Tribochemistry of bearing steels: A new AFM method to study the material–tribofilm correlation

A new AFM method for relating microstructure to tribofilm formation is presented. Three aspects of this method distinguish it. Firstly, the new method maps the same region employing atomic force microscopy (AFM) in three sequential steps: preEDTA and postEDTA, before and after the tribofilm removal; and as-etched, after revealing the steel microstructure. Secondly, a new software was written for correcting the displacement between the sequential AFM topography images, and for analysing the data. Thirdly, the method allows to correlate the tribofilm with the steel microstructure, and relating it with protrusion of residual carbides and tribofilm roughness for regions as large as 50μm×50μm. This allows to performing statistical analyses to correlate tribofilm thickness with different microstructural constituents. ▪ •New technique to observe tribofilms and relate it to microstructure.•Sequential imaging of a worn region with atomic force microscopy.•Chemical treatments used to remove the tribofilm and reveal microstructure.•Advanced data treatment to extract tribofilm and microstructure information.