Materials

Research

17 pages, 7420 KiB

Open AccessArticle

Investigation of the Corrosion Behavior of L245 Steel in 3.5 wt.% NaCl Solution with Varying Concentrations of Na₂S₂O₃

by Mingyu Bao, Yan He, Jing Li, Lingfan Zhang, Chang Liu, Lei Wang, Zidan Wen, Xiaoyan Zhang and Shuliang Wang

Materials 2025, 18(10), 2270; https://doi.org/10.3390/ma18102270 - 14 May 2025

Viewed by 170

Abstract

In the extraction of shale gas, Cl⁻ and S₂O₃²⁻ are one of the important factors causing severe corrosion and failure of equipment and pipelines. Addressing the Cl⁻/S₂O₃²⁻ corrosion challenge in shale gas [...] Read more.

In the extraction of shale gas, Cl⁻ and S₂O₃²⁻ are one of the important factors causing severe corrosion and failure of equipment and pipelines. Addressing the Cl⁻/S₂O₃²⁻ corrosion challenge in shale gas exploitation pipeline steels, this study evaluates the corrosion rates of L245 steels under diverse conditions, including S₂O₃²⁻ concentration and exposure time, utilizing the weight loss method. The microstructural, elemental, and phase compositions of the corrosion products were examined, and the electrochemical behavior of L245 steel was scrutinized under various conditions. Findings indicate that S₂O₃²⁻ addition intensifies localized corrosion on L245 steel, with the corrosion nature being contingent upon S₂O₃²⁻ concentration in the Cl⁻-containing solution. Concurrently, an escalation in S₂O₃²⁻ concentration correlates with a reduction in capacitive arc diameter and a significant decrease in film resistance, culminating in an accelerated corrosion rate. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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18 pages, 8268 KiB

Open AccessArticle

Comparative Study of the Corrosive Behaviors of Rust Layers on Bronze Ware in Different Corrosive Environments

by Bingbing Li, Qixing Xia and Wenqiang Dong

Materials 2025, 18(6), 1359; https://doi.org/10.3390/ma18061359 - 19 Mar 2025

Viewed by 382

Abstract

It is of great significance to clarify the corrosion mechanism of rust layers on bronze ware for appropriate conservation measures. In this study, the corrosion behavior of Cu-Sn bronze alloys in a 3.5 wt.% NaCl solution and a simulated archaeological soil solution was [...] Read more.

It is of great significance to clarify the corrosion mechanism of rust layers on bronze ware for appropriate conservation measures. In this study, the corrosion behavior of Cu-Sn bronze alloys in a 3.5 wt.% NaCl solution and a simulated archaeological soil solution was studied and compared using electrochemical measurements, microscopic observations, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the presence of Cl⁻ was the key factor leading to the formation of harmful rust such as Cu₂(OH)Cl₃. In the NaCl solution, the rapid accumulation of Cl-containing corrosion products provided a certain degree of protection to Cu-Sn alloys, but the products easily fell off, thus increasing the continuous corrosion reactions again. This resulted in a significant increase in the corrosion rate of the alloy (i_corr from 4.845 μA·cm⁻² to 27.21 μA·cm⁻²) and a decrease in polarization resistance (R_p from 5.17 kΩ·cm² to 3.27 kΩ·cm²). In contrast, the corrosion reactions of the Cu-Sn alloy were dominated by complex ions other than Cl⁻ in archaeological soil environments, and the corrosion products tended to form stable and dense rust layers (i_corr was always lower than 1.6 μA·cm⁻², and R_p was maintained above 24 kΩ·cm²), which improved corrosion resistance by two orders of magnitude compared to the unstable rust layer that formed in NaCl solution. In addition, Cl-containing corrosion products boosted the wettability of rust layers, thereby facilitating penetration of corrosive media that strengthened corrosion reactions. This study deepens our understanding of the degradation mechanisms of bronze artifacts and provides a scientific basis for developing bronze conservation strategies. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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20 pages, 4572 KiB

Open AccessArticle

Stainless Steel 304 and Carbon Mild Steel A36 Activity in Chloride-Containing Hybrid Pumice-Portland Cement Extract Pore Environment

by David Bonfil, Lucien Veleva and Jose Ivan Escalante-Garcia

Materials 2025, 18(6), 1216; https://doi.org/10.3390/ma18061216 - 9 Mar 2025

Viewed by 568

Abstract

The effect of chlorides on the corrosion activities of SS304 and carbon steel A36 was investigated during immersion in a hybrid pumice–Portland cement extract solution, containing high concentration of chlorides (5 g

L^{- 1}

NaCl), in order to simulate the concrete–pore marine [...] Read more.

