Electrochemical Scanning Techniques for the Examination of Bi-Metallic Coins. (10th March 2015)

• Record Type: Journal Article
• Authors: Searle, Justin Royston; Glover, Carol Frances; Khan, Khalil; Wilson, Benjamin Paul; Williams, Geraint; Worsley, David A
• Is Part Of: ECS transactions. Volume 64:Number 28(2014)
• Page Start: 47
• Page End: 59
• Publication Date: 2015-03-10
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/06428.0047ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : Scanning Kelvin Probe (SKP) and the 3D Scanning Vibrating Electrode Technique (3D-SVET) have been used to examine a selection of bi-metallic coins. The SKP has first been used to identify the electrochemical compatibility of the two alloys and inform a prediction of the anodic and cathodic regions observed in the 3D-SVET experimentation, performed in artificial sweatsolution. This is compared to open circuit potential (OCP) measurements, also measured in artificial sweat. It was observed that the SKP in atmospheric conditions records larger potential differences between the alloys than that observed in OCP under immersion conditions, however the relative activity is consistent across all 3 techniques. The 3D-SVET clearly identifies galvanic corrosion as a result of the differences in the galvanic activity between the two alloys. The anodic activity is predominantly on the nickel brass section of the coin, while the cathodic activity remains on the cupronickel portion.