Scanning tunneling microscopy study of wear induced by false brinelling on rolling bearings

The first step of the false brinelling process on rolling bearings was studied by scanning tunneling microscopy. It is demonstrated that from the beginning of fretting, the surface of the ball/raceway contact, is modified on the nanometrical scale even if using a lubricant protection. The main manifestation of wear is a progressive polishing of the surface. It is shown that during fretting, two phenomena could accelerate the wear process: an oxidation of the surface from the first minutes and a microstructural transformation after several hours. This last modification is attributed to the presence of a tribologically transformed surface as those encountered in classical fretting conditions. These two damaging processes could be considerably reduced by the use of a well-adherent lubricant.