Preparation of SiC-W2C nano-composite powders by chemical vapour deposition of the SiH4-CH4-WF6-H2 system

Abstract

SiC-W2C composite powders were prepared by chemical vapour deposition (CVD) using SiH4 + CH4 + WF6 + H2 as source gases at a temperature of 1673 K. X-ray diffraction, TEM observation and infrared absorption were used to characterize the structures of the powders. The prepared powders consisted of SiC-W2C composite particles and hollow β-SiC particles. The SiC-W2C composite particles had a W2C core and an SiC shell. The average particle diameters of the SiC-W2C composite and hollow SiC particles increased from 18 to 30 nm and from 40 to 70 nm, respectively, with an increase of SiH4 concentration. TEM and infrared spectrum analyses showed that the W2C core diameter was unchanged (about 18 nm), while the SiC shell thickness varied from 1 to 6 nm with reaction conditions.