Mechanism of polishing lutetium oxide single crystals with polyhedral diamond abrasive grains based on molecular dynamics simulation

Abstract

Lutetium oxide single crystal is an excellent laser crystal material with the advantages of low phonon energy, high thermal conductivity, and high laser-induced damage threshold. Polishing is an important method to achieve ultrasmooth, damage-free surfaces of lutetium oxide wafers. The diamond abrasive grains used in mechanical polishing are mainly in the form of blocks, flakes, and balls. In this study, the molecular dynamics simulation method is used to simulate the process of polishing a lutetium oxide single crystal with different shapes of polyhedral diamond abrasive grains, and the polishing force, subsurface damage, and material removal are analyzed. Results show that the compressive stress and thickness of the machined amorphous layer in the subsurface are minimum at the vertex contact position and maximum at the face contact position. The values at the sphere and edge contact positions are somewhere in between. In terms of material removal, polyhedral and spherical abrasive grains have a plowing effect on the material removal process. However, the vertices and edges of polyhedral abrasive grains can be more easily cut into the workpiece than spherical abrasive grains, so polyhedral abrasive grains are conducive to the removal of materials in specific cases.