To enhance the mechanical properties and poor corrosion resistance of magnesium alloy in vitro, the as‐cast Mg–2Zn–0.5Zr–1.5Dy (mass%) magnesium alloy was subjected to two types of extrusion treatment, one is hot extrusion (denoted as ET alloy), the other is heat treatment followed by hot extrusion (denoted as HE alloy). The microstructure, mechanical properties, and corrosion behaviors of these extruded alloys are assessed. The results show that the HE alloy has superior mechanical properties and a slower corrosion rate than the ET alloy. The yield strength and elongation of the HE alloy reach 287 ± 10 MPa and 17.6 ± 0.5%, respectively, and its corrosion rate is only 0.59 ± 0.16 mm year−1. After hot extrusion, microscale and nanoscale second‐phase exist in the extruded alloys, and the nanoscale second‐phase can improve their mechanical properties by second‐phase strengthening. However, the presence of microscale second phase can cause galvanic corrosion and result in poor corrosion resistance. The HE alloy has good properties due to it containing more nanoscale second‐phase and fewer microscale second‐phase.
{"title":"Enhancement of mechanical properties and corrosion resistance of Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy by a combination of heat treatment and hot extrusion","authors":"Huan Li, J. Wen, Ya Liu, Jun-guang He","doi":"10.1002/maco.202112755","DOIUrl":"https://doi.org/10.1002/maco.202112755","url":null,"abstract":"To enhance the mechanical properties and poor corrosion resistance of magnesium alloy in vitro, the as‐cast Mg–2Zn–0.5Zr–1.5Dy (mass%) magnesium alloy was subjected to two types of extrusion treatment, one is hot extrusion (denoted as ET alloy), the other is heat treatment followed by hot extrusion (denoted as HE alloy). The microstructure, mechanical properties, and corrosion behaviors of these extruded alloys are assessed. The results show that the HE alloy has superior mechanical properties and a slower corrosion rate than the ET alloy. The yield strength and elongation of the HE alloy reach 287 ± 10 MPa and 17.6 ± 0.5%, respectively, and its corrosion rate is only 0.59 ± 0.16 mm year−1. After hot extrusion, microscale and nanoscale second‐phase exist in the extruded alloys, and the nanoscale second‐phase can improve their mechanical properties by second‐phase strengthening. However, the presence of microscale second phase can cause galvanic corrosion and result in poor corrosion resistance. The HE alloy has good properties due to it containing more nanoscale second‐phase and fewer microscale second‐phase.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"19 1","pages":"587 - 601"},"PeriodicalIF":0.0,"publicationDate":"2021-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86396303","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 equiatomic Co–Cr–Fe–Mn–Ni high‐entropy alloy (HEA) shows well hydrogen embrittlement resistance under monotonic tensile load. However, the fracture behavior under cyclic load is still unclear. In this study, combining with the fracture features analysis by electron back‐scattered diffraction and electron channeling contrast imaging techniques, the hydrogen‐assisted fatigue crack propagation behavior of equiatomic Co–Cr–Fe–Mn–Ni HEA under in situ electrochemical hydrogen charging was investigated. The results suggest that the hydrogen had significant accelerating effects on the fatigue crack growth rate of Co–Cr–Fe–Mn–Ni HEA. Intergranular cracking with the formation of dislocation cells was observed at low stress intensity range (ΔK) area, while transgranular cracking with deformation twins was observed at a high ΔK area. The formation of these deformation features was assisted by hydrogen‐assisted dislocation emission.
