Anodic and cathodic polarisation of magnesium in borate buffer solutions with and without addition of chloride

Anodic and cathodic polarisation of magnesium in borate buffer solutions with and without addition of chloride | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Short Report Anodic and cathodic polarisation of magnesium in borate buffer solutions with and without addition of chloride Egil Gulbrandsen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6837551/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This report summarises the results of polarisation tests on high-purity (99.95 %) magnesium electrodes in borate buffer solutions at pH 9.2, pure or with additions of NaCl (0.1 M to 3.0 M). The investigation included both potentiostatic tests with mass loss determinations and potentiodynamic tests with H 2 gas evolution measurements. The corrosion was uniform in the absence of chloride ions, and the hydrogen evolution rate decreased steadily towards zero upon anodic polarisation above the open-circuit potential. Addition of chloride caused localised corrosion at anodic polarisation together with anomalous H 2 evolution from the localised attacks. The anomalous H 2 evolution rate started decreasing when a certain applied polarisation was reached. The potential at which this drop initiated decreased as the NaCl concentration increased. This observation may be interpreted as an effect of increasing solution conductivity lowering a high ohmic resistance in the localised attacks. Materials Chemistry magnesium borate buffer solution localised corrosion anomalous hydrogen evolution Figures Figure 1 Figure 2 Figure 3 Introduction The objective of the present investigation was to study the H 2 evolution associated with localised corrosion on high-purity Mg in a weakly alkaline pH buffer solution, pH 9.2. The relevance of this and some other alkaline buffer solutions for Mg corrosion research is that the corrosion is uniform, and the H 2 evolution follows the normally expected behaviour, i.e., decreasing with increasing anodic polarisation, as demonstrated in previous work with carbonate [ 1 – 3 ], TRIS [ 4 ], borate [ 5 ] and phosphate [ 6 ] (buffer) solutions. This is contrary to what is consistently observed for Mg in solutions containing chloride or certain other anions, where increasing H 2 evolution associated with the initiation and growth of localised corrosion attacks occurs upon anodic polarisation. Addition of chloride to these buffer solutions thus offers a way to study the onset and development of localised corrosion and the anomalous H 2 evolution [ 2 – 6 ]. On the other hand, there are some features of such buffer solutions that make them less relevant for the practical performance testing of Mg alloys, such as 1) the corrosion rate is artificially high, 2) the corrosion rate may be governed mainly by the concentration of the acidic part of the buffer solution, as demonstrated for the bicarbonate ion [ 1 ], and 3) these solutions may introduce solution-specific behaviour like the formation of poorly soluble Mg salts with the buffer components. This may modify the corrosion product layers and introduce features in the polarisation curves that are less relevant for the corrosion of Mg in practical applications. Due to these limitations, these results are communicated as supporting background information for other work to be published. Experimental Electrodes WE: High purity Mg 99.95%, impurities (ppm): Fe, 90; Cu, 10; Al, 40; Zn, 10; Na, 20; Ca, 50; Pb, 5; Si, 150; Ni, not reported. Flush-mounted in epoxy resin, 3.14 cm 2 discs, or ≈ 0.1 cm 2 to 0.5 cm 2 rectangular. Grinded to 1200 mesh with SiC paper, washed in distilled water. RE: Ag/AgCl (3.5 M KCl), E = 0.202 V vs SHE (ISO 17474 [ 7 ]), AE: Platinised titanium mesh Test protocols -Real-time volumetric measurement of H 2 gas evolution by a modified buoyance measurement method, documented in ref. [ 3 ] (preprint) -Mass loss determinations: weighing to constant mass by repeated heating to 50 o C for 30 mins until stable mass within 0.2 mg. Dissolving corrosion products in 200 g/L CrO 3 solution according to ASTM G1-03 [ 8 ] -Potentiostatic polarisation: 10–40 hrs depending on anticipated mass loss -Linear polarisation scans 0.1 mV/s -Ohmic potential drop compensation applied in tests with predominantly