Insulated bearing and bearing coating method

Abstract

An insulated bearing includes an outer ring, an inner ring, and a plurality of rolling elements. At least one of the outer ring and an inner ring is made of metal, the plurality of rolling elements are provided between the outer ring and the inner ring, so as to be freely rolled, and at least one of the outer ring and an inner ring is coated with an insulating layer. The insulating layer is formed of a mixture in which silicon carbide and/or aluminum nitride as an additive are/is dispersed in aluminum oxide as a base matrix. The content of the additive is 1 to 40 mass % with respect to the total amount of the mixture.

1 . A coating method for a bearing in which at least one of an outer ring and an inner ring which are concentrically disposed is made of metal and is coated with an insulating layer, the method comprising:
 performing thermal spraying by using a spraying material mixture powder obtained by adding silicon carbide powder having an average particle diameter of 2 μm or more and less than 10 μm and/or aluminum nitride powder having an average particle diameter of 2 μm or more and less than 10 μm to aluminum oxide powder having an average particle diameter of 1 μm or more and less than 30 μm, so as to be a total content of 2 to 40 mass % to form the insulating layer on the outer ring and/or the inner ring.   
     
     
         2 . The coating method for a bearing according to  claim 1 ,
 wherein the thermal spraying is performed in a manner of plasma spraying.   
     
     
         3 . The coating method for a bearing according to  claim 1 ,
 wherein the spraying material mixture powder is obtained by adding silicon carbide powder having an average particle diameter of 2 μm or more and less than 5 μm and/or aluminum nitride powder having an average particle diameter of 2 μm or more and less than 5 μm to aluminum oxide powder having an average particle diameter of 15 μm or more and less than 25 μm, so as to be a total content of 2 to 20 mass %.   
     
     
         4 . The coating method for a bearing according to  claim 1 ,
 wherein the spraying material mixture powder is obtained by adding silicon carbide powder having an average particle diameter of 2 μm or more and less than 5 μm and/or aluminum nitride powder having an average particle diameter of 2 μm or more and less than 5 μm to aluminum oxide powder having an average particle diameter of 1 μm or more and less than 5 μm so as to be a total content of 2 to 20 mass %, and the spraying material mixture powder is granulated by a spray dryer   
     
     
         5 . The coating method for a bearing according to  claim 1 ,
 wherein a coating thickness of the insulating layer is set to be 50 μm to 250 μm.