The microwave heating behaviour of composite systems is of considerable interest for theprocessing of ceramics or the creation of materials with interesting dielectric properties. In this investigation, the heating response of different mixtures of metallic and insulating powders is described. The heating rate as a function of metal type, mass fraction and powder types will be presented for pressed pellet samples.
From the results, three distinct heating regimes have been identified. At low temperatures. induced electric currents cause the metal particles to heat. As the temperature increases, exothermic oxidation of the metal powder particles increases the heating rate. Eventually, the insulating powder (alumina) begins to absorb microwave energy more efficiently and this dominates the high temperature behaviour. The relative importance of thesethree effects for different temperatures depends on the particular powders which are used.