Catalytic and enhanced effects of silicon carbide nanoparticles on carbonization and graphitization of polyimide films

Abstract

Silicon carbide nanoparticle (SiC NPs)/polyimide (PI) composite films were prepared by a solution blending process. To obtain carbon films, pure PI and SiC/PI composite films were carbonized at 1000 °C under a N₂ atmosphere and graphitized at 2300 °C for 2 h under an Ar atmosphere. The catalytic behaviour of SiC NPs in the carbonization and graphitization processes was investigated by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In these processes, the presence of SiC NPs obviously promoted the carbonization and graphitization yields of the SiC/PI composite films and enhanced the fracture toughness of the resulting carbon films. Because of the catalytic effects of SiC NPs, the graphitization temperatures decreased to 2300 °C and the degree of graphitization exceeded 31.40% for the 3 wt% SiC NPs sample. Furthermore, the electrical conductivity of the graphitized films was estimated by the four-point probe method.