Multiple zirconia interphase for SiC/SiC_f composites

摘要

A multiple zirconium dioxide interphase for SiC/SiC_f composites was developed using the sol-gel approach. The morphology, elemental composition, topography, and tensile strength of ZrO_2 coated Nicalon? 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/SiC_f and SiC/(ZrO_2)_n/SiC_f minicomposites were evaluated using micro indentation tests.It was shown that the presence of multiple ZrO_2 coating on Nicalon? 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/(ZrO_2)_n/SiC_f minicomposites can be regulated by designing the multiple ZrO_2 interphase.