To obtain a high efficiency and high speed rotary machine by that the core of at least the rotor or stator comprises an Si steel sheet having an Si concn. higher by specified wt.% or more in a surface layer than in the sheet thickness center and rotation speed is specified rpm or more.
The rotary machine has a rotation speed of 7000 rmp or more, the core of at least the rotor or stator comprises an Si steel sheet having an Si concn. higher by 0.3 wt.% or more in a surface layer than in the sheet thickness center and rotation speed is specified rpm or more. To provide an Si concn. gradient in the sheet thickness direction, such a method is used as e.g. the surface of an Si steel sheet is coated with an Si paste and it is thermally diffused, Si ion is deposited by the PVD and thermally diffused, or high temp. gas of SiCl4. etc., is blown on the steel, sheet to deposit Si and it is thermally diffused by the thermal VCD, and the mean Si content is pref. about 6 wt.% or less.
NAMIKAWA MISAO
YAMAJI TSUNEHIRO
KASAI KATSUJI
