Densification mechanism and microstructural evolution of sic matrix in nite process

Monolithic SiC and unidirectional SiC/SiC composites were prepared by NITE process, using SiC "nano"-slurry infiltration technique, and the effects of tailoring raw materials and of processing conditions on density, microstructural evolution and mechanical properties were investigated. In particular, the mechanism on SiC matrix densification was discussed by the characterization using monolithic SiC fabricated by NITE process at the same condition for SiC/SiC composite fabrication. The densification was dramatically promoted at the temperature of 1750-1800°C and saturated above 1800°C. Use of nano-sized powder is effective to increase capillary adhere force, resulting in denser matrix below 1900□ than submicron-powder. Additional SiO 2 enables low temperature and viscosity of liquid phase, and thus increases capillary adhere force. Furthermore, additional SiO 2 content plays significant roles to control precisely gas generation of volatile species. SiC grain growth can be controlled by nano-sized powder characteristics and process additives as well as processing conditions. Matrix densification mechanism was proposed for the case of NITE process based on the models of the following three parameters: (1) capillary adhesion force, (2) gas generation and (3) grain growth. The conditions, based on the dense matrix of monolithic SiC, were applied to SiC/SiC composites though NITE process.