Research

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14 pages, 7143 KiB

Open AccessFeature PaperArticle

Superhydrophobic Coatings from Recyclable Materials for Protection in a Real Sea Environment

by Michele Ferrari, Alessandro Benedetti and Francesca Cirisano

Coatings 2019, 9(5), 303; https://doi.org/10.3390/coatings9050303 - 06 May 2019

Cited by 14 | Viewed by 4280

Recyclable materials can be referred to as both those materials directly recycled from wastes and those derived from any kind of transformation before use. Highly water repellent coatings with wettability properties, known as superhydrophobic (SH), are related to surfaces with contact angles above [...] Read more.

Recyclable materials can be referred to as both those materials directly recycled from wastes and those derived from any kind of transformation before use. Highly water repellent coatings with wettability properties, known as superhydrophobic (SH), are related to surfaces with contact angles above 150° and a very small hysteresis. The small area available for these surfaces when in contact with water can be exploited in many applications in which interactions with an aqueous environment are usually desirable to be avoided, like for protection and friction reduction in a marine environment. SH coatings under investigation have been prepared starting from recyclable materials with the aim to provide a sustainable and low cost solution, with potential application to large surfaces in a marine environment. Wetting studies, surface characterization, and electrochemical tests show how these surfaces can be used in terms of fouling prevention and the protection of metals in underwater conditions. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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13 pages, 3004 KiB

Open AccessFeature PaperArticle

Structure and Properties of Protective Coatings Deposited by Pulsed Cathodic Arc Evaporation in Ar, N₂, and C₂H₄ Environments using the TiC–NiCr–Eu₂O₃ Cathode

by Philipp Kiryukhantsev-Korneev, Alina Sytchenko, Alexander Sheveyko and Stepan Vorotilo

Coatings 2019, 9(4), 230; https://doi.org/10.3390/coatings9040230 - 31 Mar 2019

Cited by 11 | Viewed by 3209

Abstract

Coatings were deposited by pulsed cathodic arc evaporation (PCAE) of a TiC–NiCr–Eu₂O₃ cathode fabricated by the powder metallurgy method. The deposition was carried out in different gas media, including Ar, N₂, and C₂H₄. The [...] Read more.

Coatings were deposited by pulsed cathodic arc evaporation (PCAE) of a TiC–NiCr–Eu₂O₃ cathode fabricated by the powder metallurgy method. The deposition was carried out in different gas media, including Ar, N₂, and C₂H₄. The structure, elemental, and phase compositions of coatings were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), Raman spectroscopy, and glow discharge optical emission spectroscopy (GDOES). Coatings were tested in terms of their hardness, elastic modulus, elastic recovery, friction coefficient, and wear and corrosion resistance. The obtained results demonstrated that the coatings deposited in Ar possessed higher hardness up to 20 GPa and an elastic recovery of 92%. Coatings produced using C₂H₄ showed the minimum friction coefficient (0.35 ± 0.01). The use of nitrogen as a gas medium led to the formation of coatings with the best corrosion resistance in sulfuric acid. Coatings formed in N₂ had a free corrosion potential of +0.28 V and a corrosion current density of 0.012 µA/cm². Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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15 pages, 2500 KiB

Open AccessArticle

Influences of pH Values’ Changes on the Oxide Film of U-0.79 wt.% Ti Alloy in Aqueous Solution—A Combined Study of Traditional Electrochemical Tests and Scanning Reference Electrode Technique

by Dingzhou Cai, Dongxu Zhang, Xianglin Chen, Haoxi Wu, Ming Wang, Ge Sang and Yingru Li

Coatings 2019, 9(4), 224; https://doi.org/10.3390/coatings9040224 - 29 Mar 2019

Cited by 5 | Viewed by 2779

Abstract

By combining traditional electrochemical tests including Tafel extension method and Mott-Schottky fitting, spectroscopic ellipsometry (SE) and a micro-region analysis technique, which is an integrated system of a scanning reference electrode technique and scanning tunneling microscope (SRET/STM), the changes in properties of the oxide [...] Read more.

By combining traditional electrochemical tests including Tafel extension method and Mott-Schottky fitting, spectroscopic ellipsometry (SE) and a micro-region analysis technique, which is an integrated system of a scanning reference electrode technique and scanning tunneling microscope (SRET/STM), the changes in properties of the oxide film that formed on the surface of the U-0.79 wt.% Ti alloy (U-Ti alloy in short) in 0.1 M NaNO₃ were carefully investigated as the pH value changed. The results show that the properties of the oxide film are strongly pH-dependent. The corrosion potential and corrosion current density decrease with the increasing pH value. The oxide film appears to be a p-type semiconductor at pH = 2.43. However, the transition from n-type to p-type for the oxide film as a semiconductor is observed with the increasing applied potential when the solution pH value varies from 2.43 to 7.0. The oxide film presents as an n-type semiconductor when the pH value varies from 7.0 to 11.44. In addition, during the transition of the pH, the roughness and the number of active points of the alloy surface decreases while the oxide film is thicker. It can be concluded that the corrosion resistance of the oxide film formed on the U-Ti alloy surface is enhanced in neutral or alkaline solutions. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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12 pages, 5281 KiB

