Akhil Varghese, Miguel Arana‐Catania, S. Mori, A. Encinas-Oropesa, Joy Sumner
Gas turbine superalloys experience hot corrosion, driven by factors including corrosive deposit flux, temperature, gas composition, and component material. The full mechanism still needs clarification and research often focuses on laboratory work. As such, there is interest in causal discovery to confirm the significance of factors and identify potential missing causal relationships or codependencies between these factors. The causal discovery algorithm fast causal inference (FCI) has been trialled on a small set of laboratory data, with the outputs evaluated for their significance to corrosion propagation, and compared to existing mechanistic understanding. FCI identified salt deposition flux as the most influential corrosion variable for this limited data set. However, HCl was the second most influential for pitting regions, compared to temperature for more uniformly corroding regions. Thus, FCI generated causal links aligned with literature from a randomised corrosion data set, while also identifying the presence of two different degradation modes in operation.
{"title":"Causal discovery to understand hot corrosion","authors":"Akhil Varghese, Miguel Arana‐Catania, S. Mori, A. Encinas-Oropesa, Joy Sumner","doi":"10.1002/maco.202314240","DOIUrl":"https://doi.org/10.1002/maco.202314240","url":null,"abstract":"Gas turbine superalloys experience hot corrosion, driven by factors including corrosive deposit flux, temperature, gas composition, and component material. The full mechanism still needs clarification and research often focuses on laboratory work. As such, there is interest in causal discovery to confirm the significance of factors and identify potential missing causal relationships or codependencies between these factors. The causal discovery algorithm fast causal inference (FCI) has been trialled on a small set of laboratory data, with the outputs evaluated for their significance to corrosion propagation, and compared to existing mechanistic understanding. FCI identified salt deposition flux as the most influential corrosion variable for this limited data set. However, HCl was the second most influential for pitting regions, compared to temperature for more uniformly corroding regions. Thus, FCI generated causal links aligned with literature from a randomised corrosion data set, while also identifying the presence of two different degradation modes in operation.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"133 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139842993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"EVENTS","authors":"","doi":"10.1002/maco.202470034","DOIUrl":"https://doi.org/10.1002/maco.202470034","url":null,"abstract":"","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139847844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbonation‐induced corrosion of steel in concrete can allow for premature degradation of structures. Corrosion probes in health monitoring systems can assess concrete carbonation and steel corrosion rates. The electrochemical noise (EN) technique has advantages for corrosion sensing. Instrumented concrete columns were fitted with a carbonation chamber for accelerated testing. EN was assessed through statistical evaluation of noise time signatures, noise resistance, and spectral analysis. The mean noise potential for the electrodes showed electronegative potential and correspondingly high rms noise current, indicative of corrosion activation in carbonated concrete. The estimated corrosion rates obtained from the noise impedance were comparable to those resolved from the polarization resistance and noise resistance. The shot noise analysis indicated isolated spontaneous noise events associated with the activation of local steel anodes. The outcomes of the testing indicate that the placement of low‐cost sensors and passive EN measurements can be used to monitor the onset of carbonation‐induced corrosion of steel in concrete and provide estimates on corrosion rates.
