A scanning electrochemical microscopy characterization of the localized corrosion reactions occurring on nitinol in saline solution after anodic polarization

Abdelilah Asserghine, Martina Medvidović-Kosanović, Anamarija Stanković, Lívia Nagy, Ricardo M. Souto, Géza Nagy

Research output: Contribution to journalArticle

Abstract

Scanning electrochemical microscopy (SECM) in a combined amperometric/potentiometric operation was used to characterize the electrochemical activity of nitinol, before and after anodic treatment, in 0.1 M NaCl solution. The SECM operation in the feedback mode showed that the nitinol surface was homogeneously passive after surface finishing and storage under ambient conditions, while heterogeneous surface characteristics occurred after application of anodic polarization, even for a limited time. That is, the development of anodic and cathodic sites has been detected due to the onset of localized corrosion processes on the metal surface. The evolution of hydrogen gas from localized sites was monitored using SECM in the substrate generation/tip collection mode (SG/TC), while SECM operated in potentiometric mode was used to map the pH distribution in the electrolyte volume adjacent to the nitinol surface. Local acidification was observed around anodic spots associated with the Ni2+ discharge, as well as alkalinization above the cathodic zones.

Original languageEnglish
Article number128610
JournalSensors and Actuators, B: Chemical
Volume321
DOIs
Publication statusPublished - Oct 15 2020

Keywords

  • Antimony microelectrode
  • Hydrogen evolution
  • Localized corrosion
  • Nitinol
  • Passivity breakdown
  • Scanning electrochemical microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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