Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings

Publikationen: Beitrag in FachzeitschriftArtikelForschung(peer-reviewed)

Autoren

Externe Organisationseinheiten

  • Voestalpine Eifeler Vacotec GmbH, Düsseldorf
  • Helmholtz Zentrum Dresden-Rossendorf
  • European Synchrotron Radiation Facility
  • Christian Doppler Labor für Hochentwickelte Synthese neuartiger multifunktionaler Schichten, Leoben
  • University of Jyväskylä
  • Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, Leoben

Abstract

The resistance of wear protective coatings against oxidation is crucial for their use at high temperatures. Here, three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%, 2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry, thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their Si-content. Additionally, a partially oxidized AlCrSiN coating with 5 at.% Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition, morphology, phases and residual stress evolution of the oxide scale and the non-oxidized coating underneath. The results reveal enhanced oxidation properties of the AlCr(Si)N coatings with increasing Si-content, as demonstrated by a retarded onset of oxidation to higher temperatures from 1100°C for AlCrN to 1260°C for the Si-containing coatings and a simultaneous deceleration of the oxidation process. After annealing of the AlCrSiN sample with 5 at.% Si at an extraordinary high temperature of 1400°C for 60 min in ambient air, three zones developed throughout the coating strongly differing in their composition and structure: (i) a dense oxide layer comprising an Al-rich and a Cr-rich zone formed at the very top, followed by (ii) a fine-grained transition zone with incomplete oxidation and (iii) a non-oxidized zone with a porous structure. The varying elemental composition of these zones is furthermore accompanied by micro-structural variations and a complex residual stress development revealed by cross-sectional X-ray nanodiffraction. The results provide a deeper understanding of the oxidation behavior of AlCr(Si)N coatings depending on their Si-content and the associated elemental, microstructural and residual stress evolution during high-temperature oxidation.

Details

OriginalspracheEnglisch
Seiten (von - bis)91-100
Seitenumfang10
FachzeitschriftJOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
Jahrgang100.2022
Ausgabenummer20 February
Frühes Online-Datum9 Sep 2021
DOIs
StatusVeröffentlicht - 20 Feb 2022