In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

Eventhough Fe-6.5 wt.% Si alloy shows excellent magnetic properties, magnetic components made of the alloy are not totally because of its extremely low ductility. In order to overcome this demerit of alloy, 6.7 wt.% Si alloy powders were produced by gas atomization and then post-processed to form magnetic cores. By doing so, the total core loss could be minimized by reducing both hysteresis and eddy current loss. From our experiments, we were able to achive a core loss of at 0.1 T and 50 kHz through proper processes and a permeability of 68 at low frequency.

Magnetic powder core is considered to be one of the essential parts in modern electronic devices such as power supplies, digital telecommunication equipments and automotive electronics. To satisfy the recent requirement for the miniaturization of micro-systems and portable devices, the inductors or magnetic powder cores should have reduced compact volume and high universality both in magnetic and geometric aspects. In contrast, in some application areas such as power converters, the price is also one of the important aspects to be considered. To comply with such stringent technical requirements in modern electronic industry, it is highly required to develop magnetic materials with increased frequency stability, higher saturation magnetic flux density, higher permeability and higher quality factor (Q). The magnetic alloy powders which are currently being used in PM industry are permalloy (Ni-Fe), sendust (Fe-Si-Al), iron (Fe), silicon steel (Fe-Si) and ferrous amorphous alloy powders. Recent research trends for the industrial application of soft magnetic material and magnetic powder core will be introduced in the present paper. Emphasis will be placed on the newly required properties and corresponding new PM technologies for newly emerging application fields such as hybrid electric vehicle, alternative and renewable energy systems for next generation.

We made a high-speed motor and a DC brush-less motor for factory automation (FA) to investigate applicability of powder magnetic core to motor application, and compared those performances with the similar motors having conventional electro magnetic steel core. Permeability and saturated magnetization of powder magnetic core are less than those of elect romagnetic steel core, however output performances of each core motor are almost the same. The FA motor with powder magnetic core using three-dimensional magnetic circuit showed higher torque than the same volume motor with electromag netic steel core.

Seasonal changes have been recognized in particle characteristics and forming characteristics of iron powder with insulated coating for a compacted magnetic core because of its high hygroscopicity, due to its phosphate coating and resin binder additives. For this reason, particle characteristics and molding characteristics of the powder with diverse water absorbtivity have been studied. The result shows that the higher the volume of absorbed water, the worse the fluidity becomes, resulting in the reduction in both springback during the molding process and expansion reduction after the heat treatment. The requirement on dimension accuracy for the finished product can be satisfied with an additional drying process on the material powder, which contributes to maintain its water volume constant.