Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8024657 | Surface and Coatings Technology | 2017 | 10 Pages |
Abstract
In this work, the critical Al-activity to form a continuous α-alumina was validated by Al-activity calculation using Thermo-Calc software based on survey of research results of critical Al-concentration to form α-alumina on binary Ni-Al and ternary Ni-Cr-Al systems. Long-term oxidation tests were performed to support the criterion: three different MCrAlY coatings coated on IN-792 superalloy substrates were oxidized at 1000 °C for various periods of time up to 10,000 h. The microstructural evolution of MCrAlY coatings was investigated using Scanning Electron Microscope. The near-surface Al concentration and interdiffusion behaviour between substrate and coating were measured using Energy Dispersive X-ray Spectroscopy. The new critical Al-activity criterion has been successfully adopted in α-alumina formation prediction, showing a good agreement with experiment results. Therefore, it can be concluded that the extrapolation of new criterion from binary and ternary systems to multi-alloyed MCrAlY system is reasonable. Furthermore, the partial pressure of oxygen (PO2) in atmosphere has been taken into consideration by combination with Al-activity to calculate the critical chemical reaction constant (K) of formation of α-alumina. The potential applicability of the methodology to predict MCrAlY life is also discussed.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
Pimin Zhang, Kang Yuan, Ru Lin Peng, Xin-Hai Li, Sten Johansson,