The high Mn steels are expected to become a novel steel for LNG (Liquefied Natural Gas) tank building because of their low cost, high strength and excellent low-temperature impact toughness. Up to now, it is still limited for studies on corrosion behavior of high Mn steel in a Cl- containing environment. We found that a strong Mn enrichment layers always exist in the outer rust layer, whereas a strong Al enrichment layers always exist in the inner rust layer. However, the Al and Cl simultaneously enrich in the same area. Although the corrosion resistance can be further improved by increasing Al content from 5.0 to 8.0 mass%, the improvement degree becomes weak and the pitting corrosion becomes serious due to the formation of δ-ferrite. There are two aspects to explain why Al improves corrosion resistance: 1) More Al addition can enhance the resistance of passive oxide. 2) The α-FeOOH content can be increased and the compactness of rust layer can be also enhanced by increasing Al content.
{"title":"Effect of Al addition on corrosion behavior of high Mn steels in a Cl− containing environment","authors":"Ning Liu, X. Yang, Jun Chen","doi":"10.5006/4284","DOIUrl":"https://doi.org/10.5006/4284","url":null,"abstract":"The high Mn steels are expected to become a novel steel for LNG (Liquefied Natural Gas) tank building because of their low cost, high strength and excellent low-temperature impact toughness. Up to now, it is still limited for studies on corrosion behavior of high Mn steel in a Cl- containing environment. We found that a strong Mn enrichment layers always exist in the outer rust layer, whereas a strong Al enrichment layers always exist in the inner rust layer. However, the Al and Cl simultaneously enrich in the same area. Although the corrosion resistance can be further improved by increasing Al content from 5.0 to 8.0 mass%, the improvement degree becomes weak and the pitting corrosion becomes serious due to the formation of δ-ferrite. There are two aspects to explain why Al improves corrosion resistance: 1) More Al addition can enhance the resistance of passive oxide. 2) The α-FeOOH content can be increased and the compactness of rust layer can be also enhanced by increasing Al content.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":"150 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41271531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
13Cr martensitic stainless steel is widely used in oil and gas industry. It is well known that addition of molybdenum (Mo) enhances the passivity of steel. However, the role of Mo in passive film has not been clarified completely. The subjects of the present research was to reveal role of Mo in terms of semi-conductivity. The Mott–Schottky plot, obtained by impedance spectroscopy, revealed the effect of Mo addition on the semiconducting property of a passive film under an H2S environment in a pH 4.0 solution at 25 °C. The results revealed that Cr-O of the inner film and sulfide of the outer film exhibited semiconductor p-type and n-type characteristics, respectively. The number of defects in the film on 2.5 mass% Mo-added steel was approximately half of that in the film on Mo free steel. The role of Mo was discussed through investigation using X-ray photoelectron spectrometric analysis based on the existent state of the passive films.
