Journal Description
Coatings
Coatings
is an international, peer-reviewed, open access journal on coatings and surface engineering published monthly online by MDPI. The Korean Tribology Society (KTS) is affiliated with Coatings and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Materials Science, Coatings & Films) / CiteScore - Q2 (Surfaces and Interfaces)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 13.8 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Sections: published in 14 topical sections.
- Testimonials: See what our editors and authors say about Coatings.
Impact Factor:
3.4 (2022);
5-Year Impact Factor:
3.4 (2022)
Latest Articles
Quasi-Isotropy Structure and Characteristics of the Ultrasonic-Assisted WAAM High-Toughness Al Alloy
Coatings 2024, 14(5), 551; https://doi.org/10.3390/coatings14050551 (registering DOI) - 28 Apr 2024
Abstract
Wire Arc Additive Manufacturing (WAAM) has emerged as a highly promising method for the production of large-scale metallic structures; nonetheless, the presence of microstructural inhomogeneities, anisotropic properties, and porosity defects within WAAM Al alloys has substantially hindered their broader application. To surmount these
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Wire Arc Additive Manufacturing (WAAM) has emerged as a highly promising method for the production of large-scale metallic structures; nonetheless, the presence of microstructural inhomogeneities, anisotropic properties, and porosity defects within WAAM Al alloys has substantially hindered their broader application. To surmount these obstacles, ultrasonic-assisted WAAM was applied in the fabrication of thin-wall structures utilizing 7075 Al alloy. This study investigates the effects of ultrasonic-assisted Wire Arc Additive Manufacturing (WAAM) on the structural and mechanical properties of 7075 Al alloy specimens. Microstructural analysis showed a significant refinement in grain distribution, with the average grain size notably reduced, enhancing the material’s homogeneity. Porosity across the specimens was quantified, showing a decrease in values from the upper (0.02151) to the middle (0.01347) and lower sections (0.01785), correlating with the rapid cooling effects of WAAM. Mechanical testing revealed that ultrasonic application contributes to a consistent hardness pattern, with measurements averaging 70.71 HV0.1 horizontally and 71.23 HV0.1 vertically, and significantly impacts tensile strength; the horizontally oriented specimen exhibited a tensile strength of 236.03 MPa, a yield strength of 90.29 MPa, and an elongation of 31.10% compared to the vertically oriented specimen which showed reduced mechanical properties due to the presence of defects such as porosity and cracks. The fracture morphology analysis confirmed a predominantly ductile fracture mode, supported by the widespread distribution of dimples on the fracture surface. The integration of ultrasonic vibrations not only refined the grain structure but also modified the secondary phase distribution, enhancing the quasi-isotropic properties of the alloy. These results underline the potential of ultrasonic-assisted WAAM in improving the performance of the 7075 Al alloy for critical applications in the aerospace and automotive industries, suggesting a promising direction for future research and technological advancement in additive manufacturing processes.
Full article
(This article belongs to the Special Issue Properties and Applications of Surfaces/Components Engineered Using Thermal Spray, Welding, and Directed High Energy Beam Technologies)
Open AccessArticle
Enhancing Hardness and Wear Resistance of MgAl2O4/Fe-Based Laser Cladding Coatings by the Addition of CeO2
by
Liangxun Li, Shaobai Sang, Tianbin Zhu, Yawei Li and Heng Wang
Coatings 2024, 14(5), 550; https://doi.org/10.3390/coatings14050550 (registering DOI) - 28 Apr 2024
Abstract
Laser cladding has unique advantages in improving the wear resistance of materials or workpiece surfaces. CeO2 could play a role in promoting the flow of the molten pool and grain refinement during the laser cladding process, which is likely to further improve
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Laser cladding has unique advantages in improving the wear resistance of materials or workpiece surfaces. CeO2 could play a role in promoting the flow of the molten pool and grain refinement during the laser cladding process, which is likely to further improve the wear resistance of the coating. In this work, CeO2 was introduced into the MgAl2O4/Fe-based laser cladding coating on the surface of GCr15 steel. The effects of the CeO2 content on the phase composition, microstructure, hardness, and wear resistance of the coatings were also systematically investigated. The results showed that the addition of CeO2 enhanced the continuity of the coating and reduced the size of the MgAl2O4 particles, which was associated with the addition of CeO2’s intensification of the melt pool flow. The metal grain size reduced and then increased as the CeO2 content increased, whereas the hardness and wear resistance of the MgAl2O4/Fe-based coatings increased and then decreased. Compared with the MgAl2O4/Fe-based coating without CeO2, the hardness of the MgAl2O4/Fe-based coating with 1.0 wt% CeO2 increased by 10% and the wear rate decreased by 40%, which was attributed to the metal grain refinement and particle dispersion strengthening.
