Here we demonstrate an oven-free and mold-free heating route to convert preceramic polymers to silicon carbide using carbon nanomaterials as susceptors. Silicon carbide is prized for its high thermal stability and low density and could be produced via slow oven heating of polycarbosilane (PCS). We show that addition of multiwalled carbon nanotubes (MWCNT) as susceptors to polycarbosilane results in rapid and volumetric heating upon exposure to microwaves and radio frequency. We assess microwave heating of polycarbosilane-MWCNT composites; this process is capable of reaching pyrolysis temperatures, and the resulting crystal structure is cubic (-SiC). We measure dielectric properties of these composites in the radio frequency range. We cure these composites using RF, and thermogravimetric data shows that the extent of cure for these samples is around 95 %. We demonstrate the applicability of this study for 3D printing silicon carbides by successive iterations of layer deposition and rapid RF curing. We performed on the fly measurements of dielectric values of the 3D printing ink at different temperature while curing it.We have also shown that these volumetric heating methods can rapidly cure polycarbosilane fibers to make silicon carbide fibers without melting them before crosslinking.
The SEM imaging discussed in this thesis was performed by Aniruddh Vashisth.Materials for sample preparation, temperature and strength data for the IR lamp heating process, and additional knowledge and guidance were all provided by Tyler Auvil and Dan Sophiea, from the Dow Chemical Company.
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