In this Master thesis we have researched the influence of sintering conditions on magnetic properties of commercial strontium hexaferrite (SrFe12O19) and magnetic composite materials based on strontium hexaferrite by intense radiation sintering (SITR) process.
The study compared how different conditions (sintering temperature, compressive force of greens, holding time at sintering temperature, heating rate, influence of granulation of input material and additional isostatic compression of green pellets) of sintering by intense thermal radiation affect compaction, porosity, microstructure development and consequently magnetic properties of single-phase hard magnetic ferrite, hard/soft magnetic ferrite composite and ferrite composite with the addition of cellulose nanofibers. For the preparation of composite materials, we used hard (SrFe12O19) and soft (Fe, Fe3O4 and CoFe2O4) magnetic phases and cellulose nanofibers, which will enhance the mechanical properties of the composite. In the case of composites, powder mixtures were prepared based on the previous knowledge and magnetically characterized prior to the sintering. For the above mentioned parameters, we evaluated their influence on the magnetic properties of the sintered samples. We had a lot of problems with achieving a suitable density of the material to make it technologically usable without seriously deteriorating the magnetic properties.
The aim of the Master thesis was to prepare a ferrite-based by the method of rapid radiation sintering, which, apart from being energy very efficient when compared to the conventional sintering, is also a novel consolidation technique especially in the field of magnetic ceramics.