Coatings

12 pages, 3554 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Improving the Laser Texture Strategy to Get Superhydrophobic Aluminum Alloy Surfaces

by Annalisa Volpe, Sara Covella, Caterina Gaudiuso and Antonio Ancona

Coatings 2021, 11(3), 369; https://doi.org/10.3390/coatings11030369 - 23 Mar 2021

Cited by 26 | Viewed by 3728

Changing the wetting properties of surfaces is attracting great interest in many fields, in particular to achieve a surface with a superhydrophobic behavior. Laser machining is an emerging technique to functionalize materials with high precision and flexibility without any chemical treatment. However, when [...] Read more.

Changing the wetting properties of surfaces is attracting great interest in many fields, in particular to achieve a surface with a superhydrophobic behavior. Laser machining is an emerging technique to functionalize materials with high precision and flexibility without any chemical treatment. However, when it is necessary to treat large area surfaces laser-based methods are still too slow to be exploited in industrial productions. In this work, we show that by improving the laser texture strategy it is possible to reduce the laser processing time to produce superhydrophobic aluminum alloy surfaces. Three different surface texture geometries were micromachined; namely, square, circular and triangular lattice grooves. We found that if the spacing between the grooves is narrow, i.e., when the percentage of the textured surface is high, the volume of air trapped inside the micromachined structures plays an important role in the wetting behavior. Meanwhile, when the groove spacing approaches the droplet dimensions, the texture geometry has a preponderant influence. Based on these findings an appropriate choice of the laser texture strategy allowed the fabrication of superhydrophobic aluminum alloy surfaces with a 10% reduction of processing time. Full article

(This article belongs to the Special Issue Laser Surface Engineering)

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15 pages, 4458 KiB

Open AccessArticle

Microcracks Reduction in Laser Hardened Layers of Ductile Iron

by Eduardo Hurtado-Delgado, Lizbeth Huerta-Larumbe, Argelia Miranda-Pérez and Álvaro Aguirre-Sánchez

Coatings 2021, 11(3), 368; https://doi.org/10.3390/coatings11030368 - 23 Mar 2021

Cited by 11 | Viewed by 2201

Abstract

A study of surface hardening of Ductile Iron (DI) with and without austempering heat treatment was developed. The chemical composition of the material contains alloying elements such as Cu and Ni, that allow to obtain a Ductile Iron Grade 120-90-02, based on ASTM [...] Read more.

A study of surface hardening of Ductile Iron (DI) with and without austempering heat treatment was developed. The chemical composition of the material contains alloying elements such as Cu and Ni, that allow to obtain a Ductile Iron Grade 120-90-02, based on ASTM A536, which was heat treated to be transformed to Austempered Ductile Iron (ADI). Specimens of 10 × 10 × 5 mm³ were obtained for application of surface hardening by Nd:YAG UR laser of 150 W maximum power. The parameters used were advance speed of 0.2 and 0.3 mm/s and power at 105, 120, 135 and 144 W; the departure microstructures were fully pearlitic in the samples without heat treatment, and ausferrite for austempered samples. Microstructural characterization of hardened samples was performed were analyzed and martensite and undissolved carbides were identified in the pearlitic samples, while in ausferrite samples it was found finer martensite without carbides. The depth of hardened surface to different conditions and their respective microhardness were measured. The results indicate that the surface hardening via laser is a suitable method for improving wear resistance by means of hardness increment in critical areas without compromising the core ductility of DI components, but the surface ductility is enhanced when the DI is austempered before the laser hardening, by the reduction of surface microcracks. Full article

(This article belongs to the Special Issue Mechanical Properties and Structural Analysis of Coatings and Engineered Surfaces)

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21 pages, 23642 KiB

Open AccessArticle

Controlling Fusarium oxysporum Tomato Fruit Rot under Tropical Condition Using Both Chitosan and Vanillin

by Zahir Shah Safari, Phebe Ding, Jaafar Juju Nakasha and Siti Fairuz Yusoff

Coatings 2021, 11(3), 367; https://doi.org/10.3390/coatings11030367 - 23 Mar 2021

Cited by 22 | Viewed by 3602

Abstract

Tomato Lycopersicon esculentum Mill. is one of the most cultivated and widely consumed vegetables in the world. However, it is very susceptible to the infection initiated by Fusariumoxysporum fruit rot, which shortens post-harvest life and thus reduces market value. This disease can [...] Read more.

Tomato Lycopersicon esculentum Mill. is one of the most cultivated and widely consumed vegetables in the world. However, it is very susceptible to the infection initiated by Fusariumoxysporum fruit rot, which shortens post-harvest life and thus reduces market value. This disease can be regulated appropriately by the application of synthetic fungicides. However, chemical fungicides constitute a serious health risk, and have harmful environment effects and increase disease resistance, even when microbes are dead. Hence, to overcome this problem, chitosan and vanillin, which have antimicrobial bioactive properties against the growth of microorganisms, could be an alternative to disease control, while maintaining fruit quality and prolonging shelf life. The aim of this research was to evaluate the antimicrobial activity of chitosan and vanillin towards the inoculate pathogen and to investigate the effect of chitosan and vanillin coating in vivo on Fusarium oxysporum fruit rot and defense-related enzymes (PAL, PPO and POD). Chitosan and vanillin in aqueous solutions, i.e., 0.5% chitosan + 10 mM vanillin, 1% chitosan + 10 mM vanillin, 1.5% chitosan + 10 mM vanillin, 0.5% chitosan + 15 mM vanillin, 1% chitosan + 15 mM vanillin and 1.5% chitosan + 15 mM vanillin, were used as edible coatings on tomatoes stored at 26 ± 2 °C and 60 ± 5 relative humidity. The result revealed 1.5% chitosan + 15 mM vanillin was able to control disease incidence by 70.84% and severity by 70%. These combinations of coatings were also able to retain phenylalanine ammonia-lyase (PAL), peroxidase activity (POD), and polyphenol oxidase (PPO) enzyme activities as well as prolong shelf life of tomatoes up to 15 days. Full article

(This article belongs to the Special Issue Chitosan and Other Edible Coatings with Antimicrobial Activity: Synthesis, Properties and Horticultural Applications)

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15 pages, 1870 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Environmental Impact of Wood Modification

by Callum Hill, Mark Hughes and Daniel Gudsell

Coatings 2021, 11(3), 366; https://doi.org/10.3390/coatings11030366 - 23 Mar 2021

Cited by 18 | Viewed by 4303

Abstract

The modification of wood involves extra processing over and above what is associated with un-modified material and this will involve an associated environmental impact. There is now a body of information on this due to the presence in the public domain of a [...] Read more.

