Synthesis, Characterization, and Application of Nanothermites for Joining
Notice bibliographique
Résumé
Thermite reactions were well studied in the past few decades; however, implementation of these reactions with nanoscale components is a new interest for today’s researchers both for military and civil industries. Nanothermites are mixtures of a metal fuel and a metal oxide, undergoing a redox reaction while heated, and generating a large amount of energy (heat/thrust) which can reach combustion temperatures above 3000K. Aluminum is commonly used as the fuel because of its abundance, easy handling, high reactivity and benign products. By using nano-sized components, the surface energy, contact area, and mixing homogeneity increase. These properties result in greatly improved reactivity and propagation rate as well as easier ignition compared to traditional thermites, which make them attractive as advanced propellants, pyrotechnics, and heat and thrust generators. They also find civil applications such as joining. Here, the application of nanothermites for joining metal to ceramic/glass is investigated. To approach this goal, composites of nanothermite modified by Copper powder were developed for the first time and their related properties were studied to find the best composition for joining. These energetic composites can be applied where a localized heat source is required. The advantage of using nanothermite for joining is its fast reaction, high energy density and liquid products that can wet surfaces. In this research, the reaction products were studied by X-Ray Diffraction spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy. The overall thermite reaction corresponding to the Al-NiO nanothermite was found producing the AlNi phase in a fuel-rich mixture. The microstructures of these reaction products showed the formation of a composite made from copper, AlNi and AlNi/Al2O3 spheres in an Al2O3 matrix. On the other hand, the influences of the fuel (Al) to oxidizer (NiO or CuO) mass ratio and the amount of Cu additive, on the ignition temperature and energy release were characterized using Differential Scanning Calorimetry. It was found that both parameters do not affect the ignition temperature significantly but change the energy release dramatically. Furthermore, according to these results, (Al-33%NiO)-50%Cu was selected and applied to join dissimilar materials such as copper, alumina-silica and glass. As a proof of concept, joint cross-sections were studied by SEM-EDAX revealing that the alumina phase produced by this reaction was joined to the glass/ceramic, while the metal phase wetted the metallic surfaces. Therefore, this composite was introduced as a good interlayer for dissimilar metal/ceramic surfaces.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».