A New Generation of Boron-Based Ceramic Fibers: Design, Processing and Properties of SilicoBoron CarboNitride (SiBCN) Fibers from Boron-Modified Polyvinylsilazanes
| Periodical | Advances in Science and Technology (Volume 50) |
|---|---|
| Main Theme | Advanced Inorganic Fibrous Composites V |
| Edited by | P. VINCENZINI and M. SINGH |
| Pages | 9-16 |
| DOI | 10.4028/www.scientific.net/AST.50.9 |
| Citation | Samuel Bernard et al., 2006, Advances in Science and Technology, 50, 9 |
| Online since | October, 2006 |
| Authors | Samuel Bernard, Markus Weinmann, David Cornu, Philippe Miele |
| Keywords | Boron-Modified Polyvinylsilazanes, Curing, Fiber, Melt-Spinning, Pyrolysis, SiBCN |
| Price | US$ 28,- |
Boron-modified polyvinylsilazanes have been studied for suitability as fiber precursor. A melt-tractable polymer displaying Si- and N-bonded methyl groups was successfully processed into green fibers ~18μm in diameter via a melt-spinning process. After the shaping process, the use of an ammonia curing atmosphere at 200°C allowed to increase the ceramic yield of the polymer, then avoid inter-fiber fusion during the further increase of the temperature. As-cured fibers were annealed in the temperature range 1000-1800°C in a nitrogen atmosphere to provide SiBCN ceramic fibers black colored, of flexible form and ~12μm in diameter in different crystallinity states going from totally amorphous below 1600°C to well-crystallized at 1800°C. The excellent strength retention after heat-treatment at 1600°C (1.3-1.5GPa) is clearly related to the high amorphous stability of fibers. Elemental compositions of such amorphous fibers showed a typical chemical formula of Si3.0B1.0C5.0N2.4. Between 1600°C and 1700°C, the fiber strength decreased to 0.9GPa then dropped to about one-quarter the original value at 1800°C while structural changes were evident by XRD analysis.