Open AccessArticle

Surface Deposition on Titania in a Physiological Solution with Ultraviolet Irradiation In Situ and Effect of Heat Treatment

by Chun-Yang Su, Qing Zhou and Cheng-Hong Zou

Coatings 2019, 9(2), 80; https://doi.org/10.3390/coatings9020080 - 29 Jan 2019

Cited by 4 | Viewed by 2654

Abstract

Photocatalysis-enhanced surface deposition on titanium surfaces for biomedical applications is investigated in this work. Immersion tests of commercially pure titanium (CP-Ti) pieces in a simulated body fluid adding bovine serum albumin (BSA) under ultraviolet (UV) irradiation in situ are carried out. The morphologies [...] Read more.

Photocatalysis-enhanced surface deposition on titanium surfaces for biomedical applications is investigated in this work. Immersion tests of commercially pure titanium (CP-Ti) pieces in a simulated body fluid adding bovine serum albumin (BSA) under ultraviolet (UV) irradiation in situ are carried out. The morphologies of deposition are characterized by SEM and stereo imaging microscopy, and the quantity and composition of the deposition is examined by SEM, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy. The results show a deposition layer with thickness 89 μm is produced on 600 °C heat-treated specimens. An irradiation pattern of lighting/dark repeated results in more deposition on heat-treated CP-Ti. It is confirmed that a mixture of anatase and rutile phases generated on 600 °C heat-treated specimens has enhanced photocatalysis. The decomposition of BSA by photocatalysis, a possible product of nitrite also results in enhanced deposition on Ti. EDS analysis shows large reduction of carbon in the deposition on UV-light exposed surfaces compared to no UV-light-exposed surfaces. Furthermore, C–H bond decreases and C–C, Ca–O, and P–O bond increases are found on photoactivated surfaces. The deposition produced by this method is expected to be useful for applications to biomaterials with high bioactivity. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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12 pages, 13485 KiB

Open AccessArticle

Thermal Spray Coatings of Al, ZnAl and Inconel 625 Alloys on SS304L for Anti-Saline Corrosion

by Tung-Yuan Yung, Tai-Cheng Chen, Kun-Cao Tsai, Wen-Feng Lu, Jiunn-Yuan Huang and Ting-Yu Liu

Coatings 2019, 9(1), 32; https://doi.org/10.3390/coatings9010032 - 08 Jan 2019

Cited by 37 | Viewed by 5123

Abstract

Stainless steel 304L (SS304L) has been selected as the material for canisters for spent fuel storage from three nuclear power plants in Taiwan. A crucial issue is extending the spent fuel storage safety standards of the canisters. The anti-saline corrosion abilities of three [...] Read more.

Stainless steel 304L (SS304L) has been selected as the material for canisters for spent fuel storage from three nuclear power plants in Taiwan. A crucial issue is extending the spent fuel storage safety standards of the canisters. The anti-saline corrosion abilities of three thermal spray coatings (i.e., Al, ZnAl, and 625 Inconel alloys) on the SS304L were evaluated by immersion in 3.5 wt % aqueous NaCl and with 0.025 g/cm² NaCl deposition at 80 °C and 80% relative humidity (RH) for 1000 h. The pristine thermal spray coatings were examined using the pull-off adhesion test to understand the adhesion strength, and Vickers hardness was measured for the mechanical properties of the three coatings. Confocal laser scanning microscopy (CLSM) was used to identify the porosities of the coatings. Furthermore, the surfaces of the specimens before and after corrosion were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). The composition and distribution of the oxide layers formed on the coating surfaces during corrosion were evaluated. Electrochemical measurement was also performed with the polarization method to quantify the corrosion property of the three thermal spray coatings. The results showed that the corrosion rate of Al coating was lowest from the Tafel analysis after the 1000 h corrosion test in 3.5% aqueous NaCl. In contrast, the corrosion rate of Inconel 625 was lowest after 1000 h of the NaCl deposition corrosion test in a controlled environment. Therefore, the ZnAl thermal spray coating is a potential protection layer, keeping in mind economic considerations, of SS304L for anti-corrosion in saline environments. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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11 pages, 5219 KiB

Open AccessFeature PaperArticle

Effect of Particle Size on the Corrosion Behaviour of Gold in the Presence of Chloride Impurities: An EFC-ICP-MS Potentiodynamic Study

by Primož Jovanovič, Martina Može, Ema Gričar, Martin Šala, Francisco Ruiz-Zepeda, Marjan Bele, Gregor Marolt and Nejc Hodnik

Coatings 2019, 9(1), 10; https://doi.org/10.3390/coatings9010010 - 25 Dec 2018

Cited by 15 | Viewed by 4192

Abstract

A profound understanding of the Au dissolution process is a prerequisite for optimal utilization of Au-based materials. This goes for either increasing the corrosion stability of materials in the sectors where the long-term functionality of Au is needed or decreasing the corrosion stability [...] Read more.

