Fabrication of silicon carbide microchannels by thin diamond wheel grinding

Silicon carbide (SiC) microchannels are attractive for their wide applications in microsensors, MOS devices, UV photodiodes, microcatalytic reactors, and microchannel heat exchangers in harsh environments. However, the machining of SiC microchannels poses many challenges because of the difficulty and cost involved in the material removal process due to the high hardness and brittleness of SiC ceramic. In the present study, we developed a thin diamond wheel grinding process to fabricate SiC microchannels in a conventional vertical milling machine. Microchannels with trapezoidal shapes were successfully processed in SiC substrates by thin diamond wheels. The formation, geometric dimensions, and surface quality of SiC microchannels were studied together with the analysis of material removal mechanism. The effects of grinding processing parameters, i.e., wheel speed, feed speed, grinding depth, and grinding tool parameters including grit size and thickness of diamond grinding wheel, on the geometric dimension and surface morphology were comprehensively explored. The top width of microchannels first increased and then decreased with the increase in wheel speed, whereas a reverse tendency was observed with increasing grinding depth, feed speed, and grit size. The surface roughness decreased continuously with increasing wheel speed, but it tended to increase with the increase in feed speed generally. The variations in geometric dimensions and surface roughness of SiC microchannels can be related to the crack or fracture propagations and material removal mechanism during the thin diamond wheel grinding process. Besides, the influential significance of the above processing and grinding tool parameters were also evaluated by analysis of variance (ANOVA).