleksandr V. Kapishnikov, Maria I. Mironova, Alina V. Lapega and Pavel V. Geydt

Coatings 2023, 13(7), 1281; https://doi.org/10.3390/coatings13071281 - 21 Jul 2023

Viewed by 1740

Abstract

The chemical composition, structure, and physical properties of aluminum nitride (AlN) films obtained using pulsed DC reactive magnetron sputtering in asymmetric bipolar mode have been studied. X-ray diffraction and electron diffraction confirmed the composition of c–axis textured hexagonal AlN films required for [...] Read more.

The chemical composition, structure, and physical properties of aluminum nitride (AlN) films obtained using pulsed DC reactive magnetron sputtering in asymmetric bipolar mode have been studied. X-ray diffraction and electron diffraction confirmed the composition of c–axis textured hexagonal AlN films required for piezoelectric applications. The surface of the films obtained is quite smooth; the arithmetic average roughness does not exceed 2 nm. Transmission electron microscopy has shown the presence of a transition layer at the film–substrate interface. Transmission electron microscopy and X-ray photoelectron spectroscopy depth profile analysis have shown that the films have an oxidized surface layer which has an influence on the optical model of the films derived from ellipsometric data. However, it does not significantly influence the films’ piezoresponse. Piezoelectric force microscopy indicated a piezoelectric effect in the films that is uniform over their surface. Full article

(This article belongs to the Special Issue Surface Modification of Engineering and Functional Materials)

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12 pages, 2957 KiB

Open AccessArticle

Experimental Study of Electrolytic Processing of Discharge-Assisted Jet Masks

by Chaoda Chen, Shaofang Wu, Tong Zhang, Yage Wang, Xiaoqiang Shao and Fengrong Mo

Coatings 2023, 13(7), 1280; https://doi.org/10.3390/coatings13071280 - 21 Jul 2023

Cited by 1 | Viewed by 1256

Abstract

There has been some research on jet electrolytic processing at home and abroad, and the phenomenon of discharge during the process has been reported, but there has been little research on the mode of jet electrolysis with the aid of discharge. A jet [...] Read more.

There has been some research on jet electrolytic processing at home and abroad, and the phenomenon of discharge during the process has been reported, but there has been little research on the mode of jet electrolysis with the aid of discharge. A jet mask electrolytic processing experiment was set up to prepare a blue oil mask on the surface of the workpiece using photolithography; two processing modes were achieved using different tool electrodes, the workpiece was processed by two types of motion, the processing micro-pits were observed morphologically using an optical microscope, and the test data were analyzed by plotting graphs. Experiments show that a blue oil mask with a thickness of 50 μm covers the workpiece to strengthen the fixity, and that jet electrolytic discharge machining can effectively improve the depth-to-width ratio by increasing the contribution to depth by 30%–38% and the contribution to width by 2%–18%, compared to jet electrolytic machining. The former has less island effect than the latter, with a flatter bottom and better-machined shape. Full article

(This article belongs to the Special Issue Enhanced Mechanical Properties of Metals by Surface Treatments)

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24 pages, 4523 KiB

Open AccessArticle

Investigation on the Rheological Properties and Microscopic Characteristics of Graphene and SBR Composite Modified Asphalt

by Lijun Wang, Fengxiang Liang, Zixia Li and Qiang Zhao

Coatings 2023, 13(7), 1279; https://doi.org/10.3390/coatings13071279 - 21 Jul 2023

Cited by 6 | Viewed by 1332

Abstract

Styrene-butadiene rubber (SBR) is commonly used as a modifier to enhance the low-temperature performance of asphalt. However, it is worth noting that while SBR modified asphalt exhibits good low-temperature performance, its high-temperature performance is comparatively inferior. This limitation significantly restricts the widespread use [...] Read more.