The modification of wood involves extra processing over and above what is associated with un-modified material and this will involve an associated environmental impact. There is now a body of information on this due to the presence in the public domain of a number of environmental product declarations (EPDs). Using these data, it is possible to determine what the extra impact associated with the modification is. The process of modification results in a life extension of the product, which has implications regarding the storage of sequestered atmospheric carbon in the harvested wood products (HWP) materials’ pool and also extended maintenance cycles (e.g., longer periods between applying coatings). Furthermore, the life extension benefits imparted by wood modification need to be compared with the use of other technologies, such as conventional wood preservatives. This paper analysed the published data from a number of sources (peer-reviewed literature, published EPDs, databases) to compare the impacts associated with different modification technologies. The effect of life extension was examined by modelling the carbon flow dynamics of the HWP pool and determining the effect of different life extension scenarios. Finally, the paper examined the impact of different coating periods, and the extensions thereof, imparted by the use of different modified wood substrates. Full article

(This article belongs to the Special Issue Wood Modification: Characterization, Modelling and Applications)

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12 pages, 6080 KiB

Open AccessArticle

Two-Step Deposition of Silicon Oxide Films Using the Gas Phase Generation of Nanoparticles in the Chemical Vapor Deposition Process

by Jae-Ho Suk, Sung-Chun Hong, Gil-Su Jang and Nong-Moon Hwang

Coatings 2021, 11(3), 365; https://doi.org/10.3390/coatings11030365 - 23 Mar 2021

Cited by 2 | Viewed by 2072

Abstract

Non-classical crystallization, in which charged nanoparticles (NPs) are the building blocks of film growth, has been extensively studied in chemical vapor deposition (CVD). Here, the deposition behavior of silicon oxide films by the two-step growth process, where NPs are generated in the gas [...] Read more.

Non-classical crystallization, in which charged nanoparticles (NPs) are the building blocks of film growth, has been extensively studied in chemical vapor deposition (CVD). Here, the deposition behavior of silicon oxide films by the two-step growth process, where NPs are generated in the gas phase at high temperature and deposited as films at low temperature, was studied in the CVD process. Although we supplied SiH₄, H₂, and N₂, the deposited film turned out to be silicon oxide, which is attributed to relatively poor vacuum. Also, silicon oxide NPs were captured on transmission electron microscopy (TEM) carbon membranes of a copper grid for 10 s under various conditions. When the quartz tube with a conical nozzle was used, the size of nanoparticles increased drastically with increasing processing time (or delay time) and porous films with a rough surface were deposited. When the quartz tube without a nozzle was used, however, the size did not increase much with increasing processing time and dense films with a smooth surface were deposited. These results suggest that the size of nanoparticles is an important parameter for the deposition of dense films for two-step growth at low temperatures. Full article

(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)

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18 pages, 5566 KiB

Open AccessReview

Corrosion Behavior and Surface Treatment of Cladding Materials Used in High-Temperature Lead-Bismuth Eutectic Alloy: A Review

by Hao Wang, Jun Xiao, Hui Wang, Yong Chen, Xing Yin and Ning Guo

Coatings 2021, 11(3), 364; https://doi.org/10.3390/coatings11030364 - 23 Mar 2021

Cited by 32 | Viewed by 4544

Abstract

Liquid metal fast reactors were considered to be the most promising solution to meet the enormous energy demand in the future. However, corrosion phenomenon caused by the liquid metal, especially in high-temperature lead-bismuth coolant, has greatly hindered the commercialization of the advanced Generation-IV [...] Read more.

Liquid metal fast reactors were considered to be the most promising solution to meet the enormous energy demand in the future. However, corrosion phenomenon caused by the liquid metal, especially in high-temperature lead-bismuth coolant, has greatly hindered the commercialization of the advanced Generation-IV nuclear system. This review discussed current research on the corrosion resistance of structural materials (such as EP823, T91, ODS, and authentic steels) in high-temperature liquid metal served as reactor coolants. The current corrosion resistance evaluation has proved that even for the excellent performance of EP823, the structural material selected in pressurized water reactor is not the ideal material for operation in the high-temperature lead-bismuth eutectic (LBE). Furthermore, the latest coating technologies that are expected to be applied to cladding materials for coolant system were extensively discussed, including Al-containing coatings, ceramic coatings, oxide coatings, amorphous coatings and high-entropy alloy coatings. The detailed comparison summarized the corrosion morphology and corrosion products of various coatings in LBE. This review not only provided a systematic understanding of the corrosion phenomena, but also demonstrated that coating technology is an effective method to solve the corrosion issues of the advanced next-generation reactors. Full article

(This article belongs to the Special Issue Surface Modification and Functionalization of High-Temperature Alloys)

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10 pages, 4374 KiB

Open AccessArticle

Effects of Different Post-Treatments on Arc Erosion Resistance of Cold-Sprayed AgC Composite Electric Contact

by Jingyu Li, Xin Zhou, Yan Liu, Yanming Chen, Jun Zhang, Renzhong Huang, Jun Tan, Zhenggang Li and Bing Yang

Coatings 2021, 11(3), 363; https://doi.org/10.3390/coatings11030363 - 23 Mar 2021

Cited by 1 | Viewed by 1928

Abstract

Graphite-silver (AgC) composite materials are widely used in outdoor high-voltage electrical switchgear due to their combining properties of excellent conductivity and outstanding arc-suppressing performance. However, the methods for fabricating AgC composite materials still have some limitations. In this study, the cold spray technique [...] Read more.

Graphite-silver (AgC) composite materials are widely used in outdoor high-voltage electrical switchgear due to their combining properties of excellent conductivity and outstanding arc-suppressing performance. However, the methods for fabricating AgC composite materials still have some limitations. In this study, the cold spray technique was adopted to deposit AgC composite coatings with the optimized parameters on the copper substrate. Then, AgC coatings were annealed in the furnace and treated by laser scanning, respectively, to further improve the arc erosion resistance performance of the coatings. The results show that the phase structure and electrical resistance of AgC coatings were not influenced by the post-treatment process. Furthermore, excellent hydrophobic performance was obtained after surface laser scanning treatment. The laser scanning treatment exhibited favorable advantages in enhancing the arc erosion resistance of AgC coatings, which indicated the lowest arc erosion rate compared with the cold-sprayed and annealed coatings. Full article

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13 pages, 4018 KiB

Open AccessArticle

Plasma-Enhanced Atomic Layer Deposition of Zirconium Oxide Thin Films and Its Application to Solid Oxide Fuel Cells

by Jiwon Oh, Giwon Seo, Jaehwan Kim, Seungmuk Bae, Jeong-Woo Park and Jin-Ha Hwang

Coatings 2021, 11(3), 362; https://doi.org/10.3390/coatings11030362 - 22 Mar 2021

Cited by 6 | Viewed by 2881

Abstract

Zirconium oxides were deposited using plasma-enhanced atomic layer deposition (PEALD) involving (2-(N-methylamino)1-MethylEthyleneCyclopentadienyl)Bis(DiMethylAmino)Zr (abbreviated as CMEN-Zr) and oxygen plasma as zirconium and oxygen sources. The zirconium oxide thin films demonstrate temperature-independent growth rates per cycle of 0.94 A/cycle at 150–215 °C. The deposited ZrO [...] Read more.

