The effects of carbon addition on the mechanical properties of MoSi2–TiC composites

In order to improve the mechanical properties of MoSi2 matrix composites, carbon was added to a MoSi2–20 wt.% TiC composite to remove the oxygen which exists at the grain boundaries as glassy SiO2 phase. Compared with the MoSi2–20 wt.% TiC composite without carbon addition, the bending strength and fracture toughness of a MoSi2–20 wt.% TiC–1 wt.% C composite sintered at 1600 °C can be enhanced from 481 to 689 MPa and from 3.89 to 5.4 MPa·m1/2 respectively. The experimental results show that the sintering temperature has a considerable effect on the mechanical properties of MoSi2–20 wt.% TiC–1 wt.% C composites. As a deoxidant, carbon can react with glassy SiO2 to eliminate the glassy SiO2 phase. However, a further increase of carbon addition, beyond 1 wt.% produces an abatement of the mechanical properties.