ISSN:
1662-0356
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Allgemeine Naturwissenschaft
,
Technik allgemein
Notizen:
Boron-modified polyvinylsilazanes have been studied for suitability as fiber precursor. Amelt-tractable polymer displaying Si- and N-bonded methyl groups was successfully processed intogreen fibers ~18μm in diameter via a melt-spinning process. After the shaping process, the use ofan ammonia curing atmosphere at 200°C allowed to increase the ceramic yield of the polymer, thenavoid inter-fiber fusion during the further increase of the temperature. As-cured fibers wereannealed in the temperature range 1000-1800°C in a nitrogen atmosphere to provide SiBCNceramic fibers black colored, of flexible form and ~12μm in diameter in different crystallinity statesgoing from totally amorphous below 1600°C to well-crystallized at 1800°C. The excellent strengthretention after heat-treatment at 1600°C (1.3-1.5GPa) is clearly related to the high amorphousstability of fibers. Elemental compositions of such amorphous fibers showed a typical chemicalformula of Si3.0B1.0C5.0N2.4. Between 1600°C and 1700°C, the fiber strength decreased to 0.9GPathen dropped to about one-quarter the original value at 1800°C while structural changes wereevident by XRD analysis
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.50.9.pdf
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