Zirconium oxides were deposited using plasma-enhanced atomic layer deposition (PEALD) involving (2-(N-methylamino)1-MethylEthyleneCyclopentadienyl)Bis(DiMethylAmino)Zr (abbreviated as CMEN-Zr) and oxygen plasma as zirconium and oxygen sources. The zirconium oxide thin films demonstrate temperature-independent growth rates per cycle of 0.94 A/cycle at 150–215 °C. The deposited ZrO₂ thin films were characterized using numerous analytical tools, i.e., X-ray photoelectron spectroscopy for chemical bonding state and composition, X-ray diffraction for crystallinity, atomic force microscopy for surface morphology, field-emission scanning electron microscopy for cross-sectional analysis, spectroscopic ellipsometry and UV–visible spectrophotometry for optical characterization, capacitance–voltage measurements for dielectric constants and atomic defects, and current–voltage characteristics for electrical information. The insulating features of the crystalline and stoichiometric ZrO₂ films were implemented in the anode composites to evaluate the influence of ALD-based nano-features on the electrochemical performance of solid oxide fuel cells, with the main emphasis on anode performance. The presence of nanomaterials on Ni/YSZ anode composites is analyzed to determine the negative effects on electrochemical performance and the degradation of cell performance of solid oxide fuel cells (SOFCs). The artificial design was proven to be effective in controlling the cell performance as long as proper material design was adopted in SOFC electrodes. Full article

(This article belongs to the Special Issue Atomic Layer Deposition of Thin-Films)

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15 pages, 8743 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Physical Properties of Submicron and Nano-Grained La_0.7Sr_0.3MnO₃ and Nd_0.7Sr_0.3MnO₃ Synthesised by Sol–Gel and Solid-State Reaction Methods

by Lik Nguong Lau, Kean Pah Lim, Amirah Natasha Ishak, Mohd Mustafa Awang Kechik, Soo Kien Chen, Noor Baa’yah Ibrahim, Muralidhar Miryala, Masato Murakami and Abdul Halim Shaari

Coatings 2021, 11(3), 361; https://doi.org/10.3390/coatings11030361 - 22 Mar 2021

Cited by 14 | Viewed by 3158

Abstract

La_0.7Sr_0.3MnO₃ (LSMO) and Nd_0.7Sr_0.3MnO₃ (NSMO) possess excellent colossal magnetoresistance (CMR). However, research work on the neodymium-based system is limited to date. A comparative study between LSMO and NSMO prepared by sol–gel and solid-state [...] Read more.

La_0.7Sr_0.3MnO₃ (LSMO) and Nd_0.7Sr_0.3MnO₃ (NSMO) possess excellent colossal magnetoresistance (CMR). However, research work on the neodymium-based system is limited to date. A comparative study between LSMO and NSMO prepared by sol–gel and solid-state reaction methods was undertaken to assess their structural, microstructural, magnetic, electrical, and magneto-transport properties. X-ray diffraction and structure refinement showed the formation of a single-phase composition. Sol–gel-synthesised NSMO was revealed to be a sample with single crystallite grains and exhibited intriguing magnetic and electrical transport behaviours. Magnetic characterisation highlighted that Curie temperature (T_C) decreases with the grain size. Strong suppression of the metal–insulator transition temperature (T_MI) was observed and attributed to the magnetically disordered grain surface and distortion of the MnO₆ octahedra. The electrical resistivity in the metallic region was fitted with theoretical models, and the conduction mechanism could be explained by the grain/domain boundary, electron–electron, and electron–magnon scattering process. The increase in the scattering process was ascribed to the morphology changes. Enhancement of low-field magnetoresistance (LFMR) was observed in nano-grained samples. The obtained results show that the grain size and its distribution, as well as the crystallite formation, strongly affect the physical properties of hole-doped manganites. Full article

(This article belongs to the Special Issue New Advance in Superconductor and Superconducting Thin Films)

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16 pages, 8552 KiB

Open AccessArticle

Control of the Pore Structure of Plasma-Sprayed Thermal Barrier Coatings through the Addition of Unmelted Porous YSZ Particles

by Yuanjun Li, Jibo Huang, Weize Wang, Dongdong Ye, Huanjie Fang, Dong Gao, Shantung Tu, Xueping Guo and Zexin Yu

Coatings 2021, 11(3), 360; https://doi.org/10.3390/coatings11030360 - 21 Mar 2021

Cited by 5 | Viewed by 2427

Abstract

In this study, a new pore structure control method for plasma-sprayed thermal barrier coatings (TBCs) through the addition of unmelted, porous yttria-stabilized zirconia (YSZ) particles was investigated. Through a unique way of feeding powder, two powder feeders were used simultaneously at different positions [...] Read more.

In this study, a new pore structure control method for plasma-sprayed thermal barrier coatings (TBCs) through the addition of unmelted, porous yttria-stabilized zirconia (YSZ) particles was investigated. Through a unique way of feeding powder, two powder feeders were used simultaneously at different positions of the plasma flame to deposit a composite structure coating in which a conventional plasma-sprayed coating was used as a matrix and unmelted micro-agglomerated YSZ particles were dispersed in the dense conventional coating matrix as second-phase particles. The effects of the distribution and content of second-phase particles on the microstructure, mechanical properties, and lifetime were explored in a furnace cyclic test (24 h) of the composite coating. The mechanical properties and lifetime of the composite coating depend on the content and morphology of the particles embedded in the coating. The lifetime of the composite structure coatings is significantly higher than that of the conventional coatings. By adjusting the spraying parameters, the lifetime of the composite coating prepared under the optimum process is up to 145 days, which is about three times that of the conventional coating. The results of this study provide guidance for the preparation of high-performance composite structure TBCs. Full article

(This article belongs to the Special Issue Plasma Sprayed Coatings)

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12 pages, 7057 KiB

Open AccessArticle

Characteristics and Crystal Structure of Calcareous Deposit Films Formed by Electrodeposition Process in Artificial and Natural Seawater

by Jun-Mu Park, Myeong-Hoon Lee and Seung-Hyo Lee

Coatings 2021, 11(3), 359; https://doi.org/10.3390/coatings11030359 - 21 Mar 2021

Cited by 5 | Viewed by 2799

Abstract

In this study, we tried to form the calcareous deposit films by the electrodeposition process. The uniform and compact calcareous deposit films were formed by electrodeposition process and their crystal structure and characteristics were analyzed and evaluated using various surface analytical techniques. The [...] Read more.

