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Rheological Behavior of Silicon Nitride Whiskers

Published online by Cambridge University Press:  25 February 2011

Patricio Toro  and
Oscar Wittke
Patricio Toro
Affiliation:
Depto. Química, F.C.F.M. Universidad de Chile, P.O.Box. 2777. FAX: 56-2-6994119. Santiago. Chile
Oscar Wittke
Affiliation:
Depto. Física, F.C.F.M. Universidad de Chile, P.O.Box. 2777. FAX: 56-2-6994119. Santiago. Chile
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Abstract

Si3N4 whiskers are found through SEM analysis of powder obtained by carbothermal reduction of calcined Chilean rice husks. X-ray and FTIR analysis showed that the ceramic material was mainly α-Si3N4. A stable aqueous suspension with 30 or 40 wt% Si3N4 was obtained at pH = 8.5. A maximum viscosity at pH = 4.0 and low rpm was also observed and this rheological behavior is consistent with the zeta potential data. An irregular flow behavior near pH 4.0 shows a decrease in viscosity that is related to active impurities as detected by potentiometric titrations.

These rheological studies conducted allowed production of a Si3N4 green ceramic body measuring 170 × 25 × 5 mm formed by slip casting. The optimal aqueous suspension of powder contained the following: 17.0 g Si3N4, 1.0 g Cu2O, 1.3 g bentonite, and 20.0 g water.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 287: Symposium K – Silicon Nitride Ceramics–Scientific and Technological Advances , 1992 , 271
Copyright
Copyright © Materials Research Society 1993

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References

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