| AlN/hBN 복합재료의 기계적 성질 |
| 이재형, 안현욱, 윤영식, 조명우1, 조원승2 |
영남대학교 신소재공학부
1인하대학교 기계공학부
2인하대학교 재료공학부 |
| Mechanical Properties of AlN/hBN Ceramic Composites |
| Jaehyung Lee, Hyun-Wook Ahn, Young-Sik Yoon, Myeong-Woo Cho1, Won-Seung Cho2 |
School of Materials Science and Engineering, Yeungnam University
1School of Mechanical Engineering, Inha University
2School of Materials Science and Engineering, Inha University |
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| ABSTRACT |
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AlN-BN ceramic composites were fabricated and their mechanical properties were investigated. The relative density of hot-pressed composites decreased with increasing BN content, but over $99%$ could be obtained with 30 $vol%$ BN in AlN. YAG was formed in the composites and monolithic AlN as a second phase by the reaction between $Y_2O_3$, added as sintering aid, and $Al_2O_3$. As expected, Vickers hardness and Young's modulus decreased with increasing BN content. The three-point flexural strength also showed similar behavior decreasing from 500 MPa of monolith down to 250 MPa by the addition 30 $vol%$ BN. However, interestingly, the standard deviation of the strength values decreased significantly as BN was added to AlN. As a result, the Weibull modulus of the AlN-30 $vol% BN composite was 21.3, which was extremely high. Fractography and crack path studies revealed that BN platelets induced grain pull-out and crack bridging in a bigger scale during crack propagation. Consequently, fracture toughness increased as more BN was added, reaching 4.5 $MPasqrt{m}$ at 40 $vol%$ BN. |
| Key words:
Mechanical properties, Flexural strength, Fracture toughness, BN, AlN |
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