Densification kinetics of nano-hematite using microwave assisted dilatometry

Abstract

The aim of this paper was to study the densification kinetics of nano-hematite using a microwave assisted dilatometry at 2.45 GHz and kinetics models as an approximation to understand the sintering behavior using microwave heating. A horizontal dilatometer coupled to a multimodal microwave oven and conventional horizontal dilatometer were used to compare the results. The hematite was synthesized by the modified sol-gel method in order to ensure the purity, nanometric scale and intermediate particle size distribution in the starting powder. Novel values of apparent activation energy for densification of nano-hematite were obtained for the initial and intermediate stages of sintering using microwave heating at 2.45 GHz. The results showed that the microwave heating needs 10% less energy to start the initial sintering stage and 56% less energy for densification in the intermediate stage both compared with conventional heating sintering. After the final stage of sintering, smaller grain growth was obtained in microwave heating, as well as a reduction in the final grain size considering the increase in the heating rate.