Element-resolved electrochemical database: AESEC polarization curves of ZnAlMg alloy coating constituents

Abstract

An element-resolved electrochemical database of a ZnAlMg alloy coating is presented, obtained via atomic emission spectroelectrochemistry (AESEC) linear sweep voltammetry (LSV). Nominally pure Zn, Al and Mg metals as well as MgZn2, ZnAl intermetallic phases, and commercial ZnAl alloy coatings were investigated using AESEC-LSV to understand the complex electrochemical response of multi-phase ZnAlMg alloys. The elemental dissolution rates extrapolated from AESEC-LSV curves showed a linear relationship with spontaneous elemental dissolution rates. This demonstrates the possible use of AESEC-LSV for determining long-term elemental corrosion rates, as well as the use of element-specific electrochemical data as input parameters for more accurate machine learning based corrosion resistant alloy design. Element-resolved electrochemistry reveals important corrosion phenomena not detectable in conventional electrochemistry such as cathodic dissolution, chemical dissolution, cathodic dealloying, negative correlation effects, and anomalous hydrogen evolution. These phenomena may be significant and should be taken into account in the rate equations used for numerical modeling.