Fabrication Process and Evaluation of the Sintered SiC Fiber Reinforced SiO 2-Mullite Composites

Kenya Nagahisa, Kazuteru Iwamoto, Kenji Shinozaki, Hideharu Fukunaga, Gen Sasaki, Makoto Yoshida

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Abstract

The sintered SiC fiber reinforced SiO 2-mullite composites, which have three levels of added Al 2O 3 in the matrix, i.e., SiO 23.7, 30, 50 mol%Al 2O 3, were synthesized by liquid state hot-pressing. Variation in the thermal residual stress fields in the composites caused by the difference in the thermo-mechanical mismatch between the fiber and matrices were investigated. The effects of the Al 2O 3 content in the matrix on the mechanical properties of the composites were then examined. The obtained composites had a very dense structure, and both the mullite and glassy SiO 2 phases were found in the matrices. A higher Al 2O 3 content in the matrix lead to a higher mullite volume fraction. No chemical reaction among the constituents due to the fabrication process was observed. It was confirmed that the thermal residual stress field in the composites changed with an increase in the coefficient of thermal expansion of the matrix accompanied by an increasing Al 2O 3 content in the matrices. The network structure of the mullite crystals found in the SiC fiber/SiO 2-30 mol%Al 2O 3 and SiC fiber/SiO 2-50 mol%Al 2O 2 composites seemed to effectively prevent plastic deformation of the matrices during the flexural test at 1573 K. The SiC fiber/SiO 2-30 mol%Al 2O 3 composite showed excellent mechanical properties up to 1573 K compared with previously reported ceramic matrix composites such as the SiC fiber/LAS composite or SiC fiber bonded ceramics in an inert atmosphere.

Original languageEnglish
Pages (from-to)162-171
Number of pages10
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume68
Issue number2
Publication statusPublished - 2004 Feb
Externally publishedYes

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Keywords

  • Ceramic matrix composite (CMC)
  • Mechanical properties
  • Mullite
  • SiC fiber
  • SiO

ASJC Scopus subject areas

  • Metals and Alloys

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