Investigation of cutting depth and contact area in nanoindenter scratching

Abstract

Nanostructures are widely used in various industries. Nanoscratching is an important technique for fabricating nanostructures. The cutting depth in nanoscratching is a crucial parameter that is closely related to the normal force, material properties, and tip geometry. Current prediction models are only suitable for some specific processing conditions. To extend the scope of application of prediction model, a comprehensive model is proposed. In the developed model, the indenter tip is divided into three parts: a spherical crown, transition part, and pyramid base. Accordingly, a comprehensive contact model considering elastic recovery is developed in the edge-forward, face-forward and side-forward directions based on the indenter tip geometry. The computational results indicate that face-forward nanoscratching with a conventional cube-corner indenter has the smallest contact area compared to edge-forward and side-forward nanoscratching. It is noted that the established model can reduce the prediction error by more than 10% compared with the current models when the cutting depth is lower than the tip radius. The influence of the indenter geometry is analysed based on this model. The geometric shape of the indenter has a significant influence on the contact area, and the face angle of the pyramid is the key factor. The proposed model is validated by numerous nanoscratching experiments.