Coatings

14 pages, 2153 KB

Open AccessEditor’s ChoiceArticle

Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces

by Francesca Sbardella, Lucilla Pronti, Maria Laura Santarelli, José Marìa Asua Gonzàlez and Maria Paola Bracciale

Coatings 2018, 8(8), 283; https://doi.org/10.3390/coatings8080283 - 15 Aug 2018

Cited by 41 | Viewed by 7230

Abstract

The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an [...] Read more.

The application of coating polymers to building materials is a simple and cheap way to preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly character, waterborne coating is the most popular type of coating, and improving its performance is an important key of research. The study presents the results regarding the mechanical and photo-oxidation resistance of some water-based acrylic coatings containing SiO₂ nanoparticles obtained by batch miniemulsion polymerization. Coating materials have been characterized in terms of hydrophobic/hydrophilic behavior, mechanical resistance and surface morphology by means of water-contact angle, and scrub resistance and atomic force microscopy (AFM) measurements depending on silica-nanoparticle content. Moreover, accelerated weathering tests were performed to estimate the photo-oxidation resistance of the coatings. The chemical and color changes were assessed by Fourier-transform infrared spectroscopy (FTIR) and colorimetric measurements. Furthermore, the nanofilled coatings were applied on two different calcareous lithotypes (Lecce stone and Carrara Marble). Its properties, such as capillary water absorption and color modification, before and after accelerated aging tests, were assessed. The properties acquired by the addition of silica nanoparticles in the acrylic matrix can ensure good protection against weathering of stone-based materials. Full article

(This article belongs to the Special Issue Active Organic and Organic-Inorganic Hybrid Coatings and Thin Films: Challenges, Developments, Perspectives)

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12 pages, 1430 KB

Open AccessEditor’s ChoiceArticle

Poly(Phenylene Methylene): A Multifunctional Material for Thermally Stable, Hydrophobic, Fluorescent, Corrosion-Protective Coatings

by Marco F. D’Elia, Andreas Braendle, Thomas B. Schweizer, Marco A. Ortenzi, Stefano P. M. Trasatti, Markus Niederberger and Walter Caseri

Coatings 2018, 8(8), 274; https://doi.org/10.3390/coatings8080274 - 7 Aug 2018

Cited by 16 | Viewed by 6170

Abstract

Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. PPM has been proposed earlier to be useful as a coating material but this polymer was isolated in relevant molar masses only recently, and in large quantities. Accordingly, the preparation of coatings [...] Read more.

Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. PPM has been proposed earlier to be useful as a coating material but this polymer was isolated in relevant molar masses only recently, and in large quantities. Accordingly, the preparation of coatings based on PPM and their behavior was explored in this study, with the example of the metal alloy AA2024 as a common substrate for corrosion tests. Coatings free of bubbles and cracks were obtained by hot pressing and application of the following steps: Coating on AA2024 with a layer of polybenzylsiloxane to improve the adhesion between PPM and the metal surface, the addition of polybenzylsiloxane to PPM in order to enhance the viscosity of the molten PPM, and the addition of benzyl butyl phthalate as a plasticizer. Electrochemical corrosion tests showed good protection of the metal surface towards a NaCl solution, thanks to a passive-like behavior in a wide potential window and a very low current density. Remarkably, the PPM coating also exhibited self-healing towards localized attacks, which inhibits the propagation of corrosion. Full article

(This article belongs to the Special Issue Active Organic and Organic-Inorganic Hybrid Coatings and Thin Films: Challenges, Developments, Perspectives)

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11 pages, 9213 KB

Open AccessEditor’s ChoiceArticle

Microstructure and Oxidation Resistance of a Si Doped Platinum Modified Aluminide Coating Deposited on a Single Crystal Superalloy

by Qixiang Fan, Haojun Yu, Tiegang Wang and Yanmei Liu

Coatings 2018, 8(8), 264; https://doi.org/10.3390/coatings8080264 - 27 Jul 2018

Cited by 8 | Viewed by 5335

Abstract

A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si [...] Read more.

A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si doped Pt modified aluminide coating consisted of singular β-(Ni, Pt)Al phase, and no PtAl₂ phase was detected, which might be due to the fact that the addition of Si retarded the formation of PtAl₂ phase in the outer layer. Si was dissolved in the β-(Ni, Pt)Al phase in the outer layer and might form silicide with refractory elements in the inter-diffusion zone. The Si doped Pt modified aluminide coating possesses a better oxidation resistance than the Pt modified aluminide coating since Si could promote the formation of α-Al₂O₃ and inhibit the diffusion of the refractory elements, reducing the formation of detrimental volatile phase. Full article

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12 pages, 7690 KB

Open AccessEditor’s ChoiceArticle

Corrosion Behavior of Fe/Zr Composite Coating on ZK60 Mg Alloy by Ion Implantation and Deposition

by Yang Zheng, Libin Zang, Yanze Bi, Yan Li and Yong Chen

Coatings 2018, 8(8), 261; https://doi.org/10.3390/coatings8080261 - 26 Jul 2018

Cited by 20 | Viewed by 4958

Abstract

The Fe/Zr composite coating was prepared by duplex Fe/Zr ion implantation and deposition to modify the microstructure and corrosion behavior of Mg-5.5 Zn-0.6 Zr (in wt.%, ZK60) alloy. The surface and interface characteristics were investigated using X-ray diffraction (XRD), atomic force microscope (AFM) [...] Read more.

