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Coatings, Volume 14, Issue 6 (June 2024) – 121 articles

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13 pages, 1773 KiB  
Article
Failure Causes Analysis of Circumferential Cracking on Gathering Pipeline in M Oil and Gas Field
by Xuehui Zhao, Zicheng Zhang, Zhiwu He, Yan Han and Juntao Yuan
Coatings 2024, 14(6), 770; https://doi.org/10.3390/coatings14060770 (registering DOI) - 18 Jun 2024
Viewed by 64
Abstract
The gathering and transportation pipeline experienced corrosion cracking failure after 2 years of operation. This paper conducted an analysis on the reasons for the pipeline failure by integrating background information on its usage, as well as observations, analyses, and detection of the morphology [...] Read more.
The gathering and transportation pipeline experienced corrosion cracking failure after 2 years of operation. This paper conducted an analysis on the reasons for the pipeline failure by integrating background information on its usage, as well as observations, analyses, and detection of the morphology of failure samples. The results indicated that the fracture originated from the inner wall of the pipeline and extended to the outer wall along the wall thickness until complete fracture occurred. Based on microstructure analysis of the fracture and original microcracks at the top of the pipeline, it was determined that the fracture was a multi-source brittle fracture, spreading in both inter-granular and trans-granular forms with obvious radial quasi-cleavage fractures accompanied by secondary cracks. EDS analysis revealed that the element S was present in all zones related to fracture initiation, spreading, and transient zones. XRD analysis showed that corrosion products on the fracture surface were mainly composed of FeS, indicating the presence of H2S in the service environment leading to sulfide stress corrosion cracking characteristics in line with pipeline failure. It is recommended to confirm the source of H2S in the service medium and test residual stress within the same pipeline for potential risk assessment regarding cracking in other areas. Full article
(This article belongs to the Special Issue Corrosion/Wear Mechanisms and Protective Methods)
12 pages, 1230 KiB  
Article
Size Effect of Graphite Nanosheet-Induced Anti-Corrosion of Hydrophobic Epoxy Coatings
by Kuilin Lv, Yiwang Bao, Huachao Ma, Xiaogen Liu, Ying Zhu and Detian Wan
Coatings 2024, 14(6), 769; https://doi.org/10.3390/coatings14060769 (registering DOI) - 18 Jun 2024
Abstract
In order to broaden the selectivity of graphite nanosheet additives on epoxy resin-based coatings and verify the size effect, this work aims to dope graphite nanosheets of different sizes into the three-dimensional structure produced by cross-linking and curing epoxy resin and polyamide resin. [...] Read more.
In order to broaden the selectivity of graphite nanosheet additives on epoxy resin-based coatings and verify the size effect, this work aims to dope graphite nanosheets of different sizes into the three-dimensional structure produced by cross-linking and curing epoxy resin and polyamide resin. In addition, a micro-nano level secondary structure and a surface with special roughness are constructed to obtain the composite epoxy hydrophobic coating. The influence of the size effect of graphite nanosheets on the hydrophobic performance and corrosion resistance of the coating is summarized as well. Among them, the optimized doping size (2.2 μm) of graphite nanosheets in the epoxy coating showed the largest impedance arc of 2.58 × 108 Ω cm2, which could form an excellent nano-network covering the micropores to impede the diffusion of corrosive medium. Through simulation calculation analysis, we also found that the edge site of graphene is more effective in capturing H2O and O2; therefore, a smaller size of graphene with a large edge can be more favorable. This work will be used as a reference for the industrial application of graphite anti-corrosive coating. Full article
16 pages, 19918 KiB  
Article
A Deep Learning Image Corrosion Classification Method for Marine Vessels Using an Eigen Tree Hierarchy Module
by Georgios Chliveros, Iason Tzanetatos and Stylianos V. Kontomaris
Coatings 2024, 14(6), 768; https://doi.org/10.3390/coatings14060768 - 18 Jun 2024
Viewed by 103
Abstract
This paper involves the automation of a visual characterisation technique for corrosion in marine vessels, as it appears in the hull preventive coatings of marine vessels and their surfaces. We propose a module that maximizes the utilisation of features learned by a deep [...] Read more.
This paper involves the automation of a visual characterisation technique for corrosion in marine vessels, as it appears in the hull preventive coatings of marine vessels and their surfaces. We propose a module that maximizes the utilisation of features learned by a deep convolutional neural network to identify areas of corrosion and segment pixels in regions of inspection interest for corrosion detection. Our segmentation module is based on Eigen tree decomposition and information-based decision criteria in order to produce specific corroded spots—regions of interest. To assess performance and compare it with our method, we utilize several state-of-the-art deep learning architectures.The results indicate that our method achieves higher accuracy and precision while maintaining the significance score across the entire dataset. To the best of our knowledge, this is the first Eigen tree-based module in the literature in the context of trained neural network predictors for classifying corrosion in marine vessel images. Full article
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17 pages, 3996 KiB  
Article
Study of Ceramic Hollow Buoyant Balls Prepared Based on Slip Mold Casting and Brazing Process
by Yu Lei, Jian Zhou, Guizhen Liu, Lin Wang and Zhongjun Ding
Coatings 2024, 14(6), 767; https://doi.org/10.3390/coatings14060767 - 17 Jun 2024
Viewed by 244
Abstract
In the domain of deep-sea buoyancy material applications, hollow ceramic spheres, known for their high strength and low mass-to-drainage ratio, contribute to increased buoyancy and payload capacity enhancement for deep submersibles, constituting buoyancy materials of exceptional overall performance. This study entails the brazing [...] Read more.
In the domain of deep-sea buoyancy material applications, hollow ceramic spheres, known for their high strength and low mass-to-drainage ratio, contribute to increased buoyancy and payload capacity enhancement for deep submersibles, constituting buoyancy materials of exceptional overall performance. This study entails the brazing of two ceramic hemispherical shells, obtained through slurry molding, to form a ceramic float. This process, which integrates slurry molding and ceramic brazing, facilitates buoyancy provision. Further refinement involves welding a ceramic connector onto the ceramic shell, incorporating a top opening to create a ceramic float equipped with an observation window seat. The ceramic float maintains uniform wall thickness, while the observation window facilitates external environmental observation in deep-sea research. Two pressure-resistant spherical shells, produced using this process, underwent testing, revealing the wall thickness of the prepared alumina ceramic hollow spheres to be 1.00 mm, with a mass-to-drainage ratio of 0.47 g/cm3 and a buoyancy coefficient of 53%. The resultant ceramic hollow floating ball can withstand hydrostatic pressure of 120 MPa, while the pressure-resistant ball shell with an observation window seat can endure hydrostatic pressure of 100 MPa, ensuring safe operation at depths of 5000–6000 m. This process provides a production method for subsequent large-scale ceramic float manufacturing for the transportation of objects or personnel. Full article
(This article belongs to the Special Issue Laser-Assisted Processes and Thermal Treatments of Materials)
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14 pages, 18506 KiB  
Article
Influence of Current Duty Cycle and Voltage of Micro-Arc Oxidation on the Microstructure and Composition of Calcium Phosphate Coating
by Axaule Mamaeva, Aidar Kenzhegulov, Aleksander Panichkin, Rinat Abdulvaliyev, Dametken Fischer, Nauryzbek Bakhytuly and Nazgul Toiynbaeva
Coatings 2024, 14(6), 766; https://doi.org/10.3390/coatings14060766 - 17 Jun 2024
Viewed by 196
Abstract
The micro-arc oxidation (MAO) technique was employed to produce calcium phosphate coatings on titanium surfaces using an electrolyte composed of hydroxyapatite and calcium carbonate in an aqueous solution of orthophosphoric acid. The coatings’ morphology and composition were regulated by adjusting electrical parameters, specifically [...] Read more.
