Atomic Emission Spectroelectrochemistry: Real-Time Rate Measurements of Dissolution, Corrosion, and Passivation

Abstract

Atomic emission spectroelectrochemistry (AESEC) is a relatively novel technique that gives real-time elemental dissolution rates for a material/electrolyte combination, either reacting spontaneously or with electrochemical polarization. This methodology gives direct insight into questions such as how specific elements of an alloy interact with one another, or how specific additives in a surface treatment solution will affect different alloying elements or different phases. This paper discusses AESEC instrumentation and presents the basic quantitative relationships between the electrochemical and spectroscopic measurements. A wide range of applications are used to illustrate these relationships including the surface pretreatment of aluminum alloys (etching and deoxidation) and the passivation of Fe-Cr and Ni-Cr alloys. The focus is on the use of in-line inductively coupled plasma atomic emission spectroscopy (ICP-AES), although a brief discussion of similar techniques using in-line inductively coupled mass spectroscopy (ICP-MS) is included.

Potential-pH diagrams considering complex oxide solution phases for understanding aqueous corrosion of multi-principal element alloys

“…To evaluate the current thermodynamic analysis with an experiment, the atomic emission spectroelectrochemistry (AESEC) [49][50][51][52] was introduced to measure the total quantity of dissolved alloy components in aqueous solution, which was shown to be consistent with the 3D-APT and XPS analysis 36,37,52,53 . AESEC measurements of dissolved alloy components were performed in 0.1 M (i.e., mol per liter or molarity) NaCl, pH = 4 solution at applied potentials from 0.00 to 0.34 V vs. SHE.…”

Refining anodic and cathodic dissolution mechanisms: combined AESEC-EIS applied to Al-Zn pure phase in alkaline solution

“…To facilitate the comparison, each profile is presented in arbitrary units. The phase shift of j M and j e * vs. E (ϕ j M ) results from the residence time distribution of the flow cell 5 , which means that it is not frequency dependent but time dependent. The actual phase shift between E and j e (ϕ) was nearly zero in all cases as shown in Fig.…”

“…The AESEC technique has been described in detail elsewhere 5,40 . The working electrode was in contact with the flowing electrolyte in a specially designed flow cell 5,41 with conventional three-electrode system; a Hg/HgO in 0.1 M NaOH (−165 mV vs. SHE) as a reference electrode and a Pt foil as a counter electrode. The elements released from the working electrode were transported to an Ultima 2 C Horiba Jobin-Yvon inductively coupled plasma atomic emission spectrometer (ICP-AES).…”

“…It is often useful to present j e * that represents the measured j e after a numerical convolution with the residence time distribution in the flow cell (a lognormal distribution), thereby allowing a direct comparison between the instantaneous values of j e * and j M (ref. 5 ). Cathodic reactions and the formation of insoluble or slightly soluble species are not directly detected by ICP-AES.…”

“…Atomic emission spectroelectrochemistry (AESEC) provides a direct measurement of elemental dissolution rates 5 . One of the difficulties of this technique is that dissolution may be directly related to a faradaic process, weakly related as in the case of anodic dissolution by way of an oxide intermediate, or unrelated as when dissolution is due to a non-faradaic process.…”