Formation mechanism of Si-Y-C ceramic matrix by reactive melt infiltration using Si-Y alloy and properties of C/Si-Y-C composites

Herein, Si-Y eutectic alloy were introduced into porous C/C preform by reactive melt infiltration (RMI) to prepare C/Si-Y-C composite. Phase compositions and their distributions in the as-prepared composites were investigated. Result indicated that four main regions were found in the typical zone in Si-Y-C matrix, i.e., amorphous carbon, polycrystalline SiC doped with YSi2, amorphous SiC and single crystal YSi2. Based on the reaction between Si-Y alloy and C/C preform and microstructural observations, a model regarding to microstructure formation mechanism was proposed to reveal reaction process. Moreover, improved flexural strength, fracture toughness, thermal diffusivity and thermal conductivity of C/Si-Y-C composite were achieved compared to C/C-SiC.