Abstract: A vacuum pump has a pump case having a gas suction port at an upper surface thereof, a rotor shaft mounted in the pump case for undergoing rotation, and a rotor connected to the rotor shaft for rotation therewith. The rotor has inner and outer circumferential surfaces coated with a corrosion-resistant film treated by nonelectrolytic plating. Rotor blades are disposed in the pump case and are integrally connected to the outer circumferential surface of the rotor. Stator blades are integrally connected to the pump case so that the rotor blades and the stator blades are alternately positioned and arranged. A balancing body is disposed on the inner circumferential surface of the rotor for balancing the rotor during rotation thereof.

Abstract: A vacuum pump has a pump case (1) forming a gas suction port (2) at the upper surface thereof; a rotor shaft (5) rotatably supported in the pump case; a rotor (8) being formed a corrosion-resistant film treated by nonelectrolytic plating on the inner and outer circumferential surfaces (8b, 8a) of the rotor; a plurality of rotor blades (10) accommodated in the pump case and integrally formed with an outer circumferential surface of the rotor; a plurality of stator blades (11) fixed in the pump case such that the rotor blades and the stator blades are alternately positioned and arranged; a drive motor (9) for rotating the rotor shaft; and mass-addition means (15) formed by applying an adhesive or a coating, having heat and corrosion resistances, on the inner circumferential surface of the rotor.