Full article
(This article belongs to the Special Issue Laser Surface Engineering and Additive Manufacturing)
Open AccessArticle
Research on the Ablation Resistance of TiC Particle-Reinforced Aluminium-Based Composite Coatings on Armature Surface
by
Chenlu Fan, Li Zhang, Nurbek Nurullougli Kurbonov, Ikromjon Usmonovich Rakhmonov and Guan Wang
Coatings 2024, 14(5), 549; https://doi.org/10.3390/coatings14050549 (registering DOI) - 28 Apr 2024
Abstract
The work aims to enhance and modify the armature surface in electromagnetic rail launch systems and improve its anti-ablation performance to better resist the impact ablation effects of high-temperature and high-speed arcs during the electromagnetic rail launch process and improve launch reliability. TiC
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The work aims to enhance and modify the armature surface in electromagnetic rail launch systems and improve its anti-ablation performance to better resist the impact ablation effects of high-temperature and high-speed arcs during the electromagnetic rail launch process and improve launch reliability. TiC particles are widely selected as metal material reinforcements, with advantages such as high melting points and high hardness. In this paper, the arc impact model of pure aluminum alloy and the arc impact model of TiC particle-reinforced aluminum-matrix composite coating–pure aluminum alloy were constructed based on molecular dynamics simulation. The ablation resistance of the material was evaluated by analyzing the depth of arc impact, the mass loss of the model, the number of gasification atoms, and the surface temperature of the material. The protection mechanism of the modified layer on the substrate was revealed by analyzing the damage degree of the surface and subsurface of the material after arc impact. The results showed that the strengthening mechanism of TiC particle-reinforced aluminum-matrix composites included fine grain strengthening, dispersion strengthening, dislocation strengthening, and so on. Covering TiC particle-reinforced aluminum-matrix composite coating on the surface of aluminum alloy armature is helpful in improving its ablation resistance. The research results can provide a theoretical basis and technical support for the modification design and performance control of electromagnetic rail armature.
Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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Open AccessArticle
Development of Chitosan-Based Films Incorporated with Chestnut Flower Essential Oil That Possess Good Anti-Ultraviolet Radiation and Antibacterial Effects for Banana Storage
by
Yanfei Liu, Jingyuan Zhang, Fei Peng, Kui Niu, Wenlong Hou, Bin Du and Yuedong Yang
Coatings 2024, 14(5), 548; https://doi.org/10.3390/coatings14050548 (registering DOI) - 27 Apr 2024
Abstract
New and valuable packaging materials, with high biocompatibility and biodegradability, have garnered attention in recent years. The aim of this study was to investigate the physicochemical characterization and biological activities of chitosan (CH)-based composite films with the incorporation of chestnut flower essential oil
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New and valuable packaging materials, with high biocompatibility and biodegradability, have garnered attention in recent years. The aim of this study was to investigate the physicochemical characterization and biological activities of chitosan (CH)-based composite films with the incorporation of chestnut flower essential oil (CFEO). The composite films were prepared by the casting method and characterized in terms of structural, morphological, and mechanical properties via FT-IR, XRD, UV, SEM, AFM, and TGA. Antibacterial properties were investigated using Staphylococcus aureus, Escherichia coli, and Calletotrichum musae. Antioxidant capabilities were measured by DPPH assay. The results proved the significantly increased water vapor permeability (WVP), heat resistance, and antibacterial and antioxidant capabilities of CH-CFEO films. The incorporation of CH and CFEO enhanced UV blocking, which made the film shield almost all UV light. Films with a tensile strength of 6.37 ± 0.41 MPa and an elongation at break of 22.57 ± 0.35% were obtained with 6 mg mL−1 of CFEO. Subsequently, banana preservation experiments also confirmed that the composite films could effectively extend shelf life through reducing weight loss. These desirable performances enable our newly developed composite films to be a remarkable packaging material to become alternatives to traditional petroleum-based food-packaging materials and solve the fresh fruit preservation dilemma.
