Patent ID: 8425120

Claim:
An electrolytic erosion-preventing insulated rolling bearing, comprising: a pair of metal bearing rings which are placed concentrically with each other; a pair of raceway surfaces formed on facing surfaces of the two bearing rings; and a plurality of metal rolling elements provided between the raceway surfaces such that the metal rolling elements can roll freely, wherein at least one of the bearing rings includes a ceramic insulating coating formed on surfaces other than the surface on which the raceway surface is provided, the ceramic forming the insulating coating comprises 99 wt. % or more alumina, the insulating coating being formed by grinding a surface of a ceramic sprayed layer that is formed on the surfaces other than those on which the raceway surface is provided, the alumina containing 0.01 to 0.2 wt. % titanium oxide, and the alumina having a particle size ranging from 10 to 50 μm and an average particle size ranging from 15 to 25 μm, the thickness of the ceramic sprayed layer is 0.4 mm or less except on continuous folded over portions between adjacent surfaces, and the thickness of the insulating coating obtained by grinding the ceramic sprayed layer is 0.25 mm or more.