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

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1990.0136· OSTI ID:7144497

Garg, A K; De Jonghe, L C ^[1]

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1. Center for Advanced Materials, Materials, Lawrence Berkeley Laboratory, Berkeley, California 94720 (USA) Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (US)

Procedures are described to deposit uniform layers of yttria and yttria-alumina precursors 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.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7144497
• Journal Information: Journal of Materials Research; (USA), Journal Name: Journal of Materials Research; (USA) Vol. 5:1; ISSN JMREE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALUMINIUM COMPOUNDS
ALUMINIUM NITRATES
AMIDES
CARBONIC ACID DERIVATIVES
DEPOSITION
ELECTRON MICROSCOPY
ENCAPSULATION
MICROSCOPY
MORPHOLOGY
NITRATES
NITRIDES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PNICTIDES
POWDERS
SCANNING ELECTRON MICROSCOPY
SILICON COMPOUNDS
SILICON NITRIDES
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
UREA
YTTRIUM COMPOUNDS
YTTRIUM NITRATES