uniform corrosion. Ohmic resistance determined by electrochemical impedance spectroscopy at open circuit at beginning of the tests -Ambient temperature 23 ± 2 o C, ambient pressure Current density ( cd ) Sign convention: the current density ( cd) i m calculated from mass loss is positive, the hydrogen evolution cd i H2 is negative, and the external cd i e follows the common convention (anodic = positive). Charge balance, expressed as cd’s : i m + i H2 = i e (Eq. 1) Overall reaction stoichiometry used in calculations: 2 H 2 O + 2e − = H 2 + 2 OH − (Eq. 2) Mg + 2 OH − = Mg(OH) 2 + 2e − (Eq. 3) Test solutions Solution* pH Specific conductivity, κ (mS/cm) Density, ρ (g/cm 3 ) Borate buffer: 0.1 M B(OH) 3 + 0.1 M B(OH) 4 − 9.2 6.4 1.004 Borate buffer + 0.1 M NaCl 9.2 15.4 1.011 Borate buffer + 0.3 M NaCl 9.1 30.1 1.017 Borate buffer + 1.0 M NaCl 8.9 80.3 1.045 Borate buffer + 3.0 M NaCl 8.6 183 [ 9 ] 1.124 * Test solution properties at 25 o C. Analytical reagent grade chemicals and distilled water. All the values were measured in-house except the conductivity of the most concentrated solution, which was estimated from literature data [ 9 ]. Abbreviations: WE, RE, AE: working, reference and auxiliary electrodes, respectively. OCP: open-circuit potential, sd : standard deviation, TRIS: tris(hydroxymethyl)aminomethane. Results 4.1 Potentiostatic polarisation tests Comments : The corrosion was uniform, except at the very lowest potential (-2.61 V). Thin, nearly invisible corrosion product layers were formed on the uniformly corroded electrodes. i m exhibited two more or less potential independent ranges, -2.3 V to -1.4 V and above -1.3 V. i e approached the value of i m above -1.4 V, with visible H 2 gas evolution disappearing. The observed dip in cd’s around -2.5 V and the sharp increase at even lower potentials are consistent with previous reports of such behaviour [1,10–12]. 4.2 Linear polarisation scans with H 2 gas evolution rate measurement Comments : The slow potentiodynamic polarisation curves in Fig. 2a show mostly the same features as the potentiostatic steady-state data in Fig.1. The i H2 (calc) curve included from Fig. 1 shows fair agreement with the measured i H2 curve. The Tafel slopes of the i H2 curves varied from 400 to 800 mV/decade. In the presence of 0.1 M NaCl, localised corrosion with anomalous H 2 evolution started at around -1.15 V and lasted to the end of the scan. This topic is studied further in Fig. 3. 4.3 Effect of NaCl concentration Comments : In the borate solution with 0.1 M NaCl, the localised corrosion and anomalous H 2 evolution started at E p ≈ -1.2 V and lasted to E HE drop ≈ 3.9 V. Both E p and E HE drop decreased with increasing NaCl concentrations, to ≈ -1.47 V and ≈ -1.2 V, respectively, in the solution with 3.0 M NaCl. Note that the variations in both E p and E HE drop between the duplicated tests were ≈ 0.5 V to 1 V. Still the decreasing trend is clear. Also note the frequent bursts in i H2 above E HE drop , which corresponded to peaks in i e . i e remained high to the end of the scans. The corrosion rates were very high, and i e increased considerably with increasing NaCl concentration. This may be partly caused by the decreasing pH with increasing NaCl concentration (Section3). The calculated average corrosion depths at the end of the scans thus varied from 0.5 mm to 3.4 mm with 0.1 M to 3.0 M NaCl, respectively. Discussion Comparison of the polarisation curves in Figs.1-2 with similar curves published for tests in carbonate buffer solutions [1,3] reveals significant differences, which suggests that solution-specific features are present in one, or both, of these chemistries. Nonetheless, the transition to localised corrosion appears to follow the trends seen for pure NaCl solutions, such as the formation of black, filiform-like localised attacks with H 2 evolution starting from the attacks. The decreasing trend of E HE drop with increasing NaCl concentration may be interpreted as an effect of increasing solution conductivity which lowers the ohmic potential drop in deep localised attacks, thereby bringing the electrode potential in the localised attacks gradually above the thermodynamic limit of H 2 evolution. Sporadic new events of localised corrosion still caused burst of H 2 evolution above E HE drop . Declarations Competing interests The author