Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

• Published in: Journal of physics. Conference series 2017-04, Vol.817 (1), p.12067
• Main Authors: Sugiarti, E, Zaini, K A, Sundawa, R, Wang, Y, Ohnuki, S, Hayashi, S
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Carbon steel; Coatings; Diffusion barriers; Extreme environments; High temperature; Low carbon steels; Morphology; Oxidation; Oxidation resistance; Oxidation tests; Physics; Scale (corrosion); Scale formation; Service life; Substrates; Temperature
• ISSN: 1742-6588; 1742-6596; 1742-6596
• DOI: 10.1088/1742-6596/817/1/012067

Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.