The micro-arc oxidation (MAO) technique was employed to produce calcium phosphate coatings on titanium surfaces using an electrolyte composed of hydroxyapatite and calcium carbonate in an aqueous solution of orthophosphoric acid. The coatings’ morphology and composition were regulated by adjusting electrical parameters, specifically the duty cycle and voltage. This study examined the effects of the duty cycle and voltage during the MAO process on the microstructure and composition of calcium phosphate coatings on VT1–0 titanium substrates. Scanning electron microscopy (SEM) was utilized to analyze the microstructure and thickness of the coatings, while X-ray diffraction (XRD) was employed to determine their phase composition. The findings reveal that the surface morphology of the calcium phosphate coatings transitions from a porous, sponge-like structure to flower-like formations as the duty cycle and voltage increase. A linear increase in the voltage within the applied duty cycles led to a rise in the size of the forming particles of amorphous/crystalline structures containing phases of monetite (CaPO3(OH)), monocalcium phosphate monohydrate (Ca(H2PO4)2·H2O), and calcium pyrophosphate (γ–Ca2P2O7). Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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16 pages, 5276 KiB  
Article
A New Method for Determining Necking of Sheet Metal Based on Main Strain Topography
by Liqiu Shi, Yingjie Yang, Bo Hou, Weifang Gu, Haitao Zhao, Yan Feng and Zhouming Hang
Coatings 2024, 14(6), 765; https://doi.org/10.3390/coatings14060765 - 17 Jun 2024
Viewed by 221
Abstract
There are various methods to evaluate the forming limit of a sheet, and these criteria can be classified as position-dependent, time-dependent, and position-time dependent according to the basis of judgment. However, these criteria have a single function and can only find the forming [...] Read more.
There are various methods to evaluate the forming limit of a sheet, and these criteria can be classified as position-dependent, time-dependent, and position-time dependent according to the basis of judgment. However, these criteria have a single function and can only find the forming limit of the sheet and cannot determine the strain distribution, strain change, or fracture location during the sheet forming process. This paper introduces a time–location-dependent method, i.e., the spatial strain rate method, which is used to detect the onset of necking of a sheet. The spatial strain rate is directly based on the strain and can not only find the forming limit of the sheet but also depict the strain distribution and strain variation during the two phases of the experimental process—distributed instability and concentrated instability—as well as predict the location of sheet fracture. The spatial strain rate of AA5083 aluminum alloy of different widths was analyzed and verified in detail via Nakazima experiments using digital image correlation techniques and compared with the guidelines published in the literature in recent years. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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19 pages, 2238 KiB  
Article
Effect of Chain Orientation on Coupling of Optical and Mechanical Anisotropies of Polymer Films
by Aref Samadi-Dooki, Mark A. Lamontia, Juan David Londoño, Curtis Williamson, Heidi E. Burch, Mobin Yahyazadehfar, Leopoldo A. Carbajal and Kostantinos Kourtakis
Coatings 2024, 14(6), 764; https://doi.org/10.3390/coatings14060764 - 16 Jun 2024
Viewed by 312
Abstract
Polymer films have broad applications in different industries with specific requirements for their optical and mechanical properties. In mass production, processing conditions during film formation that apply forces and motions in various directions to the film tend to manifest preferred molecular chain orientation [...] Read more.
Polymer films have broad applications in different industries with specific requirements for their optical and mechanical properties. In mass production, processing conditions during film formation that apply forces and motions in various directions to the film tend to manifest preferred molecular chain orientation in the film microstructure, which unavoidably produces optical and mechanical anisotropies. In this paper, we investigate the effect of such macromolecular orientations on the optical and mechanical anisotropies of several polymer films, including polystyrene, poly(methyl methacrylate), poly(ethylene terephthalate), poly(ethylene naphthalate), poly(ether ether ketone), poly(ether sulfones), poly(ethylene chlorotrifluoroethylene), poly(phenylsulfone), and polycarbonate, at temperatures well below their respective glass transitions (Tg). The film mechanical responses, including elasticity, yielding, and post-yield behaviors, were obtained for the in- and out-of-plane directions utilizing tensile and nanoindentation testing methods, respectively. In addition, the net chain orientation within the films was evaluated by birefringence through analyzing the film optical refractive indices, which were verified and complemented by wide-angle X-ray scattering (WAXS) measurements. The results reveal a considerable quantitative correlation between the birefringence and the degree of elastic anisotropy and a qualitative correlation between the chain orientation and the film post-yield tensile instability (necking). These observations corroborate the interrelationship between the microstructure of polymer films and their optical and mechanical properties. In addition, they emphasize that process conditions can be selected to tune the optical and mechanical anisotropies to best serve the material performance in specific devices. We also propose an empirical equation to approximate the out-of-plane film stiffness based upon the optical and in-plane mechanical properties. Full article
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18 pages, 12215 KiB  
Article
Study on the Effects of GO on the Microstructure and Wear Resistance of CuCrZr Plasma Cladding Coatings
by Yang Wang, Hongjun Xiang, Zhiming Qiao, Jianwei Zhen, Qing-Ao Lv, Xichao Yuan, Chunyan Liang and Genrong Cao
Coatings 2024, 14(6), 763; https://doi.org/10.3390/coatings14060763 - 16 Jun 2024
Viewed by 231
Abstract
This study investigates the enhancement of wear resistance in CuCrZr rails through the plasma cladding of CuCrZr-GO coatings with a varying graphene oxide (GO) content. The microstructure, phase composition, and mechanical properties of CuCrZr coatings containing 0%, 0.2%, 0.4%, 0.6%, and 0.8% GO [...] Read more.
