In Situ Reacted Rare-Earth Hexaaluminate Interphases

A novel in situ reaction between a ceria‐doped zirconia interphase coating on Saphikon fibers and an outer alumina coating has resulted in the formation of oriented hexaaluminate platelets which can act as a low fracture energy interface barrier for crack deflection in oxide—oxide ceramic‐matrix com...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 1997-07, Vol.80 (7), p.1873-1876
Main Authors: Cain, Markys G., Cain, Rebecca L., Lewis, Michael H., Gent, John
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Ceramic and carbon fibers
Ceramic industries
Chemical industry and chemicals
Exact sciences and technology
Technical ceramics
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Summary:A novel in situ reaction between a ceria‐doped zirconia interphase coating on Saphikon fibers and an outer alumina coating has resulted in the formation of oriented hexaaluminate platelets which can act as a low fracture energy interface barrier for crack deflection in oxide—oxide ceramic‐matrix composites (CMCs). The reaction proceeds only in reducing environments where the reduction of the cerium and zirconium ions to their 3+ valent state causes a destabilization phenomenon consistent with previously reported findings. The diffusion of the cerium from the zirconia into solid solution with the alumina can stabilize the layered hexaaluminate structure. Preferred orientational growth of the hexaaluminate parallel to the coating interface was observed which is the required orientation for enhanced debonding at the fiber/matrix interface in long‐fiber‐reinforced CMCs.
ISSN:0002-7820
1551-2916
DOI:10.1111/j.1151-2916.1997.tb03063.x