The Fe/Zr composite coating was prepared by duplex Fe/Zr ion implantation and deposition to modify the microstructure and corrosion behavior of Mg-5.5 Zn-0.6 Zr (in wt.%, ZK60) alloy. The surface and interface characteristics were investigated using X-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM). The results showed that the Fe/Zr composite coating exhibited a bi-layer microstructure of outer Fe-rich layer and inner Zr-rich layer. Multi-phases of α-Fe, ZrO₀.₃₅ and Zr₆Fe₃O were formed on the modified surface. The electrochemical measurements and immersion tests revealed an improvement of corrosion behavior for the surface-modified sample due to the protective effect of Fe/Zr composite coating. Full article

(This article belongs to the Special Issue Advanced Coatings for Corrosion Protection in Extreme Environments)

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15 pages, 5677 KB

Open AccessEditor’s ChoiceArticle

Effect of Laser Scanning Speed on the Wear Behavior of Nano-SiC-Modified Fe/WC Composite Coatings by Laser Remelting

by Yuncai Zhao and Huihui Du

Coatings 2018, 8(7), 241; https://doi.org/10.3390/coatings8070241 - 7 Jul 2018

Cited by 4 | Viewed by 4571

Abstract

A supersonic plasma sprayed nano-SiC-modified WC/Fe metal–cermet composite coating was remelted with a fibre-pulsed laser at four different laser scanning speeds (100, 150, 200 and 250 mm·min⁻¹) while the other parameters were kept constant. The microstructures, microhardness, and tribological properties of [...] Read more.

A supersonic plasma sprayed nano-SiC-modified WC/Fe metal–cermet composite coating was remelted with a fibre-pulsed laser at four different laser scanning speeds (100, 150, 200 and 250 mm·min⁻¹) while the other parameters were kept constant. The microstructures, microhardness, and tribological properties of the coatings were analysed by means of SEM (scanning electron microscopy), XRD (X-ray diffractometer), and a friction tester, respectively. The results show that, when the laser scanning speed is 100 mm·min⁻¹, the remelted coating is most dense with regard to the coverage of the substrate. The coating with nano-particles became more smooth, and elements Si and C in the nano-particles reacted with Fe, Ni, or Cr and formed a hard mesophase that enhanced the strength and hardness of the coating. With the increase of laser scanning speed, the hardness of the four coatings increased first and then decreased, and the nano-SiC-modified remelted coating showed a maximum microhardness of about HV_0.51350, and the nano-particles made the coating’s micro-structure finer, at a laser scanning speed of 150 mm·min⁻¹. The friction coefficient and wear rate of the four coatings were 0.58 and 12.01 × 10⁻⁵ mm³/(N·m), 0.21 and 8.50 × 10⁻⁵ mm³/(N·m), 0.62 and 20.04 × 10⁻⁵ mm³/(N·m), and 1.23 and 25.13 × 10⁻⁵ mm³/(N·m). The remelted coating at a laser scanning speed of 150 mm·min⁻¹ exhibits the best wear resistance and its wear mechanism is governed by slight adhesion wear and plastic deformation. Full article

(This article belongs to the Special Issue Nanocomposite Coatings)

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16 pages, 7182 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Catalytic Performance of Ag₂O and Ag Doped CeO₂ Prepared by Atomic Layer Deposition for Diesel Soot Oxidation

by Tatiana V. Ivanova, Tomáš Homola, Anton Bryukvin and David C. Cameron

Coatings 2018, 8(7), 237; https://doi.org/10.3390/coatings8070237 - 4 Jul 2018

Cited by 23 | Viewed by 8024

Abstract

The catalytic behaviour of Ag₂O and Ag doped CeO₂ thin films, deposited by atomic layer deposition (ALD), was investigated for diesel soot oxidation. The silver oxide was deposited from pulses of the organometallic precursor (hfac)Ag(PMe₃) and ozone at [...] Read more.

The catalytic behaviour of Ag₂O and Ag doped CeO₂ thin films, deposited by atomic layer deposition (ALD), was investigated for diesel soot oxidation. The silver oxide was deposited from pulses of the organometallic precursor (hfac)Ag(PMe₃) and ozone at 200 °C with growth rate of 0.28 Å/cycle. Thickness, crystallinity, elemental composition, and morphology of the Ag₂O and Ag doped CeO₂ films deposited on Si (100) were characterized by ellipsometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM), respectively. The catalytic effect on diesel soot combustion of pure Ag₂O, CeO_2, and Ag doped CeO₂ films grown on stainless steel foil supports was measured with oxidation tests. Nominally CeO₂:Ag 10:1 doped CeO₂ films were most effective and oxidized 100% of soot at 390 °C, while the Ag₂O films were 100% effective at 410 °C. The doped films also showed much higher stability; their performance remained stable after five tests with only a 10% initial reduction in efficiency whereas the performance of the Ag₂O films reduced by 50% after the first test. It was concluded that the presence of Ag⁺ sites on the catalyst is responsible for the high soot oxidation activity. Full article

(This article belongs to the Special Issue Atomic Layer Deposition)

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19 pages, 2272 KB

Open AccessEditor’s ChoiceArticle

Chromium Carbide Growth by Direct Liquid Injection Chemical Vapor Deposition in Long and Narrow Tubes, Experiments, Modeling and Simulation

by Alexandre Michau, Francis Maury, Frederic Schuster, Ioana Nuta, Yoan Gazal, Rapahel Boichot and Michel Pons

Coatings 2018, 8(6), 220; https://doi.org/10.3390/coatings8060220 - 13 Jun 2018

Cited by 26 | Viewed by 7812

Abstract

Chromium carbide layers were deposited using liquid-injection metal-organic chemical vapor deposition inside long (0.3 to 1 m) and narrow (8 to 24 mm in diameter) metallic tubes. The deposition was carried out using a molecular single-source, bis(benzene)chromium (BBC), as representative of the bis(arene)metal [...] Read more.

