Daniel Kelm, Tom Marquardt, Andreas Momber, Steffen Sellmeyer, Michael Irmer
The automation of coating processes allows consistent, economical, and ecological applications. In this study, the effects of various surface geometries—steel plates, plates with weld seams, plates with bolts, and plates with welded fillets—on the uniformity of dry film thickness (DFT) after robotic stripe coating applications with an electrostatic spray device are investigated and analyzed with statistical methods. Robot traverse rate, pump pressure, and voltage. Based on analysis of variance studies, the robot traverse rate was identified to be the most influential factor. For plates with weld seams, an optimization study was conducted, resulting in a multiresponse prediction model. The model achieved a DFT within the target range across all measuring points within a 95% confidence interval. At an optimized factor combination (117 mm/s, 0.3 MPa, 61.4 kV), the DFT values ranged between 100 and 142 µm. The findings of this study provide fundamentals for achieving uniform coating distributions on complex geometries and for optimizing process parameters.
{"title":"Statistical investigations into automated spray-applied stripe coats to complex geometries of floating offshore wind foundations","authors":"Daniel Kelm, Tom Marquardt, Andreas Momber, Steffen Sellmeyer, Michael Irmer","doi":"10.1002/maco.202314140","DOIUrl":"https://doi.org/10.1002/maco.202314140","url":null,"abstract":"The automation of coating processes allows consistent, economical, and ecological applications. In this study, the effects of various surface geometries—steel plates, plates with weld seams, plates with bolts, and plates with welded fillets—on the uniformity of dry film thickness (DFT) after robotic stripe coating applications with an electrostatic spray device are investigated and analyzed with statistical methods. Robot traverse rate, pump pressure, and voltage. Based on analysis of variance studies, the robot traverse rate was identified to be the most influential factor. For plates with weld seams, an optimization study was conducted, resulting in a multiresponse prediction model. The model achieved a DFT within the target range across all measuring points within a 95% confidence interval. At an optimized factor combination (117 mm/s, 0.3 MPa, 61.4 kV), the DFT values ranged between 100 and 142 µm. The findings of this study provide fundamentals for achieving uniform coating distributions on complex geometries and for optimizing process parameters.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"19 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138513872","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}
Andreas W. Momber, Tom Marquardt, Michael Irmer, Daniel Kelm
Abstract Damage to multilayer organic coating systems due to compressive loads can deteriorate the corrosion protection performance of the coatings under offshore exposure. The contribution is concerned with statistical investigations into the effects of load‐based and coating‐based factors on the protection performance of different coating systems. Accelerated cyclic laboratory tests (ISO 12944‐9) were performed on four multilayer coating systems, and the results were statistically analyzed. Results of analysis of variance investigations revealed that the effects on the anticorrosive performance of the coatings (anticorrosive effect [AE]) were dominated by coating‐based factors, namely coating system and total dry film thickness. These factors could explain 86% of all effects. Coating system was the only extremely significant factor. Load‐based factors did not deliver notable effects (5%). Except for the contact stiffness, these factors were insignificant. The load intensity was insignificant for all target parameters (blistering, delamination, AE). Coating regions, plastically deformed during the compression tests, did not lead to a reduction in the protection performance.
{"title":"Effects of compressive damage on the corrosion protection performance of offshore wind power coating systems","authors":"Andreas W. Momber, Tom Marquardt, Michael Irmer, Daniel Kelm","doi":"10.1002/maco.202314074","DOIUrl":"https://doi.org/10.1002/maco.202314074","url":null,"abstract":"Abstract Damage to multilayer organic coating systems due to compressive loads can deteriorate the corrosion protection performance of the coatings under offshore exposure. The contribution is concerned with statistical investigations into the effects of load‐based and coating‐based factors on the protection performance of different coating systems. Accelerated cyclic laboratory tests (ISO 12944‐9) were performed on four multilayer coating systems, and the results were statistically analyzed. Results of analysis of variance investigations revealed that the effects on the anticorrosive performance of the coatings (anticorrosive effect [AE]) were dominated by coating‐based factors, namely coating system and total dry film thickness. These factors could explain 86% of all effects. Coating system was the only extremely significant factor. Load‐based factors did not deliver notable effects (5%). Except for the contact stiffness, these factors were insignificant. The load intensity was insignificant for all target parameters (blistering, delamination, AE). Coating regions, plastically deformed during the compression tests, did not lead to a reduction in the protection performance.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"47 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134992059","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}
Ole Ø. Knudsen, Catalina H. M. Hagen, Anders W. B. Skilbred, Tarjei K. Bruaas, Jarand Nærland
Abstract Our understanding of the failure mechanisms of coatings, for example, cathodic disbonding, corrosion creep, blistering, and cracking, have been developed to a high level over the past decades. However, knowing what actually causes coatings to fail in the field is also important. Several atmospheric field tests of coating with duration 2–9 years have been published, showing that epoxy‐based heavy‐duty protective coating systems with zinc‐rich primers have high resistance against corrosion creep from damages in the coating. Despite this, scribe creep corrosion has become the most important evaluation parameter in standardized testing. In this work, inspection pictures from an offshore oil and gas platform, a ballast water tank system, and two coastal road bridges have been analyzed with respect to the root cause for initiation of corrosion on coated steel. The results show that corrosion mainly initiates at edges and welds. Between 50% and 90% of the corrosion attacks could be attributed to this, depending on the type of structure. The paint failed due to low film thickness, that is, the wet paint retracts from sharp edges in the surface so that the cured film has reduced barrier properties.
