Effects of internal oxide contents on the oxidation and β-phase depletion behaviour in HOVF CoNiCrAlY coatings

H. Chen, M. Fan, L. Li, W. Zhu, H. N. Li, J. Li, Y. Yin

Research output: Journal PublicationArticlepeer-review

2 Citations (Scopus)

Abstract

This paper studied the effects of internal oxide contents on the high temperature oxidation and β-phase depletion behaviour of high velocity oxygen fuel (HVOF) thermally sprayed CoNiCrAlY coatings. Two oxygen-to-kerosene ratios were employed in the HVOF thermal spraying process to generate different internal oxide contents in the as-deposited CoNiCrAlY coatings. The isothermal oxidation behaviour of the as-deposited CoNiCrAlY coatings were examined in air at 1100 °C. The as-deposited HVOF CoNiCrAlY coatings before and after oxidation were characterised by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was shown that the high oxygen-to-kerosene ratio caused significant oxidation of in-flight particles, resulting in a large volume fraction of the internal oxides in the as-deposited CoNiCrAlY coatings. Furthermore, it was found that the CoNiCrAlY coating with a higher content of internal oxides exhibited larger mass gain and significant β-phase depletion during oxidation. This is likely due to that the Al in the coating was initially consumed during the spraying process and the discrete internal oxide stringers were not effective diffusion barriers.

Original languageEnglish
Article number127666
JournalSurface and Coatings Technology
Volume424
DOIs
Publication statusPublished - 25 Oct 2021

Keywords

  • CoNiCrAlY coatings
  • HVOF thermal spray
  • Internal oxides
  • Oxidation
  • β-Phase depletion

ASJC Scopus subject areas

  • Chemistry (all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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