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Advanced Corrosion Protection through Coatings and Surface Rebuilding

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Coatings 2023, 13(1), 180; https://doi.org/10.3390/coatings13010180 - 13 Jan 2023

Cited by 2 | Viewed by 1318

Abstract

Corrosion is a costly and dangerous phenomenon that affects many industries, leading to significant economic losses and, in some cases, catastrophic failures [...] Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

Research

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Open AccessArticle

Hot Corrosion Behavior of Single-Layered Gd₂Zr₂O₇, Sm₂Zr₂O₇, and Nd₂Zr₂O₇ Thermal Barrier Coatings Exposed to Na₂SO₄ + MgSO₄ Environment

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Muhammad Jahangir Khan

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Coatings 2023, 13(8), 1311; https://doi.org/10.3390/coatings13081311 - 26 Jul 2023

Viewed by 492

Abstract

Zirconates of rare earth elements have emerged as promising candidates for thermal barrier coatings (TBC). This study investigates the hot corrosion resistance of single-layered ceramic coatings composed of Gd₂Zr₂O₇, Sm₂Zr₂O₇, and [...] Read more.

Zirconates of rare earth elements have emerged as promising candidates for thermal barrier coatings (TBC). This study investigates the hot corrosion resistance of single-layered ceramic coatings composed of Gd₂Zr₂O₇, Sm₂Zr₂O₇, and Nd₂Zr₂O₇. The coatings were prepared using air plasma spraying and applied to an Inconel [IN] 625 substrate. Experimental assessments were conducted to examine the hot corrosion behaviour by subjecting the coatings to pure magnesium sulfate (MgSO₄) salt at 1000 °C for 24 h and a 50/50 mole percent Na₂SO₄ and MgSO₄ mixture at 900 °C for cyclic durations of 5, 10, 15, and 20 h. This combination of salts creates a highly corrosive environment. This short test was carried out due to the necessity of the initial stages of the destruction process characterization. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS) techniques were utilized to identify and analyse the reaction products. At 1000 °C, no chemical reaction products were observed between MgSO₄ and Gd₂Zr₂O₇, Sm₂Zr₂O₇, and Nd₂Zr₂O₇. However, in the presence of the MgSO₄ + Na₂SO₄ mixture, the zirconate coatings reacted, resulting in the formation of reaction products such as Gd(SO₄)₃, Gd₂O₂SO₄, Gd₂O₃, Sm₂O₂SO₄, Sm₂(SO₄)₃, Sm₂O₃, MgO, Nd₂(SO₄)₃, Na₂O, and m-ZrO₂. These compounds are formed due to the interaction of rare earth oxides with a low-temperature-melting eutectic Na₂SO₄+ (3MgSO₄ × Na₂SO₄) melted at 666 °C. Despite the aggressive nature of the corrosive environment, the decomposition of rare earth zirconates was relatively limited, indicating satisfactory resistance to hot corrosion. Among the zirconate systems studied, Gd₂Zr₂O₇ exhibited the lowest resistance to the MgSO₄ + Na₂SO₄-based corrosive environment, while Sm₂Zr₂O₇ and Nd₂Zr₂O₇ demonstrated better corrosion resistance. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessFeature PaperArticle

Influence of Cr Nanoparticles on Plasma Electrolytic Oxidation Coatings on AM50 Mg Alloy

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Sergey A. Karpushenkov

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Oleg V. Ignatenko

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Fuhui Wang

Coatings 2023, 13(7), 1196; https://doi.org/10.3390/coatings13071196 - 03 Jul 2023

Viewed by 511

Abstract

The addition of Cr nanoparticles to a plasma electrolytic oxidation (PEO) electrolyte offers the possibility of producing layers with a broader range of coating compositions and improved properties. In this study, the effects of nanoparticles and various voltages on coating formation, microscopic morphology, [...] Read more.

The addition of Cr nanoparticles to a plasma electrolytic oxidation (PEO) electrolyte offers the possibility of producing layers with a broader range of coating compositions and improved properties. In this study, the effects of nanoparticles and various voltages on coating formation, microscopic morphology, and phase composition were investigated with in situ incorporation of Cr nanoparticles into PEO-coated Mg alloy. The results show that the corrosion performance of the coating was significantly improved when the final voltage was set to 460 V and the concentration of Cr nanoparticles was 1 g/L. Compared to the particle-free coating, the corrosion current density of the coating with the addition of 1 g/L Cr nanoparticles was reduced by two orders of magnitude. The impedance at the low frequency (0.01 Hz) increased by more than one order of magnitude after one hour of immersion, indicating a considerable improvement in corrosion resistance. Due to the high temperature during the coating-formation process, the Cr nanoparticles were oxidized, resulting in the formation of Cr₂O₃. The existence of Cr₂O₃ slightly increased the growth rate of the coating and sealed the open pores of the coating. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessArticle

Inhibition of Surface Corrosion Behavior of Zinc-Iron Alloy by Silicate Passivation

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Coatings 2023, 13(6), 1057; https://doi.org/10.3390/coatings13061057 - 07 Jun 2023

Cited by 1 | Viewed by 517

Abstract

The passivation of zinc alloy coating was achieved through the utilization of both silicate and trivalent chromium passivation systems, employing a specific process formula consisting of Co(NO₃)₂ at a concentration of 2.5 g/L, C₇₆H₅₂O₄₆ at [...] Read more.

