R-Curve Behavior of Si3N4–BN Composites |
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| Authors: | Young Sik Yoon,Sang Woong Na,Jaehyung Lee,&dagger ,Myeong-Woo Cho,Eun-Sang Lee,Won-Seung Cho |
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| Affiliation: | School of Metallurgical and Materials Engineering, Yeungnam University, Gyongsan, Gyongbuk 712-749, Korea;Division of Mechanical Engineering, Inha University, Incheon 402-751, Korea;School of Materials Science, Inha University, Incheon 402-751, Korea |
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| Abstract: | R -curve behavior of Si3N4–BN composites and monolithic Si3N4 for comparison was investigated. Si3N4–BN composites showed a slowly rising R -curve behavior in contrast with a steep R -curve of monolithic Si3N4. BN platelets in the composites seem to decrease the crack bridging effects of rod-shaped Si3N4 grains for small cracks, but enhanced the toughness for long cracks as they increased the crack bridging scale. Therefore, fracture toughness of the composites was relatively low for the small cracks, but it increased significantly to ∼8 MPa·m1/2 when the crack grew longer than 700 μm, becoming even higher than that of the monolithic Si3N4. |
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| Keywords: | R-curve composites silicon nitride |
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