MICROWAVE ASSISTED SINTERING KINETICS OF NANOMETRIC HEMATITE

Reference	Presenter	Authors (Institution)	Abstract
12-028	Marina Magro Togashi	Togashi, M.M.(Universidade Federal de São Carlos); Perdomo, C.F.(Universidade Federal de São Carlos); Kiminami, R.H.(Universidade Federal de São Carlos);	Microwave assisted sintering has great advantages compared to conventional sintering, such as volumetric heating, shorter processing time, a reduction in sintering temperatures and lower process energy expenditure. Materials that have high dielectric losses show good absorption properties of microwave radiation. Iron oxide, in the hematite phase, is a good radiation absorber, as reported in the literature. In this context, the thermodynamic of the process needs to be understood so that the phenomenon can be comprehended globally. Dilatometry is a technique that allows linear shrinkage monitoring of the ceramic and allows the calculation of thermodynamic parameters as initial activation energy of the initial stage sintering. The aim of this paper is to study the microwave assisted sintering kinetics using non-isothermal methods, such as Woolfrey and Bannister and Dorn. Therefore, a dilatometer coupled to a microwave oven was used. The studied material was iron oxide in the hematite phase, synthetized by sol-gel and in nanometric scale with an average particle size estimated at 35 nm. The nanopowder was characterized by XRD, SEM and BET. The results obtained by microwave assisted dilatometry were compared with the conventional dilatometry and it was observed that using the microwave radiation, there was higher total linear shrinkage, lower temperatures of maximum linear shrinkage, lower temperatures in the initial sintering stage and lower initial stage activation energy, corroborating with the fact that microwave radiation needs less energy for the initial sintering stage and less processing time for sample densification.
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