Fig. 5: Wear characterization of the graphite flake on the nanostructured surface under edge loading.

a Measured friction force during 3072 continuous sliding cycles with a displacement amplitude of \(1\,{{{{{\rm{\mu }}}}}}{{{{{\rm{m}}}}}}\) and speed of \(2\,{{{{{\rm{\mu }}}}}}{{{{{\rm{m}}}}}}/{{{{{\rm{s}}}}}}\) under a normal force of \(21.98\,{{{{{\rm{\mu }}}}}}{{{{{\rm{N}}}}}}\). b and c are the topography of the nanostructured surface before and after 3072 sliding cycles, respectively, where the newly appearing highlighted region is the wear debris, and the yellow dashed frame is the boundary of the sliding region. d–h The Raman characterization results of the sliding region on nanostructured silicon, where d is the optical observation, the red frame is the scan area of \(6\,{{{{{\rm{\mu }}}}}}{{{{{\rm{m}}}}}}\times 6\,{{{{{\rm{\mu }}}}}}{{{{{\rm{m}}}}}}\) (including the whole sliding region), e–g are the intensity distributions of D peak (1350 \({{{{{\rm{c}}}}}}{{{{{{\rm{m}}}}}}}^{-1}\)), G peak (1580 \({{{{{\rm{c}}}}}}{{{{{{\rm{m}}}}}}}^{-1}\)) and 2D peak (2700 \({{{{{\rm{c}}}}}}{{{{{{\rm{m}}}}}}}^{-1}\)), respectively, it can be seen that there is large intensity at the ___location of the wear debris in three images. h Single-point Raman spectrum at the wear debris position (blue cross mark in d), there are significant D, G and 2D graphite peaks. i Raman characterization of the graphite flake bottom surface at edge positions on the side close to the loading position after 3072 sliding cycles; points 1–3 represent the test positions, where significant D peaks appear. Source data are provided as a Source Data file.