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 fro m the beginning of fretting, the surface of the ball/raceway contact, is modified on the nanometrical scale even if using a lubricant protec tion. The main manifestation of wear is a progressive polishing of the surface. It is shown that during fretting, two phenomena could accele rate the wear process: an oxidation of the surface from the first minu tes and a microstructural transformation after several hours. This las t modification is attributed to the presence of a tribologically trans formed surface as those encountered in classical fretting conditions. These two damaging processes could be considerably reduced by the use of a well-adherent lubricant.