Chromium carbide layers were deposited using liquid-injection metal-organic chemical vapor deposition inside long (0.3 to 1 m) and narrow (8 to 24 mm in diameter) metallic tubes. The deposition was carried out using a molecular single-source, bis(benzene)chromium (BBC), as representative of the bis(arene)metal family diluted in toluene and injected with N₂ as carrier gas. A multicomponent mass transport model for the simulation of the coupled fluid flow, heat transfer and chemistry was built. The kinetic mechanism of the growth of CrC_x films was developed with the help of large-scale experiments to study the depletion of the precursors along the inner wall of the tube. The model fits well in the 400–550 °C temperature range and in the 1.3 × 10² to 7 × 10³ Pa pressure range. The pressure is shown to have a pronounced effect on the deposition rate and thickness uniformity of the resulting coating. Below 525 °C the structure, composition and morphology of the films are not affected by changes of total pressure or deposition temperature. The coatings are amorphous and their Cr:C ratio is about 2:1, i.e., intermediate between Cr₇C₃ and Cr₃C₂. The model was applied to the design of a long reactor (1 m), with a double injection successively and alternatively undertaken at each end to ensure the best uniformity with sufficient thickness. This innovative concept can be used to optimize industrial deposition processes inside long and narrow tubes and channels. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition 2018)

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12 pages, 9107 KB

Open AccessEditor’s ChoiceArticle

Characterization of Flake Boron Nitride Prepared from the Low Temperature Combustion Synthesized Precursor and Its Application for Dye Adsorption

by Jinglong Qu, Qun Li, Chang Luo, Jin Cheng and Xinmei Hou

Coatings 2018, 8(6), 214; https://doi.org/10.3390/coatings8060214 - 4 Jun 2018

Cited by 84 | Viewed by 7227

Abstract

Flake boron nitride (BN) in large yield was successfully synthesized at low temperature from the combustion synthesized precursor. The precursor was prepared by a low-temperature (350 °C) combustion synthesis (LCS) method using nitric acid (HNO₃), urea (CO(NH₂)₂), [...] Read more.

Flake boron nitride (BN) in large yield was successfully synthesized at low temperature from the combustion synthesized precursor. The precursor was prepared by a low-temperature (350 °C) combustion synthesis (LCS) method using nitric acid (HNO₃), urea (CO(NH₂)₂), boric acid (H₃BO₃), and glucose (C₆H₁₂O₆·H₂O) as starting materials. The precursor consists of B₂O₃ and amorphous carbon and the morphology is composed of blocks with average diameters of about 10 μm by statistical methods using SEM at different fields. Then BN was synthesized at 900 °C in NH₃ at a heating rate of 5 °C min⁻¹. The as-prepared BN possesses a flake morphology and high specific surface area up to 936 m² g⁻¹. It also has high density structural defects and abundant –NH₂/–OH groups. The surface groups improve its water wettability and electronegativity, which contributes to the rapid and selective adsorption performance, especially towards the cationic dyes. When 4 mg of the sample was added into a 100 mL RhB solution with an initial concentration of 5 mg L⁻¹, 95% of the RhB was removed within 1 min and the adsorption capacity is 125 mg g⁻¹. Importantly, the sample can be regenerated by heating at 400 °C in air. Full article

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18 pages, 13951 KB

Open AccessEditor’s ChoiceArticle

Surface Aging Effect on Tire/Pavement Noise Medium-Term Evolution in a Medium-Size City

by Víctor F. Vázquez, Fernando Terán, Pedro Huertas and Santiago Expósito Paje

Coatings 2018, 8(6), 206; https://doi.org/10.3390/coatings8060206 - 30 May 2018

Cited by 11 | Viewed by 4787

Abstract

This paper presents the geo-referenced acoustical results obtained throughout the close proximity noise (CPX) technique carried out on different urban sections included within the 2017 strategic noise mapping (Directive 2002/49/CE) in Ciudad Real, a Spanish medium-sized city. The employed methodology quantifies the tire/pavement [...] Read more.

This paper presents the geo-referenced acoustical results obtained throughout the close proximity noise (CPX) technique carried out on different urban sections included within the 2017 strategic noise mapping (Directive 2002/49/CE) in Ciudad Real, a Spanish medium-sized city. The employed methodology quantifies the tire/pavement noise generated in the contact between the tire and the surface of the studied sections. Measurements were carried out in different research campaigns between 2008 and 2015 (medium-term evolution). They give valuable information about the pavement-aging effect on its surface characteristics. Throughout these years, the acoustic situation of these sections has worsened mainly due to surface damage and higher mean profile depth (MPD) values, although the performance does not follow the same pattern in every section. The relationships between measured tire/pavement noise and theoretical environmental noise, just due to the geometric spreading of sound energy, is also studied in order to elaborate a simple rolling noise mapping and to assess the environmental noise evolution. Traffic noise plays the main role in the noise registered within the assessed sections, therefore, CPX assessment could be used by local authorities to take decisions regarding urban planning and traffic management, with the aim of reducing noise exposure from traffic. Full article

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13 pages, 2665 KB

Open AccessEditor’s ChoiceArticle

Application of Nanofibrillated Cellulose on BOPP/LDPE Film as Oxygen Barrier and Antimicrobial Coating Based on Cold Plasma Treatment

by Peng Lu, Mengya Guo, Zhijun Xu and Min Wu

Coatings 2018, 8(6), 207; https://doi.org/10.3390/coatings8060207 - 30 May 2018

Cited by 55 | Viewed by 11243

Abstract

The application of nanofibrillated cellulose (NC) films in packaging industry has been hindered by its lack of heat-sealing ability. Incorporation of NC films with the biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE) laminates can take advantage of each material and endow the films with [...] Read more.

