Reactively Sintered Molybdenum Disilicide-Based Composites

摘要

The objective of this research was to identify the phases formed and determinesome mechanical properties of reactively sintered MoSi2 and MoSi2 composites with carbon additions. The carbon additions were made via polymeric coatings on MoSi2 particles. Carbon was added to form silicon carbide particles (SiCp) in situ and to reduce the inherent presence of SiO2 in MoSi2. The in situ formation of SiCp would increase the low temperature toughness of MoSi2 by using it as a reinforcement and also reduce the high temperature creep by reducing grain boundary sliding caused by viscous flow of SiO2. The carbon coating of the MoSi2 powder was obtained by: phenolic resin based carbon by solvent evaporation and aqueous dispersion flocculation. The sintering temperatures and times ranged from 1600 to 1800 deg C and 1 to 100 hr., respectively. The addition of carbon did reduce the presence of SiO2 and there was formation of SiCp. However, the SiCp formation was less than expected and, therefore, did not increase toughness significantly. The Nowotny phase (Mo4.8Si3C0.6) was also found in less than expected amounts.