混凝土中碳化引起的钢材腐蚀会导致结构过早退化。健康监测系统中的腐蚀探头可以评估混凝土碳化和钢材腐蚀率。电化学噪声（EN）技术在腐蚀传感方面具有优势。带仪器的混凝土柱安装了一个碳化室，用于加速测试。通过对噪声时间特征、噪声阻抗和频谱分析的统计评估，对 EN 进行了评估。电极的平均噪声电位显示出电负电位和相应的高均方根噪声电流，表明碳化混凝土中的腐蚀活化。噪声阻抗得出的估计腐蚀率与极化电阻和噪声阻抗得出的腐蚀率相当。射击噪声分析表明，孤立的自发噪声事件与局部钢阳极的活化有关。测试结果表明，放置低成本传感器和被动 EN 测量可用于监测混凝土中钢材碳化诱导腐蚀的开始，并提供腐蚀率估计值。
{"title":"Identification of carbonation‐induced corrosion of steel in concrete by electrochemical testing","authors":"Samanbar Permeh, K. Lau","doi":"10.1002/maco.202414272","DOIUrl":"https://doi.org/10.1002/maco.202414272","url":null,"abstract":"Carbonation‐induced corrosion of steel in concrete can allow for premature degradation of structures. Corrosion probes in health monitoring systems can assess concrete carbonation and steel corrosion rates. The electrochemical noise (EN) technique has advantages for corrosion sensing. Instrumented concrete columns were fitted with a carbonation chamber for accelerated testing. EN was assessed through statistical evaluation of noise time signatures, noise resistance, and spectral analysis. The mean noise potential for the electrodes showed electronegative potential and correspondingly high rms noise current, indicative of corrosion activation in carbonated concrete. The estimated corrosion rates obtained from the noise impedance were comparable to those resolved from the polarization resistance and noise resistance. The shot noise analysis indicated isolated spontaneous noise events associated with the activation of local steel anodes. The outcomes of the testing indicate that the placement of low‐cost sensors and passive EN measurements can be used to monitor the onset of carbonation‐induced corrosion of steel in concrete and provide estimates on corrosion rates.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"37 9-10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139853494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hélène Lotz, D. Neff, F. Mercier‐Bion, C. Bataillon, Nicolas Nuns, P. Dillmann
A two‐step corrosion experiment was performed on a ferritic steel (Armco) in a synthetic solution representing the Callovo–Oxfordian at 120°C. After the development of a carbonated corrosion product layer (CPL) during the first 15 days of the experimental step, corrosion front progression was investigated using 13C marked carbonate species during the second 15 days experimental step. CPL was characterized at each step, in terms of morphology (scanning electron microscopy), composition (energy‐dispersive spectroscopy), and structure (µ‐Raman). 13C corrosion product locations were analyzed by time‐of‐flight secondary ion mass spectrometry. Results evidenced that after a step of generalized corrosion, iron corrosion continues locally at the metal/CPL interface. These results suggest that although a protective siderite layer formed on the iron surface after 15 days, a local dissolution of the carbonate layer at the M/CPL interface occurred. A galvanic effect is developed between the bared surface (anode) and the covered one (cathode). This activates iron oxidation. The precipitation of carbonate corrosion products to the metal/CPL interface is possible by the diffusion of 13CO32− ions from the bulk through the siderite layer.
{"title":"13C isotopic labeling to decipher the iron corrosion mechanisms in a carbonated anoxic environment","authors":"Hélène Lotz, D. Neff, F. Mercier‐Bion, C. Bataillon, Nicolas Nuns, P. Dillmann","doi":"10.1002/maco.202314203","DOIUrl":"https://doi.org/10.1002/maco.202314203","url":null,"abstract":"A two‐step corrosion experiment was performed on a ferritic steel (Armco) in a synthetic solution representing the Callovo–Oxfordian at 120°C. After the development of a carbonated corrosion product layer (CPL) during the first 15 days of the experimental step, corrosion front progression was investigated using 13C marked carbonate species during the second 15 days experimental step. CPL was characterized at each step, in terms of morphology (scanning electron microscopy), composition (energy‐dispersive spectroscopy), and structure (µ‐Raman). 13C corrosion product locations were analyzed by time‐of‐flight secondary ion mass spectrometry. Results evidenced that after a step of generalized corrosion, iron corrosion continues locally at the metal/CPL interface. These results suggest that although a protective siderite layer formed on the iron surface after 15 days, a local dissolution of the carbonate layer at the M/CPL interface occurred. A galvanic effect is developed between the bared surface (anode) and the covered one (cathode). This activates iron oxidation. The precipitation of carbonate corrosion products to the metal/CPL interface is possible by the diffusion of 13CO32− ions from the bulk through the siderite layer.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139860651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kathhi Palaksha Reddy, Thanjavur Krishnamoorthi Kandavel, Selvaraj Nelson Raja
Sintered low carbon steels are developed using prealloyed and elemental powders to improve the mechanical properties of powder metallurgy and powder forged parts. The research focuses on the mechanism of workability and corrosion studies on sintered preforms of Alloy 1 (ATOMET4601 + 0.35%C) and Alloy 2 (ATOMET4601‐0.35%C‐0.25%Mn‐0.1%Si‐0.9%Cr). Sintered preforms of relative densities of 81%, 84%, and 90% were used for the present work. The preforms with 84% relative density have been used to study the formability parameters. It is observed from the experimental study that the Alloy 2 preforms with the addition of alloying elements have undergone lesser densification and deformation due to the work hardening mechanism. Corrosion studies have been carried out by conducting aqueous immersion and electrochemical corrosion tests on these two alloys using 18% HCl solution at different timings. It is found that the Alloy 2 has exhibited a better corrosion resistance than the Alloy 1 due to the addition of various alloying elements. It is also observed that the corrosion rate has decreased with an increase in densification irrespective of the alloys. The microstructures, scanning electron microscopy, and X‐ray diffraction of corroded surfaces have been corroborated with densification and the corrosion behavior of alloys.
