Study on Impulse-discharge Driven Abrasive Flow Assisted Grinding of Monocrystalline SiC
The surface quality of monocrystalline SiC,as a semiconductor material,influences its electrical,magnetic,and optical performance.However,during mechanical processing,the cutting depth and the mechanical runout lead to unstable cutting force,resulting in surface micro-burr,modified layer,subsurface residual stress and damage.Thus,an impulse-discharge between wheel metal and SiC is proposed in diamond grinding to drive a loose-abrasive flow.It aims to investigate the mechanism by which the hybrid effects of mechanical processing,abrasive flow polishing,and thermochemical removal influence surface integrity.The surface formation is first modelled in relation to impulse discharge energy and hydrodynamic pressure.Then,the material removal rate and abrasive wear rate are investigated.Finally,the surface integrity is investigated.It is shown that the hybrid machined formation chain was formed in the abrasive-workpiece interface.The impulse-discharge drove the loose-abrasive and modified the interface by thermochemical modification.The loose-abrasive obtained a removal force to eliminate the modified SiO2 and expose the SiC substrate.Decreasing the impulse-discharge energy and hydrodynamic pressure promoted brittle removal to ductile removal.Under the mechanical vibrations generated by large cutting depths and spindle runout,the hybrid machining of impulse-discharge driven thermochemical modification and loose-abrasive polishing,in conjunction with diamond grinding,could effectively reduce residual compressive stress,surface micro-burrs,and subsurface damage layer thickness by 93％,73％,and 50％,respectively.
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