Surface and subsurface characterisation of bioceramic workpieces machined by micro grinding
In the past few decades, ceramics have been used in biomedical engineering applications due to their biocompatibility, low plaque affinity and particular mechanical properties like high flexural strength. Micro grinding of bioceramics can cause a poor surface integrity including residual stresses, microcracks and insufficient surface topography due to the inherent hardness and brittleness of such materials. This work aims to determine the influence of various process parameters on material properties, viz. roughness, bending strength and residual stresses. Zirconia (ZrO2) and zirconia toughened alumina (ZTA) materials are selected as typical bioceramics under test. In this regard, ceramic specimens are ground with ultrasonic vibration assistance concerning different diamond grain sizes (dg) and a variation of the machining parameters feed speed (vf) and depth of cut (ae) Roughness is measured by white light interferometry, flexural strength is evaluated by 4 point bending tests and residual stresses are characterised through X Ray Diffraction (XRD) Based on these results, it is possible to establish a relationship between the micro grinding process and material behaviour allowing to understand the mechanisms influencing ceramic materials due to the machining process. Moreover, the improvement of the workpiece integrity through the optimisation of the process parameters is enabled. Micro grinding, bioceramic, material integrity.