{"title":"Effect of Mo Addition on Passive Film of Martensitic Stainless Steels by Semiconductor Analysis in H2S-CO2 Environment","authors":"Kyohei Kanki, K. Nishihara, M. Sagara, H. Amaya","doi":"10.5006/4190","DOIUrl":"https://doi.org/10.5006/4190","url":null,"abstract":"13Cr martensitic stainless steel is widely used in oil and gas industry. It is well known that addition of molybdenum (Mo) enhances the passivity of steel. However, the role of Mo in passive film has not been clarified completely. The subjects of the present research was to reveal role of Mo in terms of semi-conductivity. The Mott–Schottky plot, obtained by impedance spectroscopy, revealed the effect of Mo addition on the semiconducting property of a passive film under an H2S environment in a pH 4.0 solution at 25 °C. The results revealed that Cr-O of the inner film and sulfide of the outer film exhibited semiconductor p-type and n-type characteristics, respectively. The number of defects in the film on 2.5 mass% Mo-added steel was approximately half of that in the film on Mo free steel. The role of Mo was discussed through investigation using X-ray photoelectron spectrometric analysis based on the existent state of the passive films.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43514628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three Al-Zn, Mg, and Mg-Al rich primers (RP) were evaluated for their ability to suppress intergranular corrosion (IGC) and intergranular stress corrosion cracking (IG-SCC) on highly sensitized aluminum alloy 5456-H116 by sacrificial anode based cathodic prevention and chemical deposition effects. Tests were conducted in 0.6 M NaCl solution under full immersion. These evaluations considered the ability of the primer to attain an intermediate open circuit potential such that the galvanic couple potential with bare 5456 resided outside a range of potentials where IGC prevention is observed. The ability of the primer to achieve open circuit potentials negative enough so that the 5456-H116 could be protected by sacrificial anode-based cathodic prevention and the ability to sustain this function over time were evaluated. The primers consisted of epoxy resins embedded with either (1) spherical Al-5 wt.% Zn, (2) spherical Al-5 wt.% Zn and spherical Mg, or (3) Mg flake pigments. A variety of electrochemical techniques evaluated the performance specified including open circuit potential, electrochemical impedance spectroscopy, diagnostic cycle testing, as well as zero resistance ammeter tests with simultaneous pH measurement. Electrochemical cycle testing demonstrated that Al-5%Zn did not activate or provide cathodic prevention. MgRP had a suitable open circuit potential for cathodic protection of 5456 but the time to primer activation as well as the activated potential both decreased upon utilization of Mg flake content in the primer. The pure Mg-rich primer activated quickly but ceased to achieve protective potentials after 1-11 cycles of DC/AC/OCP cycle testing. Cross-sectional analysis demonstrated that some flakes dissolved while uniform surface oxidation occurred on the remaining Mg flakes. which in combination led to impaired activation. The composite Mg plus Al-Zn rich primer mixed primer maintained a suitably negative open circuit potential over time, remained activated, dispensed high anodic charge, and remained an anode in zero resistance ammeter testing. Chemical stability modeling and zero resistance ammeter testing suggests that Mg corrosion elevates the pH which activates the Al-5wt.% Zn pigments, thereby providing a secondary pathway for sacrificial anode-based cathodic protection which supports the long-lasting cathodic protection achieved by the Al-5 wt.% Zn/Mg primer. These analyses set a baseline for the consideration of Al-Zn/Mg-based coatings to establish effective cathodic protection on highly sensitized 5456-H116 in an aggressive alternate immersion environment and illustrate the merit of using Al-MgRP.
{"title":"Mechanistic Insight into Al-Zn, Mg, and Al-Mg Rich Primer Design for Enhanced Cathodic Prevention on Sensitized Al-Mg Alloys","authors":"M. McMahon, Alen Korjenic, J. Scully, J. Burns","doi":"10.5006/4289","DOIUrl":"https://doi.org/10.5006/4289","url":null,"abstract":"Three Al-Zn, Mg, and Mg-Al rich primers (RP) were evaluated for their ability to suppress intergranular corrosion (IGC) and intergranular stress corrosion cracking (IG-SCC) on highly sensitized aluminum alloy 5456-H116 by sacrificial anode based cathodic prevention and chemical deposition effects. Tests were conducted in 0.6 M NaCl solution under full immersion. These evaluations considered the ability of the primer to attain an intermediate open circuit potential such that the galvanic couple potential with bare 5456 resided outside a range of potentials where IGC prevention is observed. The ability of the primer to achieve open circuit potentials negative enough so that the 5456-H116 could be protected by sacrificial anode-based cathodic prevention and the ability to sustain this function over time were evaluated. The primers consisted of epoxy resins embedded with either (1) spherical Al-5 wt.