Bibliographic record
Abstract
The use of ceramic has gradually increased over the past few years. Si3N4 is one of the most important ceramics used as structural material for high temperature applications. The practical use of advanced ceramics depends on the reliability of ceramic/metal joining techniques and the properties of the resulting interfaces. This work focuses on various aspects of diffusion bonding of Si3N4 to Ti as well as on the use of Ti-foil interlayer during the self-joining of Si3N4. Si3N4/Ti and Si3N 4/Ti-foil/Si3N4 combinations were diffusion joined by hot-uniaxial pressing and the microstructural characterization of the resulting interfaces was carried out by SEM, EPMA, and X-ray diffraction. Diffusion bonding was carried out at temperatures ranging from 1200 to 1500ºC using different holding times, pressures, and surface roughness of the joining materials. The results showed that Si3N4 could not be bonded to Ti at temperatures lower than 1400ºC, however successful joining at higher temperatures. Joining occurred by the formation of a reactive interface on the Ti side of the joint. At temperatures greater than 1330ºC, liquid formation occurred by the interaction of Ti with Si promoting bonding, as well as the high affinity of Ti for Si resulted in rapid interface formation of silicides, initially Ti5Si3. EPMA and X-ray diffraction confirmed the presence of Ti5Si3, TiSi, and TiN at the interface. The surface roughness of the joining materials plays an important role since thicker interfaces were obtained for polished samples compared to as-ground samples. The interfaces grew in a parabolic fashion with the formation of various Ti-silicides (Ti5Si3 and TiSi) as well as Ti-nitride (TiN) at the interface. Evaluation of joint strengths as a function of the experimental parameters such as, joining temperature and time was obtained by four-point bending test performed on Si3N4/Ti/Si3N4 joints. Strong joints were produced at joining temperatures greater than 1450ºC with average bend strength of more than 100 MPa. The maximum joint strength was obtained in samples hot-pressed at 1500ºC and 120 minutes reaching a value of 147 MPa.
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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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".