Processing and characterization of cobalt silicide nanoparticle-containing silicon carbide fibers through a colloidal method and their underlying mechanism

Cobalt-containing silicon carbide (Co-SiC) fibers were synthesized through a colloidal method. Dicobalt octacarbonyl [Co₂(CO)₈] was employed to react with low-molecular weight liquid polycarbosilane (LPCS) to prepare a stable Co-containing colloid (Co-colloid), which was subsequently added to high-molecular weight solid polycarbosilane to obtain the precursor. FTIR, GPC, XRD, and TEM were employed to further understand and develop the mechanism for the formation of the Co-colloid. Results show that active Co intermediates derived from the incomplete decomposition of Co ₂(CO)₈ promoted LPCS cross-linkage. The effects of the Co-colloid on the oxidation-curing nature of the green fiber were also investigated. Under heat treatment at higher temperature, carbonyls in the fibers completely decomposed and further crystallized in the morphology of cobalt silicide (CoSi) domains. The effects of Co on the electrical resistivity, magnetic properties, dielectric properties, microwave absorption properties and tensile strength of SiC fibers were also studied.