Wrought Si-steels are generally used for electromagnetic valves, which are needed good response. To date, Hitachi Powdered Metals Co., Ltd. have produced Fe-Si base sintered magnetic material, EU-52, which shows a magnetic flux density of more than 1.25T at 2000A/m and a maximum permeability of more than 3500. However these magnetic properties are lower than that of wrought Si-steels. Because EU-52 has a low density of 7.2Mg/m3. For improving the magnetic properties, it is necessary to increase the density of sintered cores. To increase density, a new mixing method of coating fine Si powders on atomized iron powders was developed, for avoiding the Kirkendall effect. As the result, developed P/M Fe-Si magnetic cores shows higher density of 7.38Mg/m3, higher magnetic flux density of 1.48T at 2000A/m and higher maximum permeability of 6800.

SMC(Soft Magnetic Composite) materials which we have newly developed were studied for their applying effects. It shows almost the same motor output power as the laminated Si-steels of 0.35mm in thickness, although core loss of SMC is about 1.5 times that of the laminations. As shown in the results, the SMC motor core is sufficient for real use as a motor core. Furthermore, a 3-D shaped motor core made of SMC can improve approximately 20% of the output compared with the same size motor made of laminations.