{"title":"Workability and corrosion behavior studies on sintered iron‐based hybrid powder metallurgy alloys","authors":"Kathhi Palaksha Reddy, Thanjavur Krishnamoorthi Kandavel, Selvaraj Nelson Raja","doi":"10.1002/maco.202213268","DOIUrl":"https://doi.org/10.1002/maco.202213268","url":null,"abstract":"Sintered low carbon steels are developed using prealloyed and elemental powders to improve the mechanical properties of powder metallurgy and powder forged parts. The research focuses on the mechanism of workability and corrosion studies on sintered preforms of Alloy 1 (ATOMET4601 + 0.35%C) and Alloy 2 (ATOMET4601‐0.35%C‐0.25%Mn‐0.1%Si‐0.9%Cr). Sintered preforms of relative densities of 81%, 84%, and 90% were used for the present work. The preforms with 84% relative density have been used to study the formability parameters. It is observed from the experimental study that the Alloy 2 preforms with the addition of alloying elements have undergone lesser densification and deformation due to the work hardening mechanism. Corrosion studies have been carried out by conducting aqueous immersion and electrochemical corrosion tests on these two alloys using 18% HCl solution at different timings. It is found that the Alloy 2 has exhibited a better corrosion resistance than the Alloy 1 due to the addition of various alloying elements. It is also observed that the corrosion rate has decreased with an increase in densification irrespective of the alloys. The microstructures, scanning electron microscopy, and X‐ray diffraction of corroded surfaces have been corroborated with densification and the corrosion behavior of alloys.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"92 1","pages":"1854 - 1864"},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81609494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jovana Pejić, Bojana M. Radojković, Dunja Marunkić, B. Jegdić, S. Stevanović, Milena Milošević, J. Bajat
The inhibitory effect of cysteine in the presence of selected lanthanide chlorides (LaCl3, NdCl3, and CeCl3) in a neutral 0.1 M NaCl solution was analyzed. The cysteine concentration of 0.3 mM was determined as an optimal one. The resistance to general and pitting corrosion of AA7075‐T6 alloy in inhibitive solutions was determined using electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The surface appearance of the aluminum alloy was determined before and after corrosion tests using scanning electron microscopy/energy dispersive spectroscopy, while the presence of an inhibitory layer on the alloy surface was confirmed by X‐ray photoelectron spectroscopy analysis and atomic force microscopy. The inhibitory effect of cysteine was significantly higher in the presence of all tested lanthanide chlorides, especially to pitting corrosion. The protective ability of cysteine was increased by lanthanides in the following sequence: Ln < Nd < Ce ions. The inhibitory effect of cysteine in the presence of cerium ions was examined in more detail as cerium ions provided the highest inhibitory effect, both to general and pitting corrosion.
