Micro-amplitude vibration-assisted scratching: a new method for one step and controllable fabrication of the microscale V-groove and nanoscale ripples

Micro/nano hierarchical structures could endow materials with various surface functions. However, the multilayer and multiscale characteristics of micro/nano hierarchical structures bring difficulties for their one step and controllable fabrication. Accordingly, based on tip-based fabrication techniques, this study proposed a micro-amplitude vibration-assisted scratching method by introducing a periodic backward displacement into the conventional scratching process, which enabled the synchronous creation of the microscale V-groove and nanoscale ripples, i.e. a typical micro/nano hierarchical structure. The experiments and finite element modeling were employed to explore the formation process and mechanism of the micro/nano hierarchical structures. Being different from conventional cutting, this method was mainly based on the plow mechanism, and it could accurately replicate the shape of the indenter on the material surface. The microscale V-groove was formed due to the scratching action, and the nanoscale ripple was formed due to the extrusion action of the indenter on the microscale V-groove's surface. Furthermore, the relationships between the processing parameters and the dimensions of the micro/nano hierarchical structures were established through experiments, and optimized processing parameters were determined to achieve regular micro/nano hierarchical structures. By this method, complex patterns constructed by various micro/nano hierarchical structures were fabricated on both flat and curved surfaces, achieving diverse surface structural colors.