% Zn, (2) spherical Al-5 wt.% Zn and spherical Mg, or (3) Mg flake pigments. A variety of electrochemical techniques evaluated the performance specified including open circuit potential, electrochemical impedance spectroscopy, diagnostic cycle testing, as well as zero resistance ammeter tests with simultaneous pH measurement. Electrochemical cycle testing demonstrated that Al-5%Zn did not activate or provide cathodic prevention. MgRP had a suitable open circuit potential for cathodic protection of 5456 but the time to primer activation as well as the activated potential both decreased upon utilization of Mg flake content in the primer. The pure Mg-rich primer activated quickly but ceased to achieve protective potentials after 1-11 cycles of DC/AC/OCP cycle testing. Cross-sectional analysis demonstrated that some flakes dissolved while uniform surface oxidation occurred on the remaining Mg flakes. which in combination led to impaired activation. The composite Mg plus Al-Zn rich primer mixed primer maintained a suitably negative open circuit potential over time, remained activated, dispensed high anodic charge, and remained an anode in zero resistance ammeter testing. Chemical stability modeling and zero resistance ammeter testing suggests that Mg corrosion elevates the pH which activates the Al-5wt.% Zn pigments, thereby providing a secondary pathway for sacrificial anode-based cathodic protection which supports the long-lasting cathodic protection achieved by the Al-5 wt.% Zn/Mg primer. These analyses set a baseline for the consideration of Al-Zn/Mg-based coatings to establish effective cathodic protection on highly sensitized 5456-H116 in an aggressive alternate immersion environment and illustrate the merit of using Al-MgRP.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46315310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The change in AC current on a pipeline as a function of cathodic protection (CP) current is well known in the industry as is the change in CP current as a function of the interfering AC current. To better understand the underlying mechanisms responsible for these observations, the interrelated nature of AC and CP was reproduced here for pipeline steel in soil-simulating environments and the results were analyzed within the context of kinetics and transport based models. The kinetics model combines the Butler-Volmer reaction kinetics for steel oxidation, oxygen reduction and hydrogen reduction with the time evolution of potential at an interface subject to alternating potentials. The critical observation from these calculations was that changes to the measured CP on a pipeline with AC interference were not due to changes in the underlying electrochemical kinetics, but rather, due to asymmetric polarization of the steel along existing Tafel slopes resulting in a change in the time-averaged DC signal. To explore the effect of CP current on the magnitude of the AC interference, a transport based model of grounding resistance at pipeline coating holidays was developed. For holiday sizes less than 20 cm2, calculations revealed that at a critical CP current density of 1 A/m2, local soil pH increases rapidly and the normalized grounding resistance decreases. Correspondingly, corrosion rate increases dramatically.
管道上交流电流的变化作为阴极保护(CP)电流的函数在工业界是众所周知的，CP电流的变化作为干扰交流电流的函数也是众所周知的。为了更好地理解导致这些观察结果的潜在机制，本文再现了土壤模拟环境中管道钢的AC和CP的相互关联性质，并在动力学和基于输运的模型的背景下分析了结果。该动力学模型将钢的氧化、氧还原和氢还原的Butler-Volmer反应动力学与界面上受交变电位影响的电位随时间的变化相结合。从这些计算中得出的关键结论是，在有交流干扰的管道上，测量CP的变化不是由于潜在的电化学动力学的变化，而是由于钢沿着现有的Tafel斜坡的不对称极化导致了时间平均直流信号的变化。为了探讨CP电流对交流干扰大小的影响，建立了基于输运的管道涂覆期接地电阻模型。对于小于20 cm2的假日面积，计算表明，在临界CP电流密度为1 a /m2时，当地土壤pH值迅速增加，归一化接地电阻降低。相应地，腐蚀速率急剧增加。
{"title":"A Modeling Approach to Understanding the Interrelated Nature of CP Current and AC Stray Current on Pipelines","authors":"A. Moran, R. Lillard","doi":"10.5006/4272","DOIUrl":"https://doi.org/10.5006/4272","url":null,"abstract":"The change in AC current on a pipeline as a function of cathodic protection (CP) current is well known in the industry as is the change in CP current as a function of the interfering AC current. To better understand the underlying mechanisms responsible for these observations, the interrelated nature of AC and CP was reproduced here for pipeline steel in soil-simulating environments and the results were analyzed within the context of kinetics and transport based models. The kinetics model