Molten fluoride salts are candidate heat transfer fluids in a number of applications such as generation IV Molten Salt Nuclear Reactors (MSRs) and Concentrated Solar Power (CSP) Plants. However, a chief concern in the design of these systems is the corrosion of structural materials that come in contact with these molten salts. Redox control methods such as purification of salt, addition of active elements, and applied electrochemical potential can be efficient methods for preventing corrosion of structural materials in molten fluoride salts. Applied electrochemical potential as a redox control method for application in molten fluoride salts has rarely been explored. This study seeks to understand the viability of impressed current Cathodic Protection (CP) at various currents as a redox control method to prevent corrosion of Stainless Steel 316H in molten LiF-NaF-KF (FLiNaK) salt. Results show that application of CP can be an effective method to prevent corrosion of SS316H in molten FLiNaK salt, but the applied current will have to be optimized to prevent undesirable side effects such as reduction of salt constituents, salt deposition on electrodes etc.
{"title":"Viability of Cathodic Protection for Preventing Corrosion of SS316H in Molten LiF-NaF-KF","authors":"K. Sankar, Preet M. Singh","doi":"10.5006/4265","DOIUrl":"https://doi.org/10.5006/4265","url":null,"abstract":"Molten fluoride salts are candidate heat transfer fluids in a number of applications such as generation IV Molten Salt Nuclear Reactors (MSRs) and Concentrated Solar Power (CSP) Plants. However, a chief concern in the design of these systems is the corrosion of structural materials that come in contact with these molten salts. Redox control methods such as purification of salt, addition of active elements, and applied electrochemical potential can be efficient methods for preventing corrosion of structural materials in molten fluoride salts. Applied electrochemical potential as a redox control method for application in molten fluoride salts has rarely been explored. This study seeks to understand the viability of impressed current Cathodic Protection (CP) at various currents as a redox control method to prevent corrosion of Stainless Steel 316H in molten LiF-NaF-KF (FLiNaK) salt. Results show that application of CP can be an effective method to prevent corrosion of SS316H in molten FLiNaK salt, but the applied current will have to be optimized to prevent undesirable side effects such as reduction of salt constituents, salt deposition on electrodes etc.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41630539","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}
Traditionally, sour severity of high-pressure, high temperature (HPHT) oil and gas production wells were assessed by H2S partial pressure (PH2S): The mole fraction of H2S in the gas (yH2S) multiplied by the total pressure (PT). However, PH2S usually over-predicts the actual sour severity of HPHT systems, leading to sub-optimal material selection choices. To reflect recent advances in thermodynamic modeling and to avoid over conservatism, after careful deliberation, ANSI/NACE MR0175-2021/ISO 15156-2:2022 recently expanded the number of sour severity metrics to four: PH2S, fugacity (fH2S), chemical activity (aH2S) and dissolved concentration (CH2S) of the aqueous phase. The new metrics are often computationally derived and account for thermodynamic non-idealities, which are significant at HPHT conditions. Regardless of preferred metric, quantifying the sensitivity of each metric to a wide range of temperatures and total pressures is critical when conducting H2S service assessments. In this article, the effect of increasing temperature and total pressure on the thermodynamically derived apparent H2S solubility (KH2S = CH2S/PH2S) was investigated. KH2S is a critical parameter for quantifying changes in H2S phase behavior/sour severity of HPHT systems. Apparent KH2S values were calculated by two different thermodynamic models and benchmarked to two publicly available H2S/H2O datasets up to 120 °C and 10.3 MPa equilibrated in a brine containing 165,000 mg/L Cl−. The model that provided the best match to the experimental data was later used in a much broader thermodynamic sensitivity study of the H2S/CH4/H2O/NaCl “oilfield” system. For this sensitivity analysis, changes in fH2S, aH2S, CH2S and KH2S were individually modeled between 4 to 204 °C, at total pressures up to 138 MPa, and in brines containing up to 25 wt % NaCl (180,000 mg/L Cl−). Lastly, a comparison of the predicted sour severity by pseudo-PH2S, fH2S, and CH2S metrics, over the same temperature and total pressure parameter space, is presented.