分析了在中性0.1 M NaCl溶液中，选择镧系氯化物(LaCl3、NdCl3和CeCl3)存在时，半胱氨酸的抑制作用。半胱氨酸的最佳浓度为0.3 mM。采用电化学阻抗谱法和动电位极化法测定了AA7075‐T6合金在缓蚀剂溶液中的抗一般腐蚀和点蚀性能。采用扫描电镜/能量色散光谱法测定了腐蚀前后铝合金的表面形貌，同时通过X射线光电子能谱分析和原子力显微镜法证实了合金表面存在抑制层。在所有被测镧系氯化物存在的情况下，半胱氨酸的抑制作用明显更高，尤其是对点蚀的抑制作用。镧系元素对半胱氨酸的保护能力增强的顺序为:Ln < Nd < Ce。对于半胱氨酸在铈离子存在下的抑制作用进行了更详细的研究，因为铈离子对一般腐蚀和点蚀都具有最高的抑制作用。
{"title":"Inhibitory effect of cysteine and lanthanides on AA7075‐T6 in neutral NaCl solution","authors":"Jovana Pejić, Bojana M. Radojković, Dunja Marunkić, B. Jegdić, S. Stevanović, Milena Milošević, J. Bajat","doi":"10.1002/maco.202213330","DOIUrl":"https://doi.org/10.1002/maco.202213330","url":null,"abstract":"The inhibitory effect of cysteine in the presence of selected lanthanide chlorides (LaCl3, NdCl3, and CeCl3) in a neutral 0.1 M NaCl solution was analyzed. The cysteine concentration of 0.3 mM was determined as an optimal one. The resistance to general and pitting corrosion of AA7075‐T6 alloy in inhibitive solutions was determined using electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The surface appearance of the aluminum alloy was determined before and after corrosion tests using scanning electron microscopy/energy dispersive spectroscopy, while the presence of an inhibitory layer on the alloy surface was confirmed by X‐ray photoelectron spectroscopy analysis and atomic force microscopy. The inhibitory effect of cysteine was significantly higher in the presence of all tested lanthanide chlorides, especially to pitting corrosion. The protective ability of cysteine was increased by lanthanides in the following sequence: Ln < Nd < Ce ions. The inhibitory effect of cysteine in the presence of cerium ions was examined in more detail as cerium ions provided the highest inhibitory effect, both to general and pitting corrosion.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"15 1","pages":"1800 - 1812"},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79121219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, micro‐galvanic corrosion of SAF 2205 duplex stainless steel (DSS) annealed at different temperatures with different phase ratios (α/γ) in a 1 M H2SO4 + 1 M NaCl solution is analyzed by zero resistance ammeter (ZRA), immersion and numerical simulation model. COMSOL Multiphysics is used to solve the numerical simulation model and predict the local current density, potential distribution, and morphology of DSS annealed at different temperatures with different phase ratios. The modeling results are in good agreement with the immersion test results, which indicate that the micro‐galvanic corrosion depth of SAF 2205 DSS annealed at different temperatures initially decreases and then increases with the increase in the phase ratios (α/γ). The best micro‐galvanic corrosion resistance is obtained at an annealing temperature of 1100°C.
采用零电阻电流表(ZRA)、浸渍法和数值模拟模型，研究了不同温度、不同相比(α/γ)退火的SAF 2205双相不锈钢(DSS)在1 M H2SO4 + 1 M NaCl溶液中的微电偶腐蚀。利用COMSOL Multiphysics对数值模拟模型进行求解，预测不同温度、不同相比退火后DSS的局部电流密度、电位分布和形貌。模拟结果与浸渍试验结果吻合较好，表明不同温度下退火的SAF 2205 DSS微电偶腐蚀深度随相比(α/γ)的增大先减小后增大。在1100℃的退火温度下，获得了最佳的微电腐蚀性能。
{"title":"Micro‐galvanic corrosion of duplex stainless steel annealed at different temperatures evaluated by experiments and a numerical simulation model","authors":"Xin Cao, Xiaojun Hu","doi":"10.1002/maco.202213297","DOIUrl":"https://doi.org/10.1002/maco.202213297","url":null,"abstract":"In this study, micro‐galvanic corrosion of SAF 2205 duplex stainless steel (DSS) annealed at different temperatures with different phase ratios (α/γ) in a 1 M H2SO4 + 1 M NaCl solution is analyzed by zero resistance ammeter (ZRA), immersion and numerical simulation model. COMSOL Multiphysics is used to solve the numerical simulation model and predict the local current density, potential distribution, and morphology of DSS annealed at different temperatures with different phase ratios. The modeling results are in good agreement with the immersion test results, which indicate that the micro‐galvanic corrosion depth of SAF 2205 DSS annealed at different temperatures initially decreases and then increases with the increase in the phase ratios (α/γ). The best micro‐galvanic corrosion resistance is obtained at an annealing temperature of 1100°C.