Threshold Chloride Concentration for Passivity Breakdown of Mg–Zn–Gd–Nd–Zr Alloy (EV31A) in Basic Solution

Ninlachart, Jakraphan; Raja, Krishnan S.

doi:10.1007/s40195-017-0548-9

Cited by 9 publications

(9 citation statements)

References 41 publications

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“…Subsequently, the secondary passivation takes place in the potential range of 0.9 V SHE to 1.1 V SHE , mainly because of the growth of protective Fe 3+ -based film. When the applied potential reaches above 1.1 V SHE , the current density starts to enlarge noticeably because of the oxygen evolution in equation (2) (Ninlachart and Raja, 2017; Cheng et al , 2018): It is seen from Figure 5 that the oxygen evolution potential decreases slightly from about 1.19 V SHE to 1 V SHE with increasing solution temperature from 25°C to 80°C. The oxygen evolved on the specimen surface may reduce the pitting sensitivity of SS (Liao et al , 2012; Wyllie and Duquette, 1998).…”

Section: Resultsmentioning

confidence: 95%

Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

Zhang

Liu

et al. 2020

ACMM

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Purpose The purpose of this paper is to investigate the electrochemical corrosion behavior of type 444 stainless steel (SS) in synthetic tap water from 25°C to 80°C, i.e. the operation environment of the electric water heater. Design/methodology/approach The corrosion behavior was studied by using electrochemical measurements such as electrochemical impedance spectroscopy and polarization curve. The specimen surfaces were observed with scanning electron microscopy. The passive films were characterized with X-ray photoelectron spectroscopy. Findings In the typical tap water, 444 SS passivates spontaneously under different temperatures. The passive films formed at higher temperatures contain relatively less Cr-species and more Cl− ions, resulting in lower polarization resistances. The stable pitting corrosion takes place in the potential region of oxygen evolution as the temperature increases to about 55°C. The critical Cl− concentration of pitting corrosion reduces from about 160 mg L−1 to 60 mg L−1 with changing temperature from 25°C to 80°C. Practical implications The pitting corrosion probability was assessed through the statistical analysis of tap water quality. The results are useful for the application of 444 SS as well as the design of electric water heater. Originality/value This paper shows the variation of polarization resistance, pitting potential, passive film composition and critical pitting chloride concentration with the temperature of tap water. It is of great significance for the development and application of SS in tap water environments.

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Section: Resultsmentioning

confidence: 95%

Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

Zhang

Liu

et al. 2020

ACMM

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“…These particles were identified as Zr-rich phase, Mg 5 Nd or Mg 7 Zn 3 . 28 The average grain size of the EV31A specimen was about 60 μm. 3a-3c show the anodic polarization behaviors of the Mg, ZE10A and EV31A alloy specimens in the 0.6M NaCl, 0.1M Na 2 SO 4 and 0.5M NaNO 3 solutions, respectively.…”

Section: Resultsmentioning

confidence: 97%

Mg-RE Alloy Anode Materials for Mg-Air Battery Application

Shrestha

Raja

Utgikar

2019

J. Electrochem. Soc.

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Commercial purity Mg, Mg-RE alloys ZE10A (UNS M11600), and EV31A (UNS M12310) were evaluated in the as-received condition for potential application as anode for Mg-air battery. Anodic and cathodic polarization studies were performed in 0.6 M of NaCl, 0.5 M of NaNO 3 and 0.1 M of Na 2 SO 4 . Hydrogen evolved during anodic polarization was measured at different current densities. Electrochemical impedance spectroscopy was carried out at open circuit conditions, and galvanostatic conditions. The results showed that commercial purity magnesium had higher corrosion resistance than the Mg-RE alloy specimens in all the electrolytes tested. All the specimens showed negative difference effect (NDE) where the rate of hydrogen evolution increased with increased anodic polarization. The NDE was more pronounced on ZE10A than on other materials. The results suggest that EV31A could be a potential anode material for Mg-air battery due to its better discharge capabilities. The surface layer formed on the Mg specimen showed predominantly a p-type semiconductivity with a charge carrier density in the order of 10 21 cm −3 . The Mg-RE alloys showed a dual layered surface layer with bottom n-type and top p-type characters. The p-type behavior could be associated with the formation cation vacancies due to dissolution of Mg from its lattice site, and the n-type semiconductivity could be attributed to segregation of trivalent rare earth cations at the metal/oxide interface. The enhanced NDE behavior of the Mg-RE alloys could also be attributed to the surface enrichment of Zr, and presence of Mg x RE y type secondary phases.

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“…1f According to the results of the annealed alloys #1-7, the phase relationship of Mg-Zn-Zr in Zn-rich at 400°C was determined. The homogeneity ranges of s 1 were detected to be Mg (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) Zn (80-88) Zr (4)(5)(6) . Besides, the solubility of Mg in the Zn 3 Zr, Zn 39 Zr 5 and Zn 22 Zr is negligibly little at 400°C.…”

Section: Resultsmentioning

confidence: 99%

“…Isothermal section at 400°C of the Mg-Zn-Zr was determined and constructed by using the equilibrated alloy method in the present work. Three ternary phases, s 1 , s 2 and s 3 , stably exist at 400°C, and the homogeneity ranges of them were, respectively, determined to be Mg (7-17)-Zn (80-88) Zr (4)(5)(6) , Mg (15)(16)(17)(18)(19)(20)(21)(22) Zn (66-68) Zr (9)(10)(11)(12)(13)(14)(15)(16) and Mg 9 Zn 68-Zr 23 . The crystal structure of s 1 is still unclear.…”

Section: Resultsmentioning

confidence: 99%

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Experimental Investigation of the Mg–Zn–Zr Isothermal Section at 400 °C

Liang

Liu

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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Mg-Zn-Zr series Mg alloys (ZK) are one of the most important commercial Mg alloys due to their good comprehensive mechanical properties. The phase equilibria of the Mg-Zn-Zr system at 400°C covering the overall composition range were investigated by X-ray diffraction and electron probe microanalyses on thirteen ternary alloys. Three ternary compounds, s 1 , s 2 and s 3 , were detected to be thermodynamically stable at 400°C, and their homogeneity range was determined to be Mg (7-17) Zn (80-88) Zr (4-6) , Mg (15-22) Zn (66-68) Zr (9-16) and Mg 9 Zn 68 Zr 23 (in at.%), respectively. Eight three-phase regions and four two-phase regions were observed. The maximum solubility of Mg in Zn 22 Zr, Zn 39 Zr 5 and Zn 3 Zr phases was measured to be 0.52, 0.37 and 0.99 at.%, respectively, while the solubility of Zr in MgZn 2 and Mg 2 Zn 3 phases is negligible. The isothermal section of the Mg-Zn-Zr system at 400°C was then constructed based on the present experimental data.

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Threshold Chloride Concentration for Passivity Breakdown of Mg–Zn–Gd–Nd–Zr Alloy (EV31A) in Basic Solution

Cited by 9 publications

References 41 publications

Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

Mg-RE Alloy Anode Materials for Mg-Air Battery Application

Experimental Investigation of the Mg–Zn–Zr Isothermal Section at 400 °C

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