Full article
(This article belongs to the Special Issue Functional Coatings in Postharvest Fruit and Vegetables)
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Open AccessArticle
Chemical Vapor Deposition of Tantalum Carbide in the TaBr5–CCl4–Cd System
by
Tibor Krenicky, Oleg Y. Goncharov, Jiri Kuchar, Irina V. Sapegina, Jan Kudlacek, Ravil R. Faizullin, Alexander I. Korshunov and Daniel Cerny
Coatings 2024, 14(5), 547; https://doi.org/10.3390/coatings14050547 (registering DOI) - 27 Apr 2024
Abstract
The tantalum carbide coatings were deposited on substrates made of 12Kh18N10T steel, ZhC6 alloy, and molybdenum by reduction of TaBr5 and CCl4 vapors with cadmium vapors at temperatures of 950–1000 K. The average deposition rate of coatings on molybdenum was ~5
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The tantalum carbide coatings were deposited on substrates made of 12Kh18N10T steel, ZhC6 alloy, and molybdenum by reduction of TaBr5 and CCl4 vapors with cadmium vapors at temperatures of 950–1000 K. The average deposition rate of coatings on molybdenum was ~5 μm/h, on ZhC6 alloy was ~6 μm/h, and on 12Kh18N10T steel was ~8 μm/h. The coatings were formed as columnar grains on the substrate surface and as a diffuse layer in the substrate material. The surface layers contained mainly tantalum monocarbide TaCy (y = 0.72–0.86) and a small fraction of tantalum. The coatings on the surface of ZhC6 alloy and 12Kh18N10T steel flaked off with increasing thickness, which was due to different thermal expansion of the coating and substrate, as well as concentration inhomogeneity and phase transitions in the substrate material during coating deposition and during the heating and cooling processes.
Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
Open AccessArticle
Preparation and Corrosion Resistance of OMMT/EP Composite Coatings in Sulfur-Containing Sodium Aluminate Solution
by
Jun Xu, Dongyu Li, Hanli Wang and Bianli Quan
Coatings 2024, 14(5), 546; https://doi.org/10.3390/coatings14050546 (registering DOI) - 27 Apr 2024
Abstract
Organic montmorillonite (OMMT) was prepared from Na-montmorillonite (MMT) by Hexadecylamine (HDA) modification. The composite material has good smoothness, acidity, and salt resistance. OMMT was characterized using small-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and a video optical contact angle measuring
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Organic montmorillonite (OMMT) was prepared from Na-montmorillonite (MMT) by Hexadecylamine (HDA) modification. The composite material has good smoothness, acidity, and salt resistance. OMMT was characterized using small-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and a video optical contact angle measuring instrument. The results showed that the layer spacing was enlarged from 1.44 nm to 2.87 nm after the modification, and the hydrophobicity performance was greatly improved. The organic modification of MMT was successful. The surface morphology, roughness, and anticorrosion properties of the organic montmorillonite/epoxy (OMMT/EP) composite coating were investigated and compared with those of the epoxy (EP) coating. The OMMT/EP composite coating had a flatter surface than the EP coating. The roughness was reduced from 65.5 nm to 10.3 nm. The electrochemical impedance spectroscopy showed that the composite coating’s thickness positively affected its anticorrosion performance, the corrosion current density (Icorr) decreased with the increase in thickness, and its maximum impedance was much larger than that of EP coating. The protection efficiency of the OMMT/EP composite coating was 77.90%, which is a significant improvement over the EP’s 31.27%. In addition, the corrosion resistance of the composite coating gradually decreased with increasing immersion time, but the change was insignificant.
Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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Open AccessArticle
Optimized Field Emission from Graphene Sheets with Rare Earth Oxides
by
ZhiJianMuCuo Dong, Jianlong Liu, Dayang Wang, Guoling Zhong, Xingyue Xiang and Baoqing Zeng
Coatings 2024, 14(5), 545; https://doi.org/10.3390/coatings14050545 (registering DOI) - 27 Apr 2024
Abstract
This paper demonstrates a simple method to improve the field emission of graphene sheets (GSs) by coating them with thin films of rare earth oxides. The rare earth oxide films are coated on GS using drop coating, without changing the surface morphology, resulting
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This paper demonstrates a simple method to improve the field emission of graphene sheets (GSs) by coating them with thin films of rare earth oxides. The rare earth oxide films are coated on GS using drop coating, without changing the surface morphology, resulting in a remarkable improvement in the field emission properties of GSs. The field emission property of GSs is tunable and can be optimized by applying various rare earth oxide films at the appropriate level. It is found that the turn-on field of GSs is reduced from 4.2 V/mm to 1.7 V/mm by Gd2O3 and to 2.2 V/mm by La2O3. The threshold field of GS is also reduced from 7.8 V/mm to 3.4 V/mm and 4.8 V/mm, respectively. Field emission results indicate that the improvement is due to the low work function surface and more effective emission sites generated around the GS surface after coating. The field emission test and the emission pattern suggest that the field emission performance of GS can be significantly enhanced through the application of La2O3 and Gd2O3 coating, as well as by optimizing the concentration of rare earth oxides in the coating. Hence, the rare earth-coated GS can serve as a potential field emitter.
Full article
(This article belongs to the Special Issue Energy Storage and Conversion: From Materials, Devices to Applications)
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Open AccessArticle
Effects of Pd Alloying and Coating on the Galvanic Corrosion between Cu Wire and Bond Pads for a Semiconductor Packaging
by
Young-Ran Yoo and Young-Sik Kim
Coatings 2024, 14(5), 544; https://doi.org/10.3390/coatings14050544 (registering DOI) - 27 Apr 2024
Abstract
Semiconductor chips are packaged in a process that involves creating a path to allow for signals to be exchanged with the outside world and ultimately achieving a form to protect against various external environmental conditions such as heat and moisture. The wire bonding
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Semiconductor chips are packaged in a process that involves creating a path to allow for signals to be exchanged with the outside world and ultimately achieving a form to protect against various external environmental conditions such as heat and moisture. The wire bonding type of packaging is a method in which thin metal wires are bonded to pads to create an electrical connection between the chip and the lead frame. An Epoxy Molding Compound (EMC) can be applied to protect semiconductor chips from external environmental conditions such as heat, shock, and moisture. However, EMC contains halogen elements and sulfides and has hydrophilic properties, which can lead to a corrosive environment. The present study aims to evaluate the influence of chloride, which is a contaminant formed during the PCB manufacturing process. To this end, the galvanic corrosion of bonding wire materials Cu wire, Cu wire alloyed with 1% Pd, and Cu wire coated with Pd was investigated. The first ball bond was bonded to the Al pad and the second stitch bond was bonded to the Au pad of the manufacturing process, after which the galvanic corrosion behavior in the semiconductor packaging module specimen was analyzed. A model of galvanic corrosion behavior was also proposed.
Full article
(This article belongs to the Special Issue Coatings for Advanced Devices)
Open AccessArticle
Uncovering the Effect of CeO2 on the Microstructure and Properties of TiAl/WC Coatings on Titanium Alloy
by
Xinmeng Sui, Yitao Weng, Lin Zhang, Jian Lu, Xiangbiao Huang, Fuquan Long and Weiping Zhang
Coatings 2024, 14(5), 543; https://doi.org/10.3390/coatings14050543 (registering DOI) - 27 Apr 2024
Abstract
It remains a popular question whether rare earth oxides encourage reinforcing phases to the uniform distribution in cermet coating to improve the mechanical properties. This study applied laser cladding to prepare the TiAl/WC/CeO2 MMC cermet coatings on the TC21 alloy substrate. The
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It remains a popular question whether rare earth oxides encourage reinforcing phases to the uniform distribution in cermet coating to improve the mechanical properties. This study applied laser cladding to prepare the TiAl/WC/CeO2 MMC cermet coatings on the TC21 alloy substrate. The effects of CeO2 content on the phase composition, microstructure formation, evolution mechanism, and properties of cermet coatings were investigated. Results show that the incorporation of CeO2 did not change the phase of composite coating, but the shape of the TiC phase has a close relation to the CeO2 content. CeO2 enhanced the fluidity of the molten pool, which further encouraged the TiC/Ti2AlC core-shell reinforcement phase. With the increase in CeO2 content, the optimized coating contributed to homogenous microstructure distribution and fine grain size. Owing to the hard phases strengthening and dispersion strengthening effects of CeO2, the microhardness of the composite coatings was all significantly higher (almost 1.6 times) than that of the substrate. Importantly, the addition of CeO2 significantly improved the wear resistance of the composite coating. This work provides a certain reference value for the study of surface strengthening of key parts in the aerospace field.