combines the Butler-Volmer reaction kinetics for steel oxidation, oxygen reduction and hydrogen reduction with the time evolution of potential at an interface subject to alternating potentials. The critical observation from these calculations was that changes to the measured CP on a pipeline with AC interference were not due to changes in the underlying electrochemical kinetics, but rather, due to asymmetric polarization of the steel along existing Tafel slopes resulting in a change in the time-averaged DC signal. To explore the effect of CP current on the magnitude of the AC interference, a transport based model of grounding resistance at pipeline coating holidays was developed. For holiday sizes less than 20 cm<sup>2</sup>, calculations revealed that at a critical CP current density of 1 A/m<sup>2</sup>, local soil pH increases rapidly and the normalized grounding resistance decreases. Correspondingly, corrosion rate increases dramatically.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42808494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Corrosion is a major concern in transmission pipelines that transport captured CO2. While dry CO2 is noncorrosive, significant corrosion has been reported in dense phase CO2 with trace amounts of water and impurities such as O2, H2S, SOx, and NOx. The aim of this work is to improve our understanding of the physicochemical aspects on the corrosion of carbon steels in the high-pressure environments associated with CO2 transmission pipelines. The effect of flow on the corrosion of X65 carbon steel was investigated in a series of autoclave tests with different combinations of impurity concentrations in supercritical CO2 condition (8 MPa and 35°C). The corrosion rate of specimens was determined by weight loss measurements. The surface morphology and composition of the corrosion product layers were characterized using surface analytical techniques (SEM, EDS and Raman microscopy). Localized corrosion was measured via surface profilometry after corrosion products were removed. Results showed that no corrosion was observed in the supercritical CO2 with 650 ppmv of water, 50 ppmv SO2, and 100 ppmv NO, but corrosion occurred when SO2 concentration was increased to 4500 ppmv and 40,000 ppmv of O2 was added to the system. The presence of flow significantly accelerated the corrosion of carbon steel. Furthermore, localized corrosion was observed in the presence of both O2 and flow.
{"title":"Effect of Flow on the Corrosion Behavior of Pipeline Steel in Supercritical CO2 Environments with Impurities","authors":"Yoon-Seok Choi, Martin Colahan","doi":"10.5006/4199","DOIUrl":"https://doi.org/10.5006/4199","url":null,"abstract":"Corrosion is a major concern in transmission pipelines that transport captured CO2. While dry CO2 is noncorrosive, significant corrosion has been reported in dense phase CO2 with trace amounts of water and impurities such as O2, H2S, SOx, and NOx. The aim of this work is to improve our understanding of the physicochemical aspects on the corrosion of carbon steels in the high-pressure environments associated with CO2 transmission pipelines. The effect of flow on the corrosion of X65 carbon steel was investigated in a series of autoclave tests with different combinations of impurity concentrations in supercritical CO2 condition (8 MPa and 35°C). The corrosion rate of specimens was determined by weight loss measurements. The surface morphology and composition of the corrosion product layers were characterized using surface analytical techniques (SEM, EDS and Raman microscopy). Localized corrosion was measured via surface profilometry after corrosion products were removed. Results showed that no corrosion was observed in the supercritical CO2 with 650 ppmv of water, 50 ppmv SO2, and 100 ppmv NO, but corrosion occurred when SO2 concentration was increased to 4500 ppmv and 40,000 ppmv of O2 was added to the system. The presence of flow significantly accelerated the corrosion of carbon steel. Furthermore, localized corrosion was observed in the presence of both O2 and flow.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49241298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haiying Dong, Juan Wang, Xin Li, Zhanpeng Lu, Xiaohui Li, Yiqi Tao, T. Shoji
The evolution of the wavy surface of iron electrode with anodic polarization time in a sulfuric acid solution under 0.4T magnetic field is quantified by 3D tomographic depth profile measurements. The electrode surface after anodic dissolution under magnetic field is irregular and the 3D profile changes with the anodic polarization time. The anodic dissolution rate is specific to the geometrical location on the electrode, which is in general insensitive to the polarization time as well as the surface irregularity.
