Microstructure and Mechanical Properties of Silicon Nitride/h-BN Based Machinable Ceramics

Won Seung Cho; Jae Hyung Lee; Myeong Woo Cho; Eun Sang Lee; Dong Sam Park; Z.A. Munir

doi:10.4028/www.scientific.net/KEM.287.340

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Microstructure and Mechanical Properties of Silicon Nitride/h-BN Based Machinable Ceramics
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HomeKey Engineering MaterialsKey Engineering Materials Vol. 287Microstructure and Mechanical Properties of...

Microstructure and Mechanical Properties of Silicon Nitride/h-BN Based Machinable Ceramics

Abstract:

The effects of h-BN content on the microstructure, mechanical properties, and machinability of Si3N4 ceramics were investigated. The relative density of the sintered compact decreased with increasing BN content. The flexural strength also decreased with h-BN content, mainly due to lower Young’s modulus of h-BN compared to Si3N4. With increasing h-BN content, Si3N4/h-BN based ceramic composites revealed enhanced crack resistance (R-curve) behavior. The Vickers indentation crack paths in specimens are sinusoidal due to bridging and pull out of grains during crack propagation. The grain size of ß-Si3N4 slightly decreased with h-BN content. During milling and micro-drilling process, monolithic Si3N4 ceramic could not be machined, due to brittle fracture. However, thrust forces measured for Si3N4/h-BN composites decreased with increasing h-BN content, showing the excellent macro and micro machinabilty.

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Periodical:

Key Engineering Materials (Volume 287)

Pages:

340-345

DOI:

https://doi.org/10.4028/www.scientific.net/KEM.287.340

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Online since:

June 2005

Authors:

Won Seung Cho, Jae Hyung Lee, Myeong Woo Cho, Eun Sang Lee, Dong Sam Park, Z.A. Munir

Keywords:

Hexagonal BN, Machinability, Mechanical Property, Microstructure, R-Curve

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