**Silicon surface characteristics in vibration-assisted machining process
via molecular dynamics**

V Nguyen and VTT Nhu and XT Vo, COMPUTATIONAL MATERIALS SCIENCE, 228, 112353 (2023).

DOI: 10.1016/j.commatsci.2023.112353

This study investigates the impacts of vibration amplitude, vibration frequency, and sliding velocity on the characteristics of the machined silicon substrate. The results show that increasing the vibration amplitude increases atomic strain, stress, and kinetic energy distributions while decreasing subsurface damage thickness, potential energy distribution, and especially surface roughness. The surface roughness values are 7.5 & ANGS;, 6.4 & ANGS;, 6.9 & ANGS;, and 6.0 & ANGS; corresponding to vibration amplitude of 15 & ANGS;, 20 & ANGS;, 25 & ANGS;, and 30 & ANGS;. Moreover, increasing the vibration frequency results in increased atomic strain, stress, and kinetic energy levels. The surface roughness values are 7.1 & ANGS;, 7.1 & ANGS;, 6.5 & ANGS;, 6.4 & ANGS;, and 6.0 & ANGS; corresponding to the vibration frequencies of 16.7 GHz, 33.3 GHz, 50 GHz, 66.7 GHz, 100 GHz, and 200 GHz. Furthermore, increasing the sliding velocity lowers the surface quality of the silicon sample. The surface roughness values of the silicon substrate are 6.5 & ANGS;, 6.7 & ANGS;, 6.9 & ANGS;, 6.9 & ANGS;, and 7.1 & ANGS; corresponding to 50 m/s, 100 m/s, 150 m/s, 200 m/s, and 250 m/s. Improving the vibration amplitude and frequency while decreasing the sliding velocity improves surface quality by increasing the collision between the diamond tips and the substrate. Remarkably, the vibration movement of the diamond tips could leave wave marks on the substrate surface. In general, the optimal parameters that generate a good surface are 30 & ANGS;, 200 GHz, and 50 m/s.

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