Preparation and characterization of SiC microtubes

Silicon carbide microtubes with medium surface area, 30-70 m(2) g(-1), were successfully prepared by shape memory synthesis involving the reaction between SiO vapors and low surface area, 1-2 m(2) g(-1), carbon microfibers. The gross morphology of the carbon microfibers was conserved during the carburization process. After calcination at 600 degrees C in order to eliminate the unreacted carbon, hollow SiC microtubes were obtained. The pore size distribution of the material was centered around 10 nm, allowing a high accessibility of potential reactants to an active phase during catalytic reactions. The surface was covered by an amorphous layer 3 nm thick, XPS measurements revealed that this amorphous phase was composed of a mixture of SiO2 and SiOxCy. Soda treatment at 80 degrees C allowed complete removal of this surface phase without any change in the material morphology. A similar result was also obtained after treatment with an aqua regia medium. (C) 1999 Elsevier Science B.V. All rights reserved.