Single point diamond turning effects on surface quality and subsurface damage in ceramics

Advanced ceramics, such as Silicon Carbide (SiC) and Quartz, are increasingly being used for industrial applications. These ceramics are hard, strong, inert, and light weight. This combination of properties makes them ideal candidates for tribological, semiconductor, MEMS and optoelectronic applications respectively. Manufacturing these materials without causing surface and subsurface damage is extremely challenging due to their high hardness, brittle characteristics and poor machinability. Often times, severe fracture can result when trying to achieve high material removal rates during machining of SiC or quartz due to their low fracture toughness. This research demonstrates that ductile regime Single Point Diamond Turning (SPDT) is possible on these materials to improve its surface quality without imparting subsurface damage. Machining parameters, such as depth of cut and feed, used to carry out ductile regime machining will be discussed. Subsurface damage analysis was carried out on the machined samples using non-destructive methods such as Optical Microscopy, Raman Spectroscopy and Scanning Acoustic Microscopy to show evidence that the chosen material removal method leaves a damage-free surface and subsurface. Optical microscopy was used to image the improvements in surface finish whereas Raman spectroscopy and scanning acoustic microscopy was used to observe the formation of amorphous layer and subsurface imaging in the machined regions. All three techniques complement the initial hypothesis of being able to remove a nominally brittle material in the ductile regime.