High-Temperature Oxidation and Oxide Scale Formation in Plasma-Sprayed CoNiCrAlYRe Coatings

Giovanni Di Girolamo, Alida Brentari, Caterina Blasi, Luciano Pilloni, Emanuele Serra

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Abstract

MCrAlY coatings are usually adopted to improve the environmental resistance of Ni-based superalloy components of turbine engines against high-temperature oxidation and hot corrosion. In this work, CoNiCrAlYRe coatings were produced by atmospheric plasma spraying. The coatings exhibited relatively low oxygen content and porosity. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that the high-temperature exposure at 1383 K (1110 °C) promoted the growth of an oxide scale on the top surface being composed of a continuous and dense Al2O3 inner layer followed by an outer mixed layer (Cr2O3 and spinels). The oxide scale was mainly composed of Al2O3, while the formation of mixed oxides occurred at lesser extent. After high-temperature exposure, the formation of internal oxides in some areas reduced the inter-lamellar cohesion, so that a decrease in microhardness was found.
Original languageEnglish
Pages (from-to)5362 - 5370
Number of pages9
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume45
Issue number12
DOIs
Publication statusPublished - 2014
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Metals and Alloys
  • Mechanics of Materials

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