Modulation of Sicnw Morphology on C/C Composite Surfaces by Adjusting Cvr Process Parameters

Abstract

SiCnw with special morphology, such as bamboo-like and beaded shapes, has better reinforcing effect on metal and ceramic-based composite coatings. In this study, SiCnw was prepared in situ on the surface of C/C composites by chemical vapor reaction (CVR) method using Si, SiO2 and graphite as raw materials. The effects of heat treatment temperature, holding time and raw material ratio on the growth of SiCnw were investigated. The synthesized SiCnw is 3C-SiC with diameters between 100 nm and 300 nm and lengths up to tens of micrometers. Due to the influence of Si, SiO and CO saturation vapor pressures, with the heat treatment temperature and holding time increase, SiCnw’s yield increases and diameter becomes more homogeneous. The optimal preparation process for SiCnw was heat treatment at 1600 °C for 3 h. And SiCnw grows in different forms depending on the ration of raw material, such as hexagonal prisms (SiO2: 70%, Si:25%, C:5%), linear (SiO2: 70%, Si:20%, C:10%), pagod-like and needle-pricked shapes (SiO2: 60%, Si:25%, C:15%). The growth of SiCnw followed the vapor-solidification (VS) and spiral dislocation growth mechanism, grow in the direction of [111], and forms a tapered tip and leaves a cylindrical nanofilament at the tip.

Keywords: C/C composites, SiCnw, Morphology modulation, Growth mechanism