The effect of pre-oxidation of chromia and alumina forming alloys on erosion in laboratory simulated fluidized-bed conditions

Margaret Stack, F.H. Stott, G.C. Wood

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The effects of pre-oxidation of alloys have been investigated in laboratory simulated fluidized bed erosion-corrosion environments. Two alloys, Incoloy 800H and Fecralloy, which formed chromia and alumina respectively, under steady state oxidation conditions, were tested. The research consisted of preoxidizing the alloys in a range of oxidation environments. including air, oxygen and H-2/H2O. The scales were then examined and analysed to determine the composition and adhesion to the metal. The erosion-corrosion tests were carried out at 500-degrees-C, using 200-mu-m silica as erodent, at velocities of 1.9 m s-1, and for exposure times of up to 168 h. The specimens were analysed subsequently by analytical scanning electron microscopy and X-ray diffraction. The pre-oxidation results showed that. for both alloys, the scales formed in H-2/H2O were more adherent and slower growing than those formed in air or oxygen. The erosion-corrosion tests on pre-oxidized specimens indicated that the scales formed in H-2/H2O were the most resistant to particle impacts. The results also showed that pre-oxidized Incoloy 800H eroded more rapidly than pre-oxidized Fecralloy. As the erosion-corrosion rates of the two non pre-oxidized alloys were dissimilar to each other, it was not possible to establish whether there was a significant difference between the erosion resistance of the pre-formed scales. under these conditions. Possible reasons for the improved performance of the scales formed in low oxygen pressures are discussed. The differences in erosion-corrosion rates of the alloys are also addressed, with emphasis on alloy deformation characteristics and transient oxidation rates.

Original languageEnglish
Pages (from-to)965-983
Number of pages19
JournalCorrosion Science
Volume33
Issue number6
DOIs
Publication statusPublished - Jun 1992

Keywords

  • corrosion
  • oxidation
  • alloys

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