Carbon nanotube composite curing through absorption of microwave radiation

The microwave absorbing properties and subsequent heating of carbon nanotubes can be used to rapidly cure ceramic composites. With less than 1 wt% carbon nanotube additives and 30–40 W of directed microwave power (2.45 GHz), bulk composite samples reach temperatures above 500 °C within 1 min. Multiwalled carbon nanotubes (MWNTs), functionalized MWNTs (f-MWNTs), raw single-walled carbon nanotubes (r-SWNTs) and purified SWNTs (p-SWNTs) were all used to produce composites in Starfire® SMP-10 silicon carbide pre-ceramic. MWNTs loaded at 0.75 wt% in SMP-10 consistently displayed the fastest rate of heating (∼500 °C in 10 s) and highest temperatures (1150 °C in 7 min). The degree of composite curing was monitored by TGA. The nanotube/matrix dispersion and integrity was imaged using optical microscopy, TEM and SEM, and Raman spectroscopy was used to determine the state of the nanotubes after exposure to microwave radiation.