Development of the tailored SiC/SiC composites by the combined fabrication process of ICVI and NITE methods

Abstract

In order to improve the thermo-mechanical performances of SiC/SiC composite, process improvement and modification by the combination of nano-infiltration and transient eutectic-phase (NITE) method and chemical vapor infiltration (CVI) method were studied. Multilayered PyC/SiC fiber coating and matrix infiltration within fiber-tows were prepared with isothermal/isobaric CVI (ICVI) method and full-densification of SiC matrix was examined with NITE methods using four kinds of processing options. Applied pressure was useful for nearly-full matrix densification due to the promoting infiltration driving force of SiC nano-powder intra-fiber-tows, but simultaneously caused the sever degradation of fibers and interphase with fracture, resulting in lower strength. Increase of additives amount and additional polymer were effective ways for matrix densification by SiC nano-power infiltration intra-fiber bundles without pressure. Thermal conductivity was greatly improved with the decrease of matrix porosity. The tailoring of thermo-mechanical properties might be easily controlled by the SiC matrix porosity without process-induced fibers and interphases degradations.