Mapping nanoscale wear field by combined atomic force microscopy and digital image correlation techniques

Surface wear of coatings occurring at extremely low loads and in nanocontacts is of great importance for the development and the reliability of structural/functional nanocomponents in micro/nanoelectromechanical systems. To date, appropriate tools for mapping the nanoscale wear of thin coatings are still lacking. In this study, a new method combining atomic force microscopy (AFM) and digital image correlation (DIC) techniques has been developed and applied for the determination and visualization of the nanoscale wear of a gold coating. It has been shown that the initiation and development of nanowear, which is usually difficult to detect directly from AFM topographical images, can be efficiently revealed by monitoring the correlation coefficient change in DIC analysis. A linear relation between the correlation coefficient and the wear depth is found and may be used to quantify the nanowear. The nanowear of gold coating is dominated by material removal without any plastic deformation.