Title: Estimation of the fracture toughness of Tyranno Si-Ti-C-O fibres from flaw size and ''fracture mirror'' data measured in situ a 3-D woven SiC/SiC composite

Authors: Ian J. Davies, Takashi Ishikawa

Addresses: Advanced Fibro-Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan. ' Airframe Division, National Aerospace Laboratory, 6-13-1 Ohsawa, Mitaka City, Tokyo 181-0015, Japan

Abstract: The fracture toughness, calculated from the size of initiating flaws, was estimated for Tyranno® LoxM Si-Ti-C-O fibres in situ a 3-D woven SiC/SiC composite that had failed under tensile loading at room temperature. The fibres had been subjected to a surface modification treatment prior to incorporation within the composite. Two distinct flaw populations (internal and surface) were noted within the fibres with associated fracture toughness values of 0.997 (± 0.062) and 1 .428 (± 0.103) Mpam1/2, respectively. The former value was similar to that of nominally similar Nicalon® Si-C-O fibres whereas the latter value was attributed to the presence of an unidentified 80 nm layer surrounding the fibre.

Keywords: Tyranno Si-Ti-C-O fibre; fracture toughness; surface flaws; silicon carbide; composites; tensile failure.

DOI: 10.1504/IJMPT.2001.005417

International Journal of Materials and Product Technology, 2001 Vol.16 No.1/2/3, pp.189 - 196

Published online: 01 Oct 2004 *

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