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Dispersion and consolidation of silicon nitride whisker in aqueous suspension

Published online by Cambridge University Press:  31 January 2011

Yoshihiro Hirata
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890, Japan
Susumu Nakagama
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890, Japan
Yoshimi Ishihara
Affiliation:
Department of Applied Chemistry, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890, Japan
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Abstract

Characteristics of aqueous silicon nitride whisker suspension and the packing nature of whiskers during consolidation (sedimentation or filtration) were investigated in order to control the microstructure and density of a whisker compact. Silicon nitride whiskers (average size 0.4 μm × 3.7 μm) coated by SiO2 film were well dispersed at pH 10.5 due to the strong repulsion force among negatively charged whiskers. Low viscosity suspension of highly charged whiskers showing Newtonian behavior formed a dense whisker compact with a narrow pore size distribution of small pores. The density increase of green compact was accompanied by the orientation of whiskers where the direction in length of whiskers was perpendicular to the direction of filtration. Application of an external pressure (isostatic pressing) to porous whisker compacts consisting of network structure of randomly packed whiskers or whiskers of low orientation increased the green density.

Type
Articles
Copyright
Copyright © Materials Research Society 1990

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References

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