Styrene-butadiene rubber (SBR) is commonly used as a modifier to enhance the low-temperature performance of asphalt. However, it is worth noting that while SBR modified asphalt exhibits good low-temperature performance, its high-temperature performance is comparatively inferior. This limitation significantly restricts the widespread use of SBR modified asphalt. As a new type of nanomaterial, graphene (GR) can change the microstructure of asphalt binder and provide asphalt with better mechanical, thermal, and adhesion properties. The main purpose of this study is to explore the influence of GR and SBR composite incorporation on the performance indexes of modified asphalt, and to study its compatibility and modification mechanism from the microscopic point of view of asphalt. The weight factor optimization system of modified asphalt was established by an analytic hierarchy process, and the optimum content of GR was determined to be 0.1% in a quantifiable way. The test results demonstrate that the inclusion of graphene substantially enhances the high-temperature rutting resistance of asphalt, reduces the temperature sensitivity of modified asphalt, and improves its storage stability. However, its effect on the low-temperature performance of asphalt is relatively minimal. Microscopic experimental results reveal the formation of a stable structure at the interface between GR and SBR in the composite modified asphalt. Furthermore, the dispersed phase exhibits improved uniformity, which positively impacts the stability of the asphalt binder. Full article

(This article belongs to the Special Issue Asphalt Pavement: Materials, Design and Characterization)

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15 pages, 6538 KiB

Open AccessArticle

Development of Resonant Cavity Film for 575 nm All-Solid-State Laser System

by Han Zhu, Yawu Xin, Yunru Chen, Shihui Ma, Yuxia Zhang, Yongchao Peng, Yixin Lin, Shifu Xiong and Zhanggui Hu

Coatings 2023, 13(7), 1278; https://doi.org/10.3390/coatings13071278 - 21 Jul 2023

Viewed by 1407

Abstract

Yellow lasers have attracted much attention due to their applications in biomedicine, astronomy and spectroscopy, and the resonant cavity is an important part of lasers. In this work, the resonant cavity film was studied and prepared using physical vapor deposition (PVD) technology to [...] Read more.

Yellow lasers have attracted much attention due to their applications in biomedicine, astronomy and spectroscopy, and the resonant cavity is an important part of lasers. In this work, the resonant cavity film was studied and prepared using physical vapor deposition (PVD) technology to couple and match the optical properties of Dy,Tb:LuLiF₄ crystal to generate yellow laser. In the process of film deposition, the substrate temperature has an important influence on the quality of the film. Therefore, we first investigated the effect of HfO₂ film quality at different substrate temperatures. Furthermore, the multilayer film was designed to couple and match the optical properties of Dy,Tb:LuLiF₄ crystal. According to the designed film system scheme, HfO₂ and UV-SiO₂ were used as high- and low-refractive index film materials for resonant cavity film preparation using the PVD technique, and the effect of process parameters on the film quality was investigated. A 450 nm pump laser was used to directly pump Dy³⁺ to excite and generate the yellow laser. In this process, the excited radiation jump occurs in the crystal, and the generated laser in the new band reaches a certain threshold after oscillation and gain in the resonant cavity, thus successfully outputting a 575 nm yellow laser. Full article

(This article belongs to the Special Issue Research on Infrared and Laser Thin Films)

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28 pages, 2359 KiB

Open AccessReview

A Review of Optical Fiber Sensing Technology Based on Thin Film and Fabry–Perot Cavity

by Chaoqun Ma, Donghong Peng, Xuanyao Bai, Shuangqiang Liu and Le Luo

Coatings 2023, 13(7), 1277; https://doi.org/10.3390/coatings13071277 - 21 Jul 2023

Cited by 11 | Viewed by 4274

Abstract

Fiber sensors possess characteristics such as compact structure, simplicity, electromagnetic interference resistance, and reusability, making them widely applicable in various practical engineering applications. Traditional fiber sensors based on different microstructures solely rely on the thermal expansion effect of silica material itself, limiting their [...] Read more.

Fiber sensors possess characteristics such as compact structure, simplicity, electromagnetic interference resistance, and reusability, making them widely applicable in various practical engineering applications. Traditional fiber sensors based on different microstructures solely rely on the thermal expansion effect of silica material itself, limiting their usage primarily to temperature or pressure sensing. By employing thin film technology to form Fabry–Perot (FP) cavities on the end-face or inside the fiber, sensitivity to different physical quantities can be achieved using different materials, and this greatly expands the application range of fiber sensing. This paper provides a systematic introduction to the principle of FP cavity fiber optic sensors based on thin film technology and reviews the applications and development trends of this sensor in various measurement fields. Currently, there is a growing need for precise measurements in both scientific research and industrial production. This has led to an increase in the variety of structures and sensing materials used in fiber sensors. The thin film discussed in this paper, suitable for various types of sensing, not only applies to fiber optic FP cavity sensors but also contributes to the research and advancement of other types of fiber sensors. Full article