The effect of chlorides on the corrosion activities of SS304 and carbon steel A36 was investigated during immersion in a hybrid pumice–Portland cement extract solution, containing high concentration of chlorides (5 g

L^{- 1}

NaCl), in order to simulate the concrete–pore marine environment. The hybrid pumice–Portland cement (HB1) has been considered an alternative “green” cement system. The initial pH of the extract (12.99) decreased to 9.5 after 14 days, inducing a severe corrosion risk for A36, as suggested by the very negative corrosion potential (OCP ≈ −363 mV). Meanwhile, the SS304 tended to passivate and its OCP shifted to positive values (≈+72 mV). Consequently, the surface of the A36 presented a corrosion layer mainly of

FeOOH

, while that of the SS304 was composed of

{Cr}_{2} O_{3}

,

{Fe}_{3} O_{4}

and

NiO

, according to the SEM-EDS and XPS analysis. An extended area of an almost uniform corrosion attack was observed on the A36 surface, due to the less protective Fe-corrosion products, while the SS304 surface presented some small pits of ≈1 µm. Based on electrochemical impedance measurements, the polarization resistance (Rp) and thickness of the passive layer were calculated. The Rp of the SS304 surface increased by two orders of magnitude up to ≈11,080

k Ω {cm}^{2}

, and the thickness of the layer reached ≈1.5 nm after 30 days of immersion. The Rp of carbon steel was ≈2.5

k Ω {cm}^{2}

due to the less protective properties of its corrosion products. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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16 pages, 7062 KiB

Open AccessArticle

Improving Corrosion and Wear Resistance of 316L Stainless Steel via In Situ Pure Ti and Ti6Al4V Coatings: Tribocorrosion and Electrochemical Analysis

by Darya Alontseva, Hasan İsmail Yavuz, Bagdat Azamatov, Fuad Khoshnaw, Yuliya Safarova (Yantsen), Dmitriy Dogadkin, Egemen Avcu and Ridvan Yamanoglu

Materials 2025, 18(3), 553; https://doi.org/10.3390/ma18030553 - 25 Jan 2025

Cited by 1 | Viewed by 1472

Abstract

This study aims to achieve in situ-formed pure Ti and Ti6Al4V coatings on 316L stainless steel through hot pressing and examine their wear and corrosion properties thoroughly in two simulated body fluids: physiological serum (0.9% NaCl) and Hanks’ solution. The sintering and diffusion [...] Read more.

This study aims to achieve in situ-formed pure Ti and Ti6Al4V coatings on 316L stainless steel through hot pressing and examine their wear and corrosion properties thoroughly in two simulated body fluids: physiological serum (0.9% NaCl) and Hanks’ solution. The sintering and diffusion bonding process was conducted at 1050 °C under a uniaxial pressure of 40 MPa for 30 min in a vacuum environment of 10⁻⁴ mbar. Following sintering, in situ-formed pure Ti and Ti6Al4V coatings, approximately 1000 µm thick, were produced on 316L substrates approximately 3000 µm in thickness. The mean hardness of 316L substrates, pure Ti, and Ti6Al4V coatings are around 165 HV, 170 HV, and 420 HV, respectively. The interface of the stainless steel substrate and the pure Ti and Ti6Al4V coatings exhibited no microstructural defects, while the interface exhibited significantly higher hardness values (ranging from 600 to 700 HV). The coatings improved corrosion resistance in both electrolytes compared to the 316L substrate. Wet wear tests revealed reduced friction coefficients in 0.9% NaCl relative to Hanks’ solution, highlighting the chemical interactions between the material surface and the electrolyte type and the significance of tribocorrosion in biocoatings. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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12 pages, 4587 KiB

