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
Investigation of the Structure and Properties of MoS2 Coatings Obtained by Electrospark Alloying
Coatings 2024, 14(5), 563; https://doi.org/10.3390/coatings14050563 - 01 May 2024
Abstract
Electrospark coatings alloyed with MoS2 have been studied. The coatings were obtained by the following two strategies: the first consisted of pre-applying molybdenum disulfide to the treated surface and alloying with a molybdenum electrode (Mo + MoS2 coating); the second consisted
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Electrospark coatings alloyed with MoS2 have been studied. The coatings were obtained by the following two strategies: the first consisted of pre-applying molybdenum disulfide to the treated surface and alloying with a molybdenum electrode (Mo + MoS2 coating); the second consisted of applying a paste with a sulfur content of 33.3% to the treated surface and alloying with a molybdenum electrode (Mo + S coating). The structure, phase composition, and tribological properties of the coatings were investigated. The coatings have a complex structure consisting of an upper soft layer, a hardened white layer, a diffusion zone, and a substrate. Element analysis and cross-sectional hardness changes indicated that element diffusion occurred at the coating/substrate interface. The phase composition of the coatings is represented by BCC and FCC solid solutions on Fe, and MoS2 is also detected. In Mo + S coatings, the molybdenum disulfide on the surface is about 8%; in Mo + MoS2 coatings, it is 27%–46%. The obtained coatings show very good tribological properties compared to molybdenum ESA coatings. The frictional forces and coefficients are reduced by a factor of 10 and 40, depending on the test conditions.
Full article
(This article belongs to the Special Issue Functional Surface Modification Using Concentrated Energy Flows)
Open AccessArticle
In Situ Study on the Structural Evolution of Flexible Ionic Gel Sensors
by
Shujun Yan, Jun Tang, Angui Zhang, Nie Zhao, Fu Wang and Shaowei Sun
Coatings 2024, 14(5), 562; https://doi.org/10.3390/coatings14050562 - 01 May 2024
Abstract
With the development of society, the demand for smart coatings is increasing. The development of flexible strain sensors using block copolymer self-assembled ionic gel materials provides a promising method for promoting the development of smart coatings. The ionic liquid in the ionic part
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With the development of society, the demand for smart coatings is increasing. The development of flexible strain sensors using block copolymer self-assembled ionic gel materials provides a promising method for promoting the development of smart coatings. The ionic liquid in the ionic part of the material is crucial for the performance of the sensor. In this study, the structural changes within FDA/dEAN (self-assembly of acrylated Pluronic F127 (F127-DA) in partially deuterated ethylammonium nitrate (dEAN)) triblock copolymer ionic gel during uniaxial tensile flow were characterized using an in situ SAXS technique. The results revealed that the characteristics of the responses of the ionic gel to strain resistance were intricately linked to the evolution of its microstructure during the tensile process. At low levels of strain, the face-centered cubic lattice arrangement of the micelles tended to remain unchanged. However, when subjected to higher strains, the molecular chains aligned along the stretching direction, resulting in a more ordered structure with reduced entropy. This alignment led to significant disruption in bridging structures within the material. Furthermore, this research explored the impact of the stretching rate on the relaxation process. It was observed that higher stretching rates led to decreases in the average relaxation time, indicating rate dependence in the microstructure’s behavior. These findings provide valuable insights into the behavior and performance of flexible strain sensors based on ionic gel materials in smart coatings.