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"61 1","pages":"2019 - 2031"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75635276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Boriding is the process of coating the metal surface with a ceramic metal boride layer by the diffusion method. Iron borides, one of the metal borides, are called ceramics because they are covalently bonded compounds. Iron boride coatings contain strong Fe–B and B–B covalent bonds. In this study, the effect of boronizing on the corrosion resistance of AISI 1010 steel was investigated. Baybora‐1 which has recently been patented was used as boronizing agent. AISI 1010 steel was borided at 950°C for 2, 4, and 6 h using the solid method. The microstructure, hardness, and corrosion rate of the samples were investigated. The change in the corrosion rate of the samples was determined by the corrosion test specified in the ASTM G31‐72 standard. The results showed that the hardness of the iron boride layer formed on the surface as a result of the boronizing process was greater than that of the matrix. As a result of the boriding process, the hardness of the iron boride layer on the steel surface reached approximately eight times the hardness of the substrate matrix. The thickness of the iron boride layer on the steel sample surface was measured at 950°C for 2 and 6 h, respectively, as 45 ± 12 and 155 ± 13 µm. It was concluded that the boriding process increased the corrosion resistance of steel.
{"title":"Increasing corrosion resistance of AISI 1010 steel by boride coatings","authors":"S. U. Bayça, O. Bican","doi":"10.1002/maco.202213326","DOIUrl":"https://doi.org/10.1002/maco.202213326","url":null,"abstract":"Boriding is the process of coating the metal surface with a ceramic metal boride layer by the diffusion method. Iron borides, one of the metal borides, are called ceramics because they are covalently bonded compounds. Iron boride coatings contain strong Fe–B and B–B covalent bonds. In this study, the effect of boronizing on the corrosion resistance of AISI 1010 steel was investigated. Baybora‐1 which has recently been patented was used as boronizing agent. AISI 1010 steel was borided at 950°C for 2, 4, and 6 h using the solid method. The microstructure, hardness, and corrosion rate of the samples were investigated. The change in the corrosion rate of the samples was determined by the corrosion test specified in the ASTM G31‐72 standard. The results showed that the hardness of the iron boride layer formed on the surface as a result of the boronizing process was greater than that of the matrix. As a result of the boriding process, the hardness of the iron boride layer on the steel surface reached approximately eight times the hardness of the substrate matrix. The thickness of the iron boride layer on the steel sample surface was measured at 950°C for 2 and 6 h, respectively, as 45 ± 12 and 155 ± 13 µm. It was concluded that the boriding process increased the corrosion resistance of steel.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"35 1","pages":"2032 - 2040"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85528670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The corrosion behavior and microstructure of a novel multicomponent Al75Mg5Li10Zn5Cu5 low entropy alloy (Al LEA) were investigated in different Cl− ion concentrations of acidic (HCl), neutral (NaCl), and alkaline (NaOH) media. The study was performed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The surface morphologies and chemical composition were examined by using a scanning electron microscope with energy‐dispersive X‐ray spectroscopy. The results indicated that with the increase of the Cl− ion concentrations, the degradation rate with more pits and cracks was observed in both acidic and neutral media. This is due to the breakdown of Al(OH)3/Al2O3 passive layer. In an alkaline medium, increasing of pH value from pH 8 to pH 12, there was a slight increment in corrosion rate (CR). However, the corrosion trend was not witnessed on alloy surfaces because of the formation of Mg32(Al, Zn)49 and AlCu phases, which are more stable than α‐Al. The order of Al‐LEA CR is found to be HCl > NaCl > NaOH. The results obtained from the polarization and EIS were in good agreement with each other.
