Instantaneous monitoring of wear on a micro-nanometer scale through hard coatings by synchroton radiation

We have shown that wear dynamics can be monitored on a lateral micrometer scale by synchrotron radiation. We have followed the wear from the change in transmission on a system of three layers of hard coatings, TiAlN, CrN and TiAlN, of approximately one micron thickness produced by sputtering deposition. These layers were deposited on a 1 mm-thick vitreous carbon sample. The instantaneous depth was determined from transmission as well as XANES (X-ray Absorption Near Edge Spectra) measurements of the K-edge of Cr from the-CrN marker layer. The wear process is highly irregular and the local wear rate varies strongly from one position to another in the wear track. The ridges, grooves as well as the transport of debris from the track were for the first time followed on a micrometer level, confirming the stochastic nature of this type of wear. Most of the features are generated within the first 500 nm and exist over several micrometers. However, also a significant fraction of grooves and ridges disappear by wear over less than one micrometer.