Porous APS YSZ TBC Manufactured at High Powder Feed Rate (100 g/min) and Deposition Efficiency (70%): Microstructure, Bond Strength and Thermal Gradients
Bibliographic record
Abstract
Abstract There is a strong driving force to improve the production efficiency of thermal barrier coatings (TBCs) manufactured via air plasma spray (APS). To address this need, the high-enthalpy APS torch Axial III Plus was employed to successfully manufacture TBCs by spraying a commercial YSZ feedstock at powder feed rate of 100 g/min using an optimized set of N 2 /H 2 spray parameters; which yielded an impressive YSZ deposition efficiency (DE) value of 70%. This exact same set of optimized spray parameters was used to manufacture the same identical YSZ TBC (over ~160 µm-thick bond-coated substrates) but at two distinct YSZ thickness levels: (i) ~420 µm-thick and (ii) ~930 µm-thick. In spite of the high YSZ feed rate and DE levels, the YSZ TBC revealed a ~14% porous (conventional looking) microstructure, without segmented cracking or horizontal delamination at both thickness levels. The bond strength values measured via the ASTM C633 standard for the ~420 µm-thick and ~930 µm-thick YSZ TBCs were ~13.0 and ~11.6 MPa (respectively); which are among at the upper end values reported in the literature. After the first objective was attained, the second key objective of this work was to evaluate the thermal insulating effectiveness of these two as-sprayed YSZ TBCs. To achieve this objective, a thermal gradient laser-rig was employed to generate a temperature reduction (ΔT) along the TBC-coated coupons under different laser power levels. These distinct laser power levels generated YSZ TBC surface temperatures varying for 1100 to 1500 °C, for the ~420 µm-thick YSZ TBC, and from 1100 to 1680 °C YSZ TBC ~930 µm-thick YSZ TBC. The respective ΔT values for both TBCs are reported. The results of this engineering paper are promising regarding the possibility of improving considerably the manufacturing efficiency of industrial quality conventional-looking porous YSZ TBCs, by using a high-enthalpy N 2 -based APS torch. This is the first paper published in the open literature showing R&D results of coatings manufactured via the Axial III Plus APS torch.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 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 | 0.000 | 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 source (direct Gemma or distilled Codex), 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".