In this study, we tried to form the calcareous deposit films by the electrodeposition process. The uniform and compact calcareous deposit films were formed by electrodeposition process and their crystal structure and characteristics were analyzed and evaluated using various surface analytical techniques. The mechanism of formation for the calcareous deposit films could be confirmed and the role of magnesium was verified by experiments in artificial and natural seawater solutions. The highest amount of the calcareous deposit film was obtained at 5 A/m² while current densities between 1–3 A/m² facilitated the formation of the most uniform and dense layers. In addition, the adhesion characteristics were found to be the best at 3 A/m². The excellent characteristics of the calcareous deposit films were obtained when the dense film of brucite-Mg(OH)₂ and metastable aragonite-CaCO₃ was formed in the appropriate ratio. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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18 pages, 10422 KiB

Open AccessArticle

Investigation into Microstructure, Wear Resistance in Air and NaCl Solution of AlCrCoNiFeCTax High-Entropy Alloy Coatings Fabricated by Laser Cladding

by Peng Zhao, Jun Li, Ruyan Lei, Baige Yuan, Manman Xia, Xiao Li and Ying Zhang

Coatings 2021, 11(3), 358; https://doi.org/10.3390/coatings11030358 - 21 Mar 2021

Cited by 8 | Viewed by 1996

Abstract

AlCrCoNiFeCTa_x (x = 0, 0.5 and 1.0) high-entropy alloys coatings were synthesized on 45# steel by laser cladding. The microstructural evolution of the coatings with the change in x was analyzed in detail. The effect of Ta content on the wear behaviors [...] Read more.

AlCrCoNiFeCTa_x (x = 0, 0.5 and 1.0) high-entropy alloys coatings were synthesized on 45# steel by laser cladding. The microstructural evolution of the coatings with the change in x was analyzed in detail. The effect of Ta content on the wear behaviors of the coatings at different circumstances (in air and 3.5 wt.% NaCl solution) was especially highlighted. The microstructure presented the following change: equiaxed BCC (Body Centered Cubic) grains + fine MC (carbide, M = Al, Cr, Co and Ni) particles (x = 0) → equiaxed BCC grains + coarse TaC blocks + fine TaC particles (x = 0.5) → flower-like BCC grains + coarse TaC blocks + eutecticum (BCC + TaC) (x = 1.0). The average microhardness of the coatings demonstrated an upward tendency with increasing x due to the combination of the stronger solid solution and dispersion strengthening from the significant difference in atomic radius between Ta and Fe and the formation of TaC with an extremely high hardness. The wear rates of the coatings were gradually reduced both in air and in NaCl solution along with the increase in Ta content, which were lower than those of the substrate. The wear rates of the coatings with x = 0.5 and 1.0 in NaCl solution were slightly reduced by about 17% and 12% when compared with those in air. However, the values of the substrate and the coating without Ta in NaCl solution were sharply enhanced by 191% and 123% when compared with those in air. This indicated that the introduction of Ta contributed to the improvement in wear resistance both in air and in NaCl solution. Full article

(This article belongs to the Special Issue Wear Behavior of Polymer Composites)

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17 pages, 6896 KiB

Open AccessArticle

Corrosion Behavior of Alloyed Cast Iron in Ethylene Glycol-Based Engine Coolants at Elevated Temperature

by Gaurav Argade, Anusha Chilukuri, Justin Perry, Monica Viers, Jacob Steenhoek, Jacob Debusk, Chinpei Wang and Corey Trobaugh

Coatings 2021, 11(3), 357; https://doi.org/10.3390/coatings11030357 - 21 Mar 2021

Cited by 5 | Viewed by 2938

Abstract

For enhanced engine performance, corrosivity of the engine coolants would play a significant role. In this work, corrosion investigation was performed on cast iron material in pre-mixed engine coolant environment to understand the threshold limits of contaminants. The pre-mixed coolant contained combination of [...] Read more.

For enhanced engine performance, corrosivity of the engine coolants would play a significant role. In this work, corrosion investigation was performed on cast iron material in pre-mixed engine coolant environment to understand the threshold limits of contaminants. The pre-mixed coolant contained combination of organic additives viz. sebacate (SA), 2-ethylhexanoate (2-EH), and tolyltriazole (TTA) with varying concentrations of chloride contaminant. Constant immersion of cast iron samples in engine coolant with different chloride levels at 90 °C was followed by room temperature electrochemical tests. The potentiodynamic polarization tests showed no instability until 100 ppm chloride additions exposed up to 28 days. At lower frequencies in electrochemical impedance spectroscopy (EIS) spectra, inhibition layer characteristics changed from highly capacitive to highly resistive and concurrently a sharp decrease in charge transfer resistance was observed with time for samples exposed to >100 ppm chloride levels. In the longer duration corrosion tests, higher pit depths with increased number density of attacks were observed for cast iron samples exposed to engine coolants containing >100 ppm chloride. For elevated temperature exposures a threshold limit of <200 ppm chloride was established for cast iron samples. Full article

(This article belongs to the Special Issue Recent Achievements in Corrosion Protection of Metals by Polymeric Coatings, Surface Pretreatments and Inhibitors)

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12 pages, 2096 KiB

Open AccessArticle

Te-Embedded Nanocrystalline PbTe Thick Films: Structure and Thermoelectric Properties Relationship

by Tingjun Wu, Jae-Hong Lim, Kyu-Hwan Lee, Jiwon Kim and Nosang V. Myung

Coatings 2021, 11(3), 356; https://doi.org/10.3390/coatings11030356 - 21 Mar 2021

Cited by 4 | Viewed by 2070

Abstract

The Te-embedded PbTe nanocrystallline thick films (i.e., 50 µm) were electrodeposited, where the fraction and average grain size of PbTe and Te phases were tuned by adjusting the applied potential followed by post thermal treatment. The crystal grain boundary and Te nano-inclusion in [...] Read more.

The Te-embedded PbTe nanocrystallline thick films (i.e., 50 µm) were electrodeposited, where the fraction and average grain size of PbTe and Te phases were tuned by adjusting the applied potential followed by post thermal treatment. The crystal grain boundary and Te nano-inclusion in the films played critical roles in their thermoelectric properties. The Te-embedded PbTe thick film with the average grain size of around 100 nm showed lower energy barrier height (E_B = 0.023 eV) than thick films with the average grain size of a few tens of nm (E_B = 0.11). Although decrease in the energy barrier reduced the Seebeck coefficient, however, it enhanced the electrical conductivity, which resulted in an increase in power factor (PF). The highest power factor was 183 μw K⁻² cm⁻¹, achieved at the energy barrier of 0.023 eV. Full article

(This article belongs to the Special Issue Thin Films for Electronic Devices)

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13 pages, 4857 KiB

Open AccessArticle

Atomic Layer Deposition of Insulating AlF₃/Polyimide Nanolaminate Films

by Xinzhi Li, Marko Vehkamäki, Mikko Heikkilä, Miika Mattinen, Matti Putkonen, Markku Leskelä and Mikko Ritala

Coatings 2021, 11(3), 355; https://doi.org/10.3390/coatings11030355 - 19 Mar 2021

Cited by 4 | Viewed by 2617

Abstract

This article describes the deposition of AlF₃/polyimide nanolaminate film by inorganic-organic atomic layer deposition (ALD) at 170 °C. AlCl₃ and TiF₄ were used as precursors for AlF₃. Polyimide layers were deposited from PMDA (pyromellitic dianhydride, 1,2,3,5-benzenetetracarboxylic anhydride) [...] Read more.