{"title":"Hydrogen‐assisted fatigue crack propagation behavior of equiatomic Co–Cr–Fe–Mn–Ni high‐entropy alloy","authors":"H. Xiao, Q. Zeng, Lin Xia, Z. Fu, Shaowei Zhu","doi":"10.1002/maco.202112866","DOIUrl":"https://doi.org/10.1002/maco.202112866","url":null,"abstract":"The equiatomic Co–Cr–Fe–Mn–Ni high‐entropy alloy (HEA) shows well hydrogen embrittlement resistance under monotonic tensile load. However, the fracture behavior under cyclic load is still unclear. In this study, combining with the fracture features analysis by electron back‐scattered diffraction and electron channeling contrast imaging techniques, the hydrogen‐assisted fatigue crack propagation behavior of equiatomic Co–Cr–Fe–Mn–Ni HEA under in situ electrochemical hydrogen charging was investigated. The results suggest that the hydrogen had significant accelerating effects on the fatigue crack growth rate of Co–Cr–Fe–Mn–Ni HEA. Intergranular cracking with the formation of dislocation cells was observed at low stress intensity range (ΔK) area, while transgranular cracking with deformation twins was observed at a high ΔK area. The formation of these deformation features was assisted by hydrogen‐assisted dislocation emission.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"16 12 1","pages":"550 - 557"},"PeriodicalIF":0.0,"publicationDate":"2021-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86309705","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}
Considering the ionic liquids (ILs) were classified as green inhibitors herein three ecofriendly imidazolium‐based ILs were employed in corrosion inhibition, where weight loss evaluations along with electrochemical methods, including potentiodynamic polarization test, electrochemical impedance spectroscopy, and cyclic voltammetry measurements were exploited to elucidate corrosion prevention performance of the considered agents. The results derived from the polarization studies attested to the fact that these ILs could effectively act as mixed‐type corrosion inhibitors. Moreover, the progress of surface reactions due to the corrosion process was studied through field emission scanning electron microscopy and atomic force microscopy. Also, UV/Vis spectroscopy corroborated chemical interaction among metal surfaces and ILs. Findings clarified that the chemisorption of the ILs onto carbon steel surface conforms to Langmuir adsorption isotherm. Finally, it was found that all proposed ILs could play an effective role in corrosion preventing, for which, the efficiencies in the range of 82%–92% were achieved by electrochemical impedance analyses for investigated ILs at 75 ppm.
{"title":"Corrosion inhibiting performance of novel imidazolium‐based ionic liquids as an efficient and green corrosion constraint for carbon steel in neutral chloride solution","authors":"S. M. Shoja, M. Abdouss, A. M. Miran Beigi","doi":"10.1002/maco.202112751","DOIUrl":"https://doi.org/10.1002/maco.202112751","url":null,"abstract":"Considering the ionic liquids (ILs) were classified as green inhibitors herein three ecofriendly imidazolium‐based ILs were employed in corrosion inhibition, where weight loss evaluations along with electrochemical methods, including potentiodynamic polarization test, electrochemical impedance spectroscopy, and cyclic voltammetry measurements were exploited to elucidate corrosion prevention performance of the considered agents. The results derived from the polarization studies attested to the fact that these ILs could effectively act as mixed‐type corrosion inhibitors. Moreover, the progress of surface reactions due to the corrosion process was studied through field emission scanning electron microscopy and atomic force microscopy. Also, UV/Vis spectroscopy corroborated chemical interaction among metal surfaces and ILs. Findings clarified that the chemisorption of the ILs onto carbon steel surface conforms to Langmuir adsorption isotherm. Finally, it was found that all proposed ILs could play an effective role in corrosion preventing, for which, the efficiencies in the range of 82%–92% were achieved by electrochemical impedance analyses for investigated ILs at 75 ppm.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"27 1","pages":"623 - 640"},"PeriodicalIF":0.0,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78466941","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}
Q. Gao, H. Shang, Q. Ma, Huijie Zhang, Hailian Zhang, Huijun Li, Ziyun Liu
Co‐based superalloys with the advantages of high melting point, high‐temperature mechanical properties, and large resistance under hot corrosion environment are potential candidates for turbine engine components. The isothermal oxidation behavior of Co–Ni–Al‐based superalloy with the addition of Mo and Cr in dry air at 1073 and 1173 K was investigated. The results showed that similar three‐layer oxides structures were composed of Co‐containing oxides, complex oxides rich in Co and Al, and Al2O3 layer formed on both 2Mo and 2Cr Co–Ni–Al‐based superalloys, and Mo‐containing oxides also existed in the subsurface. The oxides in the outer layer transferred from Co3O4 to denser CoO with the increase in temperature. The γ'‐free zone formed under the Al2O3 layer due to the depletion of Al. Co–Ni–Al‐based superalloys need to conquer a large energy barrier at an earlier stage of oxidation and exhibit good oxidation resistance at 1073 K.