The application of nanofibrillated cellulose (NC) films in packaging industry has been hindered by its lack of heat-sealing ability. Incorporation of NC films with the biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE) laminates can take advantage of each material and endow the films with novel functions for food packaging applications. In this study, a coating that consists of NC and nisin was applied onto a cold plasma treated BOPP/LDPE film to fabricate a novel active packaging with an improved oxygen barrier performance and an added antimicrobial effect. The results showed that cold plasma treatment improved the surface hydrophilicity of BOPP/LDPE films for better attachment of the coatings. NC coatings significantly enhanced oxygen barrier property of the BOPP/LDPE film, with an oxygen transmission rate as low as 24.02 cc/m²·day as compared to that of the non-coated one (67.03 cc/m²·day). The addition of nisin in the coating at a concentration of 5 mg/g caused no significant change in barrier properties but imparted the film excellent antimicrobial properties, with a growth inhibition of L. monocytogenes by 94%. All films exhibit satisfying mechanical properties and transparency, and this new film has the potential to be used as antimicrobial and oxygen barrier packaging. Full article

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14 pages, 1532 KB

Open AccessEditor’s ChoiceArticle

Hydrophilic Self-Replenishing Coatings with Long-Term Water Stability for Anti-Fouling Applications

by Isabel Jiménez-Pardo, Leendert G. J. Van der Ven, Rolf A. T. M. Van Benthem, Gijsbertus De With and A. Catarina C. Esteves

Coatings 2018, 8(5), 184; https://doi.org/10.3390/coatings8050184 - 14 May 2018

Cited by 35 | Viewed by 14035

Abstract

Hydrophilic coatings have recently emerged as a new approach to avoiding the adhesion of (bio)organisms on surfaces immersed in water. In these coatings the hydrophilic character is crucial for the anti-fouling (AF) performance. However, this property can be rapidly lost due to the [...] Read more.

Hydrophilic coatings have recently emerged as a new approach to avoiding the adhesion of (bio)organisms on surfaces immersed in water. In these coatings the hydrophilic character is crucial for the anti-fouling (AF) performance. However, this property can be rapidly lost due to the inevitable damages which occur at the surface, reducing the long-term effectiveness of the AF functionality. We report hydrophilic polycarbonate-poly(ethylene glycol) methyl ether (mPEG) polyurethane coatings with tunable hydrophilic properties as well as an excellent and long-term stability in water. The coatings exhibit low protein adhesion values and are able to self-replenish their hydrophilicity after damage, due to the existence of a reservoir of hydrophilic dangling chains incorporated in the bulk. The combination of low T_g and sufficient mobility of the mPEG dangling chains (enabled by chains with higher molecular weight) proved to be crucial to ensure autonomous surface hydrophilicity recovery when the coatings were immersed in water. This coatings and design approach offers new possibilities towards high-performance AF coatings with an extended service life-time which can be used in several major applications areas, such as marine and biomedical coatings, with major economic and environmental benefits. Full article

(This article belongs to the Special Issue Progress in Self-Healing Coatings)

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14 pages, 10945 KB

Open AccessEditor’s ChoiceArticle

Bonding Characteristics and Chemical Inertness of Zr–Si–N Coatings with a High Si Content in Glass Molding

by Li-Chun Chang, Yu-Zhe Zheng, Yung-I Chen, Shan-Chun Chang and Bo-Wei Liu

Coatings 2018, 8(5), 181; https://doi.org/10.3390/coatings8050181 - 11 May 2018

Cited by 20 | Viewed by 6318

Abstract

High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si₃N₄, which [...] Read more.

High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si₃N₄, which was higher than those of the middle-Si-content (19 at.%) coatings. In this study, the bonding characteristics of the constituent elements of Zr–Si–N coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d_5/2 levels were 179.14–180.22 and 180.75–181.61 eV for the Zr–N bonds in ZrN and Zr₃N₄ compounds, respectively. Moreover, the percentage of Zr–N bond in the Zr₃N₄ compound increased with increasing Si content in the Zr–Si–N coatings. The Zr–N bond of Zr₃N₄ dominated when the Si content was >24 at.%. Therefore, high Si content can stabilize the Zr–N compound in the M₃N₄ bonding structure. Furthermore, the thermal stability and chemical inertness of Zr–Si–N coatings were evaluated by conducting thermal cycle annealing at 270 °C and 600 °C in a 15-ppm O₂–N₂ atmosphere. The results indicated that a Zr₂₂Si₂₉N₄₉/Ti/WC assembly was suitable as a protective coating against SiO₂–B₂O₃–BaO-based glass for 450 thermal cycles. Full article

(This article belongs to the Special Issue Coatings for Dies and Molds)

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13 pages, 3837 KB

Open AccessEditor’s ChoiceArticle

Multi-Walled Carbon Nanotube Coating on Alkali Treated TiO₂ Nanotubes Surface for Improvement of Biocompatibility

by Jung-Eun Park, Yong-Seok Jang, Tae-Sung Bae and Min-Ho Lee

Coatings 2018, 8(5), 159; https://doi.org/10.3390/coatings8050159 - 26 Apr 2018

Cited by 8 | Viewed by 5604

Abstract

The aim of this study is to enhance the bioactivity of pure titanium using multiple surface treatments for the application of the implant. To form the biofunctional multilayer coating on pure titanium, anodization was conducted to make titanium dioxide nanotubes, then multi-walled carbon [...] Read more.

