| AIN 세라믹스의 미세조직과 기계적 성질에 미치는 h-BN 첨가의 영향 |
| 이영환, 김준규1, 조원승, 조명우2, 이은상2, 이재형3 |
인하대학교 재료공학부
1인하대학교 소재연구소
2인하대학교 기계공학부
3영남대학교 재료금속공학부 |
| Effect of h-BN Content on Microstructure and Mechanical Properties of AIN Ceramics |
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| ABSTRACT |
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The effect of h-BN content on microstructure, mechanical properties, and machinability of AlN-BN based machinable ceramics were investigated. The relative density of sintered compact decreased with increasing h-BN content. The four-point flexural strength also decreased from 238 MPa of monolith up to 182 MPa by the addition of 30 vol％ h-BN. Both low Young's modulus and residual tensile stress, formed by the thermal expansion coefficient difference between AIN and h-BN, might cause the strength drop in AlN-BN composite. The crack deflection, and pull-out phenomena increased by the plate-like h-BN. However, the fracture toughness decreased with h-BN content. The second phases, consisted of YAG and ${gamma}$-Al$_2$O$_3$, were formed by the reaction between Al$_2$O$_3$ and Y$_2$O$_3$. During end-milling process, feed and thrust forces measured for AlN-(10～30) vol％ BN composites decreased with increasing h-BN particles, showing excellent machinability. Also, irrespective of h-BN content, relatively good surfaces with roughness less than 0.5 m (Ra) could be achieved within short lapping time. |
| Key words:
Microstructure, Machinable ceramics, h-RN, AIN |
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