A PRELIMINARY STUDY ON CRACK HEALING BEHAVIOUR OF Si3 N4 /SiC COMPOSITE CERAMICS |
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| Authors: | K Ando,T Ikeda,S Sato,F Yao,& Y Kobayasi |
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| Affiliation: | Department of Energy and Safety Engineering, Yokohama National University, Yokohama, Japan,;R&D Center, NHK Spring Inc., Yokohama, Japan |
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| Abstract: | Ceramic (Si3 N4 /SiC) composites have been produced by sintering. From the sintered block, three point bend specimens were cut out. A semi-circular crack was made on the centre of the tension surface of the test specimen with the aid of a Vicker's indenter. The diameter of the semi-circular crack was about 60–70 μm. The specimens were subsequently heat treated at 1300°C for 1 h in vacuum, nitrogen or air. The bending strength was measured at room temperature, 800 and 1000°C. The specimens heat treated in air recovered considerably their bending strength at 1000°C, several specimens failed at a location different from the healed crack and their average strength showed the same value of that for smooth specimens. From these results, it is concluded that the recovery in bending strength of a cracked specimen was caused by crack healing. |
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| Keywords: | Si3 N4 SiC composite ceramics Crack healing Bending strength High temperature strength Strength recovery Oxide |
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