{"title":"Self-sustained constant anodic dissolution rate on iron electrode under magnetic field","authors":"Haiying Dong, Juan Wang, Xin Li, Zhanpeng Lu, Xiaohui Li, Yiqi Tao, T. Shoji","doi":"10.5006/4288","DOIUrl":"https://doi.org/10.5006/4288","url":null,"abstract":"The evolution of the wavy surface of iron electrode with anodic polarization time in a sulfuric acid solution under 0.4T magnetic field is quantified by 3D tomographic depth profile measurements. The electrode surface after anodic dissolution under magnetic field is irregular and the 3D profile changes with the anodic polarization time. The anodic dissolution rate is specific to the geometrical location on the electrode, which is in general insensitive to the polarization time as well as the surface irregularity.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44437841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Lu, D. Narayanan, Chang-Woo Kim, D. Macdonald, H. Castaneda
Steel rebars are widely applied in reinforced concrete structures due to their contribution to significant improvements in mechanical properties. However, the exposure to corrosive environments, such as solution containing chloride, may induce accelerated corrosion and jeopardize the sustainability and durability of reinforced concrete. The current work evaluated the chloride thresholds (in both wt% and [Cl-]/[OH-]) of steel rebar with different chromium contents (0, 4, and 23wt%) in synthetic concrete pore solution (SCPS) based on AC and DC electrochemical measurements, and chemical and structural characterizations. The study found thar the CT values varied slightly based on the different measurement methods and the values were compared with values obtained from the literature. The values are 0.01-0.1wt% (3.76), 0.1-1wt% (>23.8), and 2.9-3.5wt% (>23.8) for 615, 4% Cr, and SS23, respectively, where the values in parentheses are [Cl-]/[OH-]. Therefore, it is demonstrated that multiple measurements are necessary to determine a reliable CT value. Corrosion mechanisms giving rise to CT are included to illustrate the processes involved in establishing CT.
{"title":"Determination of Chloride Threshold of Cr-based Steel Rebars in Synthetic Concrete Pore Solution (SCPS) based on Electrochemical Methods","authors":"Yi Lu, D. Narayanan, Chang-Woo Kim, D. Macdonald, H. Castaneda","doi":"10.5006/4236","DOIUrl":"https://doi.org/10.5006/4236","url":null,"abstract":"Steel rebars are widely applied in reinforced concrete structures due to their contribution to significant improvements in mechanical properties. However, the exposure to corrosive environments, such as solution containing chloride, may induce accelerated corrosion and jeopardize the sustainability and durability of reinforced concrete. The current work evaluated the chloride thresholds (in both wt% and [Cl-]/[OH-]) of steel rebar with different chromium contents (0, 4, and 23wt%) in synthetic concrete pore solution (SCPS) based on AC and DC electrochemical measurements, and chemical and structural characterizations. The study found thar the CT values varied slightly based on the different measurement methods and the values were compared with values obtained from the literature. The values are 0.01-0.1wt% (3.76), 0.1-1wt% (>23.8), and 2.9-3.5wt% (>23.8) for 615, 4% Cr, and SS23, respectively, where the values in parentheses are [Cl-]/[OH-]. Therefore, it is demonstrated that multiple measurements are necessary to determine a reliable CT value. Corrosion mechanisms giving rise to CT are included to illustrate the processes involved in establishing CT.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48104797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Zhao, Wei Li, Zhen-wei Wang, Ning Li, Yanling Xu, Deyu Li
In recent years, in the field of tinplate production, it has become a trend to use lower tin coating mass to lower production cost. However, the preparation of low Sn-coated steel must face two significant problems: toxic chromate post-treatment and low corrosion resistance. In this work, we developed a Mn-Al-P chemical conversion coating using for process sequence adjusted tinplate of 0.5g·m-2 tin coating mass to alternative the chromate treatment. Meanwhile, by adjusting the subsequence of the reflowing process and the post-treatment process, the wash water and electricity consumption was effectively reduced. The influence of reflowing time on the microstructural appearance, phase composition, surface element distribution, and corrosion resistance of this new brand tinplate was studied. Moreover, the composition was determined by XPS, and further discuss the formation mechanism of this coating. The results show that this muti-element coating could effectively fill tin-free zones on the surface of tinplate and improve the corrosion resistance when the reflowing time is properly setup to 3.5 s after the process adjustment. However, continually extended the reflowing time would cause the phosphate coating to fall off, which lead to the corrosion resistance deteriorate. The coating was mainly made up by a series of amorphous phosphate compounds and metal oxides, which was suitable for tinplate with low tin coating mass.
