Environmental, economical and performance impacts of Ar/H2 & N2/H2 plasma sprayed YSZ TBCs
Bibliographic record
Abstract
Since the 1970s the Ar/H2 plasma has been the standard APS gas system employed to deposit YSZ TBCs for the gas turbine industry, particularly regarding the legacy plasma spray torches. Although much less costly and yielding higher YSZ deposition efficiency (DE) levels, N2/H2 plasmas did not become the main stream plasma system. This N2/H2 issue occurred likely due to problems like preliminary APS torch Cu-nozzle erosion (Cu contamination on TBCs) and the tendency to produce denser coatings; potentially leading to TBCs exhibiting higher thermal conductivity (TC) and lower thermal cycle lifetimes. However, in the 21st century, environmental impact and economical aspects are becoming paramount. In addition, the introduction of new technologies (e.g., W-lined Cu nozzles, particle T & V sensors and computer-controlled automation) has increased dramatically the stability and reproducibility of APS processing. Therefore, the N2/H2 plasma concept needs to be revisited with respect to the legacy plasma spray torches; which are still highly used by the gas turbine industry OEMs and service centres worldwide. In this paper different sets of APS YSZ TBCs were deposited via Ar/H2 and N2/H2 plasmas (3MB torch). The DE, TC and furnace cycle test (FCT) were evaluated. The top-performing Ar/H2 and N2/H2 TBCs exhibited equivalent FCT lifetimes and TC values within the 1.15-1.25 W/mK range at 1200oC. Moreover, the top-performing N2/H2 TBC exhibited a 2-fold increase in DE and an overall 55% reduction in production cost when compared to the top-performing Ar/H2 TBC.
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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 | 0.000 | 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 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".