Influence of MoSi2 content on the microstructure and properties of MoSi2–RSiC composites

The influence of MoSi2 content on the microstructural, mechanical, and electrical properties of MoSi2–RSiC composites was studied. Results showed that the main phases in the MoSi2–RSiC composites were SiC, MoSi2 and Mo4.8Si3C0.6. When the MoSi2 content was below 10%, most of the Mo compounds coated the surface of the coarse SiC particles. At MoSi2 contents >10%, some Mo compounds coated the surface while others filled the pores near the sintering neck between the SiC particles. MoSi2 can also accelerate the re-crystallization process of RSiC. Increases in MoSi2 content resulted in decreases in the porosity of the composite; in contrast, the flexural strength initially increased and then decreased under the same conditions. The flexural strength reached 94.0 MPa when the MoSi2 content was 10%. With increasing MoSi2 content, the volume resistivity of the composites decreased steeply, the electrical conductivity mechanism of it resembled that of a two shunt-wound equivalent circuit.