Study on the grinding characteristics of sapphire with the assistant of cerium oxide liquid

Due to its high hardness and brittleness, sapphire is difficult to obtain a low grinding roughness. In this paper, the cerium oxide liquid is used to assist the grinding of sapphire with a diamond wheel with relatively big-size grains to obtain a low roughness. The effects of grain size, the crystal orientation of the sapphire, and the pH values of the cerium oxide liquid on the assisted grinding process have been analyzed. It is shown that with the proposed method, the roughness of 45 nm and subsurface damage of 141 nm are obtained, respectively. Compared with the grinding surfaces obtained without the assistant, the roughnesses and the subsurface damage of the assisted grinding surfaces are reduced by 60.8% and 84.5% when #600 wheel is used, respectively. Moreover, in the grinding experiments, the crystal orientation of the sapphire and the pH values of the cerium oxide liquid have little effect on the roughness of the grinding surface, while the grain size has a great impact. It is concluded that the improvement of the surface roughness by using the proposed method benefits from the combined action of the grinding of grains and the polishing of the cerium oxide liquid.