Effect of Thermal Residual Stress on Matrix Cracking Strain and Fracture Behavior of the Sintered SiC Fiber Reinforced SiO2-Mullite Composites

Kenya Nagahisa, Kazuteru Iwamoto, Kenji Shinozaki, Gen Sasaki, Manabu Enoki, Makoto Yoshida

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The sintered SiC fiber reinforced SiO2-mullite composites with matrix compositions, i.e., SiO2-3.7, 30, and 50 mol%Al 2O3, had already been developed. In these composites, the thermal residual stress field changed with an increase in the coefficient of thermal expansion of the matrix accompanied by an increasing Al 2O3 content (mullite volume fraction) in the matrices. A three-point flexural test was conducted for the composites at room temperature. The strain gauge method and AE monitoring were used to detect the matrix cracking strain during the test. The effect of the thermal residual stress on the matrix cracking strain and fracture behavior were investigated. The results are as follows. The matrix cracking strain observed in the composites with a higher tensile thermal residual stress in the matrix region parallel to the fiber axis was well predicted by the BHE theory. For the SiC fiber/SiO 2-50 mol%Al2O3 composite, the first acoustic emission signal was detected just after the initial proportional limit of the stress-strain curve. For the other composites, the signals were detected below this limit. When the residual stress in the matrix region parallel to the fiber axis was compressive, the linear fracture behavior was found. On the contrary, the bi-linear fracture behavior was enhanced by the tensile residual stress in the matrix. This tendency agreed with the prediction method by Luh and Evans. The magnitude of the fracture energy obtained in each composite was qualitatively explained by the conventional theoretical formula.

Original languageEnglish
Pages (from-to)172-180
Number of pages9
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Issue number2
Publication statusPublished - 2004 Feb



  • Acoustic emission (AE)
  • Ceramic matrix composite (CMC)
  • Fracture behavior
  • Matrix cracking
  • Thermal residual stress

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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