Segregation and microstructural evolution at interfaces of atmospheric plasma sprayed thermal barrier coatings during thermal cycling

Y. Z. Liu, X. B. Hu*

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Segregation and microstructural evolution at interfaces of thermal barrier coatings (TBCs) during thermal cycling were systematically investigated using scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The as-sprayed TBCs were thermally cycled between 1100 °C and ambient temperature up to 3000 cycles. Results show that phosphorus, sulfur, and yttrium co-segregate at the top coat (TC)/bond coat (BC) interface after 3000 cycles. The above co-segregation at the BC/substrate interface was delayed by 1000 cycles. Chemical components of thermally grown oxide (TGO) layers at both the TC/BC and BC/substrate interfaces change from O and Al to O, Al, Cr, Co and Ni as the thermal cycling proceeded. The corresponding oxides in the TGO layers evolved from α-Al2O3 to α-Al2O3, Cr2O3, NiO and spinel phases. Controlled by the element diffusion rate and selective internal oxidation, evolution of the thickness of the TGO layers followed a natural logarithmic law.

Original languageEnglish (US)
Article number153026
JournalJournal of Alloys and Compounds
Volume819
DOIs
StatePublished - Apr 5 2020

Keywords

  • Element segregation
  • Interfacial oxidation
  • Microstructural evolution
  • Oxidation kinetics
  • Scanning transmission electron microscopy (STEM)
  • Thermal barrier coatings (TBCs)

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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