Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings
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Authors
Organisational units
External Organisational units
- Voestalpine Eifeler Vacotec GmbH, Düsseldorf
- Helmholtz-Zentrum Dresden-Rossendorf
- ESRF
- Christian Doppler Laboratory for Advanced Synthesis of Novel Multifunctional Coatings
- University of Jyvaskyla
- Erich Schmid Institute of Materials Science
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
Original language | English |
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Pages (from-to) | 91-100 |
Number of pages | 10 |
Journal | JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY |
Volume | 100.2022 |
Issue number | 20 February |
Early online date | 9 Sept 2021 |
DOIs | |
Publication status | Published - 20 Feb 2022 |