钴基高温合金具有高熔点、高温机械性能和在热腐蚀环境下抗腐蚀能力强等优点，是涡轮发动机部件的潜在候选材料。研究了Co-Ni-Al基高温合金在1073和1173 K干燥空气中Mo和Cr的等温氧化行为。结果表明:在2Mo和2Cr Co - ni - Al基高温合金表面均形成了相似的三层结构:含Co的氧化物、富含Co和Al的复合氧化物以及Al2O3层，并且在地下也存在含Mo的氧化物。随着温度的升高，外层的氧化物由Co3O4转变为较致密的CoO。由于Al的耗尽，在Al2O3层下形成了无γ区。Co-Ni-Al基高温合金需要在氧化早期克服较大的能垒，并在1073 K时表现出良好的抗氧化性。
{"title":"Isothermal oxidation behavior of W‐free Co–Ni–Al‐based superalloy at high temperature","authors":"Q. Gao, H. Shang, Q. Ma, Huijie Zhang, Hailian Zhang, Huijun Li, Ziyun Liu","doi":"10.1002/maco.202112789","DOIUrl":"https://doi.org/10.1002/maco.202112789","url":null,"abstract":"Co‐based superalloys with the advantages of high melting point, high‐temperature mechanical properties, and large resistance under hot corrosion environment are potential candidates for turbine engine components. The isothermal oxidation behavior of Co–Ni–Al‐based superalloy with the addition of Mo and Cr in dry air at 1073 and 1173 K was investigated. The results showed that similar three‐layer oxides structures were composed of Co‐containing oxides, complex oxides rich in Co and Al, and Al2O3 layer formed on both 2Mo and 2Cr Co–Ni–Al‐based superalloys, and Mo‐containing oxides also existed in the subsurface. The oxides in the outer layer transferred from Co3O4 to denser CoO with the increase in temperature. The γ'‐free zone formed under the Al2O3 layer due to the depletion of Al. Co–Ni–Al‐based superalloys need to conquer a large energy barrier at an earlier stage of oxidation and exhibit good oxidation resistance at 1073 K.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"17 1","pages":"513 - 525"},"PeriodicalIF":0.0,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87761691","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}
Zhihao Liang, K. Jiang, Bai-ao Feng, Lin Li, Ting’an Zhang
The effect of the anode potential on the electrochemical performance and protective ability of the passive film formed on the brass alloy in the soil solution of the Zhouyuan site was investigated by electrochemical measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy. The corrosion resistance of brass alloy in a corrosion soil environment decreases with the increase of applied anodic potential. X‐ray photoelectron spectroscopy results indicate that the passive film is mainly composed of metal oxide. Mott–Schottky results revealed that the passive films behave as p‐type semiconductors at passive potentials and the acceptor density is in the range of 1021 cm−3 and increased with an increase in the film‐forming potential.
