Si3N4 ceramics formed by HIP using different oxide additions : relation between microstructure and properties

AEM and X-ray diffractometry are used to characterize Si3N4-based ceramic materials formed by glass encapsulation and HIP employing different additions of Al2O3, Y2O3, and ZrO2. Time and temperature of HIP as well as type and amount of oxide sintering aid were found to have a conclusive influence on...

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Bibliographic Details
Published in:Journal of materials science 1991, Vol.26 (20), p.5575-5584
Main Authors: KNUTSON-WEDEL, E. M, FALK, L. K. L, BJORKLUND, H, EKSTROM, T
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Chemical industry and chemicals
Exact sciences and technology
Structural ceramics
Technical ceramics
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Summary:AEM and X-ray diffractometry are used to characterize Si3N4-based ceramic materials formed by glass encapsulation and HIP employing different additions of Al2O3, Y2O3, and ZrO2. Time and temperature of HIP as well as type and amount of oxide sintering aid were found to have a conclusive influence on the microstructure and mechanical properties of the Si3N4 ceramics. Small quantities of Al2O3 promoted densification significantly at 1550 C. HIP at 1550 C resulted in Si3N4 grains with equiaxed shape which were separated by a comparatively low volume fraction of residual glass located at smaller pockets in the microstructure. HIP at 1750 C reduced the volume-fraction-retained alpha-Si3N4 substantially, which led to a simultaneous reduction in hardness. HIP at 1750 C with separate additions of Y2O3 resulted in a large volume fraction of residual glass present as thin intergranular films merging into pockets at multigrain junctions. (P.D.)
ISSN:0022-2461
1573-4803
DOI:10.1007/bf02403960