Full article
(This article belongs to the Special Issue Oxidation, Wear, Corrosion Behaviors and Activated Bonding Properties of Coatings Deposited on Metals)
Open AccessArticle
Corrosion Resistance and Conductivity of Ta-Nb-N-Coated 316L Stainless Steel as Bipolar Plates for Proton Exchange Membrane Fuel Cells
by
Qizhong Li, Chuan Ding, Mai Yang, Meijun Yang, Tenghua Gao, Song Zhang, Baifeng Ji, Takashi Goto and Rong Tu
Coatings 2024, 14(5), 542; https://doi.org/10.3390/coatings14050542 (registering DOI) - 26 Apr 2024
Abstract
The large-scale application of stainless steel (SS) bipolar plates (BPs) in proton exchange membrane fuel cells (PEMFCs) is mainly limited by insufficient corrosion resistance and electrical conductivity. In this work, Ta-Nb-N coatings were prepared on 316L SS substrates by unbalanced magnetron sputtering to
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The large-scale application of stainless steel (SS) bipolar plates (BPs) in proton exchange membrane fuel cells (PEMFCs) is mainly limited by insufficient corrosion resistance and electrical conductivity. In this work, Ta-Nb-N coatings were prepared on 316L SS substrates by unbalanced magnetron sputtering to improve corrosion resistance and conductivity. The Ta-Nb-N coatings had a dense structure without obvious defects. In simulated PEMFC cathode environments consisting of 0.5 M H2SO4 + 2 ppm HF at 70 ± 0.5 °C, which is harsher than the U.S. Department of Energy specification, the corrosion current density of Ta-Nb-N-coated BPs was reduced to 2.2 × 10−2 Acm−2. Ta-Nb-N-coated samples showed better electrical conductivity than 316L SS, which had an excellent interfacial contact resistance of 9.2 mΩcm2. In addition, the Ta-Nb-N-coated samples had a water contact angle of 100.7°, showing good hydrophobicity for water management. These results indicate that Ta-Nb-N coatings could be a promising material for BPs.
Full article
(This article belongs to the Special Issue Advances in Thin Films for Energy Storage and Conversion)
Open AccessArticle
Optimization and Mechanism Study of Bonding Properties of CFRP/Al7075 Single-Lap Joints by Low-Temperature Plasma Surface Treatment
by
Liwei Wen, Ruozhou Wang and Entao Xu
Coatings 2024, 14(5), 541; https://doi.org/10.3390/coatings14050541 - 26 Apr 2024
Abstract
This paper studied favorable low-temperature plasma (LTP) surface treatment modes for Carbon Fiber Reinforced Polymer (CFRP)/Al7075 single-lap joints using complex experimental methods and analyzed the failure modes of the joints. The surface physicochemical properties of CFRP after LTP surface treatment were characterized using
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This paper studied favorable low-temperature plasma (LTP) surface treatment modes for Carbon Fiber Reinforced Polymer (CFRP)/Al7075 single-lap joints using complex experimental methods and analyzed the failure modes of the joints. The surface physicochemical properties of CFRP after LTP surface treatment were characterized using scanning electron microscopy (SEM), contact angle tests, and X-ray photoelectron spectroscopy (XPS). The influence mechanism of LTP surface treatment on the bonding properties of CFRP/Al7075 single-lap Joint was studied. The results of the complex experiment and range analysis showed that the favorable LTP surface treatment parameters were a speed of 10 mm/s, a distance of 10 mm, and three repeat scans. At these parameters, the shear strength of the joints reached 30.76 MPa, a 102.8% improvement compared to the untreated group. The failure mode of the joints shifted from interface failure to substrate failure. After low-temperature plasma surface treatment with favorable parameters, the CFRP surface exhibited gully like textures, which enhanced the mechanical interlocking between the CFRP surface and the adhesive. Additionally, the surface free energy of CFRP significantly increased, reaching a maximum of 78.77 mJ/m2. XPS results demonstrated that the low-temperature plasma surface treatment led to a significant increase in the content of oxygen-containing functional groups, such as C-O, C=O, and O-C=O, on the CFRP surface.
Full article
(This article belongs to the Special Issue Surface Science of Degradation and Surface Protection)
Open AccessArticle
Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China
by
Ling Shen, Yuhu Kang and Qiwu Li
Coatings 2024, 14(5), 540; https://doi.org/10.3390/coatings14050540 - 26 Apr 2024
Abstract
During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the
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During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).
