High Flexural Strength Porous Silicon Nitride Prepared via Nitridation of Silicon Powder

doi:10.3724/SP.J.1077.2011.00422

Abstract

Abstract: High flexural strength porous silicon nitride ceramics were prepared via nitridation of silicon powder, using silicon powder and Y₂O₃ as start powder with different forming pressures. The effects of Y₂O₃ contents and heating programs on nitridation rate were studied. The high nitridation rate was obtained when 9% Y₂O₃ was added, which was contributed to Y₂O₃ reacted with SiO₂ at low temperature (1200 ℃ ) to transform to Y₅Si₃O₁₂N and the elimination of SiO₂ on Si surface. Under different sintering conditions, the porous Si₃N₄ ceramics with porosity of 30% - 50% and the flexural strength of 160 - 50MPa were obtained, respectively. After post-sintering at 175 0 ℃ in 0.5MPa N₂ atmosphere, α-Si₃N₄ was fully transformed into β-Si₃N₄by the solution-precipitation process, the rod-like β-Si₃N₄ promoted the flexural strength of the porous Si₃N₄ ceramics, and the porous Si₃N₄ ceramics with a porosity of 46% and a flexural strength of 140MPa was obtained .

Key words: nitridation, porous silicon nitride, flexural strength, porosity

CLC Number:

TB332

YAO Dong-Xu,ZENG Yu-Ping. High Flexural Strength Porous Silicon Nitride Prepared via Nitridation of Silicon Powder[J]. Journal of Inorganic Materials, 2011, 26(4): 422-426.

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