Quantitative analysis of nano-wear on DLC coatings by AFM

Quantitative analysis of surface modifications due to wear tests of a diamond-like carbon (DLC)-coated cylindrical steel test sample was carried out by atomic force microscopy and confocal microscopy. In order to get a reliable metrics for the quantitative assessment of surface modifications due to nano-wear, different surface texture parameters like arithmetic average roughness Sa, surface kurtosis Sku, surface skewness Ssk, and core roughness depth Sk were analysed. The results show that, after application of a Gaussian filter to reduce the influence of the underlying longer-range surface topography variations, the surface skewness parameter Ssk was the most sensitive and reliable parameter to indicate the very small wear modifications of the DLC-coated surface. Further studies were carried out to investigate the influence of pixel sampling distance, scanning area and scanning tip dimensions.