The aim of this study is to enhance the bioactivity of pure titanium using multiple surface treatments for the application of the implant. To form the biofunctional multilayer coating on pure titanium, anodization was conducted to make titanium dioxide nanotubes, then multi-walled carbon nanotubes were coated using a dipping method after an alkali treatment. The surface characteristics at each step were analyzed using a field emission scanning electron microscope and X-ray diffractometer. The effect of the multilayer coating on the biocompatibility was identified using immersion and cytotoxicity tests. Better hydroxyapatite formation was observed on the surface of multilayer-coated pure titanium compared to non-treated pure titanium after immersion in the simulated body fluid. Improvement of biocompatibility by multiple surface treatments was identified through various cytotoxicity tests using osteoblast cells. Full article

(This article belongs to the Special Issue Carbon-Related Coatings)

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18 pages, 33990 KB

Open AccessEditor’s ChoiceArticle

Raman Microscopy for Classification and Chemical Surface Mapping of Barrier Coatings on Paper with Oil-Filled Organic Nanoparticles

by Pieter Samyn

Coatings 2018, 8(5), 154; https://doi.org/10.3390/coatings8050154 - 24 Apr 2018

Viewed by 5897

Abstract

The creation of functional papers requires a specific deposition of chemical moieties at the surface. In particular, water-repellent barrier coatings can be formed by the deposition of (poly(styrene-co-maleimide) nanoparticles filled with different vegetable oils. The analysis of coated paper surfaces by dispersive Raman [...] Read more.

The creation of functional papers requires a specific deposition of chemical moieties at the surface. In particular, water-repellent barrier coatings can be formed by the deposition of (poly(styrene-co-maleimide) nanoparticles filled with different vegetable oils. The analysis of coated paper surfaces by dispersive Raman spectroscopy allows for statistical classification of different coating types and chemical mapping of the lateral surface distribution of the coating components. The Raman spectra were used to quantify the amount of free oil and imide content. The partial least squares model with three principal components (PC) could differentiate between the type of oil (degree of saturation in PC-1), coating thickness (cellulose bands of paper substrate in PC-2), and organic coating phase (styrene, imide in PC-3). The chemical surface maps with average intensities indicate coating inhomogeneities for thin coatings located near the organic coating components, while the presence of free oil acts as a natural binder in between the organic phase and provides a more homogeneous coating. Depending on the type of oil, a higher amount of free oil coincides with lower imide content at the surface. The surface coverage of polyunsaturated oils overlaps relatively well with the areas of organic coating components, as the oil is largely encapsulated. The surface coverage for mono- and unsaturated oils is rather complementary to the organic phase as there are larger amounts of free oil. The latter is confirmed by single wavenumber maps and image processing constructing composite chemical surface maps. Full article

(This article belongs to the Special Issue Functional Coatings for Food Packaging Applications)

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13 pages, 61489 KB

Open AccessEditor’s ChoiceArticle

Effects of Laser Microtexturing on the Wetting Behavior of Ti6Al4V Alloy

by Juan Manuel Vazquez-Martinez, Jorge Salguero Gomez, Pedro Francisco Mayuet Ares, Severo Raul Fernandez-Vidal and Moises Batista Ponce

Coatings 2018, 8(4), 145; https://doi.org/10.3390/coatings8040145 - 17 Apr 2018

Cited by 22 | Viewed by 5543

Abstract

Surface modification procedures by laser techniques allow the generation of specific topographies and microstructures that enable the adaptation of the external layers of materials for specific applications. In laser texturing processes, it is possible to maintain control over the microgeometry and dimensions of [...] Read more.

Surface modification procedures by laser techniques allow the generation of specific topographies and microstructures that enable the adaptation of the external layers of materials for specific applications. In laser texturing processes, it is possible to maintain control over the microgeometry and dimensions of the surface pattern through varying the processing parameters. One of the main areas of interest in the field of surface modification treatments is the ability to generate topographies that are associated with specific surface finishes, in terms of roughness, that can improve the manufactured part’s functional capabilities. In this aspect, several types of phenomena have been detected, such as the friction and sliding wear behavior or wetting capacity, which maintain a high dependence on surface roughness. In this research, surface texturing treatments have been developed by laser techniques through using the scanning speed of the beam (V_s) as a control parameter in order to generate samples that have topographies with different natures. Through assessments of surface finish using specialized techniques, the dimensional and geometrical features of the texturized tracks have been characterized, analyzing their influence on the wetting behavior of the irradiated layer. In this way, more defined texturing grooves has been developed by increasing the V_s, which also improves the hydrophobic characteristics of the treated surface. However, due to the lack of uniformity in the solidification process of the irradiated area, some deviations from the expected trends and singular points can be observed. Using the contact angle method to evaluate the wetting behavior of the applied treatments found increases in the contact angle values for high texturing speeds, finding a maximum value of 65.59° for V_s = 200 mm/s. Full article

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

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14 pages, 3206 KB

Open AccessEditor’s ChoiceReview

2D Materials-Coated Plasmonic Structures for SERS Applications

by Ming Xia

Coatings 2018, 8(4), 137; https://doi.org/10.3390/coatings8040137 - 12 Apr 2018

Cited by 30 | Viewed by 9725

Abstract

Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride, are new kinds of materials that can serve as substrates for surface enhanced Raman spectroscopy (SERS). When combined with traditional metallic plasmonic structures, the hybrid 2D materials/metal SERS platform brings extra benefits, including [...] Read more.

Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride, are new kinds of materials that can serve as substrates for surface enhanced Raman spectroscopy (SERS). When combined with traditional metallic plasmonic structures, the hybrid 2D materials/metal SERS platform brings extra benefits, including higher SERS enhancement factors, oxidation protection of the metal surface, and protection of molecules from photo-induced damages. This review paper gives an overview of recent progress in the 2D materials-coated plasmonic structure in SERS application, focusing on the fabrication of the hybrid 2D materials/metal SERS platform and its applications for Raman enhancement. Full article

(This article belongs to the Special Issue Graphene and Other 2D Layered Nanomaterial-Based Films: Synthesis, Properties and Applications)

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10 pages, 2160 KB

Open AccessEditor’s ChoiceArticle

Application of Industrial XRF Coating Thickness Analyzer for Phosphate Coating Thickness on Steel

by Aleksandr Sokolov, Jelena Hasikova, Aleksej Pecerskis, Vladimir Gostilo, Ki Yong Lee, Hoobok Jung and Jung Hyun Lim

Coatings 2018, 8(4), 126; https://doi.org/10.3390/coatings8040126 - 30 Mar 2018

Cited by 3 | Viewed by 9814

Abstract

The results of industrial application of an online X-ray fluorescence coating thickness analyzer for measuring the thickness of phosphate coatings on moving steel strips are considered in the article. The target range of coating thickness to be measured is from tens to hundreds [...] Read more.

The results of industrial application of an online X-ray fluorescence coating thickness analyzer for measuring the thickness of phosphate coatings on moving steel strips are considered in the article. The target range of coating thickness to be measured is from tens to hundreds of mg/m² in a measurement time of 10 s. The measurement accuracy observed during long-duration factory acceptance test was 10–15%. The coating thickness analyzer consists of two XRF gauges, mounted above and below the steel strip and capable of moving across the moving strip system for their suspension and relocation and electronic control unit. Fully automated software was developed to automatically and continuously (24/7) control both gauges, scanning both sides of the steel strip, and develop and test methods for measuring new coatings. It allows performing offline storage and retrieval of the measurement results, remotely controlling the analyzer components and measurement modes from a control room. The developed XRF coating thickness analyzer can also be used for real-time measurement of other types of coatings, both metallic and non-metallic. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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12 pages, 23425 KB

Open AccessEditor’s ChoiceArticle

Comparison of Selected Properties of Shellac Varnish for Restoration and Polyurethane Varnish for Reconstruction of Historical Artefacts

by Kristýna Šimůnková, Miloš Pánek and Aleš Zeidler

Coatings 2018, 8(4), 119; https://doi.org/10.3390/coatings8040119 - 24 Mar 2018

Cited by 16 | Viewed by 7581

Abstract

At present, many historical artefacts and furniture are only reconstructed and not restored. They are preserved in terms of material reparation, but their historical value decreases significantly. This work is focused on the comparison of the resistance of high-gloss polyurethane varnish with traditional [...] Read more.

At present, many historical artefacts and furniture are only reconstructed and not restored. They are preserved in terms of material reparation, but their historical value decreases significantly. This work is focused on the comparison of the resistance of high-gloss polyurethane varnish with traditional shellac varnish. The varnishes were applied to oak wood and exposed to interior artificial accelerated ageing in Xenotest. Before and after ageing, cold liquid-resistance tests were performed on the tested specimens and gloss, colour, and adhesion were also evaluated. The structures of the surfaces were also analysed using a confocal laser scanning microscope. As expected, polyurethane varnish was much more durable than shellac varnish. Interestingly, shellac varnish was fairly resistant to water at the beginning, but this resistance was greatly reduced after artificial accelerated ageing. This illustrates the importance of sheltering the shellac treated artefacts in stable temperature-humidity conditions with the least possible effect of solar radiation. Full article

(This article belongs to the Special Issue Varnishes and Surface Treatments of Historical Wooden Artworks)

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16 pages, 21124 KB

Open AccessEditor’s ChoiceArticle

Bacterial Biofilm Characterization and Microscopic Evaluation of the Antibacterial Properties of a Photocatalytic Coating Protecting Building Material

by Thomas Verdier, Alexandra Bertron, Benjamin Erable and Christine Roques

Coatings 2018, 8(3), 93; https://doi.org/10.3390/coatings8030093 - 5 Mar 2018

Cited by 23 | Viewed by 7244

Abstract

Use of photocatalytic paint-like coatings may be a way to protect building materials from microbial colonization. Numerous studies have shown the antimicrobial efficiency of TiO

_{2}

photocatalysis on various microorganisms. However, few have focused on easy-to-apply solutions and on photocatalysis under low irradiance. [...] Read more.

Use of photocatalytic paint-like coatings may be a way to protect building materials from microbial colonization. Numerous studies have shown the antimicrobial efficiency of TiO

_{2}

photocatalysis on various microorganisms. However, few have focused on easy-to-apply solutions and on photocatalysis under low irradiance. This paper focuses on (a) the antibacterial properties of a semi-transparent coating formulated using TiO

_{2}

particles and (b) the microscopic investigations of bacterial biofilm development on TiO

_{2}

-coated building materials under accelerated growth conditions. Results showed significant antibacterial activity after few hours of testing. The efficiency seemed limited by the confinement of the TiO

_{2}

particles inside the coating binder. However, a pre-irradiation with UV light can improve efficiency. In addition, a significant effect against the formation of a bacterial biofilm was also observed. The epifluorescence approach, in which fluorescence is produced by reflect rather than transmitted light, could be applied in further studies of microbial growth on coatings and building materials. Full article

(This article belongs to the Special Issue Advanced Coatings for Buildings)

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9 pages, 17814 KB

Open AccessEditor’s ChoiceArticle

New Method to Identify Field Joint Coating Failures Based on MFL In-Line Inspection Signals

by Lianshuang Dai, Ting Wang, Caiyan Deng, Qingshan Feng and Dongpo Wang

Coatings 2018, 8(3), 86; https://doi.org/10.3390/coatings8030086 - 27 Feb 2018

Cited by 6 | Viewed by 7254

Abstract

Above ground indirect detections and random excavations that have applied the past years for buried long distance oil and gas pipelines can only identify some damaged coating locations. Hence, large number of field joint coating (FJC) failures happen unconsciously until they lead to [...] Read more.

