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Grain Boundary Microstructure of a Hot Isostatically Pressed Silicon Nitride

Published online by Cambridge University Press:  02 July 2020

L. Fu
Affiliation:
Department of Mat. Sci. & Eng., University of Michigan, Ann Arbor, MI48109
M. J. Hoffmann
Affiliation:
Institute for Ceramics in Mechanical Engineering, D-76131, Karlsruhe, Germany
X. Pan
Affiliation:
Department of Mat. Sci. & Eng., University of Michigan, Ann Arbor, MI48109
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Extract

Si3N4-based materials exhibit attractive mechanical properties for high-temperature applications. These properties are influenced strongly by the size and morphology of the grain boundaries and grain-boundary phase. An amorphous intergranular film (IGF) commonly exists at two grain junctions. The thickness of these IGFs sensitively depend on the chemical composition of the intergranular phase.In this work, our studies on the grain boundary microstructure of Si3N44 ceramics made by Hot Isostatically Pressing (HIPing).

Si3N44 materials were densified by HIPing Si3N4 powders (UBE E-10) at 1950°C at 200 MPa for 1 hour, with sintering aids of either Y2O3 or Y2O3 + A12O3. Two materials were made: material A consisting of 2 wt% Y2O3; material B consisting of 5 wt% Y2O3 and 1 wt% A12O3. Both as-HIPed and oxided samples were investigated. TEM specimens were prepared by conventional procedures. The microstructure and chemical composition were studied on a JEOL 2000FX.

Type
Ceramics and Ceramic Composites
Copyright
Copyright © Microscopy Society of America 1997

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References

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