Densification behavior of ZrB2–MoSi2–SiCw composite processed by multi stage spark plasma sintering

Abstract

This study reports the densification behavior and novel design of core-rim microstructure for different ZrB2–MoSi2-SiCw (ZMSw) composites. Four ZrB2–MoSi2 composites containing various amounts of SiCw (0, 5, 10, and 20 vol%) were densified by multistage spark plasma sintering. Optimal combinations of sintering schedule, temperature, and composition are recognized for producing dense ZrB2-based ceramic-matrix composite with core-rim grain structure in the boride matrix, where ZrB2 core is surrounded by a solid solution of (Mo,W)Si2. Fragmentation, rearrangement, plastic deformation, and grain boundary diffusion mechanisms are responsible for densification of composites sintered by multistage SPS conditions at 1700 °C. Addition of SiCw significantly improves the density and mechanical properties of ZrB2–MoSi2–SiCw composites due to the formation of a core-rim structure.