{"title":"Optimizing Sour Gas Qualification Testing – Modeling the Effects of Temperature and Total Pressure on H<sub>2</sub>S Fugacity, Activity, and Solubility Coefficients","authors":"B.W.A. Sherar, Diana Miller, Hui Li","doi":"10.5006/4325","DOIUrl":"https://doi.org/10.5006/4325","url":null,"abstract":"Traditionally, sour severity of high-pressure, high temperature (HPHT) oil and gas production wells were assessed by H<sub>2</sub>S partial pressure (P<sub>H2S</sub>): The mole fraction of H<sub>2</sub>S in the gas (y<sub>H2S</sub>) multiplied by the total pressure (P<sub>T</sub>). However, P<sub>H2S</sub> usually over-predicts the actual sour severity of HPHT systems, leading to sub-optimal material selection choices. To reflect recent advances in thermodynamic modeling and to avoid over conservatism, after careful deliberation, ANSI/NACE MR0175-2021/ISO 15156-2:2022 recently expanded the number of sour severity metrics to four: P<sub>H2S</sub>, fugacity (f<sub>H2S</sub>), chemical activity (a<sub>H2S</sub>) and dissolved concentration (C<sub>H2S</sub>) of the aqueous phase. The new metrics are often computationally derived and account for thermodynamic non-idealities, which are significant at HPHT conditions. Regardless of preferred metric, quantifying the sensitivity of each metric to a wide range of temperatures and total pressures is critical when conducting H<sub>2</sub>S service assessments. In this article, the effect of increasing temperature and total pressure on the thermodynamically derived apparent H<sub>2</sub>S solubility (K<sub>H2S</sub> = C<sub>H2S</sub>/P<sub>H2S</sub>) was investigated. K<sub>H2S</sub> is a critical parameter for quantifying changes in H<sub>2</sub>S phase behavior/sour severity of HPHT systems. Apparent K<sub>H2S</sub> values were calculated by two different thermodynamic models and benchmarked to two publicly available H<sub>2</sub>S/H<sub>2</sub>O datasets up to 120 °C and 10.3 MPa equilibrated in a brine containing 165,000 mg/L Cl<sup>−</sup>. The model that provided the best match to the experimental data was later used in a much broader thermodynamic sensitivity study of the H<sub>2</sub>S/CH<sub>4</sub>/H<sub>2</sub>O/NaCl “oilfield” system. For this sensitivity analysis, changes in f<sub>H2S</sub>, a<sub>H2S</sub>, C<sub>H2S</sub> and K<sub>H2S</sub> were individually modeled between 4 to 204 °C, at total pressures up to 138 MPa, and in brines containing up to 25 wt % NaCl (180,000 mg/L Cl<sup>−</sup>). Lastly, a comparison of the predicted sour severity by pseudo-PH2S, fH2S, and CH2S metrics, over the same temperature and total pressure parameter space, is presented.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44674926","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}
Electrochemical impedance spectroscopy (EIS) was utilized to delve into the corrosion inhibition of eutectic Cu-Ag alloy and its components (Cu and Ag) in aqueous, aerated 0.1 M KNO3 solution. This alloy plays a major role in the water cooling of central processing units in data storage centers. Two organic inhibitors, namely, 1,2,3-benzotriazole (BTA) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD) were utilized in this study. The corrosion inhibition slowly evolved over time as diagnosed by an increase in the charge transfer impedance and the gradual tendency of the Nyquist profiles to arc toward the real axis. This trend was attributed to the gradual formation of organometallic passivation layers. The EIS data underlined the specific affinity of BTA and DMTD toward the Cu and Ag surfaces, respectively. A transition of the double layer equivalent circuit element from ideal capacitance to a constant phase element was observed for the alloy compared to the pure metals. This was attributed to the heterogeneity induced by Cu-rich and Ag-rich phases in the alloy and by the formed oxides/protective film on the alloy surface. The EIS study demonstrated that both BTA and DMTD can provide sufficient corrosion inhibition to Cu-60Ag alloy with DMTD being significantly more effective.
