CHARACTERIZATION OF ZRO2-AL2O3 COMPOSITES SINTERED IN A 2.45 GHZ ELECTROMAGNETIC-FIELD

The microwave heating process has shown potential for uniform material heating with rapid heating rates possible. The ceramic composite 80 wt% ZrO2 (+ 3 mol% Y2O3) 20 wt% Al2O3 was sintered in a Cober S6F microwave oven operating at 2.45 GHz even though it was considered to be microwave transparent at room temperature. The microwave-sintered sample was densified more rapidly and in a short time and lower temperature than the conventionally sintered sample. The fracture of the conventionally sintered sample was intergranular, but one of the microwave-sintered samples was transgranular. The fraction of the monoclinic-phase zirconia was different in the conventionally and microwave-sintered samples. The unusual microstructure of microwave-processed materials is explained by a microwave heating theory.