This article describes the deposition of AlF₃/polyimide nanolaminate film by inorganic-organic atomic layer deposition (ALD) at 170 °C. AlCl₃ and TiF₄ were used as precursors for AlF₃. Polyimide layers were deposited from PMDA (pyromellitic dianhydride, 1,2,3,5-benzenetetracarboxylic anhydride) and DAH (1,6-diaminohexane). With field-emission scanning electron microscopy (FESEM) and X-ray reflection (XRR) analysis, it was found that the topmost layer (nominally 10 nm in thickness) of the nanolaminate film (100 nm total thickness) changed when exposed to the atmosphere. After all, the effect on roughness was minimal. The length of a delay time between the AlF₃ and polyimide depositions was found to affect the sharpness of the nanolaminate structure. Electrical properties of AlF₃/polyimide nanolaminate films were measured, indicating an increase in dielectric constant compared to single AlF₃ and a decrease in leakage current compared to polyimide films, respectively. Full article

(This article belongs to the Collection Coatings: 10th Anniversary)

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12 pages, 5092 KiB

Open AccessArticle

Investigation of Color Reproduction on Linen Fabrics when Printing with Mimaki TX400-1800D Inkjet with Pigment TP250 Dyes

by Tim Tofan, Rimantas Stonkus and Raimondas Jasevičius

Coatings 2021, 11(3), 354; https://doi.org/10.3390/coatings11030354 - 19 Mar 2021

Cited by 3 | Viewed by 2433

Abstract

The aim of this research is to investigate related effect of dyeability to linen textiles related to different printing parameters. The study investigated the change in color characteristics when printing on linen fabrics with an inkjet MIMAKI Tx400-1800D printer with pigmented TP 250 [...] Read more.

The aim of this research is to investigate related effect of dyeability to linen textiles related to different printing parameters. The study investigated the change in color characteristics when printing on linen fabrics with an inkjet MIMAKI Tx400-1800D printer with pigmented TP 250 inks. The dependence of color reproduction on linen fabrics on the number of print head passes, number of ink layers to be coated, linen fabric density, and different types of linen fabric was investigated. All this affects the quality of print and its mechanical properties. The change in color characteristics on different types of linen fabrics was determined experimentally. We determine at which print settings the most accurate color reproduction can be achieved on different linen fabrics. The difference between the highest and the lowest possible number of head passages was investigated. The possibilities of reproducing different linen fabric colors were determined. Full article

(This article belongs to the Collection Coatings: 10th Anniversary)

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15 pages, 4720 KiB

Open AccessArticle

Effects of Joule Heating and Viscous Dissipation on Magnetohydrodynamic Boundary Layer Flow of Jeffrey Nanofluid over a Vertically Stretching Cylinder

by Haroon Ur Rasheed, Abdou AL-Zubaidi, Saeed Islam, Salman Saleem, Zeeshan Khan and Waris Khan

Coatings 2021, 11(3), 353; https://doi.org/10.3390/coatings11030353 - 19 Mar 2021

Cited by 57 | Viewed by 3086

Abstract

This article investigates unsteady magnetohydrodynamic (MHD) mixed convective and thermally radiative Jeffrey nanofluid flow in view of a vertical stretchable cylinder with radiation absorption and heat; the reservoir was addressed. The mathematical formulation of Jeffrey nanofluid is established based on the theory of [...] Read more.

This article investigates unsteady magnetohydrodynamic (MHD) mixed convective and thermally radiative Jeffrey nanofluid flow in view of a vertical stretchable cylinder with radiation absorption and heat; the reservoir was addressed. The mathematical formulation of Jeffrey nanofluid is established based on the theory of boundary layer approximations pioneered by Prandtl. The governing model expressions in partial differential equations (PDEs) form was transformed into dimensionless form via similarity transformation technique. The set of nonlinear nondimensional partial differential equations are solved with the help of the homotopic analysis method. For the purpose of accuracy, the optimizing system parameters, convergence, and stability analysis of the analytical algorithm (CSA) were performed graphically. The velocity, temperature, and concentration flow are studied and shown graphically with the effect of system parameters such as Grashof number, Hartman number, Prandtl number, thermal radiation, Schmidt number, Eckert number, Deborah number, Brownian parameter, heat source parameter, thermophoresis parameter, and stretching parameter. Moreover, the consequence of system parameters on skin friction coefficient, Nusselt number, and Sherwood number is also examined graphically and discussed. Full article

(This article belongs to the Special Issue New Advances in Interfacial Mass Transfer)

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15 pages, 2629 KiB

Open AccessArticle

Graphene Matrices as Carriers for Metal Ions against Antibiotic Susceptible and Resistant Bacterial Pathogens

by Anthony J. Slate, Nathalie Karaky, Grace S. Crowther, Jonathan A. Butler, Craig E. Banks, Andrew J. McBain and Kathryn A. Whitehead

Coatings 2021, 11(3), 352; https://doi.org/10.3390/coatings11030352 - 19 Mar 2021

Cited by 7 | Viewed by 2645

Abstract

Due to the ever-increasing burden of antimicrobial-resistant (AMR) bacteria, the development of novel antimicrobial agents and biomaterials to act as carriers and/or potentiate antimicrobial activity is essential. This study assessed the antimicrobial efficacy of the following ionic metals, silver, gold, palladium, platinum, zinc, [...] Read more.