{"title":"Temporal Aspects of Corrosion Inhibition on Copper, Silver, and Copper-Silver Alloy: An Electrochemical Impedance Spectroscopy Study","authors":"H. Rahmani, Neil S. Spinner, E. Meletis","doi":"10.5006/4269","DOIUrl":"https://doi.org/10.5006/4269","url":null,"abstract":"Electrochemical impedance spectroscopy (EIS) was utilized to delve into the corrosion inhibition of eutectic Cu-Ag alloy and its components (Cu and Ag) in aqueous, aerated 0.1 M KNO3 solution. This alloy plays a major role in the water cooling of central processing units in data storage centers. Two organic inhibitors, namely, 1,2,3-benzotriazole (BTA) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD) were utilized in this study. The corrosion inhibition slowly evolved over time as diagnosed by an increase in the charge transfer impedance and the gradual tendency of the Nyquist profiles to arc toward the real axis. This trend was attributed to the gradual formation of organometallic passivation layers. The EIS data underlined the specific affinity of BTA and DMTD toward the Cu and Ag surfaces, respectively. A transition of the double layer equivalent circuit element from ideal capacitance to a constant phase element was observed for the alloy compared to the pure metals. This was attributed to the heterogeneity induced by Cu-rich and Ag-rich phases in the alloy and by the formed oxides/protective film on the alloy surface. The EIS study demonstrated that both BTA and DMTD can provide sufficient corrosion inhibition to Cu-60Ag alloy with DMTD being significantly more effective.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":"124 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41264824","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}
Yang Hou, T. Pojtanabuntoeng, M. Iannuzzi, Mike Rajagopal
This study evaluated the efficacy of a commercial volatile corrosion inhibitor (VCI) in mitigating the corrosion of carbon steel insulated with mineral wool insulation, especially as a retrofitted solution to CUI management. When VCI was added in dry insulation before the test solution was introduced, severity of CUI was reduced after 14-day exposure. However, when the exposure time was extended to 90 days, no significant mitigation effect was observed. Furthermore, VCI was ineffective when added to pre-corroded insulated systems, indicating that it could not be used as a retrofitted solution to alleviate CUI problems. A separate set of tests with bare steel samples exposed to 10 mL VCI in closed jars showed that VCI was adsorbed on the corrosion products but could not effectively impede the propagation of localized corrosion. The possible influences of insulation jacketing, insulation properties, VCI dosages and dosing methods were also discussed, suggesting the need for further investigations.
{"title":"Performance of a volatile corrosion inhibitor for mitigating corrosion under insulation","authors":"Yang Hou, T. Pojtanabuntoeng, M. Iannuzzi, Mike Rajagopal","doi":"10.5006/4252","DOIUrl":"https://doi.org/10.5006/4252","url":null,"abstract":"This study evaluated the efficacy of a commercial volatile corrosion inhibitor (VCI) in mitigating the corrosion of carbon steel insulated with mineral wool insulation, especially as a retrofitted solution to CUI management. When VCI was added in dry insulation before the test solution was introduced, severity of CUI was reduced after 14-day exposure. However, when the exposure time was extended to 90 days, no significant mitigation effect was observed. Furthermore, VCI was ineffective when added to pre-corroded insulated systems, indicating that it could not be used as a retrofitted solution to alleviate CUI problems. A separate set of tests with bare steel samples exposed to 10 mL VCI in closed jars showed that VCI was adsorbed on the corrosion products but could not effectively impede the propagation of localized corrosion. The possible influences of insulation jacketing, insulation properties, VCI dosages and dosing methods were also discussed, suggesting the need for further investigations.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47176816","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 creep rupture life of commercial Super304H in fireside corrosion (coal ash and flue gas) and static air environment at 650 °C was investigated. Results showed that the creep rupture life under fireside corrosion condition decreases by 26.5%-83.3% at different stress levels, comparing with that in air. The corrosion products, including their composition, morphology and distribution, and the microstructure of substrate were characterized to research the impact of the fireside corrosion on the creep rupture life. The exfoliation of oxide scales and serious surface cracking resulted from fireside corrosion were detrimental for creep properties of the alloy. The formation of internal sulfides promoted the initiation and propagation of intergranular cracks in the substrate during creep tests. These degradations of Super304H in fireside corrosion contributed to the premature creep rupture.