Full article
(This article belongs to the Special Issue Advanced Polymeric Materials and Coatings: Synthesis, Properties and Applications)
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Open AccessArticle
Influence of Few-Layer Graphene on Frictional Properties of Lithium Compound Grease
by
Yanshuang Wang, Zizhen Liu, Xudong Gao, Qingguo Qiu and Mingwei Wang
Coatings 2024, 14(5), 561; https://doi.org/10.3390/coatings14050561 - 01 May 2024
Abstract
The frictional properties of lithium compound grease (LCG) with different percentage compositions of few-layer graphene (FLG) were investigated, and the mechanisms of temperature and loading effects on LCG containing FLG are also considered. The concluding effect shows that 1 wt% FLG is more
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The frictional properties of lithium compound grease (LCG) with different percentage compositions of few-layer graphene (FLG) were investigated, and the mechanisms of temperature and loading effects on LCG containing FLG are also considered. The concluding effect shows that 1 wt% FLG is more appropriate for friction and wear modifiers for lithium compound grease at elevated temperatures and less suitable at ordinary temperatures. Thickener chemisorption film, FLG layering film, and tribo-reaction film consisting of FeO(OH), Fe2O3, Fe3O4, Li2O, and other oxides assist in the establishment of a lubricating boundary film on the friction interfaces lubricated with LCG containing FLG. The poor fluidity of lithium compound grease at low temperatures leads to poor dispersion of FLG, decreasing friction reduction capability. Under elevated temperature and low load condition, adding 1wt% FLG to LCG can only improve its wear-resistant property, the abrasion volume of steel plate reduced by 24.49%. Under elevated temperature and high load condition, adding 1wt% FLG to LCG can only enhance its anti-friction characteristics.. Conversely, FLG is unsuitable as an anti-friction and wear-resistant additive for LCG at low-temperature conditions.
Full article
(This article belongs to the Special Issue Thin Films for Tribological Applications)
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Open AccessArticle
Finite Element Analysis Study of Buried Crack Defects in B-Sleeve Fillet Welds
by
Hao Zhang, Zhengxin Wei, Xinzhan Li, Zhanwei Yuan and Min Guo
Coatings 2024, 14(5), 560; https://doi.org/10.3390/coatings14050560 - 01 May 2024
Abstract
Since it is difficult to study the influence of different defect characteristics on the stress intensity factor of B-type sleeve fillet welds via experiments, this paper adopts ABAQUS finite element analysis software(Version 2019) to model the B-type sleeve fillet welds and studies the
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Since it is difficult to study the influence of different defect characteristics on the stress intensity factor of B-type sleeve fillet welds via experiments, this paper adopts ABAQUS finite element analysis software(Version 2019) to model the B-type sleeve fillet welds and studies the stress and stress intensity factor under different crack lengths, heights, and angles. The simulation results showed that with the increase in crack length and depth, the maximum stress intensity factor gradually increased, and with the increase in the crack inclination angle, the maximum stress intensity factor first increased and then decreased.
Full article
(This article belongs to the Special Issue Recent Progress in Surface and Interface Properties of Nanostructures)
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Open AccessArticle
A Multi-Method Analysis of a Color Painting on Ancient Architecture from Anyuan Temple in Chengde, China
by
Juan Li and Rong Zhao
Coatings 2024, 14(5), 559; https://doi.org/10.3390/coatings14050559 - 01 May 2024
Abstract
Anyuan Temple, constructed in the 29th year of the Qing Dynasty (1764), serves as a repository of numerous Sanskrit inscriptions and Hexi color paintings from the Qing era. Among its collections, the green Tara Buddha statue, exquisitely carved from wood, is recognized as
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Anyuan Temple, constructed in the 29th year of the Qing Dynasty (1764), serves as a repository of numerous Sanskrit inscriptions and Hexi color paintings from the Qing era. Among its collections, the green Tara Buddha statue, exquisitely carved from wood, is recognized as a national first-class cultural relic. This edifice is instrumental in advancing our comprehension of painting artistry in royal temples. The current research focused on the pigments and binders utilized in the color paintings within Anyuan Temple, located in Chengde. An investigative process entailed collecting four samples from the paintings adorning the temple’s beams. These samples underwent comprehensive analysis using a variety of techniques, such as Scanning Electron Microscopy and Energy-Dispersive Spectrometry (EDS), Micro Raman Spectroscopy (m-RS), and X-ray Diffraction (XRD). The examination revealed that the paintings comprised pigments of lead white, cinnabar, malachite, and azurite, corresponding to the colors white, red, green, and blue, respectively. The enduring stability and aesthetic appeal of these pigments suggest their suitability for use in future conservation efforts. Additionally, Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GC/MS) analysis identified animal glue as the binding agent in the wood component paintings. These insights are pivotal for the forthcoming restoration endeavors of Anyuan Temple, offering essential guidance in selecting the appropriate materials for restoration.
Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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Open AccessArticle
The Effect of W, Cr, Mo Content on the Microstructure and Mechanical Properties of the Weld Interface of TiC Cermet and Low-Carbon Steel
by
Wei Wei, Zhiquan Huang, Haiyan Zhang and Shaokang Guan
Coatings 2024, 14(5), 558; https://doi.org/10.3390/coatings14050558 - 01 May 2024
Abstract
In this study, the influence of W, Cr, and Mo on the microstructure and mechanical properties of the arc-welded interface of TiC cermet and low-carbon steel was investigated. MIG arc welding was employed to deposit muti-alloyed low-carbon steel flux-cored wire onto the surface
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In this study, the influence of W, Cr, and Mo on the microstructure and mechanical properties of the arc-welded interface of TiC cermet and low-carbon steel was investigated. MIG arc welding was employed to deposit muti-alloyed low-carbon steel flux-cored wire onto the surface of the TiC cermet to create the arc-welded interface. Analysis of the microstructure, phase composition, and shear fracture of the interface were conducted by OM (optical microscopy), SEM (scanning electron microscope), EMPA (Electron Probe X-ray Micro-Analyzer), and XRD (X-ray diffraction) methods. The results indicate that the order of influence on the performance of the welded interface is perceived as Cr > W > Mo. The preferred ratio of element content is W at 1.0 wt.%, Cr at 0.5 wt.%, and Mo at 2.0 wt.%. During the arc-welding process, W and Mo formed a rim structure of TiC particles to inhibit the dissolution of TiC particles, while Cr formed dispersed carbides in the bonding phase. The synergistic impact of these components resulted in the simultaneous enhancement of both the TiC particles and the bonding phase. This led to a significant increase in the shear strength of the TiC cermet welded interface to 787 MPa, marking an 83% improvement compared to the welded interface without reinforcement, which exhibited a shear strength of 430 MPa.
Full article
(This article belongs to the Special Issue Functional Coatings for Metallic and Ceramic Materials)
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Open AccessEditorial
The Investigations of Novel Circuits Printing on Substrates by Aerosol Jet Printing
by
Qingyu Yao, Feng Gu, Lei Cao and Zengsheng Wang
Coatings 2024, 14(5), 557; https://doi.org/10.3390/coatings14050557 - 01 May 2024
Abstract
Aerosol jet printing (AJP) is a straightforward write–fabrication technique with high resolution, design flexibility, and integration capabilities [...]
Full article
(This article belongs to the Special Issue Nano/Micro Additive Lamination Fabrication: Novel Circuits Printing on Substrates)
Open AccessArticle
A Study on the Corrosion Behavior of RGO/Cu/Fe-Based Amorphous Composite Coatings in High-Temperature Seawater
by
Zhenhua Chu, Yunzheng Zhang, Wan Tang, Yuchen Xu and Jingxiang Xu
Coatings 2024, 14(5), 556; https://doi.org/10.3390/coatings14050556 - 01 May 2024
Abstract
In this paper, based on an Fe-based amorphous alloy, four kinds of RGO/Cu/Fe-based amorphous composite coatings with mass ratios of 5%, 10%, 15%, and 20% of RGO/Cu were prepared on the surface of 45# steel by using high-velocity oxy-fuel (HVOF) spraying. The coatings
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In this paper, based on an Fe-based amorphous alloy, four kinds of RGO/Cu/Fe-based amorphous composite coatings with mass ratios of 5%, 10%, 15%, and 20% of RGO/Cu were prepared on the surface of 45# steel by using high-velocity oxy-fuel (HVOF) spraying. The coatings were immersed in simulated seawater at room temperature and at 90 °C for different lengths of time, and their corrosion resistance was tested using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the surface morphology and phase distribution of the samples were observed. The results showed that with the increase in the introduction ratio of RGO/Cu, when the addition ratio reached 15%, the composite coating had the best corrosion resistance. After soaking in simulated seawater at 90 °C for 18 days, the surface of the coating showed slight peeling and crack propagation, but no obvious pitting phenomenon occurred. The corrosion mechanism of the RGO/Cu/Fe coating in high-temperature seawater is mainly that high temperature causes the cracking of the coating, which opens up a transport channel for corrosion media. However, due to the addition of RGO, the corrosion has a certain self-limitation effect, which is mainly due to the toughening effect of RGO on the coating and its effect on extending the corrosion channel.
