Effect of Hexagonal BN on the Microstructure and Mechanical Properties of Pressureless Sintered Porous Si₃N₄ Ceramics

Abstract:

Porous silicon nitride ceramics with various amounts (25, 35, and 45 vol %) of hexagonal boron nitride (h-BN) were fabricated at 1800°C for 2h by the pressureless sintering process. With FESEM and TEM, the effects of h-BN on the microstructure and mechanical properties of Si3N4 ceramics were investigated. Results of the microstructure and mechanical properties of Si3N4/BN composites showed that the growth of the elongated β-Si3N4 were hindered by h-BN additive, which resulted in the decrease of fracture toughness of Si3N4/BN ceramics with increasing h-BN content. The morphologies of the fracture surfaces by FESEM revealed the fracture mode for Si3N4/BN composites to be intergranular. However, phase analysis by XRD indicated that the effect of h-BN on the α- to β- Si3N4 phase transformation of Si3N4/BN composites was negligible.

• Periodical: Key Engineering Materials (Volumes 434-435)
• Pages: 697-700
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.434-435.697
• Online since: March 2010
• Authors: Yong Feng Li, Ping Liu, Xiang Dong Wang, Hai Yun Jin, Guan Jun Qiao
• Keywords: Hexagonal Boron Nitride (HBN), Mechanical Property, Pressureless Sintering, Silicon Nitride

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