This study investigates the enhancement of wear resistance in CuCrZr rails through the plasma cladding of CuCrZr-GO coatings with a varying graphene oxide (GO) content. The microstructure, phase composition, and mechanical properties of CuCrZr coatings containing 0%, 0.2%, 0.4%, 0.6%, and 0.8% GO were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), ESD surface scanning, friction and wear tests, and hardness analysis. The findings indicated that increasing the GO content from 0% to 0.6% results in a transition in the coating microstructure from columnar to equiaxed crystals, leading to an improved density. However, at 0.8% GO, numerous porosity defects were observed. The coating containing 0.6% graphene oxide (GO) exhibited a superior performance, with a hardness of 75, a friction coefficient of approximately 0.7, and a wear mass of 2.84 mg under a 10 N load. In comparison to the CuCrZr coating lacking GO, the hardness showed an increase of around 4.8%, the friction coefficient decreased by approximately 5.1%, and the wear mass diminished by 59.4%. These findings hold significant implications for extending the operational lifespan of electromagnetic railguns. Full article
(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)
14 pages, 5267 KiB  
Article
Improving Trace Detection of Methylene Blue by Designing Nanowire Array on Boron-Doped Diamond as Electrochemical Electrode
by Sihan He, Kun Lin, Shaoheng Cheng, Nan Gao, Junsong Liu and Hongdong Li
Coatings 2024, 14(6), 762; https://doi.org/10.3390/coatings14060762 - 16 Jun 2024
Viewed by 299
Abstract
In this study, a boron-doped diamond nanowire array (BDD-NWA)-based electrode is prepared by using a microwave plasma chemical vapor deposition system and treated with inductively coupled plasma reactive ion etching. The BDD-NWA electrode is used for trace detection of methylene blue, which has [...] Read more.
In this study, a boron-doped diamond nanowire array (BDD-NWA)-based electrode is prepared by using a microwave plasma chemical vapor deposition system and treated with inductively coupled plasma reactive ion etching. The BDD-NWA electrode is used for trace detection of methylene blue, which has a wide linear range of 0.04–10 μM and a low detection limit of 0.72 nM. Both the superhydrophilicity (contact angle ~0°) and the dense nanowire array’s structure after the etching process improve the sensitivity of the electrochemical detection compared to the pristine BDD. In addition, the electrode shows great repeatability (peak current fluctuation range of −3.3% to 2.9% for five detection/cleaning cycles) and stability (peak current fluctuation range of −5.3% to 6.3% after boiling) due to the unique properties of diamonds (mechanical and chemical stability). Moreover, the BDD-NWA electrode achieves satisfactory recoveries (93.8%–107.5%) and real-time monitoring in tap water. Full article
(This article belongs to the Special Issue Advances in Diamond Materials and Films)
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12 pages, 3569 KiB  
Review
PbS Colloidal Quantum Dots: Ligand Exchange in Solution
by Chuanxi Zhang, Dong Han and Xiaoyu Zhang
Coatings 2024, 14(6), 761; https://doi.org/10.3390/coatings14060761 - 16 Jun 2024
Viewed by 329
Abstract
PbS colloidal quantum dots (CQDs) have the advantages of adjustable band gap, large exciton Bohr radius, controllable size, easy synthesis, and potential multi-exciton effect, making them attractive for photodetectors and solar cells. However, the long ligand chain wrapped on PbS CQDs limits carrier [...] Read more.
PbS colloidal quantum dots (CQDs) have the advantages of adjustable band gap, large exciton Bohr radius, controllable size, easy synthesis, and potential multi-exciton effect, making them attractive for photodetectors and solar cells. However, the long ligand chain wrapped on PbS CQDs limits carrier transport, and defect states of as-synthesized CQDs increase non-radiative recombination, negatively affecting photovoltaic performance. Surface properties determine the characteristics of CQDs, so ligand exchange processes are crucial. Because solution phase ligand exchange reduces labor and time requirements, it is more advantageous than solid phase ligand exchange. This review discusses the solution phase ligand exchange process of PbS CQDs, emphasizing the impact of surface ligands on conformation and conductivity. Full article
(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings, 2nd Edition)
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16 pages, 10618 KiB  
Article
The Microstructures and Wear Resistance of CoCrFeNi2Mox High-Entropy Alloy Coatings
by Hui Liang, Jinxin Hou, Jianhong Liu, Hongtai Xu, Yaning Li, Li Jiang and Zhiqiang Cao
Coatings 2024, 14(6), 760; https://doi.org/10.3390/coatings14060760 - 15 Jun 2024
Viewed by 174
Abstract
The CoCrFeNi2Mox (x = 0, 0.4, 0.5, 1.0, x values in atomic ratio) high-entropy alloy coatings were designed and prepared on the Ti-6Al-4V substrate by laser cladding technology, their microstructures, and dry sliding wear resistance were studied in detail. When [...] Read more.
The CoCrFeNi2Mox (x = 0, 0.4, 0.5, 1.0, x values in atomic ratio) high-entropy alloy coatings were designed and prepared on the Ti-6Al-4V substrate by laser cladding technology, their microstructures, and dry sliding wear resistance were studied in detail. When x < 0.4, the coatings were mainly composed of BCC solid solution phase, (Ni, Co)Ti2 phase, and α-Ti phase. When x ≥ 0.4, the new σ phase appeared in the coatings. As the Mo content increases from 0 to 1.0, the hardness showed a trend of first increasing and then decreasing, especially when x = 0.5, the coating hardness reached its maximum (882 HV), which was 2.65 times the hardness of the Ti-6Al-4V substrate. The CoCrFeNi2Mox high-entropy alloy coatings significantly improved the wear resistance of Ti-6Al-4V substrate, and with the increase in Mo content, the friction coefficient, widths/depths of worn tracks and wear rates of the coatings showed a trend of first decreasing and then increasing. In particular, when x = 0.5, the CoCrFeNi2Mo0.5 high-entropy alloy coating has the lowest friction coefficient (0.63), widths/depths of worn tracks (width: 803.690 μm; depth: 20.630 μm) and wear rate (5.136 × 10−5 mm3/(N·m)), which is one order of magnitude smaller than that of the substrate (3.694 × 104 mm3/(N·m)), demonstrating the best wear resistance. This is mainly because the appropriate proportion of hard α-Ti and σ phases effectively played a supporting role in resisting wear, while the relatively soft and dispersed BCC and (Ni, Co)Ti2 phases could effectively prevent the occurrence of brittle fracture during wear test process. Full article
11 pages, 4131 KiB  
Article
Investigation of the Bonding Mechanism of Al Powder Particles through Pulse Current Sintering Technology
by Zhou Lv and Ruifeng Liu
Coatings 2024, 14(6), 759; https://doi.org/10.3390/coatings14060759 - 15 Jun 2024
Viewed by 193
Abstract
Compared with traditional powder metallurgy, pulse current sintering is an advanced powder-forming technology, but its bonding mechanism is still an open topic for debate. In this paper, pulse current sintering is used as the connection technology and millimeter-sized Al particles are used as [...] Read more.