The passivation of zinc alloy coating was achieved through the utilization of both silicate and trivalent chromium passivation systems, employing a specific process formula consisting of Co(NO₃)₂ at a concentration of 2.5 g/L, C₇₆H₅₂O₄₆ at 3 mL/L, Na₂SiO₃ at 25 g/L, C₆H₅Na₃O₇ at 15 g/L, and an appropriate amount of organic accelerator. The composite passivation of silicate and tannic acid was found to be more effective than the trivalent chromium passivation film, as it successfully eliminated the dendrite structure on the coating surface and reduced surface defects. The coordination between negatively charged SiO²⁻ or SiO₂ micelles and Zn²⁺ results in the formation of a passivation film that exhibits lower corrosion current and higher corrosion potential compared to the trivalent chromium passivation film. Additionally, the impedance test fitting results indicate that the silicate passivation film possesses a higher resistance value. Overall, the proposed silicate passivation system presents a viable alternative to the toxic chromate passivation system, offering non-toxicity and superior protective performance relative to the trivalent chromium passivation system. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessFeature PaperArticle

Optimization and Characterization of Centrifugal-Cast Functionally Graded Al-SiC Composite Using Response Surface Methodology and Grey Relational Analysis

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Bassiouny Saleh

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Reham Fathi

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Modawy Adam Ali Abdalla

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N. Radhika

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Aibin Ma

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Jinghua Jiang

Coatings 2023, 13(5), 813; https://doi.org/10.3390/coatings13050813 - 22 Apr 2023

Cited by 1 | Viewed by 963

Abstract

In this study, an optimization approach was employed to determine the optimal main parameters that improve the performance of functionally graded composites manufactured using a combination of stirring and horizontal centrifugal casting. Pure aluminum reinforced with silicon carbide particles was used as the [...] Read more.

In this study, an optimization approach was employed to determine the optimal main parameters that improve the performance of functionally graded composites manufactured using a combination of stirring and horizontal centrifugal casting. Pure aluminum reinforced with silicon carbide particles was used as the material for the composites. The effects of key input parameters such as mold speed, pouring temperature, stirring speed, and radial distance were optimized using a combination of grey relational analysis and response surface methodology. The statistical significance of the predicted grey relational grade model was assessed through an analysis of variance to identify the appropriate main parameters. The results showed that radial distance had the greatest impact on the performance of the composites, followed by pouring temperature. The optimal combination of main parameters was determined to be a mold speed of 1000 rpm, a pouring temperature of 750 °C, a stirring speed of 150 rpm, and a radial distance of 1 mm. Confirmation tests using these optimal values resulted in a 54.69% improvement in the grey relational grade. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessArticle

Corrosion Behaviors of Tetrasodium Iminodisuccinate (IDS) as an Environmentally Friendly Inhibitor: Experimental and Theoretical Studies

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Coatings 2023, 13(3), 613; https://doi.org/10.3390/coatings13030613 - 14 Mar 2023

Viewed by 907

Abstract

An environmentally friendly chelating agent, tetrasodium iminodisuccinate (IDS), was investigated as an inhibitor in the simulated concrete pore solution on Q235 carbon steel by using Tafel polarization (TF), electrochemical impedance spectroscopy (EIS) and surface morphology tests. The EIS and TF results indicate that [...] Read more.

An environmentally friendly chelating agent, tetrasodium iminodisuccinate (IDS), was investigated as an inhibitor in the simulated concrete pore solution on Q235 carbon steel by using Tafel polarization (TF), electrochemical impedance spectroscopy (EIS) and surface morphology tests. The EIS and TF results indicate that the IDS is a mixed type of inhibitor and exhibits excellent protection efficiency (97.54%) at 200 mg/L. Furthermore, based on the Langmuir adsorption isotherm, IDS protects carbon steel through physical and chemical adsorption. Besides, density functional theory (DFT) and molecular dynamics (MD) simulations are applied to explore the inhibition mechanism to support the experimental data, indicating that IDS can be used as a new green corrosion inhibitor. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessArticle

Functionally Gradient Coatings from HfC/ HfTaC₂ to Ti: Growth Process, Basic Mechanical Properties and Wear Behavior

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Coatings 2022, 12(12), 1941; https://doi.org/10.3390/coatings12121941 - 09 Dec 2022

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Abstract

HfC and HfTaC₂ coatings with gradient composition manufactured by double-cathode glow discharge plasma surface metallurgy technology were designed to improve the wear resistance of TA15 titanium alloy. The deposition mechanism of plasma and diffusion mechanism of atoms were investigated, and the growth [...] Read more.

