Hardness and fracture toughness of SiC-preforms infiltrated with MoSi{sub}2

摘要

The composites consisting of molybdenum disilicide (MoSi{sub}2), molybdenum carbosilicide (Mo{sub}(≤5)Si{sub}3C{sub}(≤1)) and silicon carbide were prepared by carbon(gas)-MoSi{sub}2 (melt) infiltration of SiC preforms in an environment with carbon activity close to 1. The pure MoSi{sub}2 or SiC-MoSi{sub}2 eutectic composition was used as the liquid infiltrant Carbon was incorporated into the SiC preform via gas phase due to temperature gradient between graphite heat element and preform. The low final porosity (1-3%) of prepared composites has been achieved by the infiltration in a dynamic vacuum of about 50 Pa at the temperatures between 1980°C and 2050°C. The higher values of hardness and fracture toughness were determined for composites infiltrated by SiC-MoSi{sub}2 eutectic composition.