{"title":"Impact of fireside corrosion on creep rupture life and oxide scale structure of Super304H boiler tube","authors":"Xiaofeng Yang, Yaxin Xu, Jin-Tao Lu, Dangdang Ying, Jinyang Huang, Wenya Li","doi":"10.5006/4277","DOIUrl":"https://doi.org/10.5006/4277","url":null,"abstract":"The creep rupture life of commercial Super304H in fireside corrosion (coal ash and flue gas) and static air environment at 650 °C was investigated. Results showed that the creep rupture life under fireside corrosion condition decreases by 26.5%-83.3% at different stress levels, comparing with that in air. The corrosion products, including their composition, morphology and distribution, and the microstructure of substrate were characterized to research the impact of the fireside corrosion on the creep rupture life. The exfoliation of oxide scales and serious surface cracking resulted from fireside corrosion were detrimental for creep properties of the alloy. The formation of internal sulfides promoted the initiation and propagation of intergranular cracks in the substrate during creep tests. These degradations of Super304H in fireside corrosion contributed to the premature creep rupture.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48102545","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}
Valentina Millano González, Oladis Troconis de Rincón, A. Torres‐Acosta, M. Sanchez Gomez, Pedro Castro Borges, J. Pérez-Quiróz, Tezozomoc Pérez López, R. Vera, M. Salta, M. Pedrón
This research evaluation consisted of a detailed statistical analysis of the recorded data in 72 reinforced concrete specimens, from 12 natural test sites (in nine countries) located in chloride-laden environments (marine airborne-exposure, test sites located between 50-250 m from seashore), during a natural exposure period of 10 years. The parameters evaluated included the concrete physical-mechanical characteristics; meteorochemical information; natural reinforcing steel´s instantaneous corrosion current density (icorr) and cumulative icorr; concrete chloride concentration; surface crack width and rebar cross section loss correlations. This statistical analysis resulted in empirical instantaneous icorr predictions as a function of the exposure microclimates, through linear multiple regressions. These models showed a high linear dependence of the cumulative icorr with the concrete capillary absorption as well as with the meteorochemical parameters. Results obtained in this investigation showed higher corrosion aggressiveness of tropical environments when compared to the non-tropical ones. The cumulative icorr proved to be an effective tool to indicate the corrosive likelihood and to differentiate the stages of Tuutti´s service life model.
{"title":"Modelling electrochemical performance of reinforced concrete in natural marine airborne exposure environments: DURACON project-10 years evaluation","authors":"Valentina Millano González, Oladis Troconis de Rincón, A. Torres‐Acosta, M. Sanchez Gomez, Pedro Castro Borges, J. Pérez-Quiróz, Tezozomoc Pérez López, R. Vera, M. Salta, M. Pedrón","doi":"10.5006/4235","DOIUrl":"https://doi.org/10.5006/4235","url":null,"abstract":"This research evaluation consisted of a detailed statistical analysis of the recorded data in 72 reinforced concrete specimens, from 12 natural test sites (in nine countries) located in chloride-laden environments (marine airborne-exposure, test sites located between 50-250 m from seashore), during a natural exposure period of 10 years. The parameters evaluated included the concrete physical-mechanical characteristics; meteorochemical information; natural reinforcing steel´s instantaneous corrosion current density (icorr) and cumulative icorr; concrete chloride concentration; surface crack width and rebar cross section loss correlations. This statistical analysis resulted in empirical instantaneous icorr predictions as a function of the exposure microclimates, through linear multiple regressions. These models showed a high linear dependence of the cumulative icorr with the concrete capillary absorption as well as with the meteorochemical parameters. Results obtained in this investigation showed higher corrosion aggressiveness of tropical environments when compared to the non-tropical ones. The cumulative icorr proved to be an effective tool to indicate the corrosive likelihood and to differentiate the stages of Tuutti´s service life model.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44570535","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}
Jonas de Sa, Rob Jacklin, J. P. Ponciano Gomes, R. Barker
The effect of calcium ions (Ca2+) on corrosion of API 5L X80 carbon steel in carbon dioxide (CO2)-saturated brines was studied. Tests were carried out in brines containing 0, 1000 or 5000 ppm of calcium ions with a constant chloride ion concentration, at temperatures of 35 and 60 oC, and pressure of 80 bar. The corrosion rates were determined by mass loss, and the protective properties of the film was evaluated by carrying out electrochemical measurements in a separate vessel containing a standard brine. The results showed that adding Ca2+ to the brine slightly reduced the average corrosion rate, even in the absence of a crystalline corrosion product scale. For longer exposure times, it promoted the growth of a mixed iron-calcium carbonate (FexCayCO3) scale with increasing calcium molar mass, shifting the scale morphology from prismatic crystals (pure FeCO3) to globular (mixed carbonate). At 35 oC the mixed iron-calcium carbonate scale offered better protection when compared to the pure FeCO3 scale counterpart. However, at 60 oC, where a thicker carbonate scale was formed, the increase of Ca2+ content had a minimal effect on the corrosion rate.