HfC and HfTaC₂ coatings with gradient composition manufactured by double-cathode glow discharge plasma surface metallurgy technology were designed to improve the wear resistance of TA15 titanium alloy. The deposition mechanism of plasma and diffusion mechanism of atoms were investigated, and the growth process of coatings was revealed. The mechanical properties comprising microhardness and elastic modulus were investigated via first-principles calculations and experimental verification. The results reveal that the wear resistance of HfC and HfTaC₂ coatings with abrasive wear mechanism is always better than that of the substrate with abrasive wear, adhesive wear and oxidation wear mechanism. The volume wear rates of the coatings are reduced by 90%–97% compared with the substrate, and that of HfTaC₂ coatings are reduced by 29.9%–45.5% compared with HfC coatings. Furthermore, V-shaped cross section profiles of wear scars formed on HfC coatings, and U-shaped on HfTaC₂ coatings, which is attributed to the addition of tantalum which causes HfC to form a sufficient solid solution, a 0.187–0.030 Å elongation of Ta-C bond length and 0.039–0.051 Å shortening of Hf-C bond length led to the unit cell shrinkage and the Bragg lattice changes from face-centered cubic to face-centered square lattice; accordingly, hardness and wear behavior were further improved. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessArticle

Synthesis, Characterization and Investigation of Anticorrosion Properties of an Innovative Metal–Organic Framework, ZnMOF-BTA, on Carbon Steel in HCl Solution

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Coatings 2022, 12(9), 1288; https://doi.org/10.3390/coatings12091288 - 02 Sep 2022

Cited by 9 | Viewed by 1275

Abstract

An innovative metal–organic framework (ZnMOF-BTA) with corrosion inhibition properties was prepared by the solvothermal reaction of zinc nitrate, 1,2,3-benzotriazole, and 2,5-thiophene dicarboxylic acid. ZnMOF-BTA was characterized by FTIR, XRD, XPS, SEM, and thermogravimetric analyses, and the corrosion inhibition performance on Q235 carbon steel [...] Read more.

An innovative metal–organic framework (ZnMOF-BTA) with corrosion inhibition properties was prepared by the solvothermal reaction of zinc nitrate, 1,2,3-benzotriazole, and 2,5-thiophene dicarboxylic acid. ZnMOF-BTA was characterized by FTIR, XRD, XPS, SEM, and thermogravimetric analyses, and the corrosion inhibition performance on Q235 carbon steel in 1 M HCl solution was evaluated by weight loss, polarization, and EIS measurements. XRD results showed that ZnMOF-BTA has a monoclinic crystal structure and belongs to C12/c1 space group, while DTA/TGA results revealed it has a good crystalline quality and excellent thermal stability with a melting point of 410 °C. FTIR and XPS results revealed that Zn²⁺, TDC²⁻, and BTA molecules were successfully used in ZnMOF-BTA synthesis. Electrochemical test results show that the obtained ZnMOF-BTA is effective in corrosion inhibition of Q235 carbon steel in acidic conditions and maximum inhibition efficiency of over 90% is obtained at 6 wt.% ZnMOF-BTA extract concentration. Adsorption studies revealed that the adsorption of BTA molecules follows the Langmuir isotherm model with an R² value of 0.97889, while the ΔG◦_ads value of −10.28 kJ mol⁻¹ indicates that adsorption is by physisorption. The study provides a new corrosion inhibitor compound with proven corrosion inhibition properties. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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Open AccessReview

Progress in the Graphene Oxide-Based Composite Coatings for Anticorrosion of Metal Materials

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Coatings 2023, 13(6), 1120; https://doi.org/10.3390/coatings13061120 - 18 Jun 2023

Cited by 1 | Viewed by 883

Abstract

Graphene oxide (GO), derived from the two-dimensional nanosheet graphene, has received unprecedented attention in the field of metal corrosion protection owing to its excellent barrier performance and various active functional groups. In this review, the protection mechanism “labyrinth effect” of composite coatings against [...] Read more.

Graphene oxide (GO), derived from the two-dimensional nanosheet graphene, has received unprecedented attention in the field of metal corrosion protection owing to its excellent barrier performance and various active functional groups. In this review, the protection mechanism “labyrinth effect” of composite coatings against metal corrosion was demonstrated systematically. The origination, structure and properties of GO were also analyzed. Their poor dispersion in polymer and tendency to aggregate as nanofillers in composite coatings are the main limitations during application of the coating fillers. In addition, a comprehensive overview on the perspectives of the surface modification of GO and the multi-functionalization of the composite coatings based on GO were given in particular. Green modification methods, reasonable arrangement of GO sheets in composites and development of multi-functional coatings remain challenges in current studies and should be a focus in the future development of GO-based anticorrosive coatings. This review is of value to researchers interested in the design and application of GO in corrosion protection coatings. Full article

(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)

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