A plain shaft bearing, in particular of a shaft of a wind turbine gearbox, includes a sliding surface having a surface roughness. The sliding surface is further provided with a structure formed from depressions defined by a depth which is greater than the surface roughness and less than 80 μm.

A bearing steel part having a predetermined chemical composition, in which the number density of oxide particles having an equivalent circle diameter of 5 μm or more, and containing CaO, Al.sub.2O.sub.3 and SiO.sub.2, such that the content ratio of Al.sub.2O.sub.3 with respect to the total mass of CaO, Al.sub.2O.sub.3, and SiO.sub.2 is 50% by mass or more, is 3.0/cm.sup.2 or less in an arbitrary cross section of the part, and in which the Vickers hardness at a depth of 50 μm from a rolling surface is 750 or more, and in which the compressive residual stress at the rolling surface is 900 MPa or more. Also provided is a steel bar for a bearing steel part that is suitable for obtaining the foregoing bearing steel part.

A rolling bearing includes an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring. The inner ring and the outer ring are made of stainless steel. A raceway surface with which the ball is in rolling-contact in each of the inner ring and the outer ring and is a superfinished surface and a coating layer made of a solid lubricating film is formed on the superfinished surface.

An apparatus is provided that includes a diamond bearing surface positioned in sliding engagement with an opposing bearing surface of a diamond reactive material. The opposing bearing surface is hardened via a material treatment.

A rolling bearing includes an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring. The inner ring and the outer ring are made of stainless steel. A raceway surface with which the ball is in rolling-contact in each of the inner ring and the outer ring and is a superfinished surface and a coating layer made of a solid lubricating film is formed on the superfinished surface.

A rolling component has a surface. The rolling component includes a fiber flow and a non-metallic inclusion. In a region from the surface of the rolling component to a first depth, a gap between the non-metallic inclusion and a member forming the rolling component is filled. The first depth is 50 m or more. The surface and the fiber flow form an angle of 15 or more.

A bearing steel part having a predetermined chemical composition, in which the number density of oxide particles having an equivalent circle diameter of 5 m or more, and containing CaO, Al.sub.2O.sub.3 and SiO.sub.2, such that the content ratio of Al.sub.2O.sub.3 with respect to the total mass of CaO, Al.sub.2O.sub.3, and SiO.sub.2 is 50% by mass or more, is 3.0/cm.sup.2 or less in an arbitrary cross section of the part, and in which the Vickers hardness at a depth of 50 m from a rolling surface is 750 or more, and in which the compressive residual stress at the rolling surface is 900 MPa or more. Also provided is a steel bar for a bearing steel part that is suitable for obtaining the foregoing bearing steel part.

A rolling bearing includes an inner ring, an outer ring, and rolling elements interposed between the inner ring and the outer ring. A surface layer portion, beneath a raceway surface (10a), of a base material of a raceway ring (10) which is the inner ring or the outer ring, is a wear-resistant layer (13) which has a higher hardness than a residual portion (12), beneath the surface layer portion, of the base material, and includes a minute-recess-and-projection surface. An oxide film (14) is provided which has such a film thickness (t) as to fill recesses of the minute-recess-and-projection surface of the wear-resistant layer (13), and includes recesses and projections existing along the minute-recess-and-projection surface, and the oxide film (14) coats the surface of the wear-resistant layer (13). The oxide film (14) is made from a material more fragile than the wear-resistant layer (13) of the base material.

There are provided a sealing device and a hub bearing that can reduce torque. Pear-skin-like projections and depressions are provided on each of a sliding surface in a lip for foreign object (a side lip 121a and a middle lip 121b) and a sliding surface in a lip for grease 122. Roughness of the pear-skin-like projections and depressions provided on the sliding surface of the lip for grease 122 is larger than roughness of the pear-skin-like projections and depressions provided on the sliding surface of the lip for foreign object.

There is prepared a formed body constituted of steel and having an outer circumferential surface having an annular groove having a bottom surface to serve as a raceway surface of the bearing ring. In the step of forming a heated region, the formed body is induction heated to form a heated region including the bottom surface of the groove and heated to a temperature of at least an A.sub.1 point. In the cooling step, the whole of the heated region is simultaneously cooled to a temperature of not more than an M.sub.s point. The step of retaining the formed body in a state in which heating is stopped is performed after the step of forming a heated region before the step of cooling. In the step of retaining, dispersion in temperature in the heated region in the circumferential direction is suppressed to not more than 20 C.