Microwave (MW) sintering is a rapid sintering process in which the material couples with the electromagnetic field, absorbs its energy and transforms it into heat. In the case of ceramics, the materials mainly interact with the electric field. MW/material interactions depend on the dielectric and electric properties of the material to heat. The capability to couple with MW depends on the material itself. Alumina is a low-loss dielectric material and couples weakly with the MW, especially at room temperature. Zirconia (and especially yttria-stabilized zirconia) has temperature-dependent dielectric properties. Moreover, its chemical composition can also have an influence. The dopants used to stabilize the tetragonal or cubic phases at room temperature are based on different stabilizing mechanisms. It can lead to interesting phenomena for MW heating of zirconia or zirconia-based composites.
Therefore, the aim of this investigation is to study the effect of the composition of the materials on the MW/material interactions. For this purpose, different zirconia and ZTA samples were prepared by uniaxial pressing from various zirconia powders, i.e., unstabilized and stabilized with 3 mol% Y₂O₃, 8 mol% Y₂O₃ and 10 mol% CeO₂ powders. The samples were sintered in a MW instrumented multimode cavity. They were placed inside a sintering insulating cell, with or without a silicon carbide susceptor. All the samples were fully dense with fine microstructures. The characteristics of the sintered samples exhibited small differences between the different compositions. The evolution of MW incident and absorbed powers were recorded during the thermal cycles. The densification curves were plotted from optical dilatometry. These data enable to detect differences in behaviours between the different materials during heating. The data related to sintering cycles were completed by experiments of direct heating in a MW single-mode cavity.