Microstructure and thermal characteristic of Si-coated multi-walled carbon nanotubes

The carbon nanotube (CNT) is a promising reinforcement material for manufacturing metal-or ceramic-based composites. However, CNTs are prone to interact with the matrix in a reactive atmosphere that often alters the structure and properties of CNTs and depresses their reinforcing effect. To overcome this problem, a protective silicon layer has been deposited on multi-walled carbon nanotubes (MWNTs) using cycled vacuum-feeding chemical vapour deposition by the in situ decomposition of gaseous SiH 4 . The silicon coating is well covered and continuous with a cubic-phase structure. It effectively improves the thermal stability of MWNTs by acting as a protective film, which inhibits and delays the onset of oxidation. Thermogravimetric analysis (TGA) reveals that the oxidation of Si-coated MWNTs occurs at a temperature of 676.3 °C, which is 105.1 °C higher than that of uncoated MWNTs, and the weight loss decreases with the increasing thickness of silicon coating.