Abstract: A dynamic pressure bearing for an X-ray tube having a rotary anode has a cylinder member for supporting the anode and a shaft member fitted in the cylinder member. Between the cylinder member and the shaft member is formed a given clearance, which is filled with lubricant formed of either gallium or gallium alloy. The shaft member has on its outer peripheral surface a plurality of grooves for generating dynamic pressure. A body of each of the cylinder member and the shaft member is formed of ceramic which has corrosion resistance against gallium and gallium alloy of the lubricant. The grooves for generating dynamic pressure can be easily worked on the body of the shaft member because it is formed of ceramic having a good workability. Glass, tantalum or tantalum alloy can be used instead of ceramic.

Abstract: Of the components of an anti-friction bearing, the metallic components to be subjected to rolling friction or sliding friction, such as rolling elements, are coated with a multiplicity of metal layers by ion plating. The uppermost layer is made of soft metal with lubricating property. The solid solubility of the metal of each intermediate layer in each adjacent metal is higher than the solid solubility of the soft metal in the metal material of the component.