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Crack Deflection and Propagation in Layered Silicon Nitride/Boron Nitride Ceramics
Author(s) -
Kovar Desiderio,
Thouless M. D.,
Halloran John W.
Publication year - 1998
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.1151-2916.1998.tb02438.x
Subject(s) - materials science , boron nitride , silicon nitride , composite material , deflection (physics) , ceramic , fracture mechanics , flexural strength , nitride , dissipation , interphase , layer (electronics) , optics , physics , genetics , biology , thermodynamics
Crack deflection and the subsequent growth of delamination cracks can be a potent source of energy dissipation during the fracture of layered ceramics. In this study, multilayered ceramics that consist of silicon nitride (Si 3 N 4 ) layers separated by boron nitride/silicon nitride (BN/Si 3 N 4 ) interphases have been manufactured and tested. Flexural tests reveal that the crack path is dependent on the composition of the interphase between the Si 3 N 4 layers. Experimental measurements of interfacial fracture resistance and frictional sliding resistance show that both quantities increase as the Si 3 N 4 content in the interphase increases. However, contrary to existing theories, high energy‐absorption capacity has not been realized in materials that exhibit crack deflection but also have moderately high interfacial fracture resistance. Significant energy absorption has been measured only in materials with very low interfacial fracture resistance values. A method of predicting the critical value of the interfacial fracture resistance necessary to ensure a high energy‐absorption capacity is presented.