Compared with traditional powder metallurgy, pulse current sintering is an advanced powder-forming technology, but its bonding mechanism is still an open topic for debate. In this paper, pulse current sintering is used as the connection technology and millimeter-sized Al particles are used as the research object. In the whole sintering process, no pressure was loaded; the function of the pulse current was the only source of heat with which to achieve the bonding of Al particles. The bonding mechanism of pulse current sintering was investigated from the perspective of material connection behavior. The results show that the pulse current density of the particle surface reaches 3.48 × 105 A/m2 instantly, while the current density of the particle center is only 8187 A/m2 at the initial stage, which is the main difference between pulse current sintering and traditional powder metallurgy sintering. With the densification process, the current density and temperature distribution in the contact region as well as the center of Al particles contact region tend to be more consistent. Finally, dense interfacial bonding was obtained, and the contact region of Al particles also demonstrated a high hardness value of 0.6385 GPa and yield strength value of 212.83 MPa. The whole process can be considered as a comprehensive action of melting (evaporation), diffusion, and plastic deformation. Based on the above results, a new technology, named high-frequency pulse current sintering, was proposed. Full article
(This article belongs to the Special Issue Trends in Spark Plasma Sintering of Advanced Materials)
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14 pages, 3312 KiB  
Article
Water-Borne Photo-Thermal Superhydrophobic Coating for Anti-Icing, Self-Cleaning and Oil–Water Separation
by Jinsong Huang, Shengqi Lu, Yan Hu, Liming Liu and Hui You
Coatings 2024, 14(6), 758; https://doi.org/10.3390/coatings14060758 - 14 Jun 2024
Viewed by 289
Abstract
Superhydrophobic coatings with photo-thermal effects have advantages in anti-/de-icing and self-cleaning. Here, an eco-friendly and low-cost fabrication of superhydrophobic coating was proposed by spraying a water-borne suspension including carbon black and paraffin wax onto substrate-independent surfaces. The a water-borne suspension coated on stain [...] Read more.
Superhydrophobic coatings with photo-thermal effects have advantages in anti-/de-icing and self-cleaning. Here, an eco-friendly and low-cost fabrication of superhydrophobic coating was proposed by spraying a water-borne suspension including carbon black and paraffin wax onto substrate-independent surfaces. The a water-borne suspension coated on stain steel plate showed a strong water-repellence, delaying the ice freezing time to 665 s, which is much higher than that of bare stain steel plate (210 s) under the same experimental condition. The ice-melting time was measured as 120 s under a solar irradiation of 0.1 W/cm2, while the control group had no sign of ice-melting during the same time. As a concept of proof, the self-cleaning, anti-corrosion, and oil–water separation were enabled by spraying the water-borne suspension on various substrates, demonstrating its diverse performances. Hence, the water-borne superhydrophibic coating provides an efficient, safe, and sustainable solution for wettability-related applications. Full article
(This article belongs to the Special Issue Recent Advances in Hydrophobic Surface and Materials)
15 pages, 9195 KiB  
Article
Joining and Coating of Plasma Electrolytic Oxidated Aluminum Using a Silica Preceramic Polymer
by Monica Ferraris, Alessandro Benelli, Valentina Casalegno, Pavel Shashkov and Vincenzo Maria Sglavo
Coatings 2024, 14(6), 757; https://doi.org/10.3390/coatings14060757 - 14 Jun 2024
Viewed by 415
Abstract
This study evaluates the effectiveness of a silica preceramic polymer for joining and coating Plasma Electrolytic Oxidated (PEO) aluminum components at temperatures below 200 °C. PEO aluminum slabs were coated and joined with a silica precursor polymer (Durazane1800, Merck, Darmstadt, Germany), both with [...] Read more.
This study evaluates the effectiveness of a silica preceramic polymer for joining and coating Plasma Electrolytic Oxidated (PEO) aluminum components at temperatures below 200 °C. PEO aluminum slabs were coated and joined with a silica precursor polymer (Durazane1800, Merck, Darmstadt, Germany), both with and without the addition of 48 wt% silica nanoparticles, and cured at 180 °C for 4 h in air. Thermogravimetric analysis assessed the curing process and thermal stability, while X-ray diffraction confirmed the polymer’s conversion to amorphous silica after heating at 1200 °C. Resistance to humid environments was tested by soaking coated samples in tap water for a week, with no mass variation observed. Mechanical testing through tensile mode and tensile lap tests showed that adding 48 wt% silica nanoparticles significantly improved joint cohesion and nearly quadrupled mechanical strength. Fracture surfaces were examined using Field Emission Scanning Electron Microscopy, and composition analysis was performed with Energy Dispersion X-ray Spectroscopy. Crack detection was conducted using Computer Tomography with an in situ bending test setup to obtain the mechanical resistance of the PEO coating. The results indicate that the silica preceramic polymer is suitable for joining and coating PEO aluminum components, with silica nanoparticles enhancing mechanical strength and providing excellent thermal stability and resistance to humidity. Full article
(This article belongs to the Special Issue Plasma Electrolytic Oxidation (PEO) Coatings, 2nd Edition)
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13 pages, 2088 KiB  
Article
Modeling for the Fabrication Process of a ϕ1185 mm C/C Composite Thermal Insulation Tube in an Isothermal Chemical Vapor Infiltration Reactor
by Jicheng Zhou, Jianyong Zhan, Huiling Liang, Yan Guo, Baoxing Zhao, Linzhao Hao, Tong Zhang and Bingchun Jiang
Coatings 2024, 14(6), 756; https://doi.org/10.3390/coatings14060756 - 14 Jun 2024
Viewed by 279
Abstract
The large-size chemical vapor infiltration (CVI) of the carbon/carbon (C/C) composite thermal insulation tube is a key component for drawing large diameter monocrystalline silicon rods. However, the CVI densification process is complex, and the cost of experiment optimization is extremely high. In this [...] Read more.
The large-size chemical vapor infiltration (CVI) of the carbon/carbon (C/C) composite thermal insulation tube is a key component for drawing large diameter monocrystalline silicon rods. However, the CVI densification process is complex, and the cost of experiment optimization is extremely high. In this article, a multi-physics coupling simulation model was established and validated based on COMSOL Multiphysics v.5.6 software to simulate the fabrication process of an isothermal CVI process for a Φ1185 mm C/C composite thermal insulation tube. The influence of process parameters on densification was explored, and a method of optimization was proposed. Our modeling results revealed that the deposition status in areas of low densification was effectively and significantly enhanced after process optimization. At the monitoring site, the carbon density was no less than 1.08 × 103 kg·m−3, the average density of the composite-material thermal insulation tube improved by 5.7%, and the densification rate increased by 26.5%. This article effectively simulates the CVI process of large-sized C/C composite thermal insulation tubes, providing an important technical reference scheme for the preparation of large-sized C/C composite thermal insulation tubes. Full article
12 pages, 1078 KiB  
Article
Effect of Deep Cryogenic Treatment on the Artificial Aging Behavior of 6082 Aluminum Alloy
by Sawei Qiu, Jian Tang, Yiran Tian, Changping Wu, Tuo Ye, Erli Xia and Yuanzhi Wu
Coatings 2024, 14(6), 755; https://doi.org/10.3390/coatings14060755 - 14 Jun 2024
Viewed by 215
Abstract
This study investigates the impact of cryogenic treatment duration on the mechanical properties and microstructural evolution of 6082 aluminum alloy subjected to subsequent artificial aging. Tensile tests were conducted using an electronic universal testing machine, and the microstructure was characterized by employing optical [...] Read more.