{"title":"Optimization of Mn-Al-P Chemical Conversion Coating for Process Sequence Adjusted Low Sn-coated Steel","authors":"Y. Zhao, Wei Li, Zhen-wei Wang, Ning Li, Yanling Xu, Deyu Li","doi":"10.5006/4278","DOIUrl":"https://doi.org/10.5006/4278","url":null,"abstract":"In recent years, in the field of tinplate production, it has become a trend to use lower tin coating mass to lower production cost. However, the preparation of low Sn-coated steel must face two significant problems: toxic chromate post-treatment and low corrosion resistance. In this work, we developed a Mn-Al-P chemical conversion coating using for process sequence adjusted tinplate of 0.5g·m<sup>-2</sup> tin coating mass to alternative the chromate treatment. Meanwhile, by adjusting the subsequence of the reflowing process and the post-treatment process, the wash water and electricity consumption was effectively reduced. The influence of reflowing time on the microstructural appearance, phase composition, surface element distribution, and corrosion resistance of this new brand tinplate was studied. Moreover, the composition was determined by XPS, and further discuss the formation mechanism of this coating. The results show that this muti-element coating could effectively fill tin-free zones on the surface of tinplate and improve the corrosion resistance when the reflowing time is properly setup to 3.5 s after the process adjustment. However, continually extended the reflowing time would cause the phosphate coating to fall off, which lead to the corrosion resistance deteriorate. The coating was mainly made up by a series of amorphous phosphate compounds and metal oxides, which was suitable for tinplate with low tin coating mass.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42015055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Le Chen, Yanxia Du, Yi Liang, Nianpei Tian, Zhenhong Zhu, Lei Zhang
An indoor corrosion simulation experiment device was built to explore the influence of dynamic AC interference on the corrosion behavior of pipeline steel under different cathodic protection (CP) levels. When the interference time in each interference cycle is 350 s, the dynamic AC corrosion rate was comparable to the steady AC corrosion rate. For JAC of 30 A·m-2, the corrosion rate of the specimen can be controlled below 0.0254 mm·y-1 when the CP current density is higher than 0.06 A·m-2. As JAC is greater than or equal to 100 A·m-2, with the increase of the cathodic protection current density, the corrosion rate of the specimens decreased firstly, then increased and decreased again. In this paper, the real-time AC/DC potential on the surface of the specimen is monitored, combined with Pourbaix diagram and the evolution of corrosion product film, the dynamic AC corrosion mechanism under different cathodic protection levels was explored.
