Research on Fractal Characterization in Grinding of Monocrystal Sapphire

Abstract

Monocrystal sapphire ground surfaces obtained by ductile mode and brittle mode are analyzed in this paper. A two dimension (2D) fractal properties of different ground surfaces are calculated and analyzed by a box-counting fractal method. The results show that the fractal dimension (FD) in parallel grinding direction can imply the material removal mode, especially for the surfaces with a similar roughness Ra obtained in different material removal modes. The ground surface obtained in ductile mode has much higher FD in the parallel direction than that in brittle mode. For the surface with high FD in parallel direction, its profile is more exquisite and surface quality is better. For the surface with a small FD in the parallel direction, a deeper crack and more pronounced defects occur. On the other hand, the profile FD distributions can reflect the anisotropic features of monocrystal sapphire ground surfaces. Therefore, the fractal analysis method has the potential to reveal precisely and comprehensively the ground surface characteristics of monocrystal sapphire.