This study investigates the impact of cryogenic treatment duration on the mechanical properties and microstructural evolution of 6082 aluminum alloy subjected to subsequent artificial aging. Tensile tests were conducted using an electronic universal testing machine, and the microstructure was characterized by employing optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that both the tensile strength and elongation of the alloy first increase and then decrease with the extension of cryogenic treatment duration. The alloy treated with 12 h of cryogenic treatment followed by artificial aging at 180 °C for 8 h achieved a peak strength of 390 MPa. Meanwhile, the alloy treated with 8 h of cryogenic treatment and the same artificial aging process reached a maximum elongation of 13%. All specimens of 6082 aluminum alloy subjected to cryogenic and aging treatments exhibited ductile fracture under room temperature tensile conditions. The size of dimples at the fracture surface first increased and then decreased with increasing cryogenic treatment duration, indicating a transition from deeper to shallower dimples. The cryogenic treatment did not significantly affect the grain size of the alloy, which remained approximately 230 µm on average. Cryogenic treatment facilitated the precipitation of fine, densely distributed precipitates, enhancing the pinning effect of dislocations and thus improving the tensile strength. Additionally, cryogenic treatment increased the dislocation density and promoted the formation of subgrains, while the grain boundary precipitates transitioned from a continuous to a discontinuous distribution, all of which contribute to the enhancement of the plasticity. Full article
(This article belongs to the Special Issue Microstructure, Mechanical and Tribological Properties of Alloys)
20 pages, 992 KiB  
Article
The Effects of Preharvest Silicon Treatment and Passive MAP on Quality and Shelf Life of White Button Mushrooms in Thermoformed Recycled PET Packaging System
by Tigist T. Shonte, Helen Grogan, Jesus Maria Frias Celayeta, Francesco S. Giordano, Andrew Reynolds, Orla O’Halloran, Lorraine Foley and Shivani Pathania
Coatings 2024, 14(6), 754; https://doi.org/10.3390/coatings14060754 - 14 Jun 2024
Viewed by 254
Abstract
A crop pretreatment with silicon was combined with passive modified atmosphere packaging (PMAP) in a thermoformed recycled PET packaging format as a novel approach to minimize the quality degradation in mushrooms. This study was aimed to evaluate the effects of (a) two preharvest [...] Read more.
A crop pretreatment with silicon was combined with passive modified atmosphere packaging (PMAP) in a thermoformed recycled PET packaging format as a novel approach to minimize the quality degradation in mushrooms. This study was aimed to evaluate the effects of (a) two preharvest treatments, namely preharvest control (PHTC) and preharvest silicon treatment (PHTS) and (b) four packaging lid formats, namely PMAP1: a single hole of 1.1 mm size, PMAP2: two holes of 0.53 mm size, PMAP3: three holes of 0.53 mm size, and PMAPC: OMNI-PW micro perforated cling film as a control on the quality and shelf life of mushrooms during five days of storage at 4 °C and 99.9% RH. The results of the analysis of variance showed that packaging type, storage days, and the double interaction effects of storage days × packaging type had significant effects (p < 0.0001) on the changes in O2, CO2, colour L* and a* values, ΔE, total soluble solids (TSS), and the density of mushrooms. Density, electrolyte leakage (EL), and TSS were significantly affected by the double interaction effects of preharvest treatment × packaging type. Overall, PMAP1, PMAP2, and PMAP3 resulted in lower O2 + higher CO2 within packages compared with the conventional control. A preharvest silicon treatment had little overall effect. PMAP 1, 2 and 3 had a significantly lower ΔE (=better quality) after 5 days storage compared to PMAPC which had the highest ΔE (lowest quality) overall. PMAP1 and PMAP2 had the lowest EL values compared to PMAP3 and PMAPC. PMAP1, PMAP2, and PMAP3 all gave better TSS levels and density compared to PMAPC. Notably, this study proved that a perforation-mediated MAP design for mushrooms packaged in a thermoformed recycled PET packaging format maintained improved CO2, lowered O2, and reduced EL while maintaining TSS and the density of the mushrooms during the storage period. Full article
(This article belongs to the Special Issue Advances in Modified Atmosphere Packaging and Edible Coatings)
12 pages, 6136 KiB  
Article
Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres
by Lei Huang, Lei Li, Yanfei Zhao, Yaoyao Liu, Hongyu Zheng, Zhongchen Du and Jian Liu
Coatings 2024, 14(6), 753; https://doi.org/10.3390/coatings14060753 - 14 Jun 2024
Viewed by 225
Abstract
Titanium alloys are considered lightweight alloys and are widely applied across various industries. However, titanium alloys are prone to wearing out or galvanic corrosion. In this paper, Ti6Al4V alloy was scanned by using a continuous laser in different atmospheres to prepare composite hardening [...] Read more.
Titanium alloys are considered lightweight alloys and are widely applied across various industries. However, titanium alloys are prone to wearing out or galvanic corrosion. In this paper, Ti6Al4V alloy was scanned by using a continuous laser in different atmospheres to prepare composite hardening coatings. The scanning speed was varied to adjust the heat input. When the alloy was irradiated in air, a whole coating composed of TiO2 and TiN was fabricated. With the increase in scanning speed from 10 mm/s to 20 mm/s, the melting area of the surface decreased from about 1.8 mm to 0 mm, but the thickness of the coatings underwent no significant change. When prepared under compressed oxygen with a speed of 10 mm/s, a coating with a thickness of about 60 μm was prepared. In addition, the layered phenomenon occurred, and an N-enriched layer was formed at the bottom of the coating. The coatings were composed of TiO2, TiN and Ti. With the increase in the scanning speed, the thickness of the coatings decreased obviously. The testing results show that the hardness of samples Ti-A10 and Ti-O10 increased by around 160% and 140% over that of untreated samples, respectively. The anti-corrosion performance of the samples treated via laser scanning was also improved. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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17 pages, 21168 KiB  
Article
Microstructure and Tribological Properties of HVOF-Sprayed Nanostructured WC-12Co/Fe3O4 Coatings
by Wojciech Żórawski, Anna Góral, Otakar Bokuvka, Medard Makrenek and Martin Vicen
Coatings 2024, 14(6), 752; https://doi.org/10.3390/coatings14060752 - 14 Jun 2024
Viewed by 262
Abstract
Due to wear and improper operation, many machine parts become useless, which is why issues of friction and wear remain constantly relevant across all industrial sectors. This paper presents the results of research on the microstructure and properties of a nanostructural composite coating [...] Read more.
