A study of nanoscratch experiments of the silicon and borosilicate in air

The purpose of this study is to investigate the nanometer-scale elastoplastic deformation behaviors of hard-brittle materials (silicon and borosilicate) considering the mechanochemical reaction that is generated due to the friction between a diamond tip and a materialʹs surface. At first, the effect of nanoscratch experimental parameters (normal load and tip radius) on the deformation behaviors of hard-brittle materials, such as pile-up (or sink-in), elastic recovery, and residual stress field, were studied with the finite element method. For simulations, amorphous silicon and borosilicate were used as specimens to exclude some other factors such as crystal orientation and crystal structure. For a given applied normal load, elastic recovery increased with the tip radius due to the increase of the elastic contact area. The amorphous silicon showed a lower elastic recovery than the borosilicate due to the larger value of the elastic modulus compared with that of the plastic strength (E/Y). Successively, the deformation behaviors of silicon(1 0 0) and borosilicate considering the mechanochemical reaction to diamond tip sliding were investigated through nanoscratch experiments in air. The elasoplastic deformation behavior of silicon(1 0 0) was characterized by protuberance phenomena and compared with that of the borosilicate (Pyrex 7740 glass). It was also considered how the increase of the normal load impacts both on the surface protuberance of the silicon and the interpretation of scratch test results.