Above ground indirect detections and random excavations that have applied the past years for buried long distance oil and gas pipelines can only identify some damaged coating locations. Hence, large number of field joint coating (FJC) failures happen unconsciously until they lead to failures of the pipelines. Based on the analysis of magnetic flux leakage (MFL) in-line inspection (ILI) signals, combined with the statistical results of 414 excavations from two different pipeline sections, a new method to identify the failed FJC is established. Though it can only identify FJC failures when there are signs of corrosion on pipe body, it is much more efficient and cost-saving. The concluded identification rule still needs more validations and improvements to be more applicable and accuracy. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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0 pages, 1658 KB

Open AccessEditor’s ChoiceArticle

RETRACTED: Exploration of Growth Window for Phase-Pure Cubic Boron Nitride Films Prepared in a Pure N₂ Plasma

by Wei Gao, Yujing Li, Yuyuan Zhang and Hong Yin

Coatings 2018, 8(2), 82; https://doi.org/10.3390/coatings8020082 - 24 Feb 2018

Cited by 7 | Viewed by 6645

Abstract

Cubic boron nitride (c-BN) films were prepared via radio frequency (RF) magnetron sputtering from a hexagonal boron nitride (h-BN) target in a pure N₂ plasma. The composition and microstructure morphology of the BN films with different deposition times under pure N₂ [...] Read more.

Cubic boron nitride (c-BN) films were prepared via radio frequency (RF) magnetron sputtering from a hexagonal boron nitride (h-BN) target in a pure N₂ plasma. The composition and microstructure morphology of the BN films with different deposition times under pure N₂ plasma or mixed Ar/N₂ plasma were investigated with respect to the nucleation and growth processes. The pure-phase c-BN growth window was obtained using pure N₂ gas. The effects of pure N₂ gas on the growth mechanism, structural morphology, and internal compressive stress of the as-synthesized c-BN films were studied. Using pure N₂ gas instead of additional Ar resulted in improved microstructure quality and much reduced compressive stress, suggesting a fundamental strategy for achieving high-quality c-BN films. Full article

(This article belongs to the Special Issue Carbon-Related Coatings)

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10 pages, 2751 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Analysis of the Influence of the Use of Cutting Fluid in Hybrid Processes of Machining and Laser Metal Deposition (LMD)

by Magdalena Cortina, Jon Iñaki Arrizubieta, Eneko Ukar and Aitzol Lamikiz

Coatings 2018, 8(2), 61; https://doi.org/10.3390/coatings8020061 - 7 Feb 2018

Cited by 18 | Viewed by 6441

Abstract

Hybrid manufacturing processes that combine additive and machining operations are gaining relevance in modern industry thanks to the capability of building complex parts with minimal material and, many times, with process time reduction. Besides, as the additive and subtractive operations are carried out [...] Read more.

Hybrid manufacturing processes that combine additive and machining operations are gaining relevance in modern industry thanks to the capability of building complex parts with minimal material and, many times, with process time reduction. Besides, as the additive and subtractive operations are carried out in the same machine, without moving the part, dead times are reduced and higher accuracies are achieved. However, it is not clear whether the direct material deposition after the machining operation is possible or intermediate cleaning stages are required because of the possible presence of residual cutting fluids. Therefore, different Laser Metal Deposition (LMD) tests are performed on a part impregnated with cutting fluid, both directly and after the removal of the coolant by techniques such as laser vaporizing and air blasting. The present work studies the influence of the cutting fluid in the LMD process and the quality of the resulting part. Resulting porosity is evaluated and it is concluded that if the part surface is not properly clean after the machining operation, deficient clad quality can be obtained in the subsequent laser additive operation. Full article

(This article belongs to the Special Issue Surface Preparation and Treatments for Enhancing the Coating Performance)

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17 pages, 4194 KB

Open AccessEditor’s ChoiceReview

Recent Advances in Graphene-Based Free-Standing Films for Thermal Management: Synthesis, Properties, and Applications

by Feng Gong, Hao Li, Wenbin Wang, Dawei Xia, Qiming Liu, Dimitrios V. Papavassiliou and Ziqiang Xu

Coatings 2018, 8(2), 63; https://doi.org/10.3390/coatings8020063 - 7 Feb 2018

Cited by 51 | Viewed by 11184

Abstract

Thermal management in microelectronic devices has become a crucial issue as the devices are more and more integrated into micro-devices. Recently, free-standing graphene films (GFs) with outstanding thermal conductivity, superb mechanical strength, and low bulk density, have been regarded as promising materials for [...] Read more.