Due to the ever-increasing burden of antimicrobial-resistant (AMR) bacteria, the development of novel antimicrobial agents and biomaterials to act as carriers and/or potentiate antimicrobial activity is essential. This study assessed the antimicrobial efficacy of the following ionic metals, silver, gold, palladium, platinum, zinc, and gallium alone and in combination with graphene matrices (which were coated via a drop casting coating method). The graphene foam was utilized as a carrier for the ionic metals against both, antibiotic susceptible and resistant bacterial strains of Acinetobacter baumannii,Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. Ionic gold, palladium and platinum demonstrated the greatest antimicrobial activity against the susceptible and resistant strains. Scanning electron microscopy (SEM) visualized cellular ultrastructure damage, when the bacteria were incubated upon the graphene foam alone. This study suggests that specific metal ions applied in combination with graphene foam could present a potential therapeutic option to treat AMR bacterial infections. The application of the graphene foam as a potential carrier could promote antimicrobial activity, provide a sustained release approach and reduce possible resistance acquisition. In light of this study, the graphene foam and ionic metal combinations could potentially be further developed as part of a wound dressing. Full article

(This article belongs to the Special Issue Antibacterial Surfaces, Thin Films, and Nanostructured Coatings)

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17 pages, 3691 KiB

Open AccessArticle

Development of Antibacterial, Antioxidant, and UV-Barrier Chitosan Film Incorporated with Piper betle Linn Oil as Active Biodegradable Packaging Material

by Thuong Thi Nguyen, Thu-Thao Thi Nguyen, Thuan Van Tran, Lam Van Tan, Luu Thai Danh and Van Thai Than

Coatings 2021, 11(3), 351; https://doi.org/10.3390/coatings11030351 - 19 Mar 2021

Cited by 10 | Viewed by 3068

Abstract

This study aims to introduce the antibacterial and antioxidant activities of the Piper betle Linn oil (PBLO) into chitosan film (pCS), named as pCS-PBLO film. The morphology, structure, and properties of the pCS-PBLO film, along with the PBLO concentration between 0.4% and 1.2% [...] Read more.

This study aims to introduce the antibacterial and antioxidant activities of the Piper betle Linn oil (PBLO) into chitosan film (pCS), named as pCS-PBLO film. The morphology, structure, and properties of the pCS-PBLO film, along with the PBLO concentration between 0.4% and 1.2% (v/v), were determined. The film surface became rough and heterogeneous with the addition of PBLO, which directly influenced on mechanical strength of the resultant film. The addition of the PBLO did not affect thermal stability but significant effect on flexibility and mobility of the film. Importantly, the film enhanced the UV-protective property and antioxidant activity as incorporated-PBLO. Moreover, the resulting film revealed the great inhibition efficiency against the negative-gram (E. coli, P. aeruginosa, and S. typhi) and positive-gram (S. aureus) bacteria based on phenolic compounds, such as the acetyleugenol, eugenol, 4-allyl-1,2-diacetoxybenzen, and chavicol acetate in PBLO components. In particular, the pCS-PBLO film may extend the shelf life of king oranges up to two weeks at 25 °C that is longer as compared to the uncoated sample and coated with chitosan alone. These results suggest that the pCS-PBLO film can be used as environmental-friendly and effective food packaging material in the future. Full article

(This article belongs to the Section Functional Polymer Coatings and Films)

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13 pages, 4224 KiB

Open AccessEditor’s ChoiceArticle

Polymer-Cement Composites Glazing by Concentrated Solar Energy

by Liana Sanda Baltes, Silvia Patachia, Ozgur Ekincioglu, Hulusi Ozkul, Catalin Croitoru, Corneliu Munteanu, Bogdan Istrate and Mircea Horia Tierean

Coatings 2021, 11(3), 350; https://doi.org/10.3390/coatings11030350 - 18 Mar 2021

Cited by 2 | Viewed by 3033

Abstract

Macro defect free (MDF) cements are polymer-cement composites characterized by high biaxial flexural strength compared to traditional concrete, having as a drawback a low water resistance. Glazing these composite materials with an inorganic enamel containing TiO₂ nano-particles has led to a high [...] Read more.

Macro defect free (MDF) cements are polymer-cement composites characterized by high biaxial flexural strength compared to traditional concrete, having as a drawback a low water resistance. Glazing these composite materials with an inorganic enamel containing TiO₂ nano-particles has led to a high water-stable material with advanced photocatalytic properties. Classic glazing by thermal treatment of samples, at 1050 °C, requires energy consumption and long-time performing. The purpose of this paper is to test the use of solar radiation as a source of energy in the glazing process. A vertical axis solar furnace has been used, from PROMES-CNRS Solar Laboratory, Font-Romeu Odeillo, France, and it has been observed that a uniform appearance of the glaze coating has been achieved; it shows high scratch resistance, meaning a good hardness and adhesion to the substrate. The obtained film was also characterized by SEM, EDS and XRD, aiming to evidence the coat morphology, the TiO₂ distribution and its crystallinity alteration, when compared to the samples obtained by classic thermal treatment. The conclusion of the paper is that using solar radiation in the MDF cement glazing process is a promising approach for obtaining multifunctional materials. Full article

(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)

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19 pages, 5846 KiB

Open AccessEditor’s ChoiceArticle

Low-Density Insulation Blocks and Hardboards from Amaranth (Amaranthus cruentus) Stems, a New Perspective for Building Applications

by Philippe Evon, Guyonne de Langalerie, Laurent Labonne, Othmane Merah, Thierry Talou, Stéphane Ballas and Thierry Véronèse

Coatings 2021, 11(3), 349; https://doi.org/10.3390/coatings11030349 - 18 Mar 2021

Cited by 5 | Viewed by 3112

Abstract

Nowadays, amaranth appears as a promising source of squalene of vegetable origin. Amaranth oil is indeed one of the most concentrated vegetable oils in squalene, i.e., up to 6% (w/w). This triterpene is highly appreciated in cosmetology, especially for [...] Read more.

Nowadays, amaranth appears as a promising source of squalene of vegetable origin. Amaranth oil is indeed one of the most concentrated vegetable oils in squalene, i.e., up to 6% (w/w). This triterpene is highly appreciated in cosmetology, especially for the formulation of moisturizing creams. It is almost exclusively extracted from the liver of sharks, causing their overfishing. Thus, providing a squalene of renewable origin is a major challenge for the cosmetic industry. The amaranth plant has thus experienced renewed interest in recent years. In addition to the seeds, a stem is also produced during cultivation. Representing up to 80% (w/w) of the plant aerial part, it is composed of a ligneous fraction, the bark, on its periphery, and a pith in its middle. In this study, a fractionation process was developed to separate bark and pith. These two fractions were then used to produce renewable materials for building applications. On the one hand, the bark was used to produce hardboards, with the deoiled seeds acting as natural binder. Such boards are a viable alternative to commercial wood-based panels. On the other hand, the pith was transformed into cohesive and machinable low-density insulation blocks revealing a low thermal conductivity value. Full article

(This article belongs to the Special Issue Natural Fiber Based Composites)

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10 pages, 19801 KiB

Open AccessArticle

Merging the Sol–Gel Technique with the Pulsed Microplasma Cluster Source Deposition to Improve Control over the Memristive Response of TiO₂ Thin Films

by Valentina Prusakova, Giovanni Giusti, Cristian Collini, Giancarlo Pepponi, Mario Barozzi, Leandro Lorenzelli, Salvatore Iannotta, Roberto Verucchi and Sandra Dirè

Coatings 2021, 11(3), 348; https://doi.org/10.3390/coatings11030348 - 18 Mar 2021

Viewed by 2080

Abstract

Metal oxide thin films show promising resistive switching properties, making them materials of reference for the development of memristive devices. TiO₂ is probably one of the most studied materials and is being synthesized using various techniques, each of them having specific optimizable [...] Read more.

