EFFECT OF PROCESSING PARAMETERS IN THE MICROSTRUCTURE OF Ni-Zn FERRITES OBTAINED BY CONVENTIONAL METHOD

Reference	Presenter	Authors (Institution)	Abstract
08-006	Melise Cardoso Antunes	Gama, A.M.(Instituto de Aeronáutica e Espaço); Antunes, M.C.(Universidade Federal de São Paulo); Gonçalves, E.S.(Instituto de Aeronáutica e Espaço);	The processing of nickel and zinc ferrites with NixZn1-xFe2O4 stoichiometry was studied where x = 0, 0.2, 0.4, 0.6, 0.8 and 1 by the conventional ceramic method, magnetic ceramic materials that can be applied as an electromagnetic filter and in telecommunications devices. With the milled material, samples were formed into pellets via uniaxial pressing, followed by calcination at 800°C. The calcined sample was milled again and shaped into pellets by uniaxial pressing in duplicate for each stoichiometry. One of the groups of conformed samples followed to the isostatic pressing step and both groups were submitted to sintering at 1200, 1300 and 1400°C. After being embedded in resin, they received ceramography treatment and chemical attack. The samples were analyzed by X-ray diffraction (DRX) and submitted to Archimedes densification. Scanning electron microscopy analysis (SEM) was performed on isostatic pressed samples. XRD analysis confirmed the inverse spinel structure formation.  Archimedes’ densification pointed to the significant influence of the reduction of porosity and, in general, higher densification in the isostatic pressed samples if compared to those pressed only by uniaxial. The characterization by SEM showed direct influence increasing the grains’ size formed as the sintering temperature increases. It was also noted that the densification and porosity of the materials obtained could not be directly related to the sintering temperature due to the great influence of the zinc concentration acting on the medium, making it difficult to densify when its concentration is high. In conclusion, the use of uniaxial pressing associated with the isostatic is advantageous in obtaining a material with better mechanical resistance as well as the use of a higher sintering temperature to form larger grains. The importance of controlling zinc concentration in the medium was observed to optimize material densification and grain growth.<!--[if gte mso 9]>
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