{"title":"Effect of anodic potential on the characteristics of passive films grown on a brass alloy in a soil environment","authors":"Zhihao Liang, K. Jiang, Bai-ao Feng, Lin Li, Ting’an Zhang","doi":"10.1002/maco.202112795","DOIUrl":"https://doi.org/10.1002/maco.202112795","url":null,"abstract":"The effect of the anode potential on the electrochemical performance and protective ability of the passive film formed on the brass alloy in the soil solution of the Zhouyuan site was investigated by electrochemical measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy. The corrosion resistance of brass alloy in a corrosion soil environment decreases with the increase of applied anodic potential. X‐ray photoelectron spectroscopy results indicate that the passive film is mainly composed of metal oxide. Mott–Schottky results revealed that the passive films behave as p‐type semiconductors at passive potentials and the acceptor density is in the range of 1021 cm−3 and increased with an increase in the film‐forming potential.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"13 1","pages":"404 - 413"},"PeriodicalIF":0.0,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81552730","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 effect of O2 on crevice corrosion of N80 carbon steel in acidic NaCl solution is investigated. Crevice corrosion of N80 carbon steel could be initiated with or without O2 in acidic NaCl solution. A deep corrosion groove could be formed near the crevice mouth after crevice corrosion. The crevice corrosion of N80 carbon steel is ascribed to the increased pH inside the crevice in acidic NaCl solution. The presence of O2 in the solution could enhance the cathodic reaction processes outside the crevice, but it is not significant for the cathodic reaction processes inside the crevice. The galvanic corrosion effect between inner and outer steels could be enhanced by O2 and then promote crevice corrosion.
{"title":"The crevice corrosion behavior of N80 carbon steel in acidic NaCl solution: The effect of O2","authors":"Yizhou Li, Jie Mu, Zhongyu Cui, Xin Wang","doi":"10.1002/maco.202112595","DOIUrl":"https://doi.org/10.1002/maco.202112595","url":null,"abstract":"The effect of O2 on crevice corrosion of N80 carbon steel in acidic NaCl solution is investigated. Crevice corrosion of N80 carbon steel could be initiated with or without O2 in acidic NaCl solution. A deep corrosion groove could be formed near the crevice mouth after crevice corrosion. The crevice corrosion of N80 carbon steel is ascribed to the increased pH inside the crevice in acidic NaCl solution. The presence of O2 in the solution could enhance the cathodic reaction processes outside the crevice, but it is not significant for the cathodic reaction processes inside the crevice. The galvanic corrosion effect between inner and outer steels could be enhanced by O2 and then promote crevice corrosion.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"21 1","pages":"281 - 290"},"PeriodicalIF":0.0,"publicationDate":"2021-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73046908","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}
Rui Guo, Pengyvan Yang, F. Mao, Jinlong Li, Lei Chen, Guojun Yu, D. Macdonald
This paper aims at studying the complex galvanic corrosion of galvanized steel/red copper of submarine cable armor layer in simulated seawater environments. The variation of the galvanic corrosion rate of the cable armor layer as a function of time under different environmental factors (pH, [Cl−], dissolved oxygen, etc.) has been explored. The surface morphology of the galvanized steel after galvanic corrosion was observed by scanning electron microscopy. The results indicate that galvanized steel and red copper are susceptible to galvanic corrosion when ohmically coupled in NaCl solution. Red copper, with the more positive electromotive potential, acts as the cathode in the galvanized steel/red copper galvanic couple and accelerates the corrosion of the galvanized steel. The galvanic effect of red copper on galvanized steel in NaCl solution increases with the increasing [H+] and dissolved oxygen. However, with increasing [Cl−], the galvanic effect of red copper on galvanized steel initially increases but then decreases, resulting in a maximum in the corrosion rate.
