SiC-whisker-reinforced Al₂O₃ Composites by Free Sintering of Coated Powders


Green, David J. and Halloran, John and Johnson, David W. and Klein, Lisa


SiC whiskers were coated with a thick cladding of finegrained Al2O3 powder by controlled heterogeneous precipitation in a concentrated suspension of whiskers. after calcination, the coated whiskers were compacted by cold isostatic pressing and sintered at a constant heating rate of 5°C/min in a helium atmosphere. the parameters which control the coating process and the sintering characteristics of the consolidated powders are reported. Starting with an initial matrix density of 40-45% of the theoretical, composites containing up to ≅20 vol% whiskers (aspect ratio ≅15) were sintered freely to nearly theoretical density below 1800°C. by comparison, a similar composite formed by mechanical mixing of the whiskers and the precipitated Al2O3 powder reached a density of only 68% of the theoretical after sintering under identical conditions. For a fixed whisker content, the sinterability of the composites formed from the coated whiskers shows a fairly strong dependence on the whisker aspect ratio.


Materials Science and Engineering

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version


File Type





© 1993 Wiley-Blackwell, All rights reserved.

Publication Date

01 Jan 1993