High-quality grinding of polycrystalline silicon carbide spherical surfaces

The objective of this study was to develop high-quality grinding protocols for polycrystalline silicon carbide spherical surfaces in order to achieve nanometre surface roughness and submicron form accuracy. Plastic deformation and fracture damage associated with the material removal mechanisms were studied using nano-indentation and Vickers indentation. Spherical grinding was conducted with a CNC grinding machine using metal-bond diamond tools with grit sizes of 25 and 15 μm under the machining conditions selected. The ground spherical surfaces were examined using laser interferometry, WYKO optical interferometry, and scanning electron microscopy to measure form accuracy, surface roughness, and residual defects as a function of grinding conditions. Ground silicon carbide spherical surfaces with form accuracy peak-to-valley (PV) of 0.21–0.59 wave (0.13–0.37 μm) and surface roughness of 9.92–17.22 nm Ra were obtained. Low machining-induced damage was found on the ground silicon carbide where defects were mainly associated with microstructural defects such as pores. The topography of the diamond tools was examined using a scanning electron microscope (SEM) to evaluate the performance of diamond wheels in grinding. This work provides technological insights into precision engineering for rapid manufacturing of ceramic components without the need or with less need for subsequent lapping and polishing.