Sol-gel synthesis of SiC-TiO_2 nanoparticles for microwave processing

摘要

A novel approach has been explored to facilitate microwave processing of anatase TiO_2, a material that is normally inert in a microwave field. This involves production of core-shell silicon carbide (SiC)-titania (TiO_2) structures in which the SiC exhibits significant microwave loss, and thus a susceptibility to heating via microwave radiation, as well as a high thermal conductivity. SiC nanoparticles were coated with TiO_2 using a sol-gel process, involving the hydrolysis of titanium(IV) isopropoxide. Heat treatment of the novel core-shell nanostructure carried out in a conventional furnace and a microwave oven revealed that crystallization of the titania shell to anatase phase occurred at quite different temperatures, viz. 450 deg C and 190 +- 10 deg C, respectively. A range of microstructural and N_2 adsorption/desorption techniques were used to characterize the different materials obtained from the two annealing methods. The relationship between structure and resultant physical properties of these core-shell materials and their behaviour in a microwave field is discussed.