Texture development in Si3N4 ceramics by magnetic field alignment during slip casting

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

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The effects of α-Si3N4 powder, β-Si 3N4 seed particles and sintering conditions on the texture development in Si3N4 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-Si3N4 crystals was observed, but the alignment of β-Si3N4 crystals was observed in the green body, despite the low amount of β-Si3N4 (∼1 wt%). This suggests that the grain alignment during slip casting is predominant by the grain alignment of the minor β-Si3N4 phase present in the α-Si 3N4 raw powder, which is featured by the rod-like shape and less-agglomerated form. The alignment of both α-Si3N 4 and β-Si3N4 crystals occurs by the c-axis of the crystals perpendicular to the magnetic field. The addition of 5 wt% β-Si3N4 particles leads to the enhanced grain orientation of the β-Si3N4 particles in the green body for both raw α-Si3N4 powders. It is shown that the crystallographic orientation of β-Si3N4 is enhanced by the substitution of SN-E10 for SN-E05 powder, the addition of β-Si3N4 particles and prolonged sintering, but the phase transformation of α to β may play a dominant role in the texture development in Si3N4 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-Si3N4 is crucial for the texture development in Si3N4 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 Nov
Externally publishedYes

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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