| DOI | Resolve DOI: https://doi.org/10.1007/s11085-017-9823-4 |
|---|
| Author | Search for: Chen, Kuiying1; Search for: Zhao, Linruo1; Search for: Fu, Ming; Search for: Patnaik, Prakash C.1 |
|---|
| Affiliation | - National Research Council of Canada. Aerospace
|
|---|
| Format | Text, Article |
|---|
| Subject | coefficient of thermal expansion; Pt effect; β-NiAl coating; α-Al2O3 scale; Ab initio density functional theory; phonon dispersion; interfacial stress; thermal cycling |
|---|
| Abstract | The beneficial effect of adding Pt in diffusion β-NiAl coating on reducing the tensile stress normal to the coating/α-Al2O3 scale interface has been investigated using a combination of ab initio density functional theory (DFT), phonon dispersion theory and mechanics-based interfacial stress modeling. The coefficient of thermal expansion (CTE) for Pt, β-NiAl and β-NiAl-6.25 at% Pt was calculated using the total energy DFT combined with the phonon dispersion theory. The calculated CTE of β-NiAl and β-NiAl-6.25 at% Pt and experimentally measured CTE of α-Al2O3 were used to evaluate the tensile stress of the undulated β-NiAl/α-Al2O3 and β-NiAl-6.25 at% Pt/α-Al2O3 interfaces resulting from the CTE mismatch between the coating and the oxide scale during cooling from elevated temperatures. It was found that the addition of Pt to β-NiAl is capable of lowering the interfacial tensile stress as a result of the reduced CTE of the Pt-modified β-NiAl coating, thus beneficial for improving thermal cyclic durability of the coating. The calculated results showed that the interfacial tensile stress is a function of oxide scale thickness and the interfacial wave amplitude and wavelength of an undulated interface. A thicker oxide scale and a rougher interface with a larger ratio of wave amplitude versus wavelength yield higher interfacial tensile stresses during thermal cycling. The addition of 6.25 at% Pt to β-NiAl coating reduces the coating/oxide scale interfacial tensile stress by about 27% over a wide range of scale thickness and interfacial wave amplitude and wavelength. |
|---|
| Publication date | 2017-12-18 |
|---|
| Publisher | Springer |
|---|
| In | |
|---|
| Language | English |
|---|
| Peer reviewed | Yes |
|---|
| Export citation | Export as RIS |
|---|
| Report a correction | Report a correction (opens in a new tab) |
|---|
| Record identifier | b8a1f688-0f10-4ac4-8cb4-cfed2ccee386 |
|---|
| Record created | 2019-05-03 |
|---|
| Record modified | 2020-03-16 |
|---|
