Effects of a Magnetic Field on the Intergranular Corrosion of Inconel 690 in NaCl Solution

Abstract

The intergranular corrosion of Inconel 690 alloy in NaCl solution was investigated using in-line digital holography to observe the dynamic processes occurring at the electrode| electrolyte interface in both the absence and presence of a magnetic field (MF). MF reduced the anodic currents by 6 and 3% at 1.1 V in 0.5 M NaCl (pH = 6.44) and 0.5 M NaCl +0.01 M NaOH (pH = 11.5) NaCl solutions respectively because it may increase the amount of Cr on the electrode surface and change the structure of the surface film, thus enhancing the formation of an oxide film; however, MF affected the anodic current little due to the low Lorentz force at the low potential. It was observed that the intergranular corrosion began from a certain grain boundary and developed into other grain boundaries with and without MF. Because the anodic dissolution rate of Fe or Ni is much higher with MF than that without MF and the content of Fe or Ni was higher at a grain boundary than that at the other areas on the surface of the electrode, MF accelerated the intergranular corrosion.

Review of the application of digital holography in corrosion studies

“…The image processing method for reconstructing holograms has been used thus far and has played an important role in corrosion and electrochemical studies. DH reconstruction technology has been widely used, such as in situ observation of the transient concentration gradient in the diffusion layer (Yuan et al , 2008), local corrosion at the interface (Li et al , 2012), the diffusion layer during the rupture processes of the passive film of 800 alloy (Xia et al , 2015), anodic dissolution processes in neutral and acidic sulfate solutions (Hu et al , 2016), monitoring reactions at the interface of lithium-ion batteries (Lai et al , 2017) and the effect of magnetic fields on the IGC of nickel 690 in sodium chloride solution (Xu et al , 2022).…”

Investigation of the effects of the magnetic field on the anodic dissolution of alloy 690 in SO42− + SCN− solution using digital holography

“…The anodic dissolution of Alloy 690 in neutral and alkaline NaCl solutions with or without MF was examined using in-line digital holography. It was shown that MF increased IGC even though it decreased the anodic current [ 18 ]. In-line digital holography can be used to in situ observe the dynamic processes at the interface during an electrochemical reaction and explain the effects of MF on the anodic dissolution of metallic materials [ 15 , [17] , [18] , [19] , [20] ].…”

Surface Characterization Techniques: A Systematic Review of their Principles, Applications, and Perspectives in Corrosion Studies

“…Other QPM and surface measurement techniques.-Aside from the well-researched AFM, VSI, and DHM techniques, there are other varieties of QPM and surface measuring systems, as shown in Table IV that would be relevant for discussion, including in situ scanning tunneling microscopy (STM), 119,[121][122][123] confocal laser scanning microscopy (CLSM), 114,[116][117][118] digital holography (DH) 102,104,105 digital speckle pattern interferometry (DSPI), [100][101][102] in situ special modulation interferometry (SMI) 124 and in situ light reflectivity microscopy, 125,126 etc. Interestingly, their working principles or mode of operation are quite similar to the three systems (AFM, VSI, and DHM) earlier discussed above.…”

“…As demonstrated in Table IV, the technique has been specifically employed to study the surface dissolution evolution of Inconel 600. 105,104 Another device that has been frequently adopted for 3D topography monitoring of alloy corrosion is CLSM, which is a contact-free technique with working distances between a sample and a lens of 1 mm or more. 117 In a typical CLSM configuration, a laser beam (usually an argon laser at a wavelength of 488 nm) scans the sample surface in x-and y-directions and the light intensity reflected from the sample is measured with a detector.…”