Impregnated carbon as a susceptor material for low loss oxides in dielectric heating

Dielectric heating of materials may have distinct advantages over conventional heating in view of the fact that it is a bulk heating technique, and does not rely on conduction or convection, the driving force of which are temperature gradients. Dielectric heating is currently predominantly practised in food and ceramic processing. Research is conducted also in the areas of chemistry and in solid catalysed reactions. Base materials used in these applications, like food containers, catalysts and green ceramic products, may not demonstrate sufficiently high dielectric loss factors to allow dielectric heating to be feasible. In such cases microwave susceptor materials may be added. A whole variety of such susceptor materials are known, such as zirconia, silicon carbide and carbon. In this work, the impregnation with carbon was investigated as a way to enhance the dielectric loss factor for low loss porous oxidic materials. To this end a variety of porous oxides was impregnated with poly furfuryl alcohol which was subsequently carbonised. Impregnation conditions, dielectric heating behaviour, calculations on dielectric properties and oxidation resistance will be reported. (C) 2003 Kluwer Academic Publishers.