Ceramic matrix composites derived from CrSi2-filled silicone polycyclic network

Ceramic matrix composites (CMC) were prepared by the active-filler-controlled polymer pyrolysis, using a siloxane polycyclic network filled with CrSi2. The starting CrSi2-filled polysiloxane was pyrolyzed in both nitrogen and argon atmospheres, up to 1450°C. During the pyrolysis in nitrogen atmosphere, the CrSi2 particles reacted with N2, and also with carbon from the preceramic polymer binder, still complete consumption of the filler particles. Such reactions led to a dramatic change in the composition and microstructure of the resulting ceramic monoliths, which displayed linear expansion of 1.7%. In argon atmosphere, the CrSi2 particles acted as inert filler during the pyrolysis process. The final CMC compositions obtained in N2 and Ar atmospheres were Cr0.62C0.25N0.03-Si3N4-Cr3C2 and SiOxCy-SiC-CrSi2, respectively.