Microstructural Development to Toughen Sic

Research output: Chapters, Conference Papers, Creative and Literary WorksRGC 32 - Refereed conference paper (with host publication)peer-review

3 Scopus Citations
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Author(s)

  • W. J. Moberlychan
  • R. M. Cannon
  • L. H. Chan
  • J. J. Cao
  • C. J. Gilbert
  • L. C. De Jonghe

Detail(s)

Original languageEnglish
Title of host publicationProceedings of MRS Meetings
Subtitle of host publicationSymposium S – Covalent Ceramics III-Science and Technology of Non-Oxides
PublisherCambridge University Press
Pages257-262
Volume410
Publication statusPublished - Nov 1995
Externally publishedYes

Publication series

NameMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
ISSN (Print)0272-9172

Conference

Title1995 MRS Fall Meeting
PlaceUnited States
CityBoston
Period27 November - 1 December 1995

Abstract

SiC offers a promise for high strength applications at high temperature; however, poor fracture resistance has inhibited its utility. Recent developments to control microstructure during hot pressing have improved fracture toughness >3 fold, while also improving strength 50% above that of a commercial SiC, Hexoloy. This ABC-SiC (designated for the Al, B, and C additives) utilizes liquid phase sintering to obtain full densification at 1650 °C, and to induce the β-3C to α-4H phase transformation below 1900 °C. Interlocking, plate-like, α grains, coupled with a thin (approximately 1 nm) amorphous layer, provide for tortuous intergranular fracture and high toughness. 

This study focuses on the developing microstructure; how the α-4H polytype grows as a stacking modification of the β-3C grains, and how amorphous grain boundaries and crystalline triple point phases develop and interact with the crack geometry. HR-TEM and Image-Filtered EELS characterize the amorphous grain boundaries. Field Emission - SEM, EDS and Auger Electron Spectroscopy characterize the fracture morphology and the chemistry of grain boundaries and triple points. Electron Diffraction and HR-TEM depict an epitaxial relationship between triple point phases (Al8B4C7 and Al4O4C) and matrix α-SiC grains, the development of which affects the mechanical toughening. The transformation to toughen SiC is compared to the well-studied transformation processing in Si3N4. A distinct advantage is the interlocked nature of the plate-like grains which causes strong elastic bridging behind the crack tip.

Citation Format(s)

Microstructural Development to Toughen Sic. / Moberlychan, W. J.; Cannon, R. M.; Chan, L. H. et al.
Proceedings of MRS Meetings: Symposium S – Covalent Ceramics III-Science and Technology of Non-Oxides. Vol. 410 Cambridge University Press, 1995. p. 257-262 (Materials Research Society Symposium - Proceedings).

Research output: Chapters, Conference Papers, Creative and Literary WorksRGC 32 - Refereed conference paper (with host publication)peer-review