Full article
(This article belongs to the Topic Alloys and Composites Corrosion and Mechanical Properties)
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Open AccessArticle
Effects of Annealing Temperature on Bias Temperature Stress Stabilities of Bottom-Gate Coplanar In-Ga-Zn-O Thin-Film Transistors
by
Yuyun Chen, Yi Shen, Yuanming Chen, Guodong Xu, Yudong Liu and Rui Huang
Coatings 2024, 14(5), 555; https://doi.org/10.3390/coatings14050555 - 30 Apr 2024
Abstract
Defect annihilation of the IGZO/SiO2 layer is of great importance to enhancing the bias stress stabilities of bottom-gate coplanar thin-film transistors (TFTs). The effects of annealing temperatures (Ta) on the structure of the IGZO/SiO2 layer and the stabilities of
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Defect annihilation of the IGZO/SiO2 layer is of great importance to enhancing the bias stress stabilities of bottom-gate coplanar thin-film transistors (TFTs). The effects of annealing temperatures (Ta) on the structure of the IGZO/SiO2 layer and the stabilities of coplanar IGZO TFTs were investigated in this work. An atomic depth profile showed that the IGZO/SiO2 layer included an IGZO layer, an IGZO/SiO2 interfacial mixing layer, and a SiO2 layer. Higher Ta had only one effect on the IGZO layer and SiO2 layer (i.e., strengthening chemical bonds), while it had complex effects on the interfacial mixing layer—including weakening M-O bonds (M: metallic elements in IGZO), strengthening damaged Si-O bonds, and increasing O-related defects (e.g., H2O). At higher Ta, IGZO TFTs exhibited enhanced positive bias temperature stress (PBTS) stabilities but decreased negative bias temperature stress (NBTS) stabilities. The enhanced PBTS stabilities were correlated with decreased electron traps due to the stronger Si-O bonds near the interfacial layer. The decreased NBTS stabilities were related to increased electron de-trapping from donor-like defects (e.g., weak M-O bonds and H2O) in the interfacial layer. Our results suggest that although higher Ta annihilated the structural damage at the interface from ion bombardment, it introduced undesirable defects. Therefore, to comprehensively improve electrical stabilities, controlling defect generation (e.g., by using a mild sputtering condition of source/drain electrodes and oxides) was more important than enhancing defect annihilation (e.g., through increasing Ta).
Full article
(This article belongs to the Special Issue Advanced Metal Oxide Films: Materials and Applications)
Open AccessArticle
Influence of the Phosphor Layer Composition on Flexible Electroluminescent Device Performance
by
Dina Esteves, Esra Akgül, Usha Kiran Sanivada, Inês P. Moreira, João Bessa, Carla A. Silva, Fernando Cunha and Raul Fangueiro
Coatings 2024, 14(5), 554; https://doi.org/10.3390/coatings14050554 - 30 Apr 2024
Abstract
Electroluminescence (EL) is an innovative technology in the lighting area. EL devices’ main structure consists of a phosphor layer sandwiched between two electrodes. In this work, several alternating-current EL devices were developed by applying a set of sequential layers with combinations of in-house
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Electroluminescence (EL) is an innovative technology in the lighting area. EL devices’ main structure consists of a phosphor layer sandwiched between two electrodes. In this work, several alternating-current EL devices were developed by applying a set of sequential layers with combinations of in-house prepared inks and a commercially available ink as the phosphor layer. A flexible polyester textile substrate was functionalized with the inks by spray coating, after knife coating an interfacial layer directly on the surface. A thorough study was carried out on the phosphor layer composition to optimize the EL device performance, more precisely, illuminance intensity and illuminance homogeneity. The developed phosphor layer was composed of zinc sulfide doped with copper (between 30.0 and 38.1 wt%) and diluted by using a diluent at different concentrations (from 28.0 to 35.5 wt%). The best peak illuminance intensity of 61 lux was obtained when the phosphor ink presented a 35.4% ZnS:Cu ratio and was diluted with 33.0% diluent. This study aimed to determine the best formulation of the phosphor layer, which can be highly useful for further developments of EL devices, taking into account different applications in the market.