{"title":"Research on dynamic AC corrosion behavior of X65 Pipeline Steel under cathodic protection","authors":"Le Chen, Yanxia Du, Yi Liang, Nianpei Tian, Zhenhong Zhu, Lei Zhang","doi":"10.5006/4240","DOIUrl":"https://doi.org/10.5006/4240","url":null,"abstract":"An indoor corrosion simulation experiment device was built to explore the influence of dynamic AC interference on the corrosion behavior of pipeline steel under different cathodic protection (CP) levels. When the interference time in each interference cycle is 350 s, the dynamic AC corrosion rate was comparable to the steady AC corrosion rate. For JAC of 30 A·m-2, the corrosion rate of the specimen can be controlled below 0.0254 mm·y-1 when the CP current density is higher than 0.06 A·m-2. As JAC is greater than or equal to 100 A·m-2, with the increase of the cathodic protection current density, the corrosion rate of the specimens decreased firstly, then increased and decreased again. In this paper, the real-time AC/DC potential on the surface of the specimen is monitored, combined with Pourbaix diagram and the evolution of corrosion product film, the dynamic AC corrosion mechanism under different cathodic protection levels was explored.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44973665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high energy demand and associated CO2 emissions to produce Portland cement (OPC) create the need for alternative types of binders that can be produced in a more environmentally friendly manner. These alternative binders either have a reduced OPC content or can be produced entirely without the use of OPC clinker. To allow their widespread use also in reinforced concrete components, these binders must meet the same durability requirements as types of cement that have already been standardized. This requires a thorough characterization of the materials and, in addition, a verification of the applicability of the evaluation criteria known from the traditional binders. One of the most important factors influencing the transport processes in the material and therefore the durability, is the penetration resistance of the pore structure for aggressive species, such as chloride ions. One key parameter for describing the pore structure is the formation factor (FF), which is used for various applications to evaluate durability. It is determined based on the ratio of the electrical resistivity of the concrete and of the pore solution. In this study, mortars produced with different alternative binders are characterized in terms of their formation factor and pore size distribution. In addition, chloride migration coefficients determined by the Rapid Chloride Migration (RCM) test are related to the formation factor. The test program includes nine different alternative binders and two reference cements: In addition to a CEM I and CEM III/B, two calcined clays and a modified steel mill slag were investigated as supplementary cementitious materials (SCMs), as well as a calcium sulphoaluminate (CSA) cement and a calcium silicate hydrate (C-S-H) binder. Four materials belong to the group of alkali-activated mortars: Two geopolymers and two alkali-activated slags were investigated here. It is shown that both, the AC resistances and the conductivities of the pore solutions, differ greatly among the mortars investigated. The formation factor is a suitable parameter for a simplified estimation of the chloride penetration resistance of the investigated alternative binders, provided that realistic values of the pore solution conductivities are determined and used for the calculations.
{"title":"Applicability of the formation factor for different alternative binder types investigated on mortars","authors":"R. Achenbach, M. Raupach","doi":"10.5006/4238","DOIUrl":"https://doi.org/10.5006/4238","url":null,"abstract":"The high energy demand and associated CO<sub>2</sub> emissions to produce Portland cement (OPC) create the need for alternative types of binders that can be produced in a more environmentally friendly manner. These alternative binders either have a reduced OPC content or can be produced entirely without the use of OPC clinker. To allow their widespread use also in reinforced concrete components, these binders must meet the same durability requirements as types of cement that have already been standardized. This requires a thorough characterization of the materials and, in addition, a verification of the applicability of the evaluation criteria known from the traditional binders. One of the most important factors influencing the transport processes in the material and therefore the durability, is the penetration resistance of the pore structure for aggressive species, such as chloride ions. One key parameter for describing the pore structure is the formation factor (FF), which is used for various applications to evaluate durability. It is determined based on the ratio of the electrical resistivity of the concrete and of the pore solution. In this study, mortars produced with different alternative binders are characterized in terms of their formation factor and pore size distribution. In addition, chloride migration coefficients determined by the Rapid Chloride Migration (RCM) test are related to the formation factor. The test program includes nine different alternative binders and two reference cements: In addition to a CEM I and CEM III/B, two calcined clays and a modified steel mill slag were investigated as supplementary cementitious materials (SCMs), as well as a calcium sulphoaluminate (CSA) cement and a calcium silicate hydrate (C-S-H) binder. Four materials belong to the group of alkali-activated mortars: Two geopolymers and two alkali-activated slags were investigated here. It is shown that both, the AC resistances and the conductivities of the pore solutions, differ greatly among the mortars investigated. The formation factor is a suitable parameter for a simplified estimation of the chloride penetration resistance of the investigated alternative binders, provided that realistic values of the pore solution conductivities are determined and used for the calculations.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42105215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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