has no conflicts of interest related to the content of this data set. The author is the owner and an employee of Gulbrandsen Technology AS. The company has no commercial or financial interests in the topic of this article. No funding was received for conducting this study. Data availability The raw data for the graphs presented here are available from the author on reasonable request. References E. Gulbrandsen, Anodic behaviour of Mg in HCO3−/CO32− buffer solutions. Quasi-steady measurements, Electrochim Acta 37 (1992) 1403–1412. https://doi.org/10.1016/0013-4686(92)87014-Q. P. Gore, V.S. Raja, N. Birbilis, Use of sodium bicarbonate as a chloride-free aqueous electrolyte to explore film formation and the negative difference effect on pure magnesium, J Electrochem Soc 165 (2018) C849–C859. https://doi.org/10.1149/2.0171813jes. E. Gulbrandsen, Quantification of hydrogen evolution in corrosion testing by buoyancy measurements, (2025). https://doi.org/10.21203/rs.3.rs-5726344/v1. T.W. Cain, I. Gonzalez-Afanador, N. Birbilis, J.R. Scully, The role of surface films and dissolution products on the negative difference effect for magnesium: Comparison of Cl- versus Cl- free solutions, J Electrochem Soc 164 (2017) C300–C311. https://doi.org/10.1149/2.1371706jes. L. Rossrucker, A. Samaniego, J.-P. Grote, A.M. Mingers, C.A. Laska, N. Birbilis, G.S. Frankel, K.J.J. Mayrhofer, The pH Dependence of Magnesium Dissolution and Hydrogen Evolution during Anodic Polarization, J Electrochem Soc 162 (2015) C333–C339. https://doi.org/10.1149/2.0621507jes. S. Lebouil, O. Gharbi, P. Volovitch, K. Ogle, Mg Dissolution in Phosphate and Chloride Electrolytes: Insight into the Mechanism of the Negative Difference Effect, CORROSION 71 (2015) 234–241. https://doi.org/10.5006/1459. Corrosion of metals and alloys - Conventions applicable to electrochemical measurements in corrosion testing, ISO 17474:2012(E) (2012). ASTM G1-03 Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens, (n.d.). https://doi.org/10.1520/G0001-03R17E01. R.C. Weast, CRC Handbook of Chemistry and Physics, 63rd ed., CRC Press, Boca Raton, Fl, 1982. P.F. King, Magnesium as a Passive Metal, J Electrochem Soc 110 (1963) 1113. https://doi.org/10.1149/1.2425600. A.P. Nazarov, T.A. Yurasova, Anodic Dissolution of Magnesium under Positive and Negative Difference Effects, Protection of Metals 32 (1996) 28–31. M. Curioni, The behaviour of magnesium during free corrosion and potentiodynamic polarization investigated by real-time hydrogen measurement and optical imaging, Electrochim Acta 120 (2014) 284–292. https://doi.org/10.1016/j.electacta.2013.12.109. Additional Declarations The authors declare no competing interests. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6837551","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":467720806,"identity":"61e6475a-76ad-4d76-9392-2581b1dedcb6","order_by":0,"name":"Egil Gulbrandsen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYFACxsYDHxgYZAxAbB6oGDMBLQ0HZwAVI7SwEdTCwHCYhyQt/PyLGw7b/DrMYy59+NmDN39s8hjkmw9+LsCjRXLGw4bDuX2HeSz70swN57alFTOwsSVLz8CjxeDGQaCWnsM8BmcYzKR5Gw4nNrDxmDHz4NFiD9JiCdbC/k2a589/oBb+b3i1GPA3Nhxm+AHSwmMmzcN2AGQLG14tEjeAgdzbkM5j2cNTJjm3LTmxjS3NWBqfFv7+4w8f/PhjLWfOw75N4s0fu8R+5sMPP+PTwiCRAIzNNiQBNnyqIdYcABJ/CCobBaNgFIyCkQwAdmVNLpdPdEoAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-8184-6977","institution":"Gulbrandsen Technology AS","correspondingAuthor":true,"prefix":"","firstName":"Egil","middleName":"","lastName":"Gulbrandsen","suffix":""}],"badges":[],"createdAt":"2025-06-06 13:47:57","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6837551/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6837551/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84271839,"identity":"ef295132-1568-47a5-9c96-b1c1f39d3a68","added_by":"auto","created_at":"2025-06-10 04:29:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":27838,"visible":true,"origin":"","legend":"\u003cp\u003eAverage current densities in potentiostatic polarisation tests with mass loss measurements in pure borate buffer solution, pH 9.2. \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2 \u003c/em\u003e\u003c/sub\u003e(calc) was calculated by Eq. 1. The lines between data points have been added to improve readability. The dashed ovals indicate pairs of duplicate tests being carried out at the same applied potential or OCP. The electrode potentials have been compensated for ohmic potential drop as described in Section 3.