Due to wear and improper operation, many machine parts become useless, which is why issues of friction and wear remain constantly relevant across all industrial sectors. This paper presents the results of research on the microstructure and properties of a nanostructural composite coating containing solid lubricant. The coating was deposited from a mixture of nanostructural WC-12Co powder and nanostructural Fe3O4 powder using HVOF spraying. Despite significant differences in grain size and density of both powders, the deposited coating consisted of WC-12Co matrix containing evenly distributed Fe3O4. The XRD analysis of the coating confirmed the presence of both components and the presence of W2C, which resulted from the decarburization of WC due to the high temperature during the spraying process. Furthermore, the microstructure analysis of the coatings confirmed that they contained both nanostructural WC and Fe3O4 grains that were present in the feedstock. The coefficients of friction, microhardness, and wear of the nanostructured composite coatings were determined using an experimental binomial program. Based on the ANOVA conducted, it was determined that the most significant impact on the friction coefficient is the Fe3O4 content in the sprayed mixture, while the oxygen to propane ratio affects the microhardness. For the wear of nanostructural composite coatings, the most important parameter is the spraying distance. Full article
(This article belongs to the Special Issue The Present Status of Thermally Sprayed Composite Coatings)
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11 pages, 674 KiB  
Article
The Effect of Different Coating Agents on the Microhardness, Water Sorption, and Solubility of EQUIA Forte® HT
by Saleh Y. Alqasabi, Ayman M. Sulimany, Thamer Almohareb, Abdullah S. Alayad and Omar A. Bawazir
Coatings 2024, 14(6), 751; https://doi.org/10.3390/coatings14060751 - 13 Jun 2024
Viewed by 202
Abstract
Objective: This study aimed to assess the effect of four different surface-coating agents on the microhardness, water sorption, and solubility of the highly viscous glass ionomer cement EQUIA Forte® HT. Materials and methods: A total of 100 cylindrical EQUIA Forte® HT [...] Read more.
Objective: This study aimed to assess the effect of four different surface-coating agents on the microhardness, water sorption, and solubility of the highly viscous glass ionomer cement EQUIA Forte® HT. Materials and methods: A total of 100 cylindrical EQUIA Forte® HT samples were examined, with 50 tested for Vickers hardness and the other 50 for water sorption and solubility. For each test, the specimens were divided into five groups (10 specimens/group) according to coating method: Group 1—no coating (control), Group 2—EQUIA Forte® Coat, Group 3—Single Bond™ Universal Adhesive, Group 4—ExciTE®F adhesive, and Group 5—petroleum jelly. Data were analyzed using the paired t-test, one-way analysis of variance, and Tukey’s post hoc test for multiple comparisons. Statistical significance was set at p < 0.05. Results: The mean microhardness of the coated groups was significantly higher than that of the uncoated group. Moreover, a significant difference in the microhardness value was detected between the coated groups. Furthermore, EQUIA Forte® Coat had the highest mean hardness value. The mean water sorption at 7 days showed that EQUIA Forte® Coat had the lowest values. In terms of water solubility, a statistically significant difference was found between no coating and all groups except EQUIA Forte®, between Single Bond Universal Adhesive and petroleum jelly, between petroleum jelly and EQUIA Forte Coat, and between EQUIA Forte® Coat and ExciTE®F. Conclusions: The study revealed that all coating agents significantly increased the microhardness of EQUIA Forte® HT, with EQUIA Forte® Coat showing the highest hardness and the lowest water sorption values. Full article
(This article belongs to the Special Issue Reshaping Dentistry: Coatings and Innovations in Dental Biomaterials)
20 pages, 4256 KiB  
Article
Study on High Temperature Properties of Yttrium-Modified Aluminide Coating on K444 Alloy by Chemical Vapor Deposition
by Hanzhe Yang, Yong Wu, Qingyun Sun, Fu Yang, Chunhuai Xia, Siyao Xia and Jianrong Du
Coatings 2024, 14(6), 750; https://doi.org/10.3390/coatings14060750 - 13 Jun 2024
Viewed by 207
Abstract
This work aims to explore a method of improving the high-temperature oxidation resistance and thermal corrosion resistance of a hollow blade of gas turbine. The yttrium-modified aluminide coating was prepared on the surface of nickel-based superalloy K444 by chemical vapor deposition (CVD). The [...] Read more.
This work aims to explore a method of improving the high-temperature oxidation resistance and thermal corrosion resistance of a hollow blade of gas turbine. The yttrium-modified aluminide coating was prepared on the surface of nickel-based superalloy K444 by chemical vapor deposition (CVD). The microstructure, high temperature oxidation resistance, and thermal corrosion resistance of the modified aluminide coating deposited at 950 °C, 1000 °C, and 1050 °C were compared. The microstructure and morphology of the coatings were observed and analyzed by XRD, SEM, and EDS. The results showed that adding yttrium and changing the deposition temperature had no effect on the double-layer structure (outer layer and diffusion layer) of the coating. Compared with adding yttrium, the deposition temperature had a greater effect on the coating thickness. When the deposition temperature was 1050 °C and the deposition time was 2 h, the thickness of the yttrium-modified aluminide coating increased by 33% compared to that of a single aluminide coating. The high temperature oxidation resistance and thermal corrosion resistance of the three groups of yttrium-modified aluminide coatings are better than that of the single aluminide coating. The resistance to high temperature oxidation and hot corrosion of the yttrium-modified aluminide coating deposited at 1050 °C was better than that of yttrium-modified aluminide coating deposited at 1000 °C, and both were better than that of the modified coating deposited at 950 °C. The higher the deposition temperature, the higher the yttrium content of the coating, the faster the film-forming speed of α-Al2O3, and the better the high temperature oxidation resistance and thermal corrosion resistance of the coating. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
19 pages, 3640 KiB  
Article
Research on the Skidding Resistance and Attenuation Characteristics of Asphalt Pavement Based on Image Recognition-Analysis Strategy
by Ke Zhang, Dianliang Xi, Yu Zhao, Wei Xie, Wei Zhang and Jiantao Gao
Coatings 2024, 14(6), 749; https://doi.org/10.3390/coatings14060749 - 13 Jun 2024
Viewed by 201
Abstract
To accurately evaluate the skidding resistance of asphalt pavements, a texture imaging device was developed to realize the standardized acquisition of pavement images. Based on the gray-level co-occurrence matrix and multifractal theory of texture structure, the influence of segregation degree and gradation type [...] Read more.
To accurately evaluate the skidding resistance of asphalt pavements, a texture imaging device was developed to realize the standardized acquisition of pavement images. Based on the gray-level co-occurrence matrix and multifractal theory of texture structure, the influence of segregation degree and gradation type on the texture properties of asphalt pavement was studied. Meanwhile, a comprehensive evaluation index of skidding resistance was proposed for asphalt pavement. Furthermore, the attenuation characteristics of the anti-skidding performance for asphalt mixture were explored, and the corresponding attenuation model of asphalt pavement was established. The results show that the segregation degree and gradation type significantly affected the texture parameters and anti-skidding performance of asphalt mixture. Specially, with an increase in the segregation degree of coarse aggregate, the parameters of energy, entropy, and multifractal spectrum width gradually increased, whereas the inertial moment gradually decreased. The variation range of the multifractal spectrum difference initially increased and subsequently decreased. For the texture parameters such as energy, entropy, inertial moment, and multifractal spectrum width Δα, the values of the asphalt mixture with larger nominal maximum particle were higher than those of the mixture with smaller nominal maximum particle, whereas the multifractal spectrum difference value showed the opposite law. In addition, the texture parameters of energy, entropy, and multifractal spectrum width exhibited good linear correlation with the texture depth (TD) of asphalt mixtures with various segregation levels and gradation types. The index based on the texture parameters of energy, entropy, and multifractal spectrum width effectively evaluated the skidding resistance of asphalt pavements, which showed the same trend as the TD with the increase of the abrasion number. The achievement provides an effective solution for the evaluation of skidding resistance and attenuation characteristics of asphalt mixtures. Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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16 pages, 1227 KiB  
Review
Soft Feel Material Coatings on the Surface of Plastic Products and Their Application Prospects in the Popular Fields: A Review
by Bangzheng Jiang, Yueyang Xu, Lanlan Zhang, Xing Zhou, Hui Zhang, Luqi Liu and Jun Zhao
Coatings 2024, 14(6), 748; https://doi.org/10.3390/coatings14060748 - 13 Jun 2024
Viewed by 242
Abstract
Soft-feel material (mainly polyurethane (PU), silicone rubber (SR), and polyacrylic acid (PAA), etc.) coatings can overcome the drawbacks of common plastic products such as acrylonitrile butadiene styrene copolymer (ABS), polycarbonate (PC), and polypropylene (PP), which have cold, hard, and bright surfaces, achieving warm, [...] Read more.