Metal oxide thin films show promising resistive switching properties, making them materials of reference for the development of memristive devices. TiO₂ is probably one of the most studied materials and is being synthesized using various techniques, each of them having specific optimizable characteristics. In this paper, we report on an innovative approach by combining the sol–gel and the pulsed microplasma cluster source (PMCS) methods, exploiting the low temperature and low cost of the former process and precise control over nanocristallinity of the latter. We show that this approach overcomes the reported limitations that each technique shows in fabricating memristive devices when independently used. A side-by-side comparison of the TiO₂ thin films produced by the PMCS, sol–gel, and PMCS/sol–gel hybrid methods (HM) demonstrates an improvement of the memristive properties and a reduction of the electrical shorts in the TiO₂ based devices. Full article

(This article belongs to the Special Issue Design of Functional Coatings by Chemical Methods)

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23 pages, 4024 KiB

Open AccessArticle

Water-Resistant Latex Coatings: Tuning of Properties by Polymerizable Surfactant, Covalent Crosslinking and Nanostructured ZnO Additive

by Jana Machotová, Andréa Kalendová, Denisa Steinerová, Petra Mácová, Stanislav Šlang, Jaromír Šňupárek and Jan Vajdák

Coatings 2021, 11(3), 347; https://doi.org/10.3390/coatings11030347 - 18 Mar 2021

Cited by 16 | Viewed by 3785

Abstract

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided [...] Read more.

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided by nanostructured ZnO additive) were investigated. The latexes were prepared by the standard emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as the main monomers. The addition of surface-untreated powdered nanostructured ZnO was performed during latex synthesis, resulting in stable latexes comprising dispersed nanosized additive in the content of ca 0.9−1.0 wt.% (based on solids). The coating performance with emphasis on water resistance was evaluated. It was determined that the application of the polymerizable surfactant improved coating adhesion and water-resistance, but it wasn′t able to ensure high water-resistance of coatings. Highly water-resistant coatings were obtained provided that covalent intra- and interparticle crosslinking together with ionic crosslinking were employed in the coating composition, forming densely crosslinked latex films. Moreover, coatings comprising nanostructured ZnO additive displayed a significant antibacterial activity and improved solvent resistance. Full article

(This article belongs to the Collection Coatings: 10th Anniversary)

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12 pages, 2483 KiB

Open AccessArticle

Shoulder Implant Manufacturer Detection by Using Deep Learning: Proposed Channel Selection Layer

by Atınç Yılmaz

Coatings 2021, 11(3), 346; https://doi.org/10.3390/coatings11030346 - 18 Mar 2021

Cited by 10 | Viewed by 2510

Abstract

Total Shoulder Arthroplasty (TSA) is the process of replacing the damaged ball and socket joint in the shoulder with a prosthesis made with polyethylene and metal components. After this procedure, intervention may be required as a result of damage to the prosthesis, except [...] Read more.

Total Shoulder Arthroplasty (TSA) is the process of replacing the damaged ball and socket joint in the shoulder with a prosthesis made with polyethylene and metal components. After this procedure, intervention may be required as a result of damage to the prosthesis, except for the need for an examination regarding the prosthesis at certain periods. If the patient does not have information about the model and manufacturer of the prosthesis, the treatment process is delayed. Artificial intelligence-assisted systems can speed up the treatment process by classifying the manufacturer and model of the prosthesis. In this study, artificial intelligence methods were applied to classify shoulder implants using X-ray images. The model and manufacturer of the prosthesis is detected by using the proposed deep learning method. Besides, the most commonly used machine learning classifiers were applied for the same problem to compare the results and show the effectiveness of the proposed method. In addition, the accuracy and precision analysis and measurements of the processing times for the applied methods were performed to reveal the performance, accuracy, and efficiency of the study. In order to measure the performance of the proposed method, it was compared with studies on the same problem in the literature. As a result of the comparison, it was found that the proposed method, with an accuracy rate of 97.2%, performed better than the other studies. In the study, the implant manufacturer and model are classified in order to carry out the implant surgery process in the best way with the proposed deep learning model. With the success of the proposed system, the applicability of this model in similar prosthesis classifications has been shown. Differently from the studies in the literature, the channel selection formula is presented in the proposed deep learning method recommended for selecting the most distinctive feature filters. Full article

(This article belongs to the Special Issue Advanced Coatings for Manufacturing Prosthetic Tubular Devices)

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12 pages, 2983 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Sputter-Deposited Ag Nanoparticles on Electrospun PCL Scaffolds: Morphology, Wettability and Antibacterial Activity

by Daniele Valerini, Loredana Tammaro, Roberta Vitali, Gloria Guillot and Antonio Rinaldi

Coatings 2021, 11(3), 345; https://doi.org/10.3390/coatings11030345 - 18 Mar 2021

Cited by 20 | Viewed by 3319

Abstract

Porous scaffolds made of biocompatible and environmental-friendly polymer fibers with diameters in the nano/micro range can find applications in a wide variety of sectors, spanning from the biomedical field to textiles and so on. Their development has received a boost in the last [...] Read more.

Porous scaffolds made of biocompatible and environmental-friendly polymer fibers with diameters in the nano/micro range can find applications in a wide variety of sectors, spanning from the biomedical field to textiles and so on. Their development has received a boost in the last decades thanks to advances in the production methods, such as the electrospinning technique. Conferring antimicrobial properties to these fibrous structures is a primary requirement for many of their applications, but the addition of antimicrobial agents by wet methods can present a series of drawbacks. In this work, strong antibacterial action is successfully provided to electrospun polycaprolactone (PCL) scaffolds by silver (Ag) addition through a simple and flexible way, namely the sputtering deposition of silver onto the PCL fibers. SEM-EDS analyses demonstrate that the polymer fibers get coated by Ag nanoparticles without undergoing any alteration of their morphological integrity upon the deposition process. The influence on wettability is evaluated with polar (water) and non-polar (diiodomethane) liquids, evidencing that this coating method allows preserving the hydrophobic character of the PCL polymer. Excellent antibacterial action (reduction > 99.995% in 4 h) is demonstrated against Escherichia coli. The easy fabrication of these PCL-Ag mats can be applicable to the production of biomedical devices, bioremediation and antifouling systems in filtration, personal protective equipment (PPE), food packaging materials, etc. Full article

(This article belongs to the Special Issue Antibacterial Surfaces, Thin Films, and Nanostructured Coatings)

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43 pages, 27415 KiB

Open AccessFeature PaperReview

Quo Vadis: AlCr-Based Coatings in Industrial Applications

by Joerg Vetter, Anders O. Eriksson, Andreas Reiter, Volker Derflinger and Wolfgang Kalss

Coatings 2021, 11(3), 344; https://doi.org/10.3390/coatings11030344 - 18 Mar 2021

Cited by 23 | Viewed by 4970

Abstract

AlCr-based hard nitride coatings with different chemical compositions and architectures have been successfully developed and applied over the last few decades. Coating properties are mainly influenced by deposition conditions and the Al/Cr content. The fcc structure is dominant for an Al-content up to [...] Read more.