{"title":"Formation and protectiveness of Fe/Ca carbonate layer on X80 steel in high pressure CO<sub>2</sub> corrosion environments","authors":"Jonas de Sa, Rob Jacklin, J. P. Ponciano Gomes, R. Barker","doi":"10.5006/4248","DOIUrl":"https://doi.org/10.5006/4248","url":null,"abstract":"The effect of calcium ions (Ca<sup>2+</sup>) on corrosion of API 5L X80 carbon steel in carbon dioxide (CO<sub>2</sub>)-saturated brines was studied. Tests were carried out in brines containing 0, 1000 or 5000 ppm of calcium ions with a constant chloride ion concentration, at temperatures of 35 and 60 <sup>o</sup>C, and pressure of 80 bar. The corrosion rates were determined by mass loss, and the protective properties of the film was evaluated by carrying out electrochemical measurements in a separate vessel containing a standard brine. The results showed that adding Ca<sup>2+</sup> to the brine slightly reduced the average corrosion rate, even in the absence of a crystalline corrosion product scale. For longer exposure times, it promoted the growth of a mixed iron-calcium carbonate (Fe<sub>x</sub>Ca<sub>y</sub>CO<sub>3</sub>) scale with increasing calcium molar mass, shifting the scale morphology from prismatic crystals (pure FeCO<sub>3</sub>) to globular (mixed carbonate). At 35 <sup>o</sup>C the mixed iron-calcium carbonate scale offered better protection when compared to the pure FeCO<sub>3</sub> scale counterpart. However, at 60 <sup>o</sup>C, where a thicker carbonate scale was formed, the increase of Ca<sup>2+</sup> content had a minimal effect on the corrosion rate.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47190786","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}
This study aimed to enhance the corrosion resistance of an Al–Mn–Zr alloy containing Fe impurities by employing heat treatment processes. Three processes were implemented to distribute intermetallic particles uniformly, promote Al6(Mn, Fe) and Al3Zr particle formation, and eliminate Fe and Zr segregation. Increasing the amount of Al6(Mn, Fe) reduced the galvanic effect between Al matrix and Al3Fe particles, leading to improved localized corrosion resistance. Al3Zr promoted smaller grain size by preventing recrystallization. Microstructure analysis confirmed the inhibitory effect on grain growth and the promotion of Al6(Mn, Fe) and Al3Zr particle formation. The effect of grain size on galvanic corrosion was evaluated through corrosion simulation. Furthermore, the improved localized corrosion resistance was evaluated through electrochemical and immersion tests. Consequently, the designed heat treatment process significantly improved the localized corrosion resistance of the Al–Mn–Zr alloy with Fe impurities. These results demonstrate the effectiveness of the employed heat treatment processes in improving the corrosion resistance of the alloy.
