Surface machining of fine-grain Y-TZP

The effects of diamond wheel grinding on dense (99.7% theoretical density), fine grain (0.38 μm) 3Y-TZP were investigated under various grinding conditions and after annealing temperatures at 1100 to 1300°C for the surface refinement. Scratching test was also used to simulate the interactions of the diamond grit with the TZP. The scratching tracks on the ground surface and the resulted cracks in the subsurface were observed by scanning and transmission electron microscopy (SEM and TEM). The results illustrated the features of plastic deformation, radial crack, median crack, and processing zone. The surfaces were also examined by X-ray diffraction (XRD) which indicated the formation of monoclinic phase, rhombohedral phase (r-phase), and ferroelastic domain switching (FDS). The heat treatment contributed the refinement of surface grains resulted in a reduction of average size from 0.38 to 0.15 μm. Microstructural observation, grinding force measurement, and flexural strength measurement indicate that appropriate grinding parameters are capable of preventing the formation of large defects and retaining the mechanical properties of TZP.