AlCr-based hard nitride coatings with different chemical compositions and architectures have been successfully developed and applied over the last few decades. Coating properties are mainly influenced by deposition conditions and the Al/Cr content. The fcc structure is dominant for an Al-content up to Al_0.7Cr_0.3N and is preferred for most cutting applications. Different (AlCrX)N alloying concepts, including X = Si, W, B, V, have been investigated in order to enhance oxidation resistance and wear behaviour and to provide tribological properties. AlCr-based oxynitrides and even pure oxides (Al_1−xCr_x)₂O₃ with different crystalline structures have been explored. Multi- and nanolayered coatings within the AlCr materials system, as well as in combination with (TiSi)N, for example, have also been implemented industrially. The dominant deposition technology is the vacuum arc process. Recently, advanced high-power impulse magnetron sputtering (HiPIMS) processes have also been successfully applied on an industrial scale. This paper describes basic coating properties and briefly addresses the main aspects of the coating processes as well as selected industrial applications. Full article

(This article belongs to the Special Issue Technologies of Coatings and Surface Hardening for Tool Industry)

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9 pages, 15319 KiB

Open AccessArticle

Experimental Analysis of Gas Holdup Measured by Gas Array Tool in Gas–Water Two Phase of Horizontal Well

by Shuaifei Cui, Junfeng Liu, Xulong Chen and Qinze Li

Coatings 2021, 11(3), 343; https://doi.org/10.3390/coatings11030343 - 18 Mar 2021

Cited by 9 | Viewed by 1850

Abstract

In the gas-water two phase of horizontal well, gas holdup is usually obtained by inverse calculation of the water holdup measured by the array capacitance probes. Gas Array Tool (GAT) has been developed to directly measure gas holdup. This instrument has been introduced [...] Read more.

In the gas-water two phase of horizontal well, gas holdup is usually obtained by inverse calculation of the water holdup measured by the array capacitance probes. Gas Array Tool (GAT) has been developed to directly measure gas holdup. This instrument has been introduced into China and its simulation experiment in gas-water two phase flow in horizontal wells has been carried out for the first time to study the applicability of gas holdup measurement. Firstly, the response principle and measurement method of GAT are analyzed; secondly, the experimental data of GAT under different flowrates, water cut, and different cable speed are plotted and analyzed; finally, the gas holdup data measured by GAT and Capacitance Array Tool (CAT) are compared by using an interpolation algorithm. It is found that the response of the optical fiber probe is consistent and stable. It also proves the accuracy of gas identification and the applicability of gas holdup measurement under test conditions by GAT, which lays a foundation for further gas holdup measurement, interpretation, and field test in the future. Full article

(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)

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2 pages, 162 KiB

Open AccessEditorial

Special Issue “Anti-Adhesive Surfaces”

by Giuseppe Carbone and Rosa Di Mundo

Coatings 2021, 11(3), 342; https://doi.org/10.3390/coatings11030342 - 17 Mar 2021

Viewed by 1512

Abstract

Research and review articles tackling the theme of antiadhesive surfaces are here collected [...] Full article

(This article belongs to the Special Issue Anti-Adhesive Surfaces)

39 pages, 14157 KiB

Open AccessArticle

The Effect of Interfacial Roughness on Residual Stresses in Electron Beam-Physical Vapor Deposition of Thermal Barrier Coatings

by Bochun Zhang, Kuiying Chen and Natalie Baddour

Coatings 2021, 11(3), 341; https://doi.org/10.3390/coatings11030341 - 17 Mar 2021

Cited by 2 | Viewed by 1876

Abstract

Residual stresses play an essential role in determining the failure mechanisms and life of an electron beam-physical vapour deposition thermal barrier coating (EB-PVD TBC) system. In this paper, a new transitional roughness model was proposed and applied to describe the interfacial roughness profile [...] Read more.

Residual stresses play an essential role in determining the failure mechanisms and life of an electron beam-physical vapour deposition thermal barrier coating (EB-PVD TBC) system. In this paper, a new transitional roughness model was proposed and applied to describe the interfacial roughness profile during thermal cycles. Finite element models were implemented to calculate residual stresses at specific positions close to the interface of TBCs using temperature process-dependent model parameters. Combining stresses evaluated at valleys of the topcoat (TC) and excessive sharp tip roughness profiles, positions where the maximum out-of-plane residual stresses occur were identified and used to explain possible cracking routes of EB-PVD TBCs as interfacial roughness evolves during thermal cycling. Full article

(This article belongs to the Special Issue Current Status of Fundamentals and Applications of Thermal Barrier Coatings)

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15 pages, 30595 KiB

Open AccessArticle

Effect of Calcium Carbonate Particle Size on the Scratch Resistance of Rapid Alkyd-Based Wood Coatings

by Orkun Ersoy, Sinan Fidan, Harun Köse, Dilek Güler and Ömer Özdöver

Coatings 2021, 11(3), 340; https://doi.org/10.3390/coatings11030340 - 17 Mar 2021

Cited by 6 | Viewed by 2894

Abstract

Polymer-based wood coatings are used for aesthetic purposes as well as to protect wood surfaces, especially under external conditions. High-hardness mineral fillers are thought to enhance the resistance of these polymer coatings to wear and scratching. However, recent studies suggest that the relatively [...] Read more.

Polymer-based wood coatings are used for aesthetic purposes as well as to protect wood surfaces, especially under external conditions. High-hardness mineral fillers are thought to enhance the resistance of these polymer coatings to wear and scratching. However, recent studies suggest that the relatively low-hardness mineral calcite (CaCO₃, Mohs hardness of 3) performs similarly to harder minerals under external conditions. It can replace more expensive hard minerals, thus driving research interest in its use. In this study, CaCO₃ powders with different grain sizes were applied to rapid alkyd-based coating formulations, and the effect of CaCO₃ particle size on the scratch behavior of the coatings was investigated under identical test conditions. The scratch morphologies, scratch hardness, and roughness values of the scratched surfaces indicated that the surfaces of the rapid alkyd-based wood coatings including finer-grained CaCO₃ experienced plastic plowing-type deformation in the form of regular, narrow, and shallow scratches, showing high scratch resistance. Coatings using coarser-grained CaCO₃ experienced more extensive plastic deformation of the plowing–tearing type owing to the weaker filler–polymer interface and the breakage of larger coating pieces from the coating surface. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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Coatings, Volume 11, Issue 3 (March 2021) – 109 articles

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