Microstructural Changes in PAN-based Carbon Fibers in Relation to Isothermal Oxidation
Bibliographic record
Abstract
PAN-based carbon fibers are being increasingly used across industries due to their outstanding properties such as high strength, modulus of elasticity, and thermal conductivity [1][2][3].However, some problems may occur when they are used at high temperatures exceeding 500℃ as carbon fibers break down into CO or CO 2 , and this causes a deterioration of their physical properties [4].With recent studies examining the mechanism behind carbon fiber activation, it is very important to have an accurate understanding of oxidation reactions [5,6].In this study, PAN-based carbon fibers, widely used as C-C composites or reinforcement in CFRP, were selected for isothermal oxidation at 700℃ in air, and microstructural changes were observed in relation to oxidation reactions.The raw materials were Toray's T300 and T700.After removing sizing materials at 400℃ in a tube furnace, isothermal oxidation (air, 0.5L/min) was carried out at 700℃ over varying times.The surface and the cross-section of the isothermally oxidized materials were observed using a scanning electron microscope (SEM).The results revealed a decrease in diameter and a clear development of texture.In the case of 300, the furrows in the texture had grown further apart.Cross-sectional views showed that hollow sections had formed in the lengthwise direction, and this can be attributed to differences in crystallinity arising from the manufacturing and heat treatment process of carbon fibers.
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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) | 0.001 | 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".