Effect of SiO₂ Content on the Electromagnetic Properties of CoZn-Z Type Barium Ferrite Prepared with Ferrous Micro-Beads

Abstract

Ferrous micro-beads from fly-ash were used as starting material to prepare CoZn-Z type barium ferrite. As the main impurity in the beads, SiO2plays an important role on the electromagnetic properties of the ferrites. To investigate the effect of SiO2content, a series of CoZn-Z type ferrites with various contents of SiO2(1 wt%, 2 wt% and 5 wt%) were prepared with analytical pure Fe2O3and SiO2. The density, phase composition, microstructure and electromagnetic properties of the sintered samples were investigated. The results show that the permeability of samples alters little at a low content of SiO2about 1 wt%, but deteriorates dramatically when the addition of SiO2is above 2 wt%. The ferrous micro-beads were then treated by alkali cleaning to reduce the content of SiO2to about 1 wt%, and the samples prepared with these treated beads show a similar performance on the electromagnetic properties with pure CoZn-Z type ferrite.

To heat or not to heat: a study of the performances of iron carbide nanoparticles in magnetic heating

“…The role of this layer in the on-off behaviour of the heating power has then to be clarified. It has been previously shown that the presence of more than 2 wt% of SiO2 deteriorates the magnetic permeability of a hard magnetic material such as bulk barium ferrite, 46 but here, this is not the case since the Ms of the FeC-1 NPs determined by VSM is very similar to that measured for the FeC-ref NPs (see Table 1). Then, the on-off behaviour of the heating power has to be related to the NPs agglomeration, in which the silicon containing layer can also play a role by preventing chain formation.…”