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6837551/v1/18edeae81ad05e3eaa8af0d1.png"},{"id":84271840,"identity":"704bdcae-b055-4d5a-b415-97b72d926998","added_by":"auto","created_at":"2025-06-10 04:29:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":80242,"visible":true,"origin":"","legend":"\u003cp\u003eLinear polarisation curves from cathodic to anodic potentials with H\u003csub\u003e2\u003c/sub\u003e gas measurements in borate buffer solution, with a) no additions and b) 0.1 M NaCl added. \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e (calc) was calculated by Eq. 1. The lowest \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e values are plotted on a linear scale on the right-hand y-axis. The electrode potentials have been compensated for ohmic potential drop. This compensation is uncertain for the part of the tests where localised corrosion dominated (Fig. 2b above -1.1 V). The error bars indicate ±1 \u003cem\u003esd\u003c/em\u003e in \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6837551/v1/8b7498f009df3dda2c25b19e.png"},{"id":84271842,"identity":"3bc97ed9-6bb4-4684-b117-70db92657688","added_by":"auto","created_at":"2025-06-10 04:29:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":163376,"visible":true,"origin":"","legend":"\u003cp\u003eAnodic linear polarisation curves from OCP in borate buffer solution with additions of a) 0.1 M NaCl, b) 0.3 M NaCl, c) 1.0 M NaCl, d) 3.0 M NaCl. The lowest \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e values are plotted in grey on a linear scale on the right-hand y-axis. e) The electrode potentials where the localised corrosion and anomalous H\u003csub\u003e2\u003c/sub\u003e evolution started (\u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e) and \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e started to drop again (\u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003eHE drop\u003c/em\u003e\u003c/sub\u003e), summarised from Figs. 3a-d and duplicated tests. The dashed curves in (e) have been added for readability.\u003cbr\u003e\nThe electrode potentials have not been compensated for ohmic potential drop in any of the graphs. The error bars indicate ±1 \u003cem\u003esd\u003c/em\u003e in \u003cem\u003ei\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6837551/v1/61ec0a94ca19d0ecd800f13c.png"},{"id":84272567,"identity":"739b037e-2e76-48d4-a04b-aab0227e1e43","added_by":"auto","created_at":"2025-06-10 04:53:11","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":851106,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6837551/v1/39181b66-c3b6-432a-86ee-f64b8fdba3ec.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eAnodic and cathodic polarisation of magnesium in borate buffer solutions with and without addition of chloride\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe objective of the present investigation was to study the H\u003csub\u003e2\u003c/sub\u003e evolution associated with localised corrosion on high-purity Mg in a weakly alkaline pH buffer solution, pH 9.2. The relevance of this and some other alkaline buffer solutions for Mg corrosion research is that the corrosion is uniform, and the H\u003csub\u003e2\u003c/sub\u003e evolution follows the normally expected behaviour, i.e., decreasing with increasing anodic polarisation, as demonstrated in previous work with carbonate [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], TRIS [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], borate [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and phosphate [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] (buffer) solutions. This is contrary to what is consistently observed for Mg in solutions containing chloride or certain other anions, where increasing H\u003csub\u003e2\u003c/sub\u003e evolution associated with the initiation and growth of localised corrosion attacks occurs upon anodic polarisation. Addition of chloride to these buffer solutions thus offers a way to study the onset and development of localised corrosion and the anomalous H\u003csub\u003e2\u003c/sub\u003e evolution [\u003cspan additionalcitationids=\"CR3 CR4 CR5\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOn the other hand, there are