Model of pore healing in the process of producing optical ceramics

A model of the formation and motion of twin boundaries, which created pore healing in the process of producing optical ceramics, was presented. The structural and deformation properties of the vacuum sintering and nanotechnology (VSN) ceramics were observed by using scanning electron microscopy and atomic force microscopy. The microhardness of the ceramics was found to be 15-35% higher than the value for single crystals and the fracture toughness was estimated to be 2.5-4.5 times larger than that for single crystal. The deformation structure and morphology of the ceramics projected that the layered structure of the grains and streakiness were formed due to the twining processes on the plane, which lessened stresses in the process of growing grains and practiced plastic deformation in the process of compacting the ceramic. The twining process formed the chief mechanism of plastic deformation in the the formation of VSN ceramics.