Corona discharge assisted shear thickening polishing: non-Newtonian elastohydrodynamics and electrostatics

The corona discharge, which is a kind of gas discharge technique producing electrostatic charges, is commonly applied in industrial fields such as precipitation, spray, and droplet manipulation. In this paper, a novel finishing method for cylindrical workpieces is proposed based on the combination of the centerless shear thickening polishing and the corona discharge. According to analytical computation and experimental verification upon the non-Newtonian elastohydrodynamics and the electrostatics, this method exhibited two distinguishing features: first, the slurry film was generated as a "flexible abrasives tool" under the non-Newtonian elastohydrodynamic pressure, benefiting the improvement of surface quality owing to the ductile removal; second, the abrasives slurry was charged by the corona discharge, contributing to the reduction of surface roughness deviation attributed to the charges repulsion leading to the inhibition of abrasives or particles agglomeration. The experiments of polishing Si3N4 ceramic bearing rollers on the self-made machine demonstrate that the good surface of the workpiece with a roughness of Sa 25.75 nm and few cracks was finally achieved from the initial Sa 123.70 nm.