Multiple zirconia interphase for SiC/SiCf composites

A multiple zirconium dioxide interphase for SiC/SiCf composites was developed using the sol-gel approach. The morphology, elemental composition, topography, and tensile strength of ZrO2 coated Nicalon (TM) CG fibers were examined using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), atomic force microscopy (AFM), and single filament tensile strength analysis as a function of the number of coats. The interfacial frictional stress values of the SiC/SiCf and SiC/(ZrO2)(n)/SiCf minicomposites were evaluated using micro indentation tests. It was shown that the presence of multiple ZrO2 coating on Nicalon (TM) CG promotes decoupling of the fibers from the matrix and frictional pullout, with the fiber sliding pressure decreases as a number of coats increase. Due to strong bonding at the fiber/coating and the matrix/coating boundaries, on the one hand, and weak bonding between interfacial layers, on the other hand, debonding and sliding occur within the interphase. Thus, the fiber/matrix decoupling in SiC/(ZrO2)(n)/SiCf minicomposites can be regulated by designing the multiple ZrO2 interphase. (C) 2010 Elsevier B.V. All rights reserved.