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YB2O3-Fluxed Sintered Silicon-Nitride.1. Microstructure Characterization

Vetrano, J. S.; Kleebe, H. J.; Hampp, E.; Hoffmann, M. J.; Ruhle, M.; Cannon, R. M.


Microstructural development and crystallization behaviour of
Yb2O3-fluxed sintered silicon nitride materials was investigated using
CTEM and HREM. The materials contained 5 and 10 vol% Yb2O3 as sintering
additives. After densification, both compositions were subsequently
heat treated to crystallize the residual amorphous secondary phases
present at triple-grain regions. In the material doped with 5 vol%
Yb2O3, only an amorphous secondary phase was observed after sintering,
which was about 80% crystalline (Yb2Si2O7) after the post-sintering
heat treatment. A metastable phase was formed in the material with 10
vol% additives after sintering, with about 70% crystallinity in the
triple-point pockets. Upon post-sintering heat treatment, the material
could be completely crystallized. During heat treating, the metastable
phase combined with the remaining glass to form Yb2SiO5 plus Yb2Si2O7
and a small amount of Si3N4 which deposited epitaxially on pre-existing
Si3N4 grains in areas of low-energy within the triple-point pockets.
All materials contained thin amorphous films separating the grains. The
amorphous intergranular films along grain boundaries (homophase
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Zugehörige Institution(en) am KIT Fakultät für Maschinenbau – Institut für Keramik im Maschinenbau (IKM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 1993
Sprache Englisch
Identifikator ISSN: 0022-2461
KITopen-ID: 1000007795
Erschienen in Journal of Materials Science
Verlag Springer
Band 28
Heft 13
Seiten 3529-3538
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