Enhanced mechanical properties of laminated ZrB2–SiC ceramics with porous Si3N4 interface

Abstract

In this study, bionic laminated ZrB2–SiC ceramics (LZNw) were fabricated using Si3N4 whiskers as an interface layer. The room-temperature flexural strength and fracture toughness of LZNw were determined to be 528 MPa and 15.3 MPa m1/2, respectively. With increasing testing temperature up to 1500 °C, the flexural strength of LZNw remained higher than that of monolithic ZrB2–SiC ceramics (ZS). Specifically, at the peak temperature of 1500 °C, the flexural strength of LZNw was as high as 380 MPa, while that of ZS dropped to 219 MPa. This outstanding high-temperature strength of LZNw can be ascribed to the porous structure of the Si3N4 whisker interface layer, which absorbs the glassy phase accumulated at the crack tip, and the stepped fracturing pattern, which hinders the flow of the glassy phase, thus avoiding the grain boundary sliding caused by the enrichment of the glassy phase.