Carbon nanomaterials have been shown to rapidly evolve heat in response to electromagnetic fields. Initial studies focused on the use of microwaves, but more recently, it was discovered that carbon...

Here we report for the first time that Ti3C2Tx/polymer composite films rapidly heat when exposed to low-power radio frequency fields. Ti3C2Tx MXenes possess a high dielectric loss tangent, which is correlated with this rapid heating under electromagnetic fields. Thermal imaging confirms that these structures are capable of extraordinary heating rates (as high as 303 K/s) that are frequency- and concentration-dependent. At high loading (and high conductivity), Ti3C2Tx MXene composites do not heat under RF fields due to reflection of electromagnetic waves, whereas composites with low conductivity do not heat due to the lack of an electrical percolating network. Composites with an intermediate loading and a conductivity between 10–1000 S m−1 rapidly generate heat under RF fields. This finding unlocks a new property of Ti3C2Tx MXenes and a new material for potential RF-based applications.

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.

Silicon carbide (SiC) fibers are widely used as a reinforcement in ceramic matrix composites due to their high mechanical strength and superior thermal resistance. Here, we investigate the rapid radio frequency (RF) heating response of two types of SiC fibers (Hi-Nicalon and Sylramic) in the 1–200 MHz frequency range. Hi-Nicalon fibers exhibit a surprisingly rapid RF heating response of 240 °C/s in the perpendicular orientation, and this property could be exploited for oven-free and noncontact processing of composites with SiC fibers. The presence of excess carbon on the surface of Hi-Nicalon fibers is most likely responsible for the RF heating response and significantly higher temperatures in the parallel as compared to perpendicular alignment of fibers to the electric field. The RF heating response of Hi-Nicalon SiC fibers was utilized to heat preceramic polymers (polycarbosilanes) infiltrated in SiC fibers and cure them to ceramic matrix composites (CMCs) using RF applicators. A noncontact RF heating setup to pyrolyze the precursor polymers under inert conditions and make SiC/SiC composites is also developed.

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