Effects of preform pore structure on infiltration kinetics and microstructure evolution of RMI-derived Cf/ZrC-ZrB2-SiC composite

Reactive melt infiltration (RMI) is often used to fabricate highly dense ceramic matrix composite by infiltration of alloy melt into porous preform. Here, C-f/B4C-C preforms with various pore structures were prepared, and the effects of pore structure on the ZrSi2 melt infiltration and the as-received C-f/ZrC-ZrB2-SiC composites were investigated. Compared with the preform prepared by slurry impregnation (SI), the preform prepared by sol impregnation shows more uniform pore size distribution, which leads to more homogeneous melt infiltration, as well as more uniform formation of ZrC-ZrB2-SiC and better mechanical properties in the composites. The calculation results of infiltration kinetics indicate that the pore radius decreases quickly during the melt infiltration. As the time needed for pore closure in sol-preform is longer than that in SI-preform, it makes the infiltration kinetics more favorable in the former preform. This study can provide guidance for the pore structure regulation in the fabrication of RMI-composites.