The Corrosion Behavior of Ni-Cr-Mo Ternary Alloys in Hot Concentrated Sulfuric Acids with Active Carbon (Part 1)

Katsuo Sugahara, Yoshio Takizawa, Eiji Akiyama, Koji Hashimoto

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In order to prevent dew point corrosion by sulfuric acid, the roles of chromium and molybdenum in enhancing the corrosion resistance in 60 and 80% H2SO4, at 120°C were investigated. Particular attention was paid to the addition of active carbon to H2SO4. The chromium contents of alloys were 16 and 20% and the molybdenum contents were 17, 20, 24 and 25%. In carbon-free H2SO4 increasing molybdenum content gives rise to a decrease in corrosion rate and Ni-20Cr-24Mo alloy shows high corrosion resistance by spontaneous passivation forming a remarkably molybdenum-enriched passive film. In carbon-containing H2SO4 increasing chromium content is effective in decreasing the corrosion rate. Three Ni-20Cr-Mo alloys are spontaneously passive in 80% H2SO4 with carbon. Because the carbon addition increases the open circuit potential exceeding the stability limit of tetravalent molybdenum as a result of enhancement of the cathodic activity, the spontaneously passivated film consists of remarkably concentrated chromium ions along with some molybdenum ions.

Original languageEnglish
Pages (from-to)643-650
Number of pages8
JournalZairyo to Kankyo/ Corrosion Engineering
Volume46
Issue number10
DOIs
Publication statusPublished - 1997 Jan 1

Keywords

  • Active carbon
  • Dew point corrosion
  • Hot sulfuric acid
  • Ni-cr-mo alloy
  • XPS

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrochemistry
  • Materials Chemistry

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