Mechanical properties and microstructure of monolithic SiC and SiC/SiC composites fabricated through NITE process

摘要

SiC/SiC composites have been developed through Nano-Infiltration and TransientEutectic-phase (NITE) process, which consists of SiC fiber fabrics, "Nano"-slurry infiltration and pressure sintering. This paper describes the effects of tailoring raw materials and of processing conditions on density, microstructure/microchemistry and mechanical properties of monolithic SiC and SiC/SiC composites. Fundamental characterization of SiC nano-powder and sub-micron processing additives; Al_(2)O_(3), Y_(2)O_(3) and SiO_(2), were conducted by microstructural observations; SEM and other measurements; XRD and XPS. The optimum condition on matrix densification was discussed by fabricating monolithic SiC, as the same fabricate technique as SiC/SiC composites. In particular, effects of silicon based particles; SiC and SiO_(2), were evaluated. SiO_(2) enhances the densification above 1750 deg C due to the reaction with the excess carbon of SiC nano-powder surface. However, it was revealed that excess SiO_(2) is harmful in fracture toughness. Finally, the optimum conditions, based on the dense matrix of monolithic SiC, were applied to SiC/SiC composites though NITE process.