THE EFFECTS OF MASTER SINTERING CURVE ON THE MICROSTRUCTURAL EVOLUTION AND MAGNETIC PROPERTIES

This work reports our recent work on the fabrication of NiCuZn ferrites, with the particular interests on how the master sintering curve affect the microstructural evolution and magnetic properties of this materials. NixCuyZnzFe2O4 ferrites were prepared using solid state reaction method. These ferrites were then pre-sintered under the sintering temperature of 700 degrees C-900 degrees C with the interval of 50 degrees C. The shrinkage response and densification evolution of each pre -sintered materials was studied by dilatometric runs at constant heating rates of 10 degrees C/min up to 1100 degrees C. The master sintering curve (MSC) of each graded materials was constructed based on the combined-stage sintering model and validated by and non-isothermal sintering experiments. Microstructural and structural analyses were carried out using a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The permeability of samples under the DC -bias superposition condition was measured by an Agilent LCR meter at the frequency of 1 MHz. In this work, the influences of pre-sintering on the apparent activation energy (Q), densification evolution and grain growth of NiCuZn ferrites were investigated. The experimental results demonstrated that the Q-value decreased to a lowest point of 577.6 kJ/mol with the increasing pre-sintering temperature up to 850 degrees C. In addition, the magnetic properties including the behaviors of DC -bias superposition were also discussed by studying the MSC of ferrites in this article.