{"title":"Root causes for corrosion on painted steel structures in marine environments","authors":"Ole Ø. Knudsen, Catalina H. M. Hagen, Anders W. B. Skilbred, Tarjei K. Bruaas, Jarand Nærland","doi":"10.1002/maco.202314046","DOIUrl":"https://doi.org/10.1002/maco.202314046","url":null,"abstract":"Abstract Our understanding of the failure mechanisms of coatings, for example, cathodic disbonding, corrosion creep, blistering, and cracking, have been developed to a high level over the past decades. However, knowing what actually causes coatings to fail in the field is also important. Several atmospheric field tests of coating with duration 2–9 years have been published, showing that epoxy‐based heavy‐duty protective coating systems with zinc‐rich primers have high resistance against corrosion creep from damages in the coating. Despite this, scribe creep corrosion has become the most important evaluation parameter in standardized testing. In this work, inspection pictures from an offshore oil and gas platform, a ballast water tank system, and two coastal road bridges have been analyzed with respect to the root cause for initiation of corrosion on coated steel. The results show that corrosion mainly initiates at edges and welds. Between 50% and 90% of the corrosion attacks could be attributed to this, depending on the type of structure. The paint failed due to low film thickness, that is, the wet paint retracts from sharp edges in the surface so that the cured film has reduced barrier properties.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136373000","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}
rGO/Mg(OH)2 composite films were fabricated on AZ61 alloy by the hydrothermal method in alkaline solutions containing deionized water and graphene oxide (GO). During the hydrothermal reaction, the Mg(OH)2 nanosheets and GO plates grew freely on the AZ61 substrate without any special orientation, and the GO was simultaneously reduced to rGO. With the increase of GO content in the hydrothermal solution, the corrosion resistance of the prepared composite films showed a trend of increasing first and then decreasing. When the content of GO incorporated in the hydrothermal solution is 5 mg, the corrosion current density (icorr) of the composite coating is reduced to the minimum (4.9 μA/cm2), which is seven times lower than that of the substrate and 3.5 times lower than that of the Mg(OH)2 monolayer. Based on experimental and molecular dynamics simulation results, the enhancement mechanism of the composite film was proposed, which is related to the growth of Mg(OH)2 layer, the “tortuous path” effect of GO and the slowing of chloride ion diffusion by GO functional groups.
{"title":"Enhancing corrosion resistance of magnesium alloy by rGO/Mg(OH)2 composite coating","authors":"Jing Yuan, Xiaofeng Cui, Rui Yuan, Qiushi Li, Xuerong Zheng","doi":"10.1002/maco.202213360","DOIUrl":"https://doi.org/10.1002/maco.202213360","url":null,"abstract":"rGO/Mg(OH)2 composite films were fabricated on AZ61 alloy by the hydrothermal method in alkaline solutions containing deionized water and graphene oxide (GO). During the hydrothermal reaction, the Mg(OH)2 nanosheets and GO plates grew freely on the AZ61 substrate without any special orientation, and the GO was simultaneously reduced to rGO. With the increase of GO content in the hydrothermal solution, the corrosion resistance of the prepared composite films showed a trend of increasing first and then decreasing. When the content of GO incorporated in the hydrothermal solution is 5 mg, the corrosion current density (icorr) of the composite coating is reduced to the minimum (4.9 μA/cm2), which is seven times lower than that of the substrate and 3.5 times lower than that of the Mg(OH)2 monolayer. Based on experimental and molecular dynamics simulation results, the enhancement mechanism of the composite film was proposed, which is related to the growth of Mg(OH)2 layer, the “tortuous path” effect of GO and the slowing of chloride ion diffusion by GO functional groups.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"83 1","pages":"2053 - 2062"},"PeriodicalIF":0.0,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85582778","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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