Paper Title:
Microstructure and Mechanical Properties of Si3N4/hBN Composites Prepared by Hot-Pressing Using Nitrided Si3N4 Powders
  Abstract

In order to produce Si3N4/hBN composite with low cost, it seems necessary to use nitrided Si3N4 powders since the cost of Si powder is much cheaper than that of Si3N4 powder. The purpose of the present work is to investigate the nitride conditions, and in particular, we focused on the relationship between microstructures and mechanical properties of hot-pressed Si3N4/hBN ceramic composite using nitrided Si3N4 powders. The mixed powders of Si3N4 and hBN were prepared by nitriding Si powders at 1380oC for 24 h, and subsequently sintered by hot-pressing at 1800oC for 2 h in N2 atmosphere. The microstructure and mechanical properties of the Si3N4/hBN composites were investigated. Flexural strength, Young’s modulus, and hardness decreased by the addition of 20 vol% hBN. The addition of BN resulted in a decrease in the modulus as well as an increase in the size of fracture source, both contribute to the observed decrease in mechanical properties. The Si3N4/BN based ceramic composites revealed enhanced crack deflection. The Vickers indentation crack paths in specimens are sinusoidal due to pull-out of grains during crack propagation.

  Info
Periodical
Materials Science Forum (Volumes 544-545)
Edited by
Hyungsun Kim, Junichi Hojo and Soo Wohn Lee
Pages
415-418
DOI
10.4028/www.scientific.net/MSF.544-545.415
Citation
K. J. Lee, C. H. Jin, W. S. Hwang, W. S. Cho, "Microstructure and Mechanical Properties of Si3N4/hBN Composites Prepared by Hot-Pressing Using Nitrided Si3N4 Powders", Materials Science Forum, Vols. 544-545, pp. 415-418, 2007
Online since
May 2007
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$32.00
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