The effect of particle size on the formation and structure of carbide-derived carbon on β-SiC nanoparticles by reaction with chlorine

Carbide-derived carbon (CDC) coatings were produced by reaction with pure chlorine gas on the surface of β-SiC nanoparticles. Various CDC thicknesses were obtained using moderate temperatures (565–635 °C) associated with a short time (30 min) of chlorination under atmospheric pressure. Such conditions enable controlled layer-by-layer silicon extraction from SiC material. Kinetics of CDC formation were assessed using three SiC laser pyrolysis-produced nanopowders of different average size. Under the same conditions, the smallest particle size material is more prone to chlorination and exhibits a thicker carbon coating. Effect of particle size distribution on reactivity with chlorine is also discussed. After achieving carbide to carbon partial conversion, tem observations show good covering and adherent carbon coatings on remaining SiC material, N2 adsorption analysis show that CDC coating is microporous and has a specific surface area exceeding 1000 m2 g−1. Thermogravimetric analysis coupled with mass spectroscopy under He gas flow, is used to determine the thermal stability and the nature of volatile species trapped in the microporosity. Under an O2 gas flow, the amount of CDC formed is measured by burning it off at temperatures of 400–750 °C, before the onset of oxidation of the remaining SiC.