Soft-feel material (mainly polyurethane (PU), silicone rubber (SR), and polyacrylic acid (PAA), etc.) coatings can overcome the drawbacks of common plastic products such as acrylonitrile butadiene styrene copolymer (ABS), polycarbonate (PC), and polypropylene (PP), which have cold, hard, and bright surfaces, achieving warm, soft, and matte effects, thus greatly improving the quality and price level of the products. Although these coating materials can partially meet the main requirements of the soft feel effect, their comprehensive properties, such as mechanical performance, weather resistance, and foul resistance, still have shortcomings and need to be improved. Besides, there is a lack of in-depth exploration in the literature on the design philosophy and preparation strategies of soft-feel materials. Starting from the mechanism of producing this comfortable feeling and then systematically exploring their application in popular fields with high economic added value, such as mobile phone cases, electronic cigarette cases, cosmetic containers, etc., this article attempts to systematically and meticulously review the research and development progress in the related fields in recent decades and tries to provide an open outlook on their future development directions, e.g., the employment of surface engineering and hybrid materials. This review is expected to provide some rational thinking directions and convenient practical guidance for the rapid and healthy development of soft-feel materials in the research and application fields. Full article
(This article belongs to the Topic Advances in Functional Thin Films)
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8 pages, 3931 KiB  
Article
Effect of Casting Temperature Control on Microstructure and Properties of Continuously Cast Zr-Based Bulk Metallic Glass Slabs
by Erxu Yang, Tao Ding and Tingzhi Ren
Coatings 2024, 14(6), 747; https://doi.org/10.3390/coatings14060747 - 13 Jun 2024
Viewed by 239
Abstract
In this study, a novel crawler-type continuous casting (CC) technology was designed to efficiently and cost-effectively produce bulk metallic glass (BMG) slabs. As a crucial process parameter, casting temperature has a significant impact on the operation of CC devices and the quality of [...] Read more.
In this study, a novel crawler-type continuous casting (CC) technology was designed to efficiently and cost-effectively produce bulk metallic glass (BMG) slabs. As a crucial process parameter, casting temperature has a significant impact on the operation of CC devices and the quality of slabs. CC experiments of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit1) BMG slab were carried out at the casting temperatures of 1073 K, 1123 K, and 1173 K, and the microstructure and properties of slab samples were analyzed and studied. The experimental results indicate that the BMG slabs can be prepared by CC at 1173 K and 1123 K. When the temperature is reduced to 1073 K, the Be12Ti crystal phase precipitates inside the CC slab, which has a certain impact on the thermal stability and compressive performance of the slab. The control of casting temperature does not affect the glass-forming ability (GFA) of the slab in the CC process. Full article
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12 pages, 2812 KiB  
Article
Polarization-Dependent Plasmon Coupling in Gold Nanoparticles and Gold Thin-Film Systems
by Feng Shan, Yanyan Zhu and Jingyi Huang
Coatings 2024, 14(6), 746; https://doi.org/10.3390/coatings14060746 - 13 Jun 2024
Viewed by 307
Abstract
The characteristics of gap plasmon formed by nanoparticle-on-mirror (NPOM) structures composed of metal nanoparticles (MNPs) and metal thin films have aroused interest for use in various optoelectronic devices. The resonance enhancement characteristics in the gap region of an NPOM structure composed of gold [...] Read more.
The characteristics of gap plasmon formed by nanoparticle-on-mirror (NPOM) structures composed of metal nanoparticles (MNPs) and metal thin films have aroused interest for use in various optoelectronic devices. The resonance enhancement characteristics in the gap region of an NPOM structure composed of gold nanoparticles and gold thin films are simulated theoretically by the finite element method (FEM). The resonant spectrum obtained by the internal coupling effect of the gap can be flexibly controlled by the polarization of incident light and the thickness of the dielectric layer between the MNPs and the metal thin films. We study the resonance spectra of polarization-dependent gold ellipsoidal nanoparticles (GENPs) and gold thin films in the gap region of an NPOM structure. The GENPs and gold thin films are separated by a dielectric layer with a refractive index of 1.36. We observe that the intensity of the resonance electric field in the gap region is inversely proportional to the polarization angle. Similarly, the intensity of the local electric field resonance peak in the gap region is inversely proportional to the thickness of the dielectric layer. When the thickness of the dielectric layer is 0.3 nm and the polarization angle is 0°, the best resonant electric field intensity of 2200 V/m is obtained in the gap region of the NPOM structure (the power of incident light is 1 mW). Finally, the resonant peak wavelength of the electric field in the gap region of the NPOM structure is also controlled by the polarization angle of the incident light and the thickness of the dielectric layer. Full article
(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)
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15 pages, 6900 KiB  
Article
Covalent Molecular Anchoring of Metal-Free Porphyrin on Graphitic Surfaces toward Improved Electrocatalytic Activities in Acidic Medium
by Thi Mien Trung Huynh and Thanh Hai Phan
Coatings 2024, 14(6), 745; https://doi.org/10.3390/coatings14060745 - 12 Jun 2024
Viewed by 557
Abstract
Robust engineering of two-dimensional (2D) materials via covalent grafting of organic molecules has been a great strategy for permanently tuningtheir physicochemical behaviors toward electrochemical energy applications. Herein, we demonstrated that a covalent functionalization approach of graphitic surfaces including graphene by a graftable porphyrin [...] Read more.