{"title":"Electrochemical characterization of a novel multicomponent Al75Mg5Li10Zn5Cu5 low entropy alloy in different pH environments","authors":"P. Sudha, K. Tun, M. Gupta, A. Mourad, S. Vincent","doi":"10.1002/maco.202213103","DOIUrl":"https://doi.org/10.1002/maco.202213103","url":null,"abstract":"The corrosion behavior and microstructure of a novel multicomponent Al75Mg5Li10Zn5Cu5 low entropy alloy (Al LEA) were investigated in different Cl− ion concentrations of acidic (HCl), neutral (NaCl), and alkaline (NaOH) media. The study was performed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The surface morphologies and chemical composition were examined by using a scanning electron microscope with energy‐dispersive X‐ray spectroscopy. The results indicated that with the increase of the Cl− ion concentrations, the degradation rate with more pits and cracks was observed in both acidic and neutral media. This is due to the breakdown of Al(OH)3/Al2O3 passive layer. In an alkaline medium, increasing of pH value from pH 8 to pH 12, there was a slight increment in corrosion rate (CR). However, the corrosion trend was not witnessed on alloy surfaces because of the formation of Mg32(Al, Zn)49 and AlCu phases, which are more stable than α‐Al. The order of Al‐LEA CR is found to be HCl > NaCl > NaOH. The results obtained from the polarization and EIS were in good agreement with each other.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"64 1","pages":"2071 - 2083"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77890037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rongfu Xu, Yihao Ma, Wenhao Wang, Peng Qi, Guangyu Wang
In this paper, the effect of elements such as Ni, Al, and Si in gray cast iron on the atmospheric corrosion resistance of gray cast iron was studied by using corrosion weight gain, salt spray test, electrochemistry, and X‐ray diffraction. The results show that the corrosion behavior of gray cast iron can be divided into two stages. The later stage of corrosion resistance of gray cast iron with Ni element is better than the early stage of corrosion resistance, while the reverse is true for gray cast iron with Al element. There is no significant effect of increasing the Si content on the corrosion behavior of gray cast iron. The corrosion products of each specimen are all composed of Fe2O3, α‐FeOOH, γ‐FeOOH, and Fe3O4. After the comparison test, it can be concluded that the Ni element is seen to be conducive to the formation of protective rust layer with higher α‐FeOOH content. In addition, the rust layer of gray cast iron containing Al is loose and scaly, while the rust layer of gray cast iron containing Ni is dense and spongy. The addition of Ni element can make gray cast iron stable to improve the self‐corrosion potential and reduce the self‐corrosion current density, thus reducing the corrosion rate of gray cast iron.
{"title":"Study on the effect of alloying elements Ni, Al, and Si on salt spray corrosion resistance of gray cast iron","authors":"Rongfu Xu, Yihao Ma, Wenhao Wang, Peng Qi, Guangyu Wang","doi":"10.1002/maco.202213347","DOIUrl":"https://doi.org/10.1002/maco.202213347","url":null,"abstract":"In this paper, the effect of elements such as Ni, Al, and Si in gray cast iron on the atmospheric corrosion resistance of gray cast iron was studied by using corrosion weight gain, salt spray test, electrochemistry, and X‐ray diffraction. The results show that the corrosion behavior of gray cast iron can be divided into two stages. The later stage of corrosion resistance of gray cast iron with Ni element is better than the early stage of corrosion resistance, while the reverse is true for gray cast iron with Al element. There is no significant effect of increasing the Si content on the corrosion behavior of gray cast iron. The corrosion products of each specimen are all composed of Fe2O3, α‐FeOOH, γ‐FeOOH, and Fe3O4. After the comparison test, it can be concluded that the Ni element is seen to be conducive to the formation of protective rust layer with higher α‐FeOOH content. In addition, the rust layer of gray cast iron containing Al is loose and scaly, while the rust layer of gray cast iron containing Ni is dense and spongy. The addition of Ni element can make gray cast iron stable to improve the self‐corrosion potential and reduce the self‐corrosion current density, thus reducing the corrosion rate of gray cast iron.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"390 1","pages":"2041 - 2052"},"PeriodicalIF":0.0,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82710757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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