Texture development in Si 3 N 4 ceramics by magnetic field alignment during slip casting

Xinwen Zhu, Tohru Suzuki, Tetsuo Uchikoshi, Toshiyuki Nishimura, Yoshio Sakka

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The effects of α-Si 3 N 4 powder, β-Si 3 N 4 seed particles and sintering conditions on the texture development in Si 3 N 4 ceramics, which were prepared by slip casting in a strong field of 12 T, followed by pressureless sintering. In the case of the replacement of the fine powder (UBE SN-E10) with the coarse powder (UBE SN-E05), no alignment of α-Si 3 N 4 crystals was observed, but the alignment of β-Si 3 N 4 crystals was observed in the green body, despite the low amount of β-Si 3 N 4 (∼1 wt%). This suggests that the grain alignment during slip casting is predominant by the grain alignment of the minor β-Si 3 N 4 phase present in the α-Si 3 N 4 raw powder, which is featured by the rod-like shape and less-agglomerated form. The alignment of both α-Si 3 N 4 and β-Si 3 N 4 crystals occurs by the c-axis of the crystals perpendicular to the magnetic field. The addition of 5 wt% β-Si 3 N 4 particles leads to the enhanced grain orientation of the β-Si 3 N 4 particles in the green body for both raw α-Si 3 N 4 powders. It is shown that the crystallographic orientation of β-Si 3 N 4 is enhanced by the substitution of SN-E10 for SN-E05 powder, the addition of β-Si 3 N 4 particles and prolonged sintering, but the phase transformation of α to β may play a dominant role in the texture development in Si 3 N 4 during sintering, compared to the grain growth after the complete phase transformation. Owing to the crystallographic orientation, the samples exhibited anisotropic shrinkage behavior during sintering and the anisotropy becomes strong with enhanced grain orientation. The present study suggests that the control of the alignment of β-Si 3 N 4 is crucial for the texture development in Si 3 N 4 by the magnetic field alignment.

Original languageEnglish
Pages (from-to)979-987
Number of pages9
JournalJournal of the Ceramic Society of Japan
Volume114
Issue number1335
DOIs
Publication statusPublished - 2006 Jan 1
Externally publishedYes

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Keywords

  • Anisotropy
  • Magnetic field
  • Orientation
  • Seed
  • Silicon nitride
  • Sintering
  • Slip casting

ASJC Scopus subject areas

  • Ceramics and Composites
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry

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