some features of such buffer solutions that make them less relevant for the practical performance testing of Mg alloys, such as 1) the corrosion rate is artificially high, 2) the corrosion rate may be governed mainly by the concentration of the acidic part of the buffer solution, as demonstrated for the bicarbonate ion [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], and 3) these solutions may introduce solution-specific behaviour like the formation of poorly soluble Mg salts with the buffer components. This may modify the corrosion product layers and introduce features in the polarisation curves that are less relevant for the corrosion of Mg in practical applications. Due to these limitations, these results are communicated as supporting background information for other work to be published.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Taba\" border=\"1\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eElectrodes\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eWE: High purity Mg 99.95%, impurities (ppm): Fe, 90; Cu, 10; Al, 40; Zn, 10; Na, 20; Ca, 50; Pb, 5; Si, 150; Ni, not reported. Flush-mounted in epoxy resin, 3.14 cm\u003csup\u003e2\u003c/sup\u003e discs, or \u0026asymp;\u0026thinsp;0.1 cm\u003csup\u003e2\u003c/sup\u003e to 0.5 cm\u003csup\u003e2\u003c/sup\u003e rectangular. Grinded to 1200 mesh with SiC paper, washed in distilled water. RE: Ag/AgCl (3.5 M KCl), E\u0026thinsp;=\u0026thinsp;0.202 V vs SHE (ISO 17474 [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e]), AE: Platinised titanium mesh\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTest protocols\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e-Real-time volumetric measurement of H\u003csub\u003e2\u003c/sub\u003e gas evolution by a modified buoyance measurement method, documented in ref. [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e] (preprint)\u003c/p\u003e\n \u003cp\u003e-Mass loss determinations: weighing to constant mass by repeated heating to 50 \u003csup\u003eo\u003c/sup\u003eC for 30 mins until stable mass within 0.2 mg. Dissolving corrosion products in 200 g/L CrO\u003csub\u003e3\u003c/sub\u003e solution according to ASTM G1-03 [\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\n \u003cp\u003e-Potentiostatic polarisation: 10\u0026ndash;40 hrs depending on anticipated mass loss\u003c/p\u003e\n \u003cp\u003e-Linear polarisation scans 0.1 mV/s\u003c/p\u003e\n \u003cp\u003e-Ohmic potential drop compensation applied in tests with predominantly uniform corrosion. Ohmic resistance determined by electrochemical impedance spectroscopy at open circuit at beginning of the tests\u003c/p\u003e\n \u003cp\u003e-Ambient temperature 23\u0026thinsp;\u0026plusmn;\u0026thinsp;2 \u003csup\u003eo\u003c/sup\u003eC, ambient pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCurrent density (\u003cem\u003ecd\u003c/em\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eSign convention: the current density (\u003cem\u003ecd) i\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e calculated from mass loss is positive, the hydrogen evolution \u003cem\u003ecd i\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2\u003c/em\u003e\u003c/sub\u003e is negative, and the external \u003cem\u003ecd i\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e follows the common convention (anodic\u0026thinsp;=\u0026thinsp;positive). Charge balance, expressed as \u003cem\u003ecd\u0026rsquo;s\u003c/em\u003e:\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ei\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003em\u003c/strong\u003e\u003c/sub\u003e \u003cstrong\u003e+\u003c/strong\u003e \u003cstrong\u003ei\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eH2\u003c/strong\u003e\u003c/sub\u003e \u003cstrong\u003e=\u003c/strong\u003e \u003cstrong\u003ei\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003ee\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e(Eq.\u0026nbsp;1)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eOverall reaction stoichiometry used in calculations:\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e2 H\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eO\u0026thinsp;+\u0026thinsp;2e\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e\u0026minus;\u003c/strong\u003e\u003c/sup\u003e \u003cstrong\u003e= H\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u0026thinsp;\u003cstrong\u003e+\u0026thinsp;2 OH\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e\u0026minus;\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e(Eq.