Passive and transpassive films formed on a nickel alloy in ammoniacal solution

E. Asselin, A. Alfantazi, S. Rogak

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The surface of alloy 625 (Ni-22Cr-9Mo) was characterized with XPS and AES depth profiling after exposure to mildly alkaline ammoniacal solution at open circuit andafterpotentiostatic treatments at various potentials. Itwas determined that thepassive surface film was a Cr and Mo oxide that was depleted in Ni with respect to the bulk alloy. Increased solution temperatures or oxygen concentrations decreased the Ni to Cr ratio in the passive film. The alloy's transpassive film was characterized using SEM and EDX as well as XPS. The transpassive film was heavily depleted in Ni and Cr and consisted mainly of an oxide of Fe.

Original languageBritish English
Pages (from-to)489-495
Number of pages7
JournalSurface and Interface Analysis
Volume41
Issue number6
DOIs
StatePublished - Jun 2009

Keywords

  • AES
  • Alloy 625
  • Ammonia
  • Ni alloys
  • Passive film
  • XPS

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