Thermal management in microelectronic devices has become a crucial issue as the devices are more and more integrated into micro-devices. Recently, free-standing graphene films (GFs) with outstanding thermal conductivity, superb mechanical strength, and low bulk density, have been regarded as promising materials for heat dissipation and for use as thermal interfacial materials in microelectronic devices. Recent studies on free-standing GFs obtained via various approaches are reviewed here. Special attention is paid to their synthesis method, thermal conductivity, and potential applications. In addition, the most important factors that affect the thermal conductivity are outlined and discussed. The scope is to provide a clear overview that researchers can adopt when fabricating GFs with improved thermal conductivity and a large area for industrial applications. Full article

(This article belongs to the Special Issue Graphene and Other 2D Layered Nanomaterial-Based Films: Synthesis, Properties and Applications)

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16 pages, 5701 KB

Open AccessEditor’s ChoiceReview

Thermal Growth of Graphene: A Review

by Hai Tan, Deguo Wang and Yanbao Guo

Coatings 2018, 8(1), 40; https://doi.org/10.3390/coatings8010040 - 19 Jan 2018

Cited by 60 | Viewed by 11456

Abstract

A common belief proposed by Peierls and Landau that two-dimensional material cannot exist freely in a three-dimensional world has been proved false when graphene was first synthesized in 2004. Graphene, which is the base structure of other carbon materials, has drawn much attention [...] Read more.

A common belief proposed by Peierls and Landau that two-dimensional material cannot exist freely in a three-dimensional world has been proved false when graphene was first synthesized in 2004. Graphene, which is the base structure of other carbon materials, has drawn much attention of scholars and researchers due to its extraordinary electrical, mechanical and thermal properties. Moreover, methods for its synthesis have developed greatly in recent years. This review focuses on the mechanism of the thermal growth method and the different synthesis methods, where epitaxial growth, chemical vapor deposition, plasma-enhanced chemical vapor deposition and combustion are discussed in detail based on this mechanism. Meanwhile, to improve the quality and control the number of graphene layers, the latest research progress in optimizing growth parameters and developmental technologies has been summarized. The strategies for synthesizing high-quality and large-scale graphene are proposed and an outlook on the future synthesis direction is also provided. Full article

(This article belongs to the Special Issue Graphene and Other 2D Layered Nanomaterial-Based Films: Synthesis, Properties and Applications)

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12 pages, 30713 KB

Open AccessEditor’s ChoiceArticle

Cutting Performance of Low Stress Thick TiAlN PVD Coatings during Machining of Compacted Graphite Cast Iron (CGI)

by Kenji Yamamoto, Majid Abdoos, Jose Mario Paiva, Pietro Stolf, Ben Beake, Sushant Rawal, German Fox-Rabinovich and Stephen Veldhuis

Coatings 2018, 8(1), 38; https://doi.org/10.3390/coatings8010038 - 18 Jan 2018

Cited by 26 | Viewed by 8330

Abstract

A new family of physical vapor deposited (PVD) coatings is presented in this paper. These coatings are deposited by a superfine cathode (SFC) using the arc method. They combine a smooth surface, high hardness, and low residual stresses. This allows the production of [...] Read more.

A new family of physical vapor deposited (PVD) coatings is presented in this paper. These coatings are deposited by a superfine cathode (SFC) using the arc method. They combine a smooth surface, high hardness, and low residual stresses. This allows the production of PVD coatings as thick as 15 µm. In some applications, in particular for machining of such hard to cut material as compacted graphite iron (CGI), such coatings have shown better tool life compared to the conventional PVD coatings that have a lower thickness in the range of up to 5 μm. Finite element modeling of the temperature/stress profiles was done for the SFC coatings to present the temperature/stress profiles during cutting. Comprehensive characterization of the coatings was performed using XRD, TEM, SEM/EDS studies, nano-hardness, nano-impact measurements, and residual stress measurements. Application of the coating with this set of characteristics reduces the intensity of buildup edge formation during turning of CGI, leading to longer tool life. Optimization of the TiAlN-based coatings composition (Ti/Al ratio), architecture (mono vs. multilayer), and thickness were performed. Application of the optimized coating resulted in a 40–60% improvement in the cutting tool life under finishing turning of CGI. Full article

(This article belongs to the Special Issue Coatings for Cutting Tools)

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12 pages, 3019 KB

Open AccessEditor’s ChoiceArticle

Corrosion Inhibition Properties of Waterborne Polyurethane/Cerium Nitrate Coatings on Mild Steel

by Mohammad Mizanur Rahman, Md. Hasan Zahir, Md. Bashirul Haq, Dhafer A. Al Shehri and A. Madhan Kumar

Coatings 2018, 8(1), 34; https://doi.org/10.3390/coatings8010034 - 15 Jan 2018

Cited by 28 | Viewed by 7368

Abstract

Waterborne polyurethane (WBPU)/cerium nitrate (Ce(NO₃)₃) dispersions were synthesized with different defined Ce(NO₃)₃ content. All pristine dispersions were stable with different poly(tetramethylene oxide) glycol (PTMG) number average molecular weights (Mn) of 650, 1000, and 2000. The interaction [...] Read more.

Waterborne polyurethane (WBPU)/cerium nitrate (Ce(NO₃)₃) dispersions were synthesized with different defined Ce(NO₃)₃ content. All pristine dispersions were stable with different poly(tetramethylene oxide) glycol (PTMG) number average molecular weights (Mn) of 650, 1000, and 2000. The interaction between the carboxyl acid salt group and Ce(NO₃)₃ was analyzed by Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques. Coating hydrophilicity, water swelling (%), water contact angle, leaching, and corrosion protection efficiency were all affected when using different Ce(NO₃)₃ content and PTMG molecular weights. The maximal corrosion protection of the WBPU coating was recorded using a higher molecular weight of PTMG with 0.016 mole Ce(NO₃)₃ content. Full article

(This article belongs to the Special Issue Active Organic and Organic-Inorganic Hybrid Coatings and Thin Films: Challenges, Developments, Perspectives)

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