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Microencapsulation of silicon nitride particles with yttria and yttria-alumina precursors

Published online by Cambridge University Press:  31 January 2011

Ajay K. Garg  and
Lutgard C. De Jonghe
Ajay K. Garg
Affiliation:
Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720
Lutgard C. De Jonghe
Affiliation:
Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720
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Abstract

Procedures are described to deposit uniform layers of yttria and yttria-alumina prccursors on fine powders and whiskers of silicon nitride. The coatings were produced by aging at elevated temperatures aqueous systems containing the silicon nitride core particles, yttrium and aluminum nitrates, and urea. Optimum concentrations of the core particles, in relation to the reactants, were established to promote surface deposition of the oxide precursors. Polymeric dispersants were used effectively to prevent agglomeration of the solids during the microencapsulation process. The morphology of the powders was characterized using scanning and transmission electron microscopy. The mechanisms for the formation of the coated layers are discussed. A description is provided that allows qualitative assessment of the experimental factors that determine microencapsulation by a slurry method.

Type
Articles
Information
Journal of Materials Research , Volume 5 , Issue 1 , January 1990 , pp. 136 - 142
Copyright
Copyright © Materials Research Society 1990

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References

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