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Design of a Laminated Ceramic Composite for Improved Strength and Toughness
Author(s) -
Russo Charles J.,
Harmer Martin P.,
Chan Helen M.,
Miller Gary A.
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb04440.x
Subject(s) - materials science , composite material , toughness , indentation , ceramic , composite number , fracture toughness , strength of materials
Adding aluminum titanate to alumina can result in dramatic improvements in toughness and R ‐curve properties. However, the improved toughness is offset by a significant reduction in strength at small flaw sizes. This problem can be overcome through the use of a laminated composite construction. By placing a thin layer of high‐strength material on the surface of a high‐toughness body, the toughness and flaw tolerance of the body material can be maintained without sacrificing small flaw strength. In this study, alumina + 20 vol% aluminum titanate (AAT20) was used for both the surface layer and the bulk material. The surface material was a homogeneous, fine‐grained mixture of the two phases, while the bulk was an inhomogeneous mixture having a bimodal grain structure. In monolithic form, the homogeneous AAT20 displays a nearly P −1/3 indentation strength response, and the inhomogeneous material displays a flat strength response, indicative of R ‐curve behavior. The trilayer material shows a composite indentation strength response, with high strength throughout the entire range of starting flaw sizes. A method for predetermining the optimum surface layer thickness is presented. The processing and mechanical properties of these materials will be discussed.