\u0026nbsp;2)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eMg\u0026thinsp;+\u0026thinsp;2 OH\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e\u0026minus;\u003c/strong\u003e\u003c/sup\u003e \u003cstrong\u003e= Mg(OH)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e \u003cstrong\u003e+ 2e\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e\u0026minus;\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e(Eq.\u0026nbsp;3)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eTest solutions\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSolution*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003epH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSpecific conductivity, \u003cem\u003e\u0026kappa;\u003c/em\u003e (mS/cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDensity,\u003c/p\u003e\n \u003cp\u003e\u003cem\u003e\u0026rho;\u003c/em\u003e (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBorate buffer:\u003c/p\u003e\n \u003cp\u003e0.1 M B(OH)\u003csub\u003e3\u003c/sub\u003e + 0.1 M B(OH)\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.004\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBorate buffer\u003c/p\u003e\n \u003cp\u003e+ 0.1 M NaCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.011\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBorate buffer\u003c/p\u003e\n \u003cp\u003e\u0026thinsp;+\u0026thinsp;0.3 M NaCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.017\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBorate buffer\u003c/p\u003e\n \u003cp\u003e+ 1.0 M NaCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.045\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBorate buffer\u003c/p\u003e\n \u003cp\u003e+ 3.0 M NaCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e183 [\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.124\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e* Test solution properties at 25 \u003csup\u003eo\u003c/sup\u003eC. Analytical reagent grade chemicals and distilled water. All the values were measured in-house except the conductivity of the most concentrated solution, which was estimated from literature data [\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eAbbreviations: WE, RE, AE: working, reference and auxiliary electrodes, respectively. OCP: open-circuit potential,\u0026nbsp;\u003cbr\u003e\u003cem\u003esd\u003c/em\u003e: standard deviation, TRIS: tris(hydroxymethyl)aminomethane.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e4.1 Potentiostatic polarisation tests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComments\u003c/strong\u003e: The corrosion was uniform, except at the very lowest potential (-2.61 V). Thin, nearly invisible corrosion product layers were formed on the uniformly corroded electrodes. \u003cem\u003ei\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e exhibited two more or less potential independent ranges, -2.3 V to -1.4 V and above -1.3 V. \u003cem\u003ei\u003csub\u003ee\u003c/sub\u003e\u003c/em\u003e approached the value of \u003cem\u003ei\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e above -1.4 V, with visible\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e gas evolution disappearing. The observed dip in \u003cem\u003ecd\u0026rsquo;s\u003c/em\u003e around -2.5 V and the sharp increase at even lower potentials are consistent with previous reports of such behaviour [1,10\u0026ndash;12].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2 Linear polarisation scans with H\u003csub\u003e2\u003c/sub\u003e gas evolution rate measurement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComments\u003c/strong\u003e: The slow potentiodynamic polarisation curves in Fig. 2a show mostly the same features as the potentiostatic steady-state data in Fig.1. The \u003cem\u003ei\u003c/em\u003e\u003cem\u003e\u003csub\u003eH2\u0026nbsp;\u003c/sub\u003e\u003c/em\u003e(calc)\u0026nbsp;curve included from Fig. 1 shows fair agreement with the measured \u003cem\u003ei\u003csub\u003eH2\u003c/sub\u003e\u003c/em\u003e curve. The Tafel slopes of the \u003cem\u003ei\u003csub\u003eH2\u003c/sub\u003e\u003c/em\u003e curves varied from 400 to 800 mV/decade. In the presence of 0.1 M NaCl, localised corrosion with anomalous\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e evolution started at around -1.15 V and lasted to the end of the scan. This topic is studied further in Fig. 3.