Open AccessArticle

Dynamic Electrochemical Impedance Spectroscopy in Galvanostatic Mode as a Tool for Passive Layer State Monitoring in a Chloride Solution Under a Mechanical Load

by Mateusz Cieślik, Juliusz Orlikowski, Stefan Krakowiak and Krzysztof Żakowski

Materials 2025, 18(1), 167; https://doi.org/10.3390/ma18010167 - 3 Jan 2025

Viewed by 594

Abstract

Mechanical stress is one of the factors influencing the initiation of pitting corrosion and deterioration of the protective properties of the passive layer on stainless steel. The tests carried out on AISI 304L stainless steel showed that, in the 3.5% NaCl environment for [...] Read more.

Mechanical stress is one of the factors influencing the initiation of pitting corrosion and deterioration of the protective properties of the passive layer on stainless steel. The tests carried out on AISI 304L stainless steel showed that, in the 3.5% NaCl environment for samples loaded in the elastic and plastic range, no pitting corrosion initiation was observed. Only mechanical damage of the passive layer occurred. Galvanodynamic electrochemical impedance spectroscopy (g-DEIS) was used as the measuring technique. This technique ensures the monitoring of corrosion processes at zero external current (I_DC = 0) and no potential perturbation of the system. It also allows one to perform many measurements, so that short-term changes such as cracking of the layer and its repassivation are possible to monitor. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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12 pages, 2940 KiB

Open AccessArticle

Synthesis and Electrochemical Properties of Oleylamine as a Sour Saline Corrosion Inhibitor Under Laminar Flow at 40 °C

by Jorge Alvarez-Malpica, Karime Carrera-Gutiérrez, Manuel Chinchillas-Chinchillas, Manuel Herrera Zaldivar, Alfredo Martinez-Garcia and Victor M. Orozco-Carmona

Materials 2024, 17(21), 5284; https://doi.org/10.3390/ma17215284 - 30 Oct 2024

Viewed by 932

Abstract

In this study, the synthesis of a long-chain aliphatic amino compound and its sour corrosion inhibition properties were reported. Oleylamine was obtained through the reaction of 4-(Aminomethyl) pyridine with 1-chloro-octadecane. The identification and characterization of reaction products were carried out through Fourier transform [...] Read more.

In this study, the synthesis of a long-chain aliphatic amino compound and its sour corrosion inhibition properties were reported. Oleylamine was obtained through the reaction of 4-(Aminomethyl) pyridine with 1-chloro-octadecane. The identification and characterization of reaction products were carried out through Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectroscopy (GC-MS). Oleylamine was tested as a sour corrosion inhibitor for steels. Different concentrations of oleylamine (0, 5, 10, 25, and 100 ppm) in a sour saline electrolyte were analyzed. The dynamic anticorrosive behavior of oleylamine on carbon mild steel (AISI 1018) surfaces was evaluated using a laminar flow of 100 rpm and tested with potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements. After electrochemical testing, the surface of the steel specimens that were used was characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The electrochemical results of the anticorrosive efficiency of oleylamine for steel showed an exponential behavior as a function of inhibitor concentration. At a concentration of 20 ppm of the inhibitor, the anticorrosive efficiency did not show any significant changes. However, at 100 ppm of the inhibitor, an efficiency of over 95% was achieved. After the electrochemical tests, the surface of the steel samples with the inhibitor revealed the formation of an inhibitor layer that prevented the corrosion of the steel. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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15 pages, 14975 KiB

Open AccessArticle

In-Situ Coating of Iron with a Conducting Polymer, Polypyrrole, as a Promise for Corrosion Protection

by Jaroslav Stejskal, Marek Jurča, Miroslava Trchová, Jan Prokeš and Ivo Křivka

Materials 2024, 17(19), 4783; https://doi.org/10.3390/ma17194783 - 29 Sep 2024

Viewed by 1171

Abstract

Iron microparticles were coated with polypyrrole in situ during the chemical oxidation of pyrrole with ammonium peroxydisulfate in aqueous medium. A series of hybrid organic/inorganic core–shell materials were prepared with 30–76 wt% iron content. Polypyrrole coating was revealed by scanning electron microscopy, and [...] Read more.