Robust engineering of two-dimensional (2D) materials via covalent grafting of organic molecules has been a great strategy for permanently tuningtheir physicochemical behaviors toward electrochemical energy applications. Herein, we demonstrated that a covalent functionalization approach of graphitic surfaces including graphene by a graftable porphyrin (g-Por) derivative, abbreviated as g-Por/HOPG or g-Por/G, is realizable. The efficiency of this approach is determined at both the molecular and global scales by using a state-of-the-art toolbox including cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). Consequently, g-Por molecules were proven to covalently graft on graphitic surfaces via C-C bonds, resulting in the formation of a robust novel hybrid 2D material visualized by AFM and STM imaging. Interestingly, the resulting robust molecular material was elucidated as a novel bifunctional catalyst for both the oxygen evolution (OER) and the hydrogen evolution reactions (HER) in acidic medium with highly catalytic stability and examined at the molecular level. These findings contribute to an in-depth understanding at the molecular level ofthe contribution of the synergetic effects of molecular structures toward the water-splitting process. Full article
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15 pages, 10942 KiB  
Article
Calculation of Stress Intensity Factor for Annular Double Cracks on Inner Surface of Pipeline
by Jintai Cui, Huifang Li, Zhiwei Wu and Caifu Qian
Coatings 2024, 14(6), 744; https://doi.org/10.3390/coatings14060744 - 12 Jun 2024
Viewed by 189
Abstract
Cracks in engineered pipelines often appear in the form of multiple cracks or crack clusters with interactions between them. It is important to study the interaction between cracks if the pipeline crack cluster is to be evaluated in terms of equivalence and safety [...] Read more.
Cracks in engineered pipelines often appear in the form of multiple cracks or crack clusters with interactions between them. It is important to study the interaction between cracks if the pipeline crack cluster is to be evaluated in terms of equivalence and safety assessment. In this paper, based on FRANC3D crack analysis software, the interaction between circumferential parallel double cracks on the inner surface of pipelines was investigated, the factors affecting the interaction were examined, and the empirical equations for calculating the stress intensity factor (SIF) of double cracks was proposed. The results show that if there is no bias between the double cracks, the crack leading edge is shielded, but if there is offset between the double cracks, the crack leading edge is subjected to different interactions at different locations. The distal end of the cracks is generally strengthened, while the proximal end of the cracks is probably more shielded. The interaction effects between cracks are dependent on their relative positions rather than the pipe size or concerned crack size. According to the numerical simulation, boundaries for shielding or enhancing interactions were obtained, and the stress intensity factor calculation equations were fitted. Full article
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16 pages, 2118 KiB  
Article
Preparation of Paste Filling Body and Study on Supported Transportation Laws Using Flac3D Simulation
by Pengfei Wu, Zhenbo Gao, Jiaxu Jin, Fengmei Lian, Yanfeng Li and Tao Liu
Coatings 2024, 14(6), 743; https://doi.org/10.3390/coatings14060743 - 12 Jun 2024
Viewed by 168
Abstract
This paper proposes a new type of gangue filling body (GFB) to address the issues of the low stability, strength, poor shrinkage performance, and inadequate seepage resistance of paste filling materials in overburdened mining conditions, as well as the challenge of fully utilizing [...] Read more.
This paper proposes a new type of gangue filling body (GFB) to address the issues of the low stability, strength, poor shrinkage performance, and inadequate seepage resistance of paste filling materials in overburdened mining conditions, as well as the challenge of fully utilizing solid waste gangue. The coal gangue (CG), U-expanding agent (UEA), and amount of water added were kept constant, and the mass ratio of the various components was adjusted to the design. The standard for filling was assessed using slump tests, uniaxial compression tests, shrinkage tests, and penetration tests. A further microscopic analysis of the pastes with an optimal filling performance was conducted using SEM. The support pressure and overburden migration patterns in the GFBs were evaluated using Flac3D. The results indicate that the GFB with ratio 4 performed best, highlighting the significant role of Portland cement (OPC). The GFB with ratio 3 demonstrated the second-best performance, suggesting that GFBs with a higher early strength should be chosen to fill hollow zones for an effective filling outcome. This study introduced a new type of paste filling material and confirmed the rock transport law of this material under overburdened conditions using Flac3D, offering significant insights for the engineering field. Full article
(This article belongs to the Special Issue Recent Progress in Reinforced Concrete and Building Materials)
16 pages, 7703 KiB  
Article
Experimental Analysis and Wear Prediction Model Based on Friction Heat for Dry Sliding Contact
by Qiming Sun and Dayu Zheng
Coatings 2024, 14(6), 742; https://doi.org/10.3390/coatings14060742 - 12 Jun 2024
Viewed by 230
Abstract
In this study, the influence of the frictional heat effect on the degree of wear is explored from the perspectives of initial contact positive pressure and frictional relative slip velocity. Experiments based on a multifunctional friction and wear machine show that the friction [...] Read more.
In this study, the influence of the frictional heat effect on the degree of wear is explored from the perspectives of initial contact positive pressure and frictional relative slip velocity. Experiments based on a multifunctional friction and wear machine show that the friction temperature increases with an increase in friction relative velocity and initial normal contact load, which exacerbates the frictional thermal expansion and normal load fluctuation, and with the generation of frictional heat, the normal force fluctuates periodically; the wear mass and temperature in the contact area iterate cyclically, which results in the wear mass increasing. 316L stainless steel, 5A06 aluminium alloy and pure titanium are used in the Archard wear model due to their applications in severe wear environments. Since 316L stainless steel, 5A06 aluminium alloy and pure titanium are mostly used in wear-intensive environments, the Archard wear model is optimised based on the frictional heat effect of these three materials, and the accuracy of the improved model in 316L stainless steel, 5A06 aluminium alloy and pure titanium is improved by 52.6%, 7.4% and 23.9%, respectively, when compared with the conventional model. This study lays a theoretical foundation for the wear prediction models of 316L stainless steel, 5A06 aluminium alloy and pure titanium. Full article
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11 pages, 6266 KiB  
Article
Organic–Inorganic Composite Antifouling Coatings with Complementary Bioactive Effects
by Huixian Kong, Jinhui Fu, Rentong Yu, Mingyu Wang, Jinchun Tu, Qiang Wu, Xuewei Zhang, Lina Niu and Kexi Zhang
Coatings 2024, 14(6), 741; https://doi.org/10.3390/coatings14060741 - 12 Jun 2024
Viewed by 311
Abstract
Traditional antifouling coatings are toxic to marine life, which makes developing new environmentally friendly marine antifouling coatings imperative. Antifouling coatings that are nonadhesive and antimicrobial may provide an effective approach to achieving this goal. In this study, an organic–inorganic composite coating consisting of [...] Read more.
Traditional antifouling coatings are toxic to marine life, which makes developing new environmentally friendly marine antifouling coatings imperative. Antifouling coatings that are nonadhesive and antimicrobial may provide an effective approach to achieving this goal. In this study, an organic–inorganic composite coating consisting of fluorinated polyurethane (FPU) and carboxymethyl chitosan–zinc oxide (CMC–ZnO) was prepared to achieve antifouling. The coating took advantage of the complementary bioactive effects of the low surface energy of FPU and the antimicrobial properties of CMC–ZnO. The coating showed good antifouling performance, with a survival rate for Escherichia coli of 3.15% and that for Staphylococcus aureus of 3.97% and an anti-protein adsorption rate of more than 90%. This study provides a simple method for preparing antifouling coatings using nonpolluting raw materials with minimal adverse effects on marine environments. Full article
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