Modelling of unlubricated oscillating sliding wear of DLC-coatings considering surface topography, oxidation and graphitisation

The improvement of high-performance anti-wear diamond-like carbon-coatings (DLC-coatings) for industrial applications is usually supported by using an oscillating sliding model test. A ball-on-disc setup allows the simulation of accelerated conditions in an unlubricated contact at increased contact pressure. Although the wear behaviour of DLC-coatings has been frequently investigated in literature, wear models for the prediction of the coating's lifetime and for the quantification of wear in the steel counterpart are missing. In this study a unified wear model has been developed based on the dissipated energy approach. This novel model includes evolution equations for the quantitative description of the surface topography of the coated sample, the oxidation of the 100Cr6 steel counterpart as well as the characteristic graphitisation of the DLC-coating. It has been implemented in the Global Incremental Wear Model (GIWM), which accounts for the geometry change during wear and allows a fast wear calculation and model development by simulating all important quantities of the model tests. This GIWM has been validated with experimental results and its predictive capabilities have been demonstrated for different types of DLC-coatings.