Sintering and Microstructure Modification of Mullite/Zirconia Composites Derived from Silica‐Coated Alumina Powders
Bibliographic record
Abstract
This paper addresses the densification and microstructure development during firing of mullite/zirconia composites made from silica‐coated‐alumina (SCA) microcomposite powders. Densification occurs in two stages: in the presence of a silica–alumina mixture and after conversion to mullite. The first stage of densification occurs through transient viscous phase sintering (TVS). This is best promoted by rapid heating, which delays the crystallization of silica to higher temperatures. A further sintering stage is observed following mullitization. The introduction of seeds promotes solid‐state sintering, most probably due to refinement of the mullite matrix. For seed concentrations up to about 1% the sintering kinetics depend on seed concentration. This suggests that nucleation still remains the rate‐controlling mullitization step. Above this concentration the reaction becomes growth controlled. Introduction of seeds also promotes direct mullitization without transient zircon formation that was observed in a previous study of the same process without seeding. Seeding also promotes the development of elongated grains by way of a solid‐state recrystallization process.
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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".