Full article
(This article belongs to the Section Surface Engineering for Energy Harvesting, Conversion, and Storage)
Open AccessArticle
Development and Application of a Nano-Gas Sensor for Monitoring and Preservation of Ancient Books in the Library
by
Jia Wang, Qingyu Wang, Susu He, Zhiyin Chen, Wentong Qiu and Yunjiang Yu
Coatings 2024, 14(5), 553; https://doi.org/10.3390/coatings14050553 - 30 Apr 2024
Abstract
Monitoring the gas composition in library environments is crucial for the preservation of ancient books. In this study, TiO2 NTs/CNTs composites were synthesized via a hydrothermal method and utilized as nano-gas sensors for NO2 detection. The surface morphology and element composition
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Monitoring the gas composition in library environments is crucial for the preservation of ancient books. In this study, TiO2 NTs/CNTs composites were synthesized via a hydrothermal method and utilized as nano-gas sensors for NO2 detection. The surface morphology and element composition of the samples were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Additionally, the gas sensitivity of the prepared TiO2 nanocomposites was evaluated at different temperatures, both with and without ultraviolet light irradiation. The results demonstrate that the synthesized TiO2 NTs/CNTs samples exhibit a large specific surface area due to their titanium dioxide nanotubes (TiO2 NTs) and carbon nanotubes (CNTs) composition. Moreover, these samples display excellent gas sensitivity under ultraviolet light irradiation at temperatures of 120 °C. Compared to uncomposited and non-ultraviolet light irradiated samples, the sensor response rate is significantly improved, enabling effective monitoring of NO2 gas in library environments conducive to preserving ancient books. Overall, our findings highlight that the developed TiO2 NTs/CNTs nano gas sensor holds great potential for monitoring and safeguarding ancient books.
Full article
(This article belongs to the Special Issue Current Trends in Coatings and Films for Optical Sensors)
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Open AccessArticle
Research and Development of Online Monitoring Protection Sensors for Paper Books Based on TiO2 NT/MoS2
by
Jia Wang, Lifang Ke, Jieling Wu, Feng Liang and Yanxiong Xiang
Coatings 2024, 14(5), 552; https://doi.org/10.3390/coatings14050552 - 30 Apr 2024
Abstract
NO2 is a prevalent environmental pollutant, and its reaction with water produces nitric acid, which is one of the main factors contributing to the degradation of books and paper. Therefore, it is crucial to develop a real-time monitoring system for NO2
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NO2 is a prevalent environmental pollutant, and its reaction with water produces nitric acid, which is one of the main factors contributing to the degradation of books and paper. Therefore, it is crucial to develop a real-time monitoring system for NO2 gas content in the air and establish timely response measures to delay book aging and provide effective protection. In this study, TiO2 nanotubes (NTs) were fabricated using the anodic oxidation method, followed by the preparation of TiO2 NT/MoS2 composites through hydrothermal synthesis. It was observed that flaky MoS2 is attached to the surface of TiO2 nanotubes, forming aggregated structures resembling flower balls. The TiO2 NT/MoS2 nanocomposites were found to exhibit a rapid response with a 5 s response time and an 80 s recovery time towards 367 ppm NO2 at 260 °C. The gas response to 100 ppm NO2 vapor was 3.3, which is higher than all the other gases under the same concentration. Our experimental results demonstrate that compared to pure TiO2 NTs, TiO2 NT/MoS2 composites exhibit a larger specific surface area along with higher sensitivity and faster response times towards various concentrations of NO2 gas.
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(This article belongs to the Special Issue Current Trends in Coatings and Films for Optical Sensors)
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Open AccessArticle
Quasi-Isotropy Structure and Characteristics of the Ultrasonic-Assisted WAAM High-Toughness Al Alloy
by
Wei Luo, Peng Xu, Ming Zhang and Jiangshan Li
Coatings 2024, 14(5), 551; https://doi.org/10.3390/coatings14050551 - 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)
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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 - 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 - 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.
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(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 - 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 - 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.
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(This article belongs to the Section Surface Characterization, Deposition and Modification)
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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 - 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.
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(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 - 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.
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(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 - 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)
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