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.3 Effect of NaCl concentration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComments\u003c/strong\u003e: In the borate solution with 0.1 M NaCl, the localised corrosion and anomalous\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e evolution started at \u003cem\u003eE\u003csub\u003ep\u003c/sub\u003e\u003c/em\u003e \u0026asymp;\u0026nbsp;-1.2 V and lasted to \u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e \u0026asymp;\u0026nbsp;3.9 V. Both \u003cem\u003eE\u003csub\u003ep\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e decreased with increasing NaCl concentrations, to\u0026nbsp;\u0026asymp; -1.47 V and \u0026asymp; -1.2 V, respectively, in the solution with 3.0 M NaCl. Note that the variations in both\u0026nbsp;\u003cem\u003eE\u003csub\u003ep\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e between the duplicated tests were\u0026nbsp;\u0026asymp;\u0026nbsp;0.5 V to 1 V. Still the decreasing trend is clear.\u0026nbsp;Also note the\u0026nbsp;frequent bursts in\u0026nbsp;\u003cem\u003ei\u003csub\u003eH2\u003c/sub\u003e\u003c/em\u003e above\u0026nbsp;\u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e, which corresponded to peaks in\u0026nbsp;\u003cem\u003ei\u003csub\u003ee\u003c/sub\u003e\u003c/em\u003e.\u0026nbsp;\u003cem\u003ei\u003csub\u003ee\u003c/sub\u003e\u003c/em\u003e remained high to the end of the scans. The corrosion rates were very high, and\u0026nbsp;\u003cem\u003ei\u003csub\u003ee\u003c/sub\u003e\u003c/em\u003e increased considerably with increasing NaCl concentration. This may be partly caused by the decreasing pH with increasing NaCl concentration (Section3). The calculated average corrosion depths at the end of the scans thus varied from 0.5 mm to 3.4 mm with 0.1 M to 3.0 M NaCl, respectively.\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eComparison of the polarisation curves in Figs.1-2 with similar curves published for tests in carbonate buffer solutions [1,3] reveals significant differences, which suggests that solution-specific features are present in one, or both, of these chemistries. Nonetheless, the transition to localised corrosion appears to follow the trends seen for pure NaCl solutions, such as the formation of black, filiform-like localised attacks with\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e evolution starting from the attacks.\u003c/p\u003e\n\u003cp\u003eThe decreasing trend of \u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e with increasing NaCl concentration may be interpreted as an effect of increasing solution conductivity which lowers the ohmic potential drop in deep localised attacks, thereby bringing the electrode potential in the localised attacks gradually above the thermodynamic limit of\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e evolution. Sporadic new events of localised corrosion still caused burst of\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e evolution above \u003cem\u003eE\u003csub\u003eHE drop\u003c/sub\u003e\u003c/em\u003e.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e The author has no conflicts of interest related to the content of this data set. The author is the owner and an employee of Gulbrandsen Technology AS. The company has no commercial or financial interests in the topic of this article. No funding was received for conducting this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e The raw data for the graphs presented here are available from the author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eE. Gulbrandsen, Anodic behaviour of Mg in HCO3\u0026minus;/CO32\u0026minus; buffer solutions. Quasi-steady measurements, Electrochim Acta 37 (1992) 1403\u0026ndash;1412. https://doi.org/10.1016/0013-4686(92)87014-Q.\u003c/li\u003e\n\u003cli\u003eP. Gore, V.S. Raja, N. Birbilis, Use of sodium bicarbonate as a chloride-free aqueous electrolyte to explore film formation and the negative difference effect on pure magnesium, J Electrochem Soc 165 (2018) C849\u0026ndash;C859. https://doi.org/10.1149/2.0171813jes.