Boron Nitride Obtained from Molecular Precursors: Aminoboranes Used as a BN Source for Coatings, Matrix, and Si3N4–BN Composite Ceramic Preparation
✍ Scribed by F. Thévenot; C. Doche; H. Mongeot; F. Guilhon; P. Miele; D. Cornu; B. Bonnetot
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 341 KB
- Volume
- 133
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Aminoboranes, pure or partially converted into aminoborazines using thermal or aminolysis polymerization, have been used as boron nitride precursors. An amorphous BN preceramic is obtained when pyrolysed up to 1000°C that can be stabilized using further annealing up to 1400°C or crystallized into h-BN above 1700°C. These molecular precursors have been used to prepare carbon fiber/ BN matrix microcomposites to get an efficient BN coating on graphite and as a BN source in Si 3 N 4 / BN composite ceramic. The properties of these new types of samples have been compared with those obtained by classical processes. The boron nitride obtained from these precursors is a good sintering agent during the hot-pressing of the samples. However, the crystallinity of BN, even sintered up to 1800°C, remains poor. In fact, most of the mechanical properties of the composite ceramic (density, porosity, hardness) are clearly improved and the aminoboranes can be considered as convenient boron nitride sources and helpful sintering agents in hot-pressing technology.