Characterization of Zirconia-Based Ceramics After Microgrinding

Despite the recent developments of ductile mode machining, microgrinding of bioceramics can cause an insufficient surface and subsurface integrity due to the inherent hardness and brittleness of such materials. This work aims to determine the influence of a two-step grinding operation on zirconia-based ceramics. In this regard, zirconia (ZrO₂) and zirconia toughened alumina (ZTA) specimens are ground with ultrasonic vibration assistance within a variation of the machining parameters using two grinding steps and different diamond grain sizes of the tools in each of the machining procedure. White light interferometry, scanning electron microscope, X-ray diffraction (XRD), and four-point bending tests are performed to evaluate surface roughness, microstructure, residual stresses, and flexural strength, respectively. The strategy applied suggests that the finished parts are suitable for certain biomedical uses like dental implants due to their optimum surface roughness. Moreover, concerning the mechanical properties, an increase of the flexural strength and compressive residual stresses of ground ZrO₂ and ZTA workpieces were observed in comparison to the as-received specimens. These results, as well as the methodology proposed to investigate the surface integrity of the ground workpieces, are helpful to understand the bioceramic materials response under microgrinding conditions and to set further machining investigations.