Paper Title:

Toughening of Ceramic Composite Designed by Silica-Based Transformation Weakening Interphases

Periodical Key Engineering Materials (Volume 287)
Main Theme Advanced Si-Based Ceramics and Composites
Edited by Hai-Doo Kim, Hua-Tay Lin and Michael J. Hoffmann
Pages 358-366
DOI 10.4028/www.scientific.net/KEM.287.358
Citation Sang Jin Lee et al., 2005, Key Engineering Materials, 287, 358
Online since June, 2005
Authors Sang Jin Lee, C.H. Lee, Jong Hee Hwang
Keywords Composite, Cristobalite, Hexacelsian, Interphase, Microcrack, Transformation
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Abstract

A new concept for achieving graceful failure in oxide composites is introduced. It is based on crack deflection in a weak interphase between a matrix and reinforcement (e.g. fiber), or in a laminated composite. The interphase can be phase transformation weakened by volume contraction and/or unit cell shape change. Microcracking induced by a displacive, crystallographic phase transformation in silica-based interphases resulted in increase in the toughness of the bulk composites. In the present study, mullite/cordierite laminates with b®a-cristobalite (SiO2) transformation weakened interphase, and alumina matrix fibrous monolith with metastable hexacelsian (BaAl2Si2O8) interphases were investigated for interphase debonding behavior. In mechanical test, the laminates showed step-wise load drop behavior dependent on a grain size of b-cristobalite. In particular, in the fibrous monolith design, the load-deflection curve showed unusual plastic-like behavior with reasonable work of fracture.