{"title":"Electrochemical noise studies on complex galvanic corrosion of submarine cable armor layer in artificial seawater","authors":"Rui Guo, Pengyvan Yang, F. Mao, Jinlong Li, Lei Chen, Guojun Yu, D. Macdonald","doi":"10.1002/maco.202112803","DOIUrl":"https://doi.org/10.1002/maco.202112803","url":null,"abstract":"This paper aims at studying the complex galvanic corrosion of galvanized steel/red copper of submarine cable armor layer in simulated seawater environments. The variation of the galvanic corrosion rate of the cable armor layer as a function of time under different environmental factors (pH, [Cl−], dissolved oxygen, etc.) has been explored. The surface morphology of the galvanized steel after galvanic corrosion was observed by scanning electron microscopy. The results indicate that galvanized steel and red copper are susceptible to galvanic corrosion when ohmically coupled in NaCl solution. Red copper, with the more positive electromotive potential, acts as the cathode in the galvanized steel/red copper galvanic couple and accelerates the corrosion of the galvanized steel. The galvanic effect of red copper on galvanized steel in NaCl solution increases with the increasing [H+] and dissolved oxygen. However, with increasing [Cl−], the galvanic effect of red copper on galvanized steel initially increases but then decreases, resulting in a maximum in the corrosion rate.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"112 1","pages":"379 - 392"},"PeriodicalIF":0.0,"publicationDate":"2021-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82994348","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}
Sathiyapriya T., M. Dhayalan, Jagadeeswari R., Rathika Govindasamy, Mohammed Riyaz S. U., Moonis Ali Khan, M. Sillanpää
The present investigation was aimed at exploring the anticorrosive behavior of bio‐organic Auraucaria heterophylla gum exudate (AHGE) on mild steel (MS) corrosion in 1 M phosphoric acid solution by weight loss technique, electrochemical studies, and computational analysis. Additionally, the performance was analyzed by morphological and quantum chemical analyses. The weight loss data revealed that AHGE showed 80% of inhibition efficiency at 303 K temperature. Inhibitor adsorption on MS was in line with Langmuir and Tempkin adsorption isotherms. Potentiodynamic studies showed that the investigated AHGE performed as a mixed‐type inhibitor. Electrochemical parameters like charge transfer resistance, double‐layer capacitance, and inhibition efficiency were determined and presented. Results obtained through computational analysis, scanning electron microscopy/energy dispersive X‐ray analysis, and atomic force microscopy studies were well supported by the inhibitive potential of AHGE.
{"title":"Assessing bioorganic gum performance as a corrosion inhibitor in phosphoric acid medium: Electrochemical and computational analysis","authors":"Sathiyapriya T., M. Dhayalan, Jagadeeswari R., Rathika Govindasamy, Mohammed Riyaz S. U., Moonis Ali Khan, M. Sillanpää","doi":"10.1002/maco.202112742","DOIUrl":"https://doi.org/10.1002/maco.202112742","url":null,"abstract":"The present investigation was aimed at exploring the anticorrosive behavior of bio‐organic Auraucaria heterophylla gum exudate (AHGE) on mild steel (MS) corrosion in 1 M phosphoric acid solution by weight loss technique, electrochemical studies, and computational analysis. Additionally, the performance was analyzed by morphological and quantum chemical analyses. The weight loss data revealed that AHGE showed 80% of inhibition efficiency at 303 K temperature. Inhibitor adsorption on MS was in line with Langmuir and Tempkin adsorption isotherms. Potentiodynamic studies showed that the investigated AHGE performed as a mixed‐type inhibitor. Electrochemical parameters like charge transfer resistance, double‐layer capacitance, and inhibition efficiency were determined and presented. Results obtained through computational analysis, scanning electron microscopy/energy dispersive X‐ray analysis, and atomic force microscopy studies were well supported by the inhibitive potential of AHGE.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"16 1","pages":"259 - 271"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78935711","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}
Aiming to enhance the biodegradable magnesium alloys' poor mechanical properties and corrosion resistance in aggressive chloride mediums, micro‐arc oxidation coatings with oxidation times range from 3 to 15 min were prepared on the surface of extruded Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy. Assessments were carried out using electrochemical experiments, hydrogen evolution experiments, and tensile tests, respectively. The results show that the micro‐arc oxidation coating is porous and mainly consists of the MgO phase. When the oxidation time increases from 3 to 15 min, the thickness and the pore size of the coating increase, while the coating's porosity decreases. The coating with the oxidation time of 15 min can effectively prevent the formation of pitting holes on the surface of the alloy, which remarkably reduces the decay rate of ultimate tensile strength, yield strength, and elongation of the alloy after immersion in simulated body fluid for 0–28 days, and keep the alloy with higher and more stable corrosion resistance. This increases the application possibility of extruded Mg–2Zn–0.5Zr–1.5Dy alloy as a biodegradable material.