Full article
(This article belongs to the Special Issue Surface and Interface Analysis of Cultural Heritage, 2nd Edition)
Open AccessReview
A Review of Cross-Scale Theoretical Contact Models for Bolted Joints Interfaces
by
Yilong Liu, Min Zhu, Xiaohan Lu, Shengao Wang and Ziwei Li
Coatings 2024, 14(5), 539; https://doi.org/10.3390/coatings14050539 - 26 Apr 2024
Abstract
Bolted joints structures are critical fastening components widely used in mechanical equipment. Under long-term loading conditions, the bolted joints interface generates strong nonlinearities within the system. The nonlinear stiffness inside the bolt leads to changes in the stiffness of the whole system. This
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Bolted joints structures are critical fastening components widely used in mechanical equipment. Under long-term loading conditions, the bolted joints interface generates strong nonlinearities within the system. The nonlinear stiffness inside the bolt leads to changes in the stiffness of the whole system. This affects the dynamic characteristics of the whole system. It brings challenges and difficulties to the performance prediction and reliability assessment of the equipment. A cross-scale theoretical model study based on the microscopic contact mechanism can provide a more comprehensive understanding and cognition of the degradation behavior of bolted joints interfaces. The current development status and deformation process of asperity models are summarized. The research progress of statistical summation model and contact fractal model based on microscopic contact mechanism is analyzed. The experimental methods for parameter identification of connection interfaces are reviewed. The study of numerical modelling of bolted joints structures from the surface contact mechanism is briefly described. Future research directions for cross-scale modelling of bolted joints structures are outlined.
Full article
(This article belongs to the Special Issue Friction and Wear Behaviors in Mechanical Engineering)
Open AccessArticle
Simulation of Preload Relaxation of Bolted Joint Structures under Transverse Loading
by
Yilong Liu, Min Zhu, Xiaohan Lu, Shengao Wang and Ziwei Li
Coatings 2024, 14(5), 538; https://doi.org/10.3390/coatings14050538 - 26 Apr 2024
Abstract
In this study, based on the Iwan model, the connection interface of the bolted joint structure subjected to lateral loads was simulated and comparatively analyzed. Commercial finite element software was used to model the bolted joint structure. Monotonic lateral loads and cyclic displacement
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In this study, based on the Iwan model, the connection interface of the bolted joint structure subjected to lateral loads was simulated and comparatively analyzed. Commercial finite element software was used to model the bolted joint structure. Monotonic lateral loads and cyclic displacement loads were applied to the model. The changes in the preload force of the bolted connection structure, as well as the changes in the sticking zone and stress state of the connection interface, were analyzed, and the loading results of monotonic load and cyclic displacement load were compared. The results show that the contact interface stress decreases with the increase in displacement load, and this increase is also a nonlinear relationship, which is approximately in phase with the trend of the contact surface slip curve. The amount of contact surface stress loss and the amount of preload loss are not directly related to the magnitude of the initial preload, regardless of the loading conditions. The contact surface is also circular under any form of displacement loading, whether it is stressed or slipped. The amount of preload loss is proportional to the amount of bolt compression for that variable.
Full article
(This article belongs to the Special Issue Friction and Wear Behaviors in Mechanical Engineering)
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Open AccessArticle
Photocatalytic Activities of Methylene Blue Using ZrO2 Thin Films at Different Annealing Temperatures
by
Yuliana de Jesús Acosta-Silva, Salvador Gallardo-Hernández, Sandra Rivas, Fabricio Espejel-Ayala and Arturo Méndez-López
Coatings 2024, 14(5), 537; https://doi.org/10.3390/coatings14050537 - 26 Apr 2024
Abstract
Tetragonal ZrO2, synthesized by the sol–gel method and dip-coating technique, was found to be photocatalytically active for the degradation of methylene blue. The ZrO2 thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning
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Tetragonal ZrO2, synthesized by the sol–gel method and dip-coating technique, was found to be photocatalytically active for the degradation of methylene blue. The ZrO2 thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV-vis spectroscopy. The photocatalytic degradation of methylene blue was carried out with this material. We identified the tetragonal phase in ZrO2 thin film at different annealing temperatures from 400 °C to 550 °C. The XRD study indicated that the films were monocrystalline in nature with preferred grain orientation along (011) plane and exhibited a tetragonal crystal structure. The crystallite size of the films increased with increasing annealing temperature. FTIR explained the bonding nature and confirmed the formation of the composite. UV-Vis showed the optical absorbance was high in the visible region and the optical band gap value increased with annealing temperature. The photocatalytic experimental results revealed that ZrO2 thin films degraded MB by 20%, 24%, 29%, and 36%, with annealing temperatures of 400 °C at 550 °C for 10 h, respectively. Our results provide useful insights into the development of photocatalytic materials and degradation of methylene blue.
Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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Open AccessArticle
Theoretical Study of the Competition Mechanism of Alloying Elements in L12-(Nix1Crx2Cox3)3Al Precipitates
by
Yu Liu, Lijun Wang, Juangang Zhao, Zhipeng Wang, Touwen Fan, Ruizhi Zhang, Yuanzhi Wu, Xiangjun Zhou, Jie Zhou and Pingying Tang
Coatings 2024, 14(5), 536; https://doi.org/10.3390/coatings14050536 - 26 Apr 2024
Abstract
The impact of variations in the content of single alloying element on the properties of alloy materials has been extensively discussed, but the influence of this change on the content of multiple alloying elements in the alloy materials has been disregarded, as the
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The impact of variations in the content of single alloying element on the properties of alloy materials has been extensively discussed, but the influence of this change on the content of multiple alloying elements in the alloy materials has been disregarded, as the performances of alloy materials should be determined by the collective influence of multiple alloying elements. To address the aforementioned issue, the present study conducted a comprehensive investigation into the impact of variations in the content of alloying elements, namely Ni, Cr, and Co, on the structural and mechanical properties of L12-(Nix1Crx2Cox3)3Al precipitates using the high-throughput first-principles calculations and the partial least squares (PLS) regression, and the competitive mechanism among these three elements was elucidated. The findings demonstrate that the same alloying element may exhibit opposite effects in both single element analysis and comprehensive multi-element analysis, for example, the effect of Ni element on elastic constant C11, and the influence of Cr element on Vickers hardness and yield strength. The reason for this is that the impact of the content of other two alloying elements is ignored in the single element analysis. Meanwhile, the Co element demonstrates a significant competitive advantage in the comparative analysis of three alloying elements for different physical properties. Therefore, the methodology proposed in this study will facilitate the elucidation of competition mechanisms among different alloy elements and offer a more robust guidance for experimental preparation.
Full article
(This article belongs to the Special Issue Microstructure, Mechanical and Tribological Properties of Alloys)
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Open AccessArticle
Intelligent Space Thermal Control Radiator Based on Phase Change Material with Partial Visible Transparency
by
Xianghao Kong, Hezhi Sun, Shiri Liang, Zao Yi, Naiting Gu and Yougen Yi
Coatings 2024, 14(5), 535; https://doi.org/10.3390/coatings14050535 - 25 Apr 2024
Abstract
Coating structures with dynamically adjustable infrared emissivity are crucial in spacecraft components to cope with the transient thermal environments of space. For a long time, thermochromic phase change materials have been widely used in applications requiring emissivity adjustment, and optimizing the range of
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Coating structures with dynamically adjustable infrared emissivity are crucial in spacecraft components to cope with the transient thermal environments of space. For a long time, thermochromic phase change materials have been widely used in applications requiring emissivity adjustment, and optimizing the range of adjustable infrared emissivity has always been at the forefront of research. However, reducing the absorption of solar radiation has significant implications for the practical application and thermal stability of spacecraft components in space environments. In this paper, we propose a multilayer film structure based on the phase change material VO2 combined with the materials ZnSe and ITO to achieve low solar radiation absorption and adjustable infrared emissivity for intelligent thermal radiators in space. Through finite element simulation analysis of the structure, we achieve a solar radiation absorption rate of 0.3 and an adjustable infrared emissivity of 0.49. According to Stefan–Boltzmann’s law, the structure exhibits strong radiative heat dissipation at high temperatures and weak energy dissipation at low temperatures to maintain the thermal stability of the device and ensure efficient operation. The intelligent thermal radiator operates based on the principles of Fabry–Perot resonance. Therefore, the multilayer structure based on the phase change material VO2 demonstrates excellent performance in both solar radiation absorption and adjustable infrared emissivity, showcasing its tremendous potential in the field of intelligent thermal control in aerospace.
Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
Open AccessArticle
Sustainable and Cost-Efficient Production of Micro-Patterned Reduced Graphene Oxide on Graphene Oxide Films
by
Satam Alotibi, Talal F. Qahtan, Amani M. Alansi, Taoreed O. Owolabi, Salah T. Hameed, Naveed Afzal, Sadia Bilal and Dina Salah
Coatings 2024, 14(5), 534; https://doi.org/10.3390/coatings14050534 - 25 Apr 2024
Abstract
This study tackles the critical demand for sustainable synthesis methods of reduced graphene oxide (rGO), highlighting the environmental drawbacks of conventional chemical processes. We introduce a novel, green synthesis technique involving the irradiation of a 500 eV argon ion beam, which not only
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This study tackles the critical demand for sustainable synthesis methods of reduced graphene oxide (rGO), highlighting the environmental drawbacks of conventional chemical processes. We introduce a novel, green synthesis technique involving the irradiation of a 500 eV argon ion beam, which not only facilitates the creation of micro-patterned rGO on a graphene oxide (GO) film but also enables simultaneous material characterization and patterning. By adjusting the irradiation exposure time between 0 and 80 s, we achieve meticulous control over the attributes and the reduction process of the material. The use of X-ray photoelectron spectroscopy (XPS) allows for real-time monitoring of the reduction from GO to rGO, evidenced by a notable reduction in the intensities of C-O, C=O, and O-C=O bonds, and an increase in C-C bond intensities, indicating a significant reduction level. Our research demonstrates the efficient production of eco-friendly rGO using precise, controlled argon ion beam irradiation, proving its advantages over traditional methods. These results contribute to the development of sustainable material science technologies, with potential applications in electronics, energy storage, and more.
Full article
(This article belongs to the Special Issue Advances in Low-Cost Energy Materials and Thin Films)
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Open AccessCorrection
Correction: Bu et al. A Decomposition-Based Multi-Objective Evolutionary Algorithm for Solving Low-Carbon Scheduling of Ship Segment Painting. Coatings 2024, 14, 368
by
Henan Bu, Xianpeng Zhu, Zikang Ge, Teng Yang, Zhuwen Yan and Yingxin Tang
Coatings 2024, 14(5), 533; https://doi.org/10.3390/coatings14050533 - 25 Apr 2024
Abstract
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Open AccessArticle
Influence of HNT-ZnO Nanofillers on the Performance of Epoxy Resin Composites for Marine Applications
by
Raluca Şomoghi, Sonia Mihai, George-Mihail Teodorescu, Zina Vuluga, Augusta Raluca Gabor, Cristian-Andi Nicolae, Bogdan Trică, Daniel Mihai Stănescu Vătău, Florin Oancea and Cătălin Marian Stănciulescu
Coatings 2024, 14(5), 532; https://doi.org/10.3390/coatings14050532 - 25 Apr 2024
Abstract
Epoxy resin was conjugated with halloysite nanotubes (HNT) and different types of ZnO nanoparticles (commercial ZnO and modified ZnO-ODTES) to obtain HNT-ZnO/epoxy resin composites. These ZnO nanoparticles (ZnO NPs) were utilized with the intention to enhance the interfacial bonding between the epoxy resin
[...] Read more.
Epoxy resin was conjugated with halloysite nanotubes (HNT) and different types of ZnO nanoparticles (commercial ZnO and modified ZnO-ODTES) to obtain HNT-ZnO/epoxy resin composites. These ZnO nanoparticles (ZnO NPs) were utilized with the intention to enhance the interfacial bonding between the epoxy resin and the reinforcing agent (HNT). The properties of resulted epoxy resin composites were characterized by various methods such as FTIR-ATR, TGA, DSC, TEM-EDX, and Nanoindentation analyses. The thermal properties of the epoxy resin composites were enhanced to a greater extent by the addition of HNT-ZnO nanofillers. DSC testing proved that the modification in the glass transition temperature can be due to the physical bonding between the epoxy resin and filler (HNT and/or ZnO). It was seen that the epoxy resin modified with HNT and ZnO-ODTES has the highest resistance to scratching by having a good elastic recovery as well as high values for surface hardness (~187.6 MPa) and reduced modulus (2980 MPa). These findings can pave the way for the developing of ZnO-based marine coatings with improved properties.
Full article
(This article belongs to the Special Issue Functional Films/Coatings Processing Technologies: Deposition and Process)
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