A profound understanding of the Au dissolution process is a prerequisite for optimal utilization of Au-based materials. This goes for either increasing the corrosion stability of materials in the sectors where the long-term functionality of Au is needed or decreasing the corrosion stability where the recovery of the Au component is crucial. By employing an extremely sensitive online analytical system, consisting of an electrochemical flow cell coupled to an inductively coupled plasma mass spectrometry, in situ potential-resolved dissolution of Au in the ppb range is enabled. A comparative study of two Au based materials, (i) a polycrystalline Au disk and (ii) carbon-supported Au nanoparticles, is presented. As a probe, chloride ions were used to elucidate the distinct differences in the corrosion behavior of the two analogues. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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14 pages, 6013 KiB

Open AccessFeature PaperArticle

Electrochemical and Surface Analysis of 2-Phenylimidazole Adsorbed on Copper from Chloride Solution

by Matjaž Finšgar and Klodian Xhanari

Coatings 2018, 8(7), 234; https://doi.org/10.3390/coatings8070234 - 03 Jul 2018

Cited by 7 | Viewed by 3653

Abstract

The electroanalytical and surface characterization of copper immersed in 3 wt.% NaCl solution containing 1 mM of 2-phenylimidazole (2PhI) is presented. It was proven that 2PhI can be employed as corrosion inhibitor for copper using various electrochemical analyses, such as cyclic voltammetry, chronopotentiometry, [...] Read more.

The electroanalytical and surface characterization of copper immersed in 3 wt.% NaCl solution containing 1 mM of 2-phenylimidazole (2PhI) is presented. It was proven that 2PhI can be employed as corrosion inhibitor for copper using various electrochemical analyses, such as cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy, and potentiodynamic curve measurements. The adsorption of 2PhI on copper was further analyzed by 3D-profilometry, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements, and scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. This system was therefore comprehensively described by various analytical approaches. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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Review

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20 pages, 3268 KiB

Open AccessFeature PaperReview

In-Vivo Corrosion Characterization and Assessment of Absorbable Metal Implants

by Mokhamad Fakhrul Ulum, Wahyu Caesarendra, Reza Alavi and Hendra Hermawan

Coatings 2019, 9(5), 282; https://doi.org/10.3390/coatings9050282 - 26 Apr 2019

Cited by 26 | Viewed by 5539

Abstract

Absorbable metals have been introduced as materials to fabricate temporary medical implants. Iron, magnesium and zinc have been considered as major base elements of such metals. The metallurgical characterization and in-vitro corrosion assessment of these metals have been covered by the new ASTM [...] Read more.

Absorbable metals have been introduced as materials to fabricate temporary medical implants. Iron, magnesium and zinc have been considered as major base elements of such metals. The metallurgical characterization and in-vitro corrosion assessment of these metals have been covered by the new ASTM standards F3160 and F3268. However, the in-vivo corrosion characterization and assessment of absorbable metal implants are not yet well established. The corrosion of metals in the in-vivo environment leads to metal ion release and corrosion product formation that may cause excessive toxicity. The aim of this work is to introduce the techniques to assess absorbable metal implants and their in-vivo corrosion behavior. This contains the existing approaches, e.g., implant retrieval and histological analysis, ultrasonography and radiography, and the new techniques for real-time in-vivo corrosion monitoring. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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30 pages, 14107 KiB

Open AccessReview

Ångström-Scale, Atomically Thin 2D Materials for Corrosion Mitigation and Passivation

by Md Rubayat-E Tanjil, Yunjo Jeong, Zhewen Yin, Wyatt Panaccione and Michael Cai Wang

Coatings 2019, 9(2), 133; https://doi.org/10.3390/coatings9020133 - 19 Feb 2019

Cited by 21 | Viewed by 15312

Abstract

Metal deterioration via corrosion is a ubiquitous and persistent problem. Ångström-scale, atomically thin 2D materials are promising candidates for effective, robust, and economical corrosion passivation coatings due to their ultimate thinness and excellent mechanical and electrical properties. This review focuses on elucidating the [...] Read more.

Metal deterioration via corrosion is a ubiquitous and persistent problem. Ångström-scale, atomically thin 2D materials are promising candidates for effective, robust, and economical corrosion passivation coatings due to their ultimate thinness and excellent mechanical and electrical properties. This review focuses on elucidating the mechanism of 2D materials in corrosion mitigation and passivation related to their physicochemical properties and variations, such as defects, out-of-plane deformations, interfacial states, temporal and thickness variations, etc. In addition, this review discusses recent progress and developments of 2D material coatings for corrosion mitigation and passivation as well as the significant challenges to overcome in the future. Full article

(This article belongs to the Special Issue Corrosion Characterization and Surface Analysis of Metallic Materials)

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