{"title":"Roles of the micro‐arc oxidation coating on the corrosion resistance and mechanical properties of extruded Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy","authors":"Huan Li, J. Wen, Jie Jin, Ya Liu, Jun-guang He","doi":"10.1002/maco.202112762","DOIUrl":"https://doi.org/10.1002/maco.202112762","url":null,"abstract":"Aiming to enhance the biodegradable magnesium alloys' poor mechanical properties and corrosion resistance in aggressive chloride mediums, micro‐arc oxidation coatings with oxidation times range from 3 to 15 min were prepared on the surface of extruded Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy. Assessments were carried out using electrochemical experiments, hydrogen evolution experiments, and tensile tests, respectively. The results show that the micro‐arc oxidation coating is porous and mainly consists of the MgO phase. When the oxidation time increases from 3 to 15 min, the thickness and the pore size of the coating increase, while the coating's porosity decreases. The coating with the oxidation time of 15 min can effectively prevent the formation of pitting holes on the surface of the alloy, which remarkably reduces the decay rate of ultimate tensile strength, yield strength, and elongation of the alloy after immersion in simulated body fluid for 0–28 days, and keep the alloy with higher and more stable corrosion resistance. This increases the application possibility of extruded Mg–2Zn–0.5Zr–1.5Dy alloy as a biodegradable material.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"3 2","pages":"414 - 426"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91437256","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}
Zhan Zhang, T. Fang, Jiuyang Xia, Bowei Zhang, Junsheng Wu
In the present study, the distribution and vitality of the sulfate‐reducing bacteria (SRB) inside the crevice were characterized by scanning electron microscopy and confocal laser scanning microscopy. Potentiodynamic polarization curve tests and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance. Furthermore, a starvation experiment was conducted by controlling nutrients to investigate the effects of the crevices on the transportation of nutrients and the vitality of the SRB. The results demonstrate that it was more difficult for the SRB to enter the crevice, resulting in an incomplete biofilm formed on the surface. In addition, the insufficient supply of nutrients was also the reason for the low vitality of the SRB inside the crevice. Based on these results, it was inferred that the incomplete biofilm inside the crevice acted as a micro‐galvanic, thus making the corrosion rate of 2205 stainless steel in the initial crevice corrosion much more serious than that in the open system.
{"title":"Distribution of sulfate‐reducing bacteria in the crevice and its effect on the initial corrosion behavior of 2205 stainless steel in artificial seawater","authors":"Zhan Zhang, T. Fang, Jiuyang Xia, Bowei Zhang, Junsheng Wu","doi":"10.1002/maco.202112759","DOIUrl":"https://doi.org/10.1002/maco.202112759","url":null,"abstract":"In the present study, the distribution and vitality of the sulfate‐reducing bacteria (SRB) inside the crevice were characterized by scanning electron microscopy and confocal laser scanning microscopy. Potentiodynamic polarization curve tests and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance. Furthermore, a starvation experiment was conducted by controlling nutrients to investigate the effects of the crevices on the transportation of nutrients and the vitality of the SRB. The results demonstrate that it was more difficult for the SRB to enter the crevice, resulting in an incomplete biofilm formed on the surface. In addition, the insufficient supply of nutrients was also the reason for the low vitality of the SRB inside the crevice. Based on these results, it was inferred that the incomplete biofilm inside the crevice acted as a micro‐galvanic, thus making the corrosion rate of 2205 stainless steel in the initial crevice corrosion much more serious than that in the open system.","PeriodicalId":18223,"journal":{"name":"Materials and Corrosion","volume":"32 1","pages":"367 - 378"},"PeriodicalIF":0.0,"publicationDate":"2021-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87973874","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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