{"title":"Effect of homogenization and precipitation heat treatments on localized corrosion of Al–Mn–Zr alloy with Fe impurity","authors":"Y. So, Jeong-Min Lim, T. Nguyen, Jung-Gu Kim","doi":"10.5006/4319","DOIUrl":"https://doi.org/10.5006/4319","url":null,"abstract":"This study aimed to enhance the corrosion resistance of an Al–Mn–Zr alloy containing Fe impurities by employing heat treatment processes. Three processes were implemented to distribute intermetallic particles uniformly, promote Al6(Mn, Fe) and Al3Zr particle formation, and eliminate Fe and Zr segregation. Increasing the amount of Al6(Mn, Fe) reduced the galvanic effect between Al matrix and Al3Fe particles, leading to improved localized corrosion resistance. Al3Zr promoted smaller grain size by preventing recrystallization. Microstructure analysis confirmed the inhibitory effect on grain growth and the promotion of Al6(Mn, Fe) and Al3Zr particle formation. The effect of grain size on galvanic corrosion was evaluated through corrosion simulation. Furthermore, the improved localized corrosion resistance was evaluated through electrochemical and immersion tests. Consequently, the designed heat treatment process significantly improved the localized corrosion resistance of the Al–Mn–Zr alloy with Fe impurities. These results demonstrate the effectiveness of the employed heat treatment processes in improving the corrosion resistance of the alloy.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42202514","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}
This paper investigates the initiation and propagation of localized corrosion on cold sprayed (CS) aluminum alloy 2024 and 7075 deposits. CS deposits on AA2024-T351 and AA7075-T651 substrates were produced with commercially available AA2024 and AA7075 powders using helium as carrier gas. Electrochemical and immersion tests in 0.6M NaCl and ASTM G110 test were employed to evaluate the corrosion properties of CS AA2024 and AA7075 deposits. For analysis, optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were utilized before and after the experiment. The results indicated that the initiation and propagation of localized corrosion highly depend on microstructural characteristics, such as the distribution and chemical composition of intermetallic networks with the matrix and propagated along these networks and prior particle boundaries, where an ultrafine grain (UFG) structure is present. Accelerated localized corrosion tests generated deep penetration as well as a large area of defects owing to the coalescence of fissures.
{"title":"Initiation and Propagation of Localized Corrosion on Cold Sprayed Aluminum Alloy 2024 and 7075","authors":"Mun-Chul Kim, L. Brewer, G. Kubacki","doi":"10.5006/4239","DOIUrl":"https://doi.org/10.5006/4239","url":null,"abstract":"This paper investigates the initiation and propagation of localized corrosion on cold sprayed (CS) aluminum alloy 2024 and 7075 deposits. CS deposits on AA2024-T351 and AA7075-T651 substrates were produced with commercially available AA2024 and AA7075 powders using helium as carrier gas. Electrochemical and immersion tests in 0.6M NaCl and ASTM G110 test were employed to evaluate the corrosion properties of CS AA2024 and AA7075 deposits. For analysis, optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were utilized before and after the experiment. The results indicated that the initiation and propagation of localized corrosion highly depend on microstructural characteristics, such as the distribution and chemical composition of intermetallic networks with the matrix and propagated along these networks and prior particle boundaries, where an ultrafine grain (UFG) structure is present. Accelerated localized corrosion tests generated deep penetration as well as a large area of defects owing to the coalescence of fissures.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47938718","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}
As-cast and semi-solid AZ91D magnesium alloys samples were corroded in distilled water, 0.9% NaCl solution and 3.5% NaCl solution for various time, respectively. With the increase of corrosion time and the concentration of corrosion solution, the corrosion degree of the alloys gradually deepened. The corrosion resistance of semi-solid alloy with nearly spherical grain refinement was significantly reduced, resulting in more corrosion pits and higher corrosion rate. According to the fractal analysis, the corrosion process of semi-solid alloy was more uniform under the same conditions. The fractal theory accurately described the corrosion process, further providing a better grasp of the corrosion behavior of AZ91D magnesium alloy.
{"title":"Corrosion research and fractal characteristics of as-cast and semi-solid AZ91D magnesium alloys","authors":"Yang Lei, Yonglai Lai, Kailin Yue, Y. Liu, H. Jin","doi":"10.5006/4282","DOIUrl":"https://doi.org/10.5006/4282","url":null,"abstract":"As-cast and semi-solid AZ91D magnesium alloys samples were corroded in distilled water, 0.9% NaCl solution and 3.5% NaCl solution for various time, respectively. With the increase of corrosion time and the concentration of corrosion solution, the corrosion degree of the alloys gradually deepened. The corrosion resistance of semi-solid alloy with nearly spherical grain refinement was significantly reduced, resulting in more corrosion pits and higher corrosion rate. According to the fractal analysis, the corrosion process of semi-solid alloy was more uniform under the same conditions. The fractal theory accurately described the corrosion process, further providing a better grasp of the corrosion behavior of AZ91D magnesium alloy.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46732388","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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