Growth mechanism of β-SiC nanowires in SiC reticulated porous ceramics

Abstract

Polycarbosilane (PCS) was used as a precursor to prepare SiC reticulated porous ceramics (RPCs) with in situ growth of β-SiC nanowires at 1000–1300 °C. The nanowires in diameters of ∼50 nm exist on the surface of the strut and in the fracture surface of strut in SiC RPCs. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) indicate that the nanowire consists of a twinned β-SiC, which grows along the 〈1 1 1〉 direction. Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) reveal that β-SiC nanowire grows by the vapor–liquid–solid (VLS) process at low temperature. The morphologies of the nanowire formed at different temperatures testify the process. As the heat-treated temperature increased, the growth mechanism of the nanowire changes from VLS to vapor–solid (VS).