\u003c/li\u003e\n\u003cli\u003eE. Gulbrandsen, Quantification of hydrogen evolution in corrosion testing by buoyancy measurements, (2025). https://doi.org/10.21203/rs.3.rs-5726344/v1.\u003c/li\u003e\n\u003cli\u003eT.W. Cain, I. Gonzalez-Afanador, N. Birbilis, J.R. Scully, The role of surface films and dissolution products on the negative difference effect for magnesium: Comparison of Cl- versus Cl- free solutions, J Electrochem Soc 164 (2017) C300\u0026ndash;C311. https://doi.org/10.1149/2.1371706jes.\u003c/li\u003e\n\u003cli\u003eL. Rossrucker, A. Samaniego, J.-P. Grote, A.M. Mingers, C.A. Laska, N. Birbilis, G.S. Frankel, K.J.J. Mayrhofer, The pH Dependence of Magnesium Dissolution and Hydrogen Evolution during Anodic Polarization, J Electrochem Soc 162 (2015) C333\u0026ndash;C339. https://doi.org/10.1149/2.0621507jes.\u003c/li\u003e\n\u003cli\u003eS. Lebouil, O. Gharbi, P. Volovitch, K. Ogle, Mg Dissolution in Phosphate and Chloride Electrolytes: Insight into the Mechanism of the Negative Difference Effect, CORROSION 71 (2015) 234\u0026ndash;241. https://doi.org/10.5006/1459.\u003c/li\u003e\n\u003cli\u003eCorrosion of metals and alloys - Conventions applicable to electrochemical measurements in corrosion testing, ISO 17474:2012(E) (2012).\u003c/li\u003e\n\u003cli\u003eASTM G1-03 Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens, (n.d.). https://doi.org/10.1520/G0001-03R17E01.\u003c/li\u003e\n\u003cli\u003eR.C. Weast, CRC Handbook of Chemistry and Physics, 63rd ed., CRC Press, Boca Raton, Fl, 1982.\u003c/li\u003e\n\u003cli\u003eP.F. King, Magnesium as a Passive Metal, J Electrochem Soc 110 (1963) 1113. https://doi.org/10.1149/1.2425600.\u003c/li\u003e\n\u003cli\u003eA.P. Nazarov, T.A. Yurasova, Anodic Dissolution of Magnesium under Positive and Negative Difference Effects, Protection of Metals 32 (1996) 28\u0026ndash;31.\u003c/li\u003e\n\u003cli\u003eM. Curioni, The behaviour of magnesium during free corrosion and potentiodynamic polarization investigated by real-time hydrogen measurement and optical imaging, Electrochim Acta 120 (2014) 284\u0026ndash;292. https://doi.org/10.1016/j.electacta.2013.12.109.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Gulbrandsen Technology AS","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"magnesium, borate buffer solution, localised corrosion, anomalous hydrogen evolution","lastPublishedDoi":"10.21203/rs.3.rs-6837551/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6837551/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis report summarises the results of polarisation tests on high-purity (99.95 %) magnesium electrodes in borate buffer solutions at pH 9.2, pure or with additions of NaCl (0.1 M to 3.0 M). The investigation included both potentiostatic tests with mass loss determinations and potentiodynamic tests with H\u003csub\u003e2\u003c/sub\u003e gas evolution measurements. The corrosion was uniform in the absence of chloride ions, and the hydrogen evolution rate decreased steadily towards zero upon anodic polarisation above the open-circuit potential. Addition of chloride caused localised corrosion at anodic polarisation together with anomalous H\u003csub\u003e2\u003c/sub\u003e evolution from the localised attacks. The anomalous H\u003csub\u003e2\u003c/sub\u003e evolution rate started decreasing when a certain applied polarisation was reached. The potential at which this drop initiated decreased as the NaCl concentration increased. This observation may be interpreted as an effect of increasing solution conductivity lowering a high ohmic resistance in the localised attacks.\u003c/p\u003e","manuscriptTitle":"Anodic and cathodic polarisation of magnesium in borate buffer solutions with and without addition of chloride","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-10 04:29:02","doi":"10.21203/rs.3.rs-6837551/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9a806a41-5c11-4316-a306-15ab2e20e8a6","owner":[],"postedDate":"June 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":49665876,"name":"Materials Chemistry"}],"tags":[],"updatedAt":"2025-06-10T04:29:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-10 04:29:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6837551","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6837551","identity":"rs-6837551","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}