Fabrication of Aluminum-Alumina Metal Matrix Composite Coatings Via Cold Gas Dynamic Spraying at Low Pressure Followed by Friction-Stir Processing
Bibliographic record
Abstract
Abstract Cold gas dynamic spraying (“cold spraying”) at low pressure (150 psig) was used to fabricate Al-Al2O3 metal-matrix composite (MMC) coatings onto 6061 Al alloy. The powder contained -45 µm Al stock powder admixed with -10 Al2O3 in fractions ranging from 0-90 wt%. Scanning electron microscopy (SEM), Vickers microhardness testing, and image analysis were conducted on the as-sprayed coatings. The coatings were then friction-stir processed (FSP) using a milling machine and a 12 mm diameter cylindrical tool. Microhardness testing, SEM, and image analysis were then repeated to study the effect that FSP had on the MMC coating hardness. Hardness increased with increasing fraction of Al2O3 in the feedstock powder, resulting in a maximum as-sprayed coating hardness of 85 HV when 90 wt% Al2O3 is used. After FSP, the hardness of the MMC fabricated from a 90 wt% Al2O3 powder blend increased to a maximum of 140 HV. SEM micrographs showed that the as-sprayed MMC coatings contained Al2O3 particles that had been trapped between the larger Al particles. FSP succeeded in redistributing the Al2O3 particles, decreasing the mean free interparticle distance and increasing the probability of load sharing between the reinforcing particles. It was suggested that this redistribution may be the primary reason for hardness improvement in the MMC 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 | 0.000 | 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 | 0.001 |
| 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".