Densification kinetics of nano-hematite using microwave assisted dilatometry

Densification Kinetics and In Situ Electrical Resistivity Measurements of Hematite Nanopowders during High-Frequency Microwave Sintering

“…These values were compared with the values reported by Togashi et al [7], who used the same hematite nanopowder of this work and sintered it by conventional dilatometry. It is possible to observe an accentuated decrease in the onset of shrinkage temperature, using microwave energy at 30 GHz, and it varied approximately at 200°C…”

“…Hematite nanopowders (Fe 2 O 3 ) with an average particle size of 30 AE 2 nm were synthesized by a modified sol-gel method, as described by Togashi et al [7]. For the dielectric characterization, the dielectric permittivity was measured with a cavity perturbation system, as the similar to the experimental scheme of Soldatov et al [21].…”

“…Figure 4(a) shows the graphical differences in the behavior of the linear shrinkage and the first derivative as a function of temperature in the microwave assisted in highfrequency (30 GHz) and conventional dilatometer measurements. Figure 4(b) shows the comparison between the microwave in high-frequency (30 GHz), microwaveassisted at 2.45 GHz (hybrid heating with the aid of a susceptor), and conventional dilatometer results, where the values at 2.45 GHz and conventional are from the literature and reported by Togashi et al [7].…”

“…Thus, the viability of using these classic models has encouraged the use of dilatometers heated by microwave radiation, both at 2.45 and at 30 GHz. This allows to evaluate the instantaneous linear shrinkage and enable studies of the kinetics behavior during sintering at different frequencies [2,4,6,7]. Gyrotrons are used as the high-power microwave source at 30 GHz.…”

“…Other studies were performed on the hematite under microwave heating, such as reported by Togashi et al [7]. The densification kinetics of the hematite nanopowders was evaluated using the linear thermal shrinkage curves in the analysis, obtained in a microwave-heated dilatometer at 2.45 GHz aided with a microwave susceptor and by dilatometry with conventional heating.…”