MICROENCAPSULATION OF SILICON-NITRIDE PARTICLES WITH YTTRIA AND YTTRIA-ALUMINA PRECURSORS

被引:50
作者
GARG, AK
DEJONGHE, LC
机构
[1] Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley
基金
美国能源部;
关键词
D O I
10.1557/JMR.1990.0136
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
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. © 1990, Materials Research Society. All rights reserved.
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页码:136 / 142
页数:7
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