Iron microparticles were coated with polypyrrole in situ during the chemical oxidation of pyrrole with ammonium peroxydisulfate in aqueous medium. A series of hybrid organic/inorganic core–shell materials were prepared with 30–76 wt% iron content. Polypyrrole coating was revealed by scanning electron microscopy, and its molecular structure and completeness were proved by FTIR and Raman spectroscopies. The composites of polypyrrole/carbonyl iron were obtained as powders and characterized with respect to their electrical properties. Their resistivity was monitored by the four-point van der Pauw method under 0.01–10 MPa pressure. In an apparent paradox, the resistivity of composites increased from the units Ω cm for neat polypyrrole to thousands Ω cm for the highest iron content despite the high conductivity of iron. This means that composite conductivity is controlled by the electrical properties of the polypyrrole matrix. The change of sample size during the compression was also recorded and provides a parameter reflecting the mechanical properties of composites. In addition to conductivity, the composites displayed magnetic properties afforded by the presence of iron. The study also illustrates the feasibility of the polypyrrole coating on macroscopic objects, demonstrated by an iron nail, and offers potential application in the corrosion protection of iron. The differences in the morphology of micro- and macroscopic polypyrrole objects are described. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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33 pages, 12834 KiB

Open AccessArticle

Effect of Citric Acid Hard Anodizing on the Mechanical Properties and Corrosion Resistance of Different Aluminum Alloys

by José Cabral-Miramontes, Facundo Almeraya-Calderón, Ce Tochtli Méndez-Ramírez, Juan Pablo Flores-De los Rios, Erick Maldonado-Bandala, Miguel Ángel Baltazar-Zamora, Demetrio Nieves-Mendoza, María Lara-Banda, Gabriela Pedraza-Basulto and Citlalli Gaona-Tiburcio

Materials 2024, 17(17), 4285; https://doi.org/10.3390/ma17174285 - 29 Aug 2024

Cited by 2 | Viewed by 1685

Abstract

Hard anodizing is used to improve the anodic films’ mechanical qualities and aluminum alloys’ corrosion resistance. Applications for anodic oxide coatings on aluminum alloys include the space environment. In this work, the aluminum alloys 2024-T3 (Al-Cu), 6061-T6 (Al-Mg-Si), and 7075-T6 (Al-Zn) were prepared [...] Read more.

Hard anodizing is used to improve the anodic films’ mechanical qualities and aluminum alloys’ corrosion resistance. Applications for anodic oxide coatings on aluminum alloys include the space environment. In this work, the aluminum alloys 2024-T3 (Al-Cu), 6061-T6 (Al-Mg-Si), and 7075-T6 (Al-Zn) were prepared by hard anodizing electrochemical treatment using citric and sulfur acid baths at different concentrations. The aim of the work is to observe the effect of citric acid on the microstructure of the substrate, the mechanical properties, the corrosion resistance, and the morphology of the hard anodic layers. Hard anodizing was performed on three different aluminum alloys using three citric–sulfuric acid mixtures for 60 min and using current densities of 3.0 and 4.5 A/dm². Vickers microhardness (HV) measurements and scanning electron microscopy (SEM) were utilized to determine the mechanical characteristics and microstructure of the hard anodizing material, and electrochemical techniques to understand the corrosion kinetics. The result indicates that the aluminum alloy 6061-T6 (Al-Mg-Si) has the maximum hard-coat thickness and hardness. The oxidation of Zn and Mg during the anodizing process found in the 7075-T6 (Al-Zn) alloy promotes oxide formation. Because of the high copper concentration, the oxide layer that forms on the 2024-T6 (Al-Cu) Al alloy has the lowest thickness, hardness, and corrosion resistance. Citric and sulfuric acid solutions can be used to provide hard anodizing in a variety of aluminum alloys that have corrosion resistance and mechanical qualities on par with or better than traditional sulfuric acid anodizing. Full article

(This article belongs to the Special Issue Corrosion Electrochemistry and Protection of Metallic Materials)

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