Threshold Stress for Crack Healing of Mullite Reinforced by SiC Whiskers and SiC Particles and Resultant Fatigue Strength at the Healing Temperature |
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Authors: | Koji Takahashi Kenichi Uchiide Yoshitaka Kimura Wataru Nakao Kotoji Ando Masahiro Yokouchi |
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Affiliation: | Department of Energy &Safety Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama, 240-8501, Japan; Kanagawa Industrial Technology Center, Ebina 243-0435, Japan |
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Abstract: | A mullite/SiC whisker/SiC particle multi-composite, having excellent crack-healing ability and mechanical properties, was hot pressed in order to investigate the crack-healing behavior under stress and the resultant fatigue strength at the temperature of healing. A semi-elliptical surface crack 100 μm in surface length was introduced on each specimen. The pre-cracked specimens were crack healed under cyclic or constant stress by using a three-point bending stress at 1473 K, and the resultant bending strength and cyclic fatigue strength were measured at 1473 K. The pre-crack on the surface of the specimens could be healed even under stress. The threshold stresses for crack healing, as determined by evaluating the strengths of crack-healed specimens at a healing temperature of 1473 K, were 170 MPa for both constant and cyclic stresses, corresponding to 77% of the bending strength of the pre-cracked specimens. The static and cyclic fatigue behaviors of crack-healed specimens were also investigated at a healing temperature of 1473 K. |
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