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Lookup NU author(s): Dr Zafer Tatli
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Ceramic matrix composites are attractive as candidate materials for high-temperature applications offering some advantages compared to monolithic ceramics and high-temperature metal alloys. SiC fibre reinforced silicon nitride is one such composite system. However, the processing route is critical to the production of a reliable composite. In this study, silicon nitride matrix densification was improved and sintering temperature was lowered by coating of Si3N4 particles with oxides deposited from hydrolysed metal alkoxides. The solution containing oxide coated Si3N4 powders was used as a slurry to infiltrate Nicalon SiC fibre tows. Following previous studies, the fibres were heat-treated in carbon monoxide to improve mechanical and surface properties. Infiltrated green bodies were hot-pressed at elevated temperatures to produce dense composites. The results showed that particle coating accelerated densification kinetics, eliminated pores and reduced the required hot-pressing temperature. There was also less fibre degradation as a result of the lower temperature of densification. Bending strength and fracture toughness of the composites were measured and fractography was conducted using scanning electron microscope. Composites manufactured using coated Si3N4 powders showed improved properties, specifically matrix stiffening and delayed crack initiation under load.
Author(s): Tatli Z; Demir A
Publication type: Article
Publication status: Published
Journal: Composites Part A: Applied Science and Manufacturing
Year: 2004
Volume: 35
Issue: 12
Pages: 1433-1440
ISSN (print): 1359-835X
Publisher: Pergamon
URL: http://dx.doi.org/10.1016/j.compositesa.2004.05.007
DOI: 10.1016/j.compositesa.2004.05.007
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