(This article belongs to the Special Issue Recent Advances in the Development of Thin Films)

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36 pages, 6604 KiB

Open AccessArticle

New Azo Dyes-Based Mg Complex Pigments for Optimizing the Anti-Corrosion Efficiency of Zinc-Pigmented Epoxy Ester Organic Coatings

by Miroslav Kohl, Fouzy Alafid, Karolína Boštíková, Marek Bouška, Anna Krejčová, Jan Svoboda, Stanislav Slang, Ludmila Michalíčková, Andréa Kalendová, Radim Hrdina, Ladislav Burgert, Eva Schmidová, Pravin P. Deshpande and Abhijit A. Bhopale

Coatings 2023, 13(7), 1276; https://doi.org/10.3390/coatings13071276 - 20 Jul 2023

Cited by 7 | Viewed by 2280

Abstract

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C [...] Read more.

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C₃₄H₂₆MgN₈O₆), Mg-Dye-II (C₂₆H₁₉MgN₃O₅), Mg-Dye-III (C₁₇H₁₀MgN₂O₃), and Mg-Dye-IV (C₂₅H₁₈MgN₄O₆) with a series of azo carboxylate ligands were prepared from the diazo-coupling reaction of anthranilic acid with 5-methyl-2-phenyl-3-pyrazolone (Dye I; C₁₇H₁₄N₄O₃), anthranilic acid with naphthol AS-PH (Dye II; C₂₆H₂₁N₃O₅), anthranilic acid with 2-naphthol (Dye III; C₁₇H₁₂N₂O₃), and 2-amino-5-nitrophenol with naphthol AS-PH (Dye IV; C₂₅H₂₀N₄O₆). The synthesized novel magnesium complex dyes were characterized by analytical methods. Model coatings containing these dyes at pigment volume concentrations (PVCs) = 1, 3, 5 and 10% and zinc at a ratio of pigment volume concentration/critical pigment volume concentration (PVC/CPVC) = 0.60 were formulated to study the inhibitory properties of the individual synthesized magnesium complex dyes. Model coatings containing inorganic pigments (MgO and Ca-Mg-HPO₄) at PVCs = 1%, 3%, 5% and 10% and zinc at PVC/CPVC = 0.60 were also formulated. The coating pigmented only by zinc at PVC/CPVC = 0.60 was prepared as a standard organic coating. Corrosion resistance was also evaluated by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The properties of organic coatings were also tested using other standardized and derived corrosion tests. In addition, the mechanical properties of the studied organic coatings were determined using standard tests. The aim of the work was to verify the possible synergistic efficiency of novel magnesium complex dyes by improving the mechanical, anti-corrosion, and chemical properties of zinc pigmented organic coatings. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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14 pages, 3825 KiB

Open AccessArticle

Quality of Low-Carbon Steel as a Distribution of Pollution and Fatigue Strength Heated in Oxygen Converter

by Tomasz Lipiński

Coatings 2023, 13(7), 1275; https://doi.org/10.3390/coatings13071275 - 20 Jul 2023

Viewed by 1144

Abstract

The works available in the literature presenting the influence of impurities on the properties (mainly fatigue strength) of material give an answer with a high degree of probability for hard steels and large precipitations (usually above 10 µm). The impact of non-metallic impurities [...] Read more.

The works available in the literature presenting the influence of impurities on the properties (mainly fatigue strength) of material give an answer with a high degree of probability for hard steels and large precipitations (usually above 10 µm). The impact of non-metallic impurities on the durability of high-ductility steels causes much greater problems and is much more difficult to explain. The results of the existing studies rarely take into account the diameter of the impurities in relation to the distance between the impurities. This paper presents the results of tests carried out on a low-carbon steel heated in a 100-tonne oxygen converter and deoxidized under vacuum. The fatigue strength test was carried out on cylindrical samples using rotational bending for different tempering temperatures of the steel. The quotient of the average size of the inclusions and the average distance between the inclusions were analyzed. Based on the obtained results, it was found that steel annealed in the converter and vacuum degassed has a content of both phosphorus and sulfur below 0.02% and a total volume of impurities of 0.086%. The main fraction of impurities are oxide inclusions with a diameter below 2 µm. An increase in fatigue strength was found along with an increase in the number of impurities, mainly of small diameters. Full article

