Influence of Thermal Aging on Interface Delamination of Thermal Barrier Coatings
Bibliographic record
Abstract
Knowledge of the degradation mode in thermal barrier coatings (TBCs) is a prerequisite for the prediction of their remaining life of gas turbine blades. This paper describes the effects of thermal aging on the microstructure in a YSZ-based thermal barrier coating system deposited on Ni based superalloy substrates. The heat treatment of the TBC specimens were conducted at 1373K for 100h, 500h and 1000h in air for thermal aging. The thermally aged coating system had thermally grown oxide (TGO) layer between the substrate and the TBC. TGO consisted of not only alumina but also other oxides. This oxide layer that named mixed oxides (MO) is composed of Ni, Co, Cr and O. Double cantilever beam (DCB) tests and 4 point bending tests were carried out in order to evaluate the TBC/substrate interface strength. The interface strength depended on the period of thermal aging in both type of tests. The interface strength increased initially up to the aging time of 100h, and then decreased drastically for the longer aging time. In DCB tests, crack propagated in the middle of YSZ layer for the thermally aged specimens, whereas delamination took place close to the YSZ-bondcoat interface in the unheated specimens. In 4 point bending tests, crack propagated along the interface between TBC and substrate. These results suggested that the interface strength depended on not only the formation of oxides but also the fracture properties of the top coatings.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".