Research on the Mechanical Properties of CaF_2 Crystal for Ultra-Precision Machining

摘要

Indentations on the main crystallographic plane (111) of CaF_2 were analyzed. Appropriate material parameters were obtained by experiments. The process of CaF_2 indentations had been investigated by the finite element approach in order to obtain the initial shear yield strength. The results show a value of 110 MPa for the initial shear yield strength. Vickers hardness of plane (111) was also investigated. The results show the dependence on the orientation of the CaF_2 crystal. The hardness is small at the angular direction 0° and 120°, and at the angular direction 60°, the hardness of the largest value is 1.67GPa. The Young's Modulus and Fracture Toughness are also obtained. These properties are valuable to the ultra-precise machining of CaF_2 crystal.