(This article belongs to the Special Issue Recent Progress in Metal Additive Manufacturing)

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19 pages, 33047 KiB

Open AccessArticle

The Corrosion Behavior of Al/Al₂O₃ Composite Films with Ultra-Dense Structure Exposed to Lead-Bismuth Eutectic at 450 to 650 °C

by Xing Yin, Xiteng Li, Hao Wang, Ke Zhao, Jun Wang, Le Chen, Zhongzhen Wu and Yong Chen

Coatings 2023, 13(7), 1274; https://doi.org/10.3390/coatings13071274 - 20 Jul 2023

Cited by 2 | Viewed by 1967

Abstract

Al₂O₃ coatings are the most promising candidate material for mitigating (lead-bismuth eutectic) LBE corrosion at elevated temperatures, but preventing inward diffusion of Pb, Bi, and O for the ceramic coating remains a critical challenge. Here, we have fabricated an amorphous [...] Read more.

Al₂O₃ coatings are the most promising candidate material for mitigating (lead-bismuth eutectic) LBE corrosion at elevated temperatures, but preventing inward diffusion of Pb, Bi, and O for the ceramic coating remains a critical challenge. Here, we have fabricated an amorphous Al₂O₃ coating with an ultra-dense structure by continuous high-power magnetron sputtering (C-HPMS). After LBE corrosion at 550 °C for 2000 h, nanocavities induced by the phase transformation from amorphous to γ-Al₂O₃ provide the diffusion path for Fe, O, Pb, and Bi in which the corrosion products, such as Fe₃O₄, PbO₂, or their mixed oxides, form. Furthermore, the diffusion of Pb to the substrate and Cr segregation at the interface between the coating and substrate are observed for the sample exposed to LBE at 550 °C for 4000 h. Additionally, the hardness and interface bonding strength are enhanced after LBE corrosion. Moreover, pit corrosion was found to be the main failure mode of coating, and pits that merged with each other induced large area failure at a temperature of 650 °C. The corrosion mechanism of Al₂O₃ includes element diffusion, phase transformation, and chemical reaction. This work not only provides a deep understanding of the corrosion mechanism of amorphous Al₂O₃ coatings, but also shows the optimization method on the corrosion resistance of Al₂O₃ coating. Full article

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21 pages, 1088 KiB

Open AccessEditor’s ChoiceReview

Present and Future of ZrO₂ Nanostructure as Reservoir for Drug Loading and Release

by Ramona-Daniela Radu (Dușman) and Doina Drăgănescu

Coatings 2023, 13(7), 1273; https://doi.org/10.3390/coatings13071273 - 20 Jul 2023

Cited by 6 | Viewed by 2359

Abstract

Extensive research has been conducted on ZrO₂ nanostructures due to their favorable biocompatibility, low toxicity, and promising prospects in various biomedical applications. They can be used as drug carriers, facilitating the administration of therapeutic substances into the body while enhancing their effectiveness [...] Read more.

Extensive research has been conducted on ZrO₂ nanostructures due to their favorable biocompatibility, low toxicity, and promising prospects in various biomedical applications. They can be used as drug carriers, facilitating the administration of therapeutic substances into the body while enhancing their effectiveness and safety. This is achieved by regulating the timing, location, and rate at which drugs are released within the body. Several factors can influence the effectiveness of drug loading onto ZrO₂ nanostructures, such as the physicochemical characteristics of the drugs, the surface properties of the ZrO₂ nanostructures, and the specific methods used for drug loading. A wide range of drugs may be loaded onto ZrO₂ nanostructures including anti-cancer drugs, antibiotics, anti-inflammatory drugs, antifungal drugs, anti-osteoporotic drugs, etc. The release kinetics of drugs can be influenced by different factors, such as the size and shape of ZrO₂ nanostructures, the pH and temperature of the release medium, and the characteristics and molecular weight of the specific drug being released. While ZrO₂ nanostructures have demonstrated significant potential as drug delivery systems, further research on these structures is essential to optimize drug loading and release strategies. Full article

(This article belongs to the Special Issue New Strategies and Recent Advances in Investigations of Micro- and Nano-Coatings for Technological and Biomedical Applications)

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17 pages, 10326 KiB

Open AccessArticle

A Comparative Study on Characterization and High-Temperature Wear Behaviors of Thermochemical Coatings Applied to Cobalt-Based Haynes 25 Superalloys

by Ali Günen and Ömer Ergin

Coatings 2023, 13(7), 1272; https://doi.org/10.3390/coatings13071272 - 20 Jul 2023

Cited by 9 | Viewed by 1678

Abstract

This study investigated the characteristic properties of aluminizing, boronizing, and boro-aluminizing coatings grown on Haynes 25 superalloys and their effects on the high-temperature wear behavior. The coating processes were conducted in a controlled atmosphere at 950 °C for 3 h. Characterization studies were [...] Read more.

This study investigated the characteristic properties of aluminizing, boronizing, and boro-aluminizing coatings grown on Haynes 25 superalloys and their effects on the high-temperature wear behavior. The coating processes were conducted in a controlled atmosphere at 950 °C for 3 h. Characterization studies were performed using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, nanoindentation testing, and high-temperature wear tests. It was determined that the thickness values of aluminide, boride, and boride–aluminide coatings were 140 ± 1.50 µm, 37.58 ± 2.85 µm, and 14.73 ± 1.71 µm, and their hardness values were 12.23 ± 0.9 GPa, 26.34 ± 2.33 GPa, and 23.46 ± 1.29 GPa, respectively. The hardness of the coatings resulted in reduced wear volume losses both at room temperature and at 500 °C. While the best wear resistance was obtained in the boronized sample at room temperature due to its high hardness, the best wear resistance at 500 °C was obtained in the boro-aluminized sample with the oxidation–reduction effect of Al content and the lubricating effect of B content in the boro-aluminide coating. This indicates that the presence of aluminum in boride layers improves the high-temperature wear resistance of boride coatings. The coated samples underwent abrasive wear at room temperature, whereas at 500 °C, the wear mechanism shifted to an oxidative-assisted adhesive wear mechanism. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

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13 pages, 4179 KiB

Open AccessArticle

The Glaze Icing Performance of a Robust Superhydrophobic Film Composed of Epoxy Resin and Polydimethylsiloxane

by Aoyun Zhuang, Chao Li, Jianping Yu and Yao Lu

Coatings 2023, 13(7), 1271; https://doi.org/10.3390/coatings13071271 - 20 Jul 2023

Cited by 1 | Viewed by 1495

Abstract

Ice accretion on transmission lines can cause operational difficulties and disastrous events. In this study, a micro/nano-structured epoxy resin/polydimethylsiloxane (EP/PDMS) film on glass, with water droplet contact angles (CA) observed as high as 160° and the water droplet sliding angle (SA) < 1° [...] Read more.

Ice accretion on transmission lines can cause operational difficulties and disastrous events. In this study, a micro/nano-structured epoxy resin/polydimethylsiloxane (EP/PDMS) film on glass, with water droplet contact angles (CA) observed as high as 160° and the water droplet sliding angle (SA) < 1° was fabricated by aerosol-assisted chemical vapor deposition (AACVD). The glaze icing performance of the superhydrophobic EP/PDMS films have been investigated by comparing the bare glass and room temperature vulcanized (RTV) silicon rubber-coated glass substrate representing the glass insulators and silicone rubber insulators, respectively. Compared with the bare glass and the RTV silicon rubber coating, the EP/PDMS superhydrophobic coating showed excellent performance in delaying glaze icing, especially in the early stages of icing. After 20 min of glaze icing with tilting angle of 90° at −5 and −10 °C, 38.9% and 85.7% of the RTV silicon rubber coating were covered, respectively, and less than 3% of the EP/PDMS coating was covered by ice when the blank glass sheet was completely covered. The EP/PDMS films also showed good mechanical robustness and long-term stability, which are important considerations in their widespread real-world adoption